Cambridge, England, September 4 / PRNewswire-FirstCall / - the industry's leading factories, ship design and engineering lifecycle solutions provider AVEVA (LSE: AVV design) today announced the launch of AVEVAPDMS12. AVEVAPDMS12 are the work of its leading design company plant the latest generation of design tools. This version fully supports the Microsoft.NET with CIS Design households graphic design interface, and highly interactive 3D image editing features, making it the packaging design easier user to grasp more quickly be able to use, but also higher labor productivity . 设计. Aveva CEO RichardLo design don said: "PDMS has been recognized as the market's most powerful plant design system. With aveva reliable, brand design is based on the objectives of global unique design technology, our customers in the implementation of a global review of miscellaneous project web page design will have unmatched flexibility. "This is the design of a version of PDMS12 design companies put the technology platform for Health termites improve productivity to a new level. PDMS12 for clients achieve significant innovations, including the output from a single designer to improve by disinsected in data management and control and achieve significant improvements in the overall project more savings. PDMS12 keyword new features include: - for the design of equipment, piping layout, pipe, structural steel and supports the advanced design features a wide range of applications broach enhancement; - permit to conduct parameter design and implementation review Miscellaneous access configured to move to amend the new easy access ping shbjgs Units, stairs and ladders application software; - can reduce the creation, modify the directory and norms required by the technology and the efforts of the new directory with the standard management application software;
- Be able to make ropes and cableway in the PDMS model for layout design of the new ropes Products; - can in a factory model of the relationship between the definition of the key and can continuously monitor the process of designing a new target of these relations association function; -- As a standard rule-based automatic pipe layout and quality inspection function; - be able to let the language compatible with Microsoft.NET application of PDMS configured with custom extension functions;
- New P & ID (piping and equipment schematics) integration method; by a number of creative tools for creating P & ID can into one can AVEVAPDMS12 environment management model in the diagram. With the new AVEVA P & IDManager and AVEVAP & IDIntegrator products, this model diagram can be used to set up and compare 3D plant model. New AVEVAP & IDManager and AVEVAP & IDIntegrator aveva Products are as open P & ID part of the strategy introduced. Aveva continuous upgrading of the principle means that the original PDMS customers can easily upgrade
Tuesday, February 24, 2009
PDMS 12
AVEVA PDMS 12.0
Aveva Group sells and supports its engineering software to plant and marine industries around the globe. Aveva Plant is engineering software used to design, build and operate plants of any size and complexity, the vendor said. Meanwhile, Aveva's PDMS, or plant design management system, is engineering software that uses rule-based functions to verify material information and, in turn, cut down on errors and delays.
Aveva PDMS
Aveva also offers Aveva PDMS 12 as a complement to Aveva Plant. (PDMS stands for plant design management system.) The software has a Microsoft Office-like interface and uses rule-based functions and checking tools to eliminate design errors, thus removing on-site delays due to inaccurate materials information, the vendor said. Moreover, designers can view an entire design at all times and create design databases by adding instances of parametric components from an existing catalog.
Using configurable PDMS applications, designers and managers can produce an array of reports and drawings, and hundreds of users can simultaneously work on a project. Standards-based P&ID integration eliminates errors that can result from the use of multiple authoring systems, while automatic change highlighting and tracking helps identify who has changed what in a design, Aveva said. Finally, since Aveva PDMS features a Programmable Macro Language, users can customize and automate the application as needed.
The process and power industries need powerful design applications that can be used effectively across globally distributed project teams. AVEVA PDMS delivers this proven capability, for the smallest refit or the largest green field project.
AVEVA PDMS 12 is a major new release of this world-leading product. Its upgraded technology and data structures provide a strong, extensible platform for its enhanced applications, increasing productivity, providing simple upgrade paths and making PDMS even easier to adopt.
Key Features
* Fully interactive, easy-to-use 3D design environment, with a Microsoft Office-style user interface based on .NET technology.
* Open P&ID approach consolidates P&IDs from multiple authoring systems into the PDMS database.
* Individual designers can see the entire design
at all times.
* Designers progressively construct a highly intelligent design database by placing instances of parametric components from a catalogue.
* Clash checking and configurable integrity checking rules identify errors and inconsistencies across the design.
* A wide range of reports and drawings can be produced automatically from the design database using highly configurable PDMS applications.
* Hundreds of users can work together in a fully controlled manner.
* Conventional issue and change control processes can all be applied efficiently.
* AVEVA PDMS is highly configurable and includes a powerful programmable macro language (PML) to customise the system and automate key tasks.
Aveva Group sells and supports its engineering software to plant and marine industries around the globe. Aveva Plant is engineering software used to design, build and operate plants of any size and complexity, the vendor said. Meanwhile, Aveva's PDMS, or plant design management system, is engineering software that uses rule-based functions to verify material information and, in turn, cut down on errors and delays.
Aveva PDMS
Aveva also offers Aveva PDMS 12 as a complement to Aveva Plant. (PDMS stands for plant design management system.) The software has a Microsoft Office-like interface and uses rule-based functions and checking tools to eliminate design errors, thus removing on-site delays due to inaccurate materials information, the vendor said. Moreover, designers can view an entire design at all times and create design databases by adding instances of parametric components from an existing catalog.
Using configurable PDMS applications, designers and managers can produce an array of reports and drawings, and hundreds of users can simultaneously work on a project. Standards-based P&ID integration eliminates errors that can result from the use of multiple authoring systems, while automatic change highlighting and tracking helps identify who has changed what in a design, Aveva said. Finally, since Aveva PDMS features a Programmable Macro Language, users can customize and automate the application as needed.
The process and power industries need powerful design applications that can be used effectively across globally distributed project teams. AVEVA PDMS delivers this proven capability, for the smallest refit or the largest green field project.
AVEVA PDMS 12 is a major new release of this world-leading product. Its upgraded technology and data structures provide a strong, extensible platform for its enhanced applications, increasing productivity, providing simple upgrade paths and making PDMS even easier to adopt.
Key Features
* Fully interactive, easy-to-use 3D design environment, with a Microsoft Office-style user interface based on .NET technology.
* Open P&ID approach consolidates P&IDs from multiple authoring systems into the PDMS database.
* Individual designers can see the entire design
at all times.
* Designers progressively construct a highly intelligent design database by placing instances of parametric components from a catalogue.
* Clash checking and configurable integrity checking rules identify errors and inconsistencies across the design.
* A wide range of reports and drawings can be produced automatically from the design database using highly configurable PDMS applications.
* Hundreds of users can work together in a fully controlled manner.
* Conventional issue and change control processes can all be applied efficiently.
* AVEVA PDMS is highly configurable and includes a powerful programmable macro language (PML) to customise the system and automate key tasks.
Defining Offsite Facilities for Process Plants
B: Defining Offsite Facilities for Process Plants
Contributors (In alphabetical order):
Jadeep Coudhary, Anita R. Legvold, James O. Pennock
Introduction
Some have asked questions such as: "What is Balance of Plant?"; "What is Offsites?" What is OSBL?" and "What needs to be considered when a project includes Offsites."
The term Offsites is a general term and does not mean the same for every project or every plant. A project may include extensive tankage for feed storage along with tankage for in-process product, intermediate product, run-down tankage, slops and finished product tankage. Another project may include none of this because they already exist. The point here is just because you are told that the project includes "Offsites" you need to ask a lot of questions to determine exactly what they mean and what will be required.
The purpose of this document is to aid in answering this type of question. This document will not tell you how to design the Offsites or design any of the individual sub-items or equipment found on this list. That design guidance should properly be left up to you, your supervisors and your management. I do however intend to start a listing of major elements along with some minor key issues that should be considered.
I invite others to submit their own thoughts and comments to add to and improve this list.
Contents:
Section Subject
1 Definitions -- Offsite vs. Onsite
2 Codes, Standards, and Practices
3 Site Issues
4 Terrain, Grading, Roads, & Drainage
5 Tankage
6 Flares
7 Piperacks & Sleepers
8 Pipelines
9 Loading / Unloading Racks (Truck, Rail, Barge, and Ship)
10 Cooling Water Supply Systems
11 Hazardous Chemicals
12 Waste Treatment Facilities
13 Electrical
14 Buildings & Auxiliaries
15 Fire Protection & Safety
16 LPG Bottling Facilities
17 Solids Storage & Disposal
1, Definitions
Offsite -- In a process plant (Refinery, Chemical, Petrochemical, Power, etc.), any supporting facility that is not a direct part of the primary or secondary process reaction train or utility block. Offsites are also called OSBL.
Onsite - Any single or collection of inter-related and inter-connected process equipment that performs an integrated process function. Typically any Onsite Unit could be made to function independently of another Onsite Unit. Onsite Units are also called ISBL.
Utility Block - A single or multiple grouping of facilities that generate the support services required by the Onsite Process units to function. This normally includes: Steam Generation, Plant Air, Instrument Air, Decimalized Water, Plant Water, etc.
Balance of Plant - This is another term for Offsites and/or anything else other than the Onsite Units or the Utility Block.
Battery Limit -- Line used on a plot plan to determine the outside limit of a unit. The Battery Limit line is usually established early in the project and documented on all discipline documents such as Plot Plans, Site Plans, Drawing Indexes, etc... (1)
Property Line -- A Property Line is the recorded boundary of a plot of land. (2) Defines the separation between what is recognized legally as Owner's land and non-Owner's or other land.
On Property -- All land and or water inside the Property line shown on the property map or deed.
Off Property - Off property is any land (or water) outside of the Property line shown on the property map or deed.
Right of Way (ROW) -- Any land (On Property or Off Property) set aside and designated for a specific use or purpose. A Right-of-Way within a piece of property may also be designated for use by someone other than the property owner.
Setback or Setback Line -- A line established by law, deed restriction, or custom, fixing the minimum distance from the property line of the exterior face of buildings, walls and any other construction form; s street, road, or highway right-of-way line (3). Setback is a clear area normally at the boundary of a piece of property with conditions and restrictions for building or use.
Easements -- A vested or acquired right to use land other than as a tenant, for a specific purpose; such right being held by someone other than the owner who holds the title to the land (2). An easement is typically a strip of land within which overhead power lines or underground pipes are run.
(1) -- Lamit, Louis Gary, 1981 Prentice-Hall
(2) -- Construction Dictionary
2, Codes, Standards, & Practices
ANSI (American National Standards Institute)
API (American Petroleum Institute)
ASME (American Society of Mechanical Engineers)
ASTM - American Society of Testing Materials
AWS (American Welding Society)--
AWWA (American Water Works Association)
CFR (Code of Federal Regulations)
Division of Weights & Measures --
DOT (Department of Transportation)
FAR (Federal Accounting Regulations)
IRI (Insurance Regulators Institute)
Local Permits (Country, State, City, etc.)
MSS (Manufacturing Standards Society) --
NACE (National Association of Corrosion Engineers)--
NFPA (National Fire Protection Association)
OIA (Oil Insurers Association)
PFI (Pipe Fabrication Institute)
USCG (United States Coast Guard) Regulations
3, Site Issues
Brownfield (Revamp Existing)
Climate (Wind Rose)
Demolition
Feed stock type, source and method of delivery
Future growth
Grass Roots or Greenfield (New construction)
Impact across the fence
Power requirements and source
Products, Primary, Secondary and by-products
Seismic zone
SHE (Safety, Health and Environmental)
Utilities requirements
4, Terrain, Grading, Roads, Ditches & Drainage
Terrain
- Level vs. Sloping
Geotechnical influences
- Type of soil
- Angle of repose
- Grading
- Contours
- Grubbing (Tree and shrub removal)
- Rough Grading
- Finished Grading
Roads
- Primary
- Secondary
- Type and purpose of traffic
- Right hand or left hand drive
- Traffic pattern, potential for congestion
- Pipeway or Sleeper Crossings (Overhead Vs Ramp & Culvert)
Rail Spurs (see Loading and Unloading for additional criteria)
- Number
- Location
- Capacity (number of rail cars)
- Elevation
- Roadbed & Ballast Details
- Vertical and Horizontal Clearance requirements
- Standards and jurisdiction of Rail company (Right of Way)
Drainage systems
- Storm
- Oily Water
- Chemical
- Sanitary Sewage
- Contaminated
- Other
Ditches
- Depth
- Width
- Slope
Culverts
- Location, Size, Type
- Invert Elevation
Basins & Ponds
- In ground or On ground
- Lined vs. Unlined (or Rip Rap)
- Skimmers & Aerators
- Overflows & Runoff
- Fenced or Unfenced
- Access
Stiles, Stairs, Catwalks, and Platforms
- Existing or new
- Material if existing
- Material if new
- Location & Elevation
- Access
- Valve extension stem requirements
5, Tankage
Types & Purpose
- Atmospheric vs. Pressurized
- Cone Roof
- Floating Roof
- Bullets
- Spheres
- Spheroids
- Other (Used tank cars as storage)
Tank Construction
- Single Wall vs. Double Wall
- Metallic vs. nonmetallic
- Unlined vs. Lined
- Insulated, Jacketed, Heated, Cooled,
Commodity Grouping & Spacing Criteria
- Commodity (Compatible vs. non compatible)
- Single Tank
- Multiple Tank Group -- Same Size
- Multiple Tank Group -- Different Sizes
Spill Containment
- Containment Criteria
- Earthen Berm (Dike)
- Wall (Concrete)
- Topography
- Combination
Tank Supports and Foundations
- Foundation Types
- Foundation Details
- Sloping Bottoms
- Settlement
Tank Auxiliary Equipment
- Heaters & Coolers
- Internal Coil Type
- Internal Bayonet Type
- External Type
- Mixers
- Motor Driven Mechanical Types
- Jet Types
- Support requirements
- Removal methods and clearance
Fire or ignition suppression
- Snuffing steam to V/PRV (Vacuum & Pressure Relief Valve) Tail Pipes
- Water Spray Systems (Deluge Systems)
Tank Nozzles & Appurtenance
- Primary Inlet & Outlet Connections (Single vs. Multiple)
- Vent Connections (Closed, Open, Flame Arresters)
- Drain Connections (Closed, Winterized, Non-winterized)
- Instrument Connections (Flow, Level, Pressure, and Temperature)
- -- Level Controller & Gage
- -- Float & Target Board
- -- Automatic (Tape Type) Tank Gage
- -- Gage Hatch
- -- Pressure Taps
- -- Thermowells
- -- Radar type Level Instruments
- -- Sonar
- Heating Coil Connections (Inlet/Outlet)
- Mixer Mounting Nozzles
- Manholes
- Internal Nozzles
- -- Internal Piping
- -- Swing Lines (Winch, Clearance, Accessibility)
- -- Internal Pipe Supports
- -- Internal Floating Roof Supports
- Orientation & Elevation
- Size & Rating
- Projection
- Recommendations
- -- Avoid weld seams
Ladders, Stairs, and Platforms
- Orientation
- Primary access - entrance and exit
- Roof traffic Vs Formal Platform
- Safety - Tank Edge Handrail
Pumps
- Types
- Location
- Sumps
- Piping Elements
Product Piping
- Differential Settlement
- Location of First Support
- Natural Anchors (Dike Sleeves)
- Slops Collection System
Hot Oil Systems
- Asphalt Tankage & Distribution
Utilities Piping
- Condensate
- Instrument Air
- Nitrogen
- Plant Water
- Plant Air
- Potable Water
- Steam
- Glycol
- Ammonia
- Cooling Water
- Chilled Water
- Tracing Fluids (Low Temp. or High Temp.)
Dike Penetrations (Piping)
- Sleeves (U/G Protection & Grounding)
- Double Containment
- Casings
Operations Issues
- "Roll Over"
- "Boil Over"
Maintenance Issues
- Access (Mobile Equipment)
- Cleaning and Repair
- Housekeeping Pads (Spillage control)
- Utility Station Location & Access
- CIP (Clean in place)
- Wash Stations & Spray Wands
6, Flare, Incinerator, and Thermal Oxidizer
Flare
- Location Criteria
- Prevailing Wind (Wind Rose)
- Flare Header
- System Study
Flare KO Drums
- Horizontal
- Vertical/Stack base integrated
- Support
- Pump out
Flare Number and Types
- Number of Flare Stacks
- Ground Flare
- Elevated -- Free Standing
- Elevated -- Derrick Supported
- Elevated -- Cable Guided
Flare Accessories
- Flame Arrester
Flare Stack Utilities
- Fuel Gas
- Pilot Gas
- Igniter Line
- Atomizing Steam
- Flame Arrester Drain
Incinerators
- Location Criteria
- Prevailing Wind (Wind Rose)
- Collection System
Incinerator Utilities
- Fuel Gas
- Pilot Gas
- Igniter Line
- Atomizing Steam
Thermal Oxidizers
- Location Criteria
- Prevailing Wind (Wind Rose)
- Collection System
Thermal Oxidizer Utilities
- Fuel Gas
- Pilot Gas
- Igniter Line
- Atomizing Steam
7, Piperacks and Sleepers
Support Types
- Elevated (Overhead) Racks
- Sleeper Racks
- Bridges
Materials of construction
- Steel
- Concrete
- Combination
Overhead Racks
- Height
- Number of levels
- Current Space Requirements
- Future Space Requirements
- Operating Temperature induced expansion
- Solar induced expansion
- Maximum Spans
- Minimum Line Sizes
- Piping Loops
- Shoes, Anchors, & Guides
Pipe Sleepers
- Height
- Changes in Direction (Flat Turn vs. Elevated)
- Current Space Requirements
- Future Space Requirements
- Operating Temperature induced expansion
- Solar induced expansion
- Maximum Spans
- Minimum Line Sizes
- Piping Loops
- Shoes, Anchors, & Guides
Pipe Bridges
- Number
- Location
- Height
- Span
Auxiliary Piping Services & Systems
- Utility Systems
- Steam Tracing
- Jacketed Piping
- Internal Cleaning requirements for piping systems
- Future (space allowance)
Miscellaneous Piping Details
- Process Vents & Drains
- Hydrotest Vents & Drains
- Size, location, and access
- Cleaning connections (Maintenance)
- Slip Lining
8, Pipelines
Types and Purpose
- Cross Country
- Inter Plant
- Intra Plant
Accounting Meters
- Meter Provers
- "Bonded Zone"
- Fencing and Security
Pig Launchers & Pig Catchers (Receivers)
- Package System
- Vendor or Third Party Sub contracted
- Stick build
Pipe Line Pigging Criteria
- Minimum bend radius
Slug Catchers
- Types
Special Valving Considerations
- Types
- Support
Special Instrumentation
- SCADA
- Pig Signals (Pig Sig)
9, Loading / Unloading Racks (Truck, Rail, Barge, and Ship)
Product Data
- Liquid Products
- Gas Products
- Dry Products
- Non-flammable Liquid Chemical Products
- Flammable Liquid Hydrocarbon Products
- Liquefied Petroleum Gas (LPG) Products
Shipping method
- Truck
- Rail
- Barge
- Ship
Loading & Unloading Method
- Loading Arms or Loading Hoses
- Top Loading
- Bottom Loading (Truck & Rail only)
- Vapor recovery criteria
Shipping Plan
- Number of shipments
- Frequency of shipments
- Loading time
- Unloading time
Loading Rack Size & Location Criteria
- NFPA Criteria
- Size of Carrier (Truck, Rail Car, Barge/Ship)
- Minimum distance between loading "Spots"
- Outline of structure
- Loading Arm Type
- Loading Arm reach
- Loading Arm rest position
- Height and reach of swing-down platforms
- Access & clearance for Operators
- Stair and Ladder access and egress
Barge & Ship only
- Fixed or Floating Dock
- Tide & Current Data
- Maximum "Swing" envelope (Vessel empty at high tide vs. vessel full at low tide)
Auxiliaries
- Meters
- Grounding Lugs
- Spill containment
- Shelters
- Piping
Utility Requirements
- Utility Steam
- Plant Water
- Plant Air
- Breathing Air
- Nitrogen (for blanketing)
Safety & Fire Protection
- Monitors
- Hydrants
- Deluge Systems
- Fire Blankets
- Fire Extinguishers
- ESD (Emergency Shut Down) System
- Foam Systems
10, Cooling Water Supply Systems
Types
- Once through system
- Closed loop Cooling Tower system
- Atmospheric (Flooded) System
Water Source
- Municipal Water Supply (City, County, etc.)
- River Intake
- Ocean Intake
- Lake
- Wells
- Surge Pond
Water Intake & Outfall Structures
- River
- Oceans & Bays
Tower Types
- Forced Draft
- Induced Draft
- Natural Draft
Prevailing Wind
- Direction (primary and secondary)
- Timing (Spring, Summer, Fall, and Winter?)
- Force
- Duration
Basin Design
- In-ground
- Under-ground
- Strainers and Filters
- Fixed Screens
- Rotating Screens
Pump Types & Location
- Vertical
- Horizontal (same level next to basin)
- Horizontal (elevated above basin)
Operations
- Stand alone
- Manned
Maintenance
- Portable crane
- Built-in lifting facilities
Cooling Water Supply and Return Piping
- Material
- Location (Above ground or below ground)
Water Treatment Chemical piping
- PVC
- FRP
- Stainless Steel
- Alloys
Cathotic Protection
- Type
- Pipe Riser Location
- Insulating Flange Sets
11, Hazardous Chemicals Handling and Storage
Commodities List
MSDS (Material Safety Data Sheet)
Unloading Facilities
Storage
Loading
Handling
Safety
- Safety Shower/Eye Wash
Winterized (Tempered water system)
12, Waste Treatment Facilities
Types
- Storm Water
- Oily Water
- Chemical
- Sanitary
- Contaminated
Collection Locations
Collection and transfer methods
- Gravity (only) to Treatment
- Gravity to Sump & Pump to Treatment
Types of Treatment
13, Electrical & Instrumentation
Equipment Types
- Instrument Rack/Cabinets
- Junction Boxes
- Load Centers
- Substations
- Switch and Starter Racks
- Transformers
Aboveground Distribution
- Cable Trays
- Conduit Racks
- Light Standards
- Power Poles
- Push Button Stations
- Telephone Poles
- Transmission Towers
Underground Distribution
- Direct Bury Cable
- Duct Banks (Concrete encasement)
- Electrical Manholes
- Electrical Pull Boxes
Clearance criteria Electrical to:
- Process Equipment
- Piping
- Structures
- Pipe Racks
- Roads
- Rail Facilities
14, Buildings & Auxiliaries
Buildings and purpose
- Administration -
- Cafeteria --
- Change House (Locker Room) --
- Chemical Storage --
- Control (House) Center --
- Fire House --
- First Aid --
- Gate or Guard Houses --
- House of Worship (Mosque) --
- Laboratory (Product QC) --
- Machine Shop --
- Maintenance --
- Safety Center & Training --
- Warehouse --
Auxiliaries
- Parking Lots
- Truck Loading/Unloading Docks
Utility Services
- Chemical Waste --
- Chilled Water --
- Comfort Steam & Condensate --
- Contaminated Waste
- Hot & Cold Water
- Lab Gas --
- Potable Water --
- Sanitary Waste --
- Storm Water --
Piping Materials
15, Fire Protection & Safety
Fire Protection & Safety Plan
- Basic Safety Plan
- Contingency Plan
Fire Water System
- Fire Water Source
- Fire Water Storage
- Fire Water Pumps
- Fire Water Loop (Mains and Laterals)
- Fire Hydrants and Monitors
- Foam Chambers (Number and Orientation)
- Foam Stations (Number and Orientation)
- Fire Protection Manifolds (Pumper Connections)
- Fire Hose Carts
Materials of Construction
- Carbon Steel w/ external coating
- Carbon Steel w/ Internal Lining & external coating
- Ductile Iron
- FRP Piping
- Cement Lining
- Nonmetallic Linings
- Thrust Blocks & Anchors
Fire Training Area
- Location
- Facilities
Fire Equipment
16, Product packaging
LPG Bottling Facility
- Type,
- Open, sheltered, enclosed
- Empty bottle receiving
- Filling
- Full bottle storage
- Bottle shipping
- Truck scales (weighbridge)
Lube Oil packaging facility
- Type
- Sheltered
- Enclosed
- Size
Shipping method
- Truck
- Rail
17, Solids Storage & Disposal
Type
- Sulphur
- Coke
- Treated waste
Consistency
- Dry
- Semi-dry
Storage
- Open
- Sheltered
Disposal
- On property
- Off property
Shipping method
- Truck
- Rail
- Barge
- Other
Contributors (In alphabetical order):
Jadeep Coudhary, Anita R. Legvold, James O. Pennock
Introduction
Some have asked questions such as: "What is Balance of Plant?"; "What is Offsites?" What is OSBL?" and "What needs to be considered when a project includes Offsites."
The term Offsites is a general term and does not mean the same for every project or every plant. A project may include extensive tankage for feed storage along with tankage for in-process product, intermediate product, run-down tankage, slops and finished product tankage. Another project may include none of this because they already exist. The point here is just because you are told that the project includes "Offsites" you need to ask a lot of questions to determine exactly what they mean and what will be required.
The purpose of this document is to aid in answering this type of question. This document will not tell you how to design the Offsites or design any of the individual sub-items or equipment found on this list. That design guidance should properly be left up to you, your supervisors and your management. I do however intend to start a listing of major elements along with some minor key issues that should be considered.
I invite others to submit their own thoughts and comments to add to and improve this list.
Contents:
Section Subject
1 Definitions -- Offsite vs. Onsite
2 Codes, Standards, and Practices
3 Site Issues
4 Terrain, Grading, Roads, & Drainage
5 Tankage
6 Flares
7 Piperacks & Sleepers
8 Pipelines
9 Loading / Unloading Racks (Truck, Rail, Barge, and Ship)
10 Cooling Water Supply Systems
11 Hazardous Chemicals
12 Waste Treatment Facilities
13 Electrical
14 Buildings & Auxiliaries
15 Fire Protection & Safety
16 LPG Bottling Facilities
17 Solids Storage & Disposal
1, Definitions
Offsite -- In a process plant (Refinery, Chemical, Petrochemical, Power, etc.), any supporting facility that is not a direct part of the primary or secondary process reaction train or utility block. Offsites are also called OSBL.
Onsite - Any single or collection of inter-related and inter-connected process equipment that performs an integrated process function. Typically any Onsite Unit could be made to function independently of another Onsite Unit. Onsite Units are also called ISBL.
Utility Block - A single or multiple grouping of facilities that generate the support services required by the Onsite Process units to function. This normally includes: Steam Generation, Plant Air, Instrument Air, Decimalized Water, Plant Water, etc.
Balance of Plant - This is another term for Offsites and/or anything else other than the Onsite Units or the Utility Block.
Battery Limit -- Line used on a plot plan to determine the outside limit of a unit. The Battery Limit line is usually established early in the project and documented on all discipline documents such as Plot Plans, Site Plans, Drawing Indexes, etc... (1)
Property Line -- A Property Line is the recorded boundary of a plot of land. (2) Defines the separation between what is recognized legally as Owner's land and non-Owner's or other land.
On Property -- All land and or water inside the Property line shown on the property map or deed.
Off Property - Off property is any land (or water) outside of the Property line shown on the property map or deed.
Right of Way (ROW) -- Any land (On Property or Off Property) set aside and designated for a specific use or purpose. A Right-of-Way within a piece of property may also be designated for use by someone other than the property owner.
Setback or Setback Line -- A line established by law, deed restriction, or custom, fixing the minimum distance from the property line of the exterior face of buildings, walls and any other construction form; s street, road, or highway right-of-way line (3). Setback is a clear area normally at the boundary of a piece of property with conditions and restrictions for building or use.
Easements -- A vested or acquired right to use land other than as a tenant, for a specific purpose; such right being held by someone other than the owner who holds the title to the land (2). An easement is typically a strip of land within which overhead power lines or underground pipes are run.
(1) -- Lamit, Louis Gary, 1981 Prentice-Hall
(2) -- Construction Dictionary
2, Codes, Standards, & Practices
ANSI (American National Standards Institute)
API (American Petroleum Institute)
ASME (American Society of Mechanical Engineers)
ASTM - American Society of Testing Materials
AWS (American Welding Society)--
AWWA (American Water Works Association)
CFR (Code of Federal Regulations)
Division of Weights & Measures --
DOT (Department of Transportation)
FAR (Federal Accounting Regulations)
IRI (Insurance Regulators Institute)
Local Permits (Country, State, City, etc.)
MSS (Manufacturing Standards Society) --
NACE (National Association of Corrosion Engineers)--
NFPA (National Fire Protection Association)
OIA (Oil Insurers Association)
PFI (Pipe Fabrication Institute)
USCG (United States Coast Guard) Regulations
3, Site Issues
Brownfield (Revamp Existing)
Climate (Wind Rose)
Demolition
Feed stock type, source and method of delivery
Future growth
Grass Roots or Greenfield (New construction)
Impact across the fence
Power requirements and source
Products, Primary, Secondary and by-products
Seismic zone
SHE (Safety, Health and Environmental)
Utilities requirements
4, Terrain, Grading, Roads, Ditches & Drainage
Terrain
- Level vs. Sloping
Geotechnical influences
- Type of soil
- Angle of repose
- Grading
- Contours
- Grubbing (Tree and shrub removal)
- Rough Grading
- Finished Grading
Roads
- Primary
- Secondary
- Type and purpose of traffic
- Right hand or left hand drive
- Traffic pattern, potential for congestion
- Pipeway or Sleeper Crossings (Overhead Vs Ramp & Culvert)
Rail Spurs (see Loading and Unloading for additional criteria)
- Number
- Location
- Capacity (number of rail cars)
- Elevation
- Roadbed & Ballast Details
- Vertical and Horizontal Clearance requirements
- Standards and jurisdiction of Rail company (Right of Way)
Drainage systems
- Storm
- Oily Water
- Chemical
- Sanitary Sewage
- Contaminated
- Other
Ditches
- Depth
- Width
- Slope
Culverts
- Location, Size, Type
- Invert Elevation
Basins & Ponds
- In ground or On ground
- Lined vs. Unlined (or Rip Rap)
- Skimmers & Aerators
- Overflows & Runoff
- Fenced or Unfenced
- Access
Stiles, Stairs, Catwalks, and Platforms
- Existing or new
- Material if existing
- Material if new
- Location & Elevation
- Access
- Valve extension stem requirements
5, Tankage
Types & Purpose
- Atmospheric vs. Pressurized
- Cone Roof
- Floating Roof
- Bullets
- Spheres
- Spheroids
- Other (Used tank cars as storage)
Tank Construction
- Single Wall vs. Double Wall
- Metallic vs. nonmetallic
- Unlined vs. Lined
- Insulated, Jacketed, Heated, Cooled,
Commodity Grouping & Spacing Criteria
- Commodity (Compatible vs. non compatible)
- Single Tank
- Multiple Tank Group -- Same Size
- Multiple Tank Group -- Different Sizes
Spill Containment
- Containment Criteria
- Earthen Berm (Dike)
- Wall (Concrete)
- Topography
- Combination
Tank Supports and Foundations
- Foundation Types
- Foundation Details
- Sloping Bottoms
- Settlement
Tank Auxiliary Equipment
- Heaters & Coolers
- Internal Coil Type
- Internal Bayonet Type
- External Type
- Mixers
- Motor Driven Mechanical Types
- Jet Types
- Support requirements
- Removal methods and clearance
Fire or ignition suppression
- Snuffing steam to V/PRV (Vacuum & Pressure Relief Valve) Tail Pipes
- Water Spray Systems (Deluge Systems)
Tank Nozzles & Appurtenance
- Primary Inlet & Outlet Connections (Single vs. Multiple)
- Vent Connections (Closed, Open, Flame Arresters)
- Drain Connections (Closed, Winterized, Non-winterized)
- Instrument Connections (Flow, Level, Pressure, and Temperature)
- -- Level Controller & Gage
- -- Float & Target Board
- -- Automatic (Tape Type) Tank Gage
- -- Gage Hatch
- -- Pressure Taps
- -- Thermowells
- -- Radar type Level Instruments
- -- Sonar
- Heating Coil Connections (Inlet/Outlet)
- Mixer Mounting Nozzles
- Manholes
- Internal Nozzles
- -- Internal Piping
- -- Swing Lines (Winch, Clearance, Accessibility)
- -- Internal Pipe Supports
- -- Internal Floating Roof Supports
- Orientation & Elevation
- Size & Rating
- Projection
- Recommendations
- -- Avoid weld seams
Ladders, Stairs, and Platforms
- Orientation
- Primary access - entrance and exit
- Roof traffic Vs Formal Platform
- Safety - Tank Edge Handrail
Pumps
- Types
- Location
- Sumps
- Piping Elements
Product Piping
- Differential Settlement
- Location of First Support
- Natural Anchors (Dike Sleeves)
- Slops Collection System
Hot Oil Systems
- Asphalt Tankage & Distribution
Utilities Piping
- Condensate
- Instrument Air
- Nitrogen
- Plant Water
- Plant Air
- Potable Water
- Steam
- Glycol
- Ammonia
- Cooling Water
- Chilled Water
- Tracing Fluids (Low Temp. or High Temp.)
Dike Penetrations (Piping)
- Sleeves (U/G Protection & Grounding)
- Double Containment
- Casings
Operations Issues
- "Roll Over"
- "Boil Over"
Maintenance Issues
- Access (Mobile Equipment)
- Cleaning and Repair
- Housekeeping Pads (Spillage control)
- Utility Station Location & Access
- CIP (Clean in place)
- Wash Stations & Spray Wands
6, Flare, Incinerator, and Thermal Oxidizer
Flare
- Location Criteria
- Prevailing Wind (Wind Rose)
- Flare Header
- System Study
Flare KO Drums
- Horizontal
- Vertical/Stack base integrated
- Support
- Pump out
Flare Number and Types
- Number of Flare Stacks
- Ground Flare
- Elevated -- Free Standing
- Elevated -- Derrick Supported
- Elevated -- Cable Guided
Flare Accessories
- Flame Arrester
Flare Stack Utilities
- Fuel Gas
- Pilot Gas
- Igniter Line
- Atomizing Steam
- Flame Arrester Drain
Incinerators
- Location Criteria
- Prevailing Wind (Wind Rose)
- Collection System
Incinerator Utilities
- Fuel Gas
- Pilot Gas
- Igniter Line
- Atomizing Steam
Thermal Oxidizers
- Location Criteria
- Prevailing Wind (Wind Rose)
- Collection System
Thermal Oxidizer Utilities
- Fuel Gas
- Pilot Gas
- Igniter Line
- Atomizing Steam
7, Piperacks and Sleepers
Support Types
- Elevated (Overhead) Racks
- Sleeper Racks
- Bridges
Materials of construction
- Steel
- Concrete
- Combination
Overhead Racks
- Height
- Number of levels
- Current Space Requirements
- Future Space Requirements
- Operating Temperature induced expansion
- Solar induced expansion
- Maximum Spans
- Minimum Line Sizes
- Piping Loops
- Shoes, Anchors, & Guides
Pipe Sleepers
- Height
- Changes in Direction (Flat Turn vs. Elevated)
- Current Space Requirements
- Future Space Requirements
- Operating Temperature induced expansion
- Solar induced expansion
- Maximum Spans
- Minimum Line Sizes
- Piping Loops
- Shoes, Anchors, & Guides
Pipe Bridges
- Number
- Location
- Height
- Span
Auxiliary Piping Services & Systems
- Utility Systems
- Steam Tracing
- Jacketed Piping
- Internal Cleaning requirements for piping systems
- Future (space allowance)
Miscellaneous Piping Details
- Process Vents & Drains
- Hydrotest Vents & Drains
- Size, location, and access
- Cleaning connections (Maintenance)
- Slip Lining
8, Pipelines
Types and Purpose
- Cross Country
- Inter Plant
- Intra Plant
Accounting Meters
- Meter Provers
- "Bonded Zone"
- Fencing and Security
Pig Launchers & Pig Catchers (Receivers)
- Package System
- Vendor or Third Party Sub contracted
- Stick build
Pipe Line Pigging Criteria
- Minimum bend radius
Slug Catchers
- Types
Special Valving Considerations
- Types
- Support
Special Instrumentation
- SCADA
- Pig Signals (Pig Sig)
9, Loading / Unloading Racks (Truck, Rail, Barge, and Ship)
Product Data
- Liquid Products
- Gas Products
- Dry Products
- Non-flammable Liquid Chemical Products
- Flammable Liquid Hydrocarbon Products
- Liquefied Petroleum Gas (LPG) Products
Shipping method
- Truck
- Rail
- Barge
- Ship
Loading & Unloading Method
- Loading Arms or Loading Hoses
- Top Loading
- Bottom Loading (Truck & Rail only)
- Vapor recovery criteria
Shipping Plan
- Number of shipments
- Frequency of shipments
- Loading time
- Unloading time
Loading Rack Size & Location Criteria
- NFPA Criteria
- Size of Carrier (Truck, Rail Car, Barge/Ship)
- Minimum distance between loading "Spots"
- Outline of structure
- Loading Arm Type
- Loading Arm reach
- Loading Arm rest position
- Height and reach of swing-down platforms
- Access & clearance for Operators
- Stair and Ladder access and egress
Barge & Ship only
- Fixed or Floating Dock
- Tide & Current Data
- Maximum "Swing" envelope (Vessel empty at high tide vs. vessel full at low tide)
Auxiliaries
- Meters
- Grounding Lugs
- Spill containment
- Shelters
- Piping
Utility Requirements
- Utility Steam
- Plant Water
- Plant Air
- Breathing Air
- Nitrogen (for blanketing)
Safety & Fire Protection
- Monitors
- Hydrants
- Deluge Systems
- Fire Blankets
- Fire Extinguishers
- ESD (Emergency Shut Down) System
- Foam Systems
10, Cooling Water Supply Systems
Types
- Once through system
- Closed loop Cooling Tower system
- Atmospheric (Flooded) System
Water Source
- Municipal Water Supply (City, County, etc.)
- River Intake
- Ocean Intake
- Lake
- Wells
- Surge Pond
Water Intake & Outfall Structures
- River
- Oceans & Bays
Tower Types
- Forced Draft
- Induced Draft
- Natural Draft
Prevailing Wind
- Direction (primary and secondary)
- Timing (Spring, Summer, Fall, and Winter?)
- Force
- Duration
Basin Design
- In-ground
- Under-ground
- Strainers and Filters
- Fixed Screens
- Rotating Screens
Pump Types & Location
- Vertical
- Horizontal (same level next to basin)
- Horizontal (elevated above basin)
Operations
- Stand alone
- Manned
Maintenance
- Portable crane
- Built-in lifting facilities
Cooling Water Supply and Return Piping
- Material
- Location (Above ground or below ground)
Water Treatment Chemical piping
- PVC
- FRP
- Stainless Steel
- Alloys
Cathotic Protection
- Type
- Pipe Riser Location
- Insulating Flange Sets
11, Hazardous Chemicals Handling and Storage
Commodities List
MSDS (Material Safety Data Sheet)
Unloading Facilities
Storage
Loading
Handling
Safety
- Safety Shower/Eye Wash
Winterized (Tempered water system)
12, Waste Treatment Facilities
Types
- Storm Water
- Oily Water
- Chemical
- Sanitary
- Contaminated
Collection Locations
Collection and transfer methods
- Gravity (only) to Treatment
- Gravity to Sump & Pump to Treatment
Types of Treatment
13, Electrical & Instrumentation
Equipment Types
- Instrument Rack/Cabinets
- Junction Boxes
- Load Centers
- Substations
- Switch and Starter Racks
- Transformers
Aboveground Distribution
- Cable Trays
- Conduit Racks
- Light Standards
- Power Poles
- Push Button Stations
- Telephone Poles
- Transmission Towers
Underground Distribution
- Direct Bury Cable
- Duct Banks (Concrete encasement)
- Electrical Manholes
- Electrical Pull Boxes
Clearance criteria Electrical to:
- Process Equipment
- Piping
- Structures
- Pipe Racks
- Roads
- Rail Facilities
14, Buildings & Auxiliaries
Buildings and purpose
- Administration -
- Cafeteria --
- Change House (Locker Room) --
- Chemical Storage --
- Control (House) Center --
- Fire House --
- First Aid --
- Gate or Guard Houses --
- House of Worship (Mosque) --
- Laboratory (Product QC) --
- Machine Shop --
- Maintenance --
- Safety Center & Training --
- Warehouse --
Auxiliaries
- Parking Lots
- Truck Loading/Unloading Docks
Utility Services
- Chemical Waste --
- Chilled Water --
- Comfort Steam & Condensate --
- Contaminated Waste
- Hot & Cold Water
- Lab Gas --
- Potable Water --
- Sanitary Waste --
- Storm Water --
Piping Materials
15, Fire Protection & Safety
Fire Protection & Safety Plan
- Basic Safety Plan
- Contingency Plan
Fire Water System
- Fire Water Source
- Fire Water Storage
- Fire Water Pumps
- Fire Water Loop (Mains and Laterals)
- Fire Hydrants and Monitors
- Foam Chambers (Number and Orientation)
- Foam Stations (Number and Orientation)
- Fire Protection Manifolds (Pumper Connections)
- Fire Hose Carts
Materials of Construction
- Carbon Steel w/ external coating
- Carbon Steel w/ Internal Lining & external coating
- Ductile Iron
- FRP Piping
- Cement Lining
- Nonmetallic Linings
- Thrust Blocks & Anchors
Fire Training Area
- Location
- Facilities
Fire Equipment
16, Product packaging
LPG Bottling Facility
- Type,
- Open, sheltered, enclosed
- Empty bottle receiving
- Filling
- Full bottle storage
- Bottle shipping
- Truck scales (weighbridge)
Lube Oil packaging facility
- Type
- Sheltered
- Enclosed
- Size
Shipping method
- Truck
- Rail
17, Solids Storage & Disposal
Type
- Sulphur
- Coke
- Treated waste
Consistency
- Dry
- Semi-dry
Storage
- Open
- Sheltered
Disposal
- On property
- Off property
Shipping method
- Truck
- Rail
- Barge
- Other
Field Trip Guidlines
A: Field Trip Guidlines
By: James O. Pennock
What is involved when you are asked to go to the field? If you are truly a knowledgeable and experienced designer or engineer you are supposed to know the answer to that question. If you are a novice, new to the business or if you have never been to a job site you will not know. However, you should be smart enough to ask. Yet, we see many cases where people show up at a job site, uninformed of what they are supposed to do, and unprepared to do it.
I remember a case that is a classic. A team of four were selected and sent to a job site. All the members had ten plus years of experience so the supervisor made the assumption that they all knew what was expected. The individuals involved happened to live in a widely scattered area and were to travel from different airports and at different times. This point eventually contributed in part to the problem because there was no face to face meeting in the office or at the airport before getting on the plane. Friday they were all given (or sent) plane tickets and directions for finding the plant and were to meet at the job site on arrival on Monday.
Three of the four seemed to know what was expected. The forth, a contract employee, new to the company, but with more than thirty years of total experience proved to be the exception. This person showed up in “dress casual” and with nothing in hand. The supervisor, thinking the person had left his work clothes in the car or some place close by, told him to change into his field gear and be ready to go to work. “Change, into what?” “What field gear?” To make a long story short, this person had only brought casual clothes and had brought nothing in the way of field gear or tools. He had no work shoes, no work clothes, no hard hat, no safety glasses, and no hearing protection. He also had no pencil, eraser, sketch paper, no clipboard, and no tape measure. Nothing! When asked why not, the answer was that he expected the company or the client to supply everything. As quietly as possible the person was told that he was fired and to leave the job site, go get on the plane and go home.
The situation proved to be an embarrassment to not only the supervisor but also the company. You see job sites such as the type we had in this case are tight little communities and you cannot keep secrets from people who are in charge. It was not long before the company construction manager and the client both knew about the fiasco. Although they agreed with sending the employee away, they were not happy with the cost and the effect on the schedule. They expected everyone to show up ready, willing and able to work.
Ready, willing, and able to work means everybody. It means all the members of the team. It includes the team leader and each individual engineer or designer. The balance of this article is intended to be a guide to any individual who is required to go to a job site to perform work. It is offered to held define the major procedural and technical issues related to making the field trip both cost effective and safe.
When it is recognized that a trip is required, the first thing that is normally done is to define the purpose of the trip and obtain all required approvals. This is normally done at the project senior supervisory and management levels. We will not dwell on why a field trip is required. What we need to do is insure that it is done right.
The next thing to do is activate the team. Engineers or designers assigned to a field team for routine fieldwork or specific problem solving need to be selected carefully. They should be selected on the basis of knowledge and prior experience. They may also need specific skills, or the familiarity with operations, maintenance, or construction.
In order to activate the team the following may be required:
Names & phone numbers of client site primary & secondary "Key" contacts
Names of the engineering company primary & secondary contacts
Name of the person responsible for decision making, time sheet and expense report approval
Team member names
Assign someone as the team leader, someone in charge
Team member release from present assignment (if applicable)
Travel arrangements (Airline, lodging, ground transportation, meals, etc.)
Maps to site location, site logistics, site safety criteria, badges, camera pass and site access
Charge number for this (Problem/Solution) assignment
Next, before leaving for the site, there should be a pre-trip meeting of all the team members. The direct supervisor who is responsible for the team and the results should conduct this pre-trip meeting. The agenda for this meeting should include a review of the purpose of the trip and the expected results. Have a plan for everyone and for all the work objectives. Other items that should be covered would include the chain of command, the schedule, the cost and expense issues, and an exchange of phone numbers for emergency contacts. Review what to do if someone misses the plane, etc.
On arrival, check in with the key Client contact person and the jobsite construction manager. Safety is the first and most important step of the actual site visit. Make sure that every member of the team has received the site-specific safety training. Know and understand the emergency warning system and the evacuation routes. Identify and agree on a place to meet, if there is a possibility of getting separated.
Engineers and Designers who visit a Client facility or site are expected to know the type of work they will be doing when they arrive and should be prepared to take prompt action to address that work. They are also expected to have with them the tools and supplies required for their jobs.
Standard safety clothing and personal protective equipment (PPE) Requirements:
- Hard hat
- Goggles or safety glasses w/ permanent side shields (no contact lenses and no removable side shields)
- Work shoes (check, some job sites require steel toed work boots)
- Gloves
- Ear protection
- Respirator with Cartridges (When required)
- NOMEX or Equivalent flame retarding outer wear (This is sometimes optional depending on the client or type of plant)
Basic tools:
- Pencils and markers, a clip board, straightedge
- Sketch paper and Isometric forms
- 25 ft. Tape measure
Alternate tools that may be helpful
- String line, Plumb Bob, and String Level (Used for measurements)
- Stopwatch (Used for checking frequency of events)
- Medical type Stethoscope (Used for listening for unusual noises inside of pipes)
- Camera (Requires Client approval and pass)
The team should not expect to borrow any tools or supplies from the Client. If a new requirement for tools or supplies is identified, after arrival at the site, the team should arrange to rent or purchase the item and turn in the cost on an expense report. An exception may be made if the required item is unusual and or very costly and the client has the item available.
Once in the field and trained in the site safety criteria, the team is ready to go to work. Everyone should go about the work in a prompt and professional manner. Where possible, fieldwork should be done by two person teams. The people on each team should check each other’s work as the work progresses. They should review their list of activities and tasks as they proceed. Review the trip plan. It’s better to get too much information thus insuring you do not miss something. Remember that this job site may be thousands of miles from your home office. A return trip for one missed item could be very costly.
Check in with the home office daily or per previous instructions. Let the home office supervisor know the progress of the planned work and ask if there are any new requirements. Proceed through the list of all planned trip requirements. Perform all activities and tasks. Do no return from the job site until all planned items are complete (unless directed otherwise). It is also recommended that you check in with the site construction manager on a daily basis. There may be additional project needs that have come up. There may also be a change in some critical site condition that could effect the team safety. When leaving the job site you should check out with the construction manager and your client host.
Upon return to the office, there should be a debriefing meeting. The responsible supervisor, the project engineer (or manager) and all team members should attend. Review the purpose of the trip, the results. Review the trip plan. Did you accomplish everything that was required? If not, why not? Were there any problems? Were they solved and what were the solutions? Are there any lessons to be learned from this trip? Is another trip required? If so why? And when will the next trip be required?
Every field trip should be planned and executed in a proper and cost effective manner. If so, then the project will benefit. The individuals on the team also benefit. They gain value and a reputation for being an experienced and effective candidate for future fieldwork. Good luck and have a safe and successful trip.
By: James O. Pennock
What is involved when you are asked to go to the field? If you are truly a knowledgeable and experienced designer or engineer you are supposed to know the answer to that question. If you are a novice, new to the business or if you have never been to a job site you will not know. However, you should be smart enough to ask. Yet, we see many cases where people show up at a job site, uninformed of what they are supposed to do, and unprepared to do it.
I remember a case that is a classic. A team of four were selected and sent to a job site. All the members had ten plus years of experience so the supervisor made the assumption that they all knew what was expected. The individuals involved happened to live in a widely scattered area and were to travel from different airports and at different times. This point eventually contributed in part to the problem because there was no face to face meeting in the office or at the airport before getting on the plane. Friday they were all given (or sent) plane tickets and directions for finding the plant and were to meet at the job site on arrival on Monday.
Three of the four seemed to know what was expected. The forth, a contract employee, new to the company, but with more than thirty years of total experience proved to be the exception. This person showed up in “dress casual” and with nothing in hand. The supervisor, thinking the person had left his work clothes in the car or some place close by, told him to change into his field gear and be ready to go to work. “Change, into what?” “What field gear?” To make a long story short, this person had only brought casual clothes and had brought nothing in the way of field gear or tools. He had no work shoes, no work clothes, no hard hat, no safety glasses, and no hearing protection. He also had no pencil, eraser, sketch paper, no clipboard, and no tape measure. Nothing! When asked why not, the answer was that he expected the company or the client to supply everything. As quietly as possible the person was told that he was fired and to leave the job site, go get on the plane and go home.
The situation proved to be an embarrassment to not only the supervisor but also the company. You see job sites such as the type we had in this case are tight little communities and you cannot keep secrets from people who are in charge. It was not long before the company construction manager and the client both knew about the fiasco. Although they agreed with sending the employee away, they were not happy with the cost and the effect on the schedule. They expected everyone to show up ready, willing and able to work.
Ready, willing, and able to work means everybody. It means all the members of the team. It includes the team leader and each individual engineer or designer. The balance of this article is intended to be a guide to any individual who is required to go to a job site to perform work. It is offered to held define the major procedural and technical issues related to making the field trip both cost effective and safe.
When it is recognized that a trip is required, the first thing that is normally done is to define the purpose of the trip and obtain all required approvals. This is normally done at the project senior supervisory and management levels. We will not dwell on why a field trip is required. What we need to do is insure that it is done right.
The next thing to do is activate the team. Engineers or designers assigned to a field team for routine fieldwork or specific problem solving need to be selected carefully. They should be selected on the basis of knowledge and prior experience. They may also need specific skills, or the familiarity with operations, maintenance, or construction.
In order to activate the team the following may be required:
Names & phone numbers of client site primary & secondary "Key" contacts
Names of the engineering company primary & secondary contacts
Name of the person responsible for decision making, time sheet and expense report approval
Team member names
Assign someone as the team leader, someone in charge
Team member release from present assignment (if applicable)
Travel arrangements (Airline, lodging, ground transportation, meals, etc.)
Maps to site location, site logistics, site safety criteria, badges, camera pass and site access
Charge number for this (Problem/Solution) assignment
Next, before leaving for the site, there should be a pre-trip meeting of all the team members. The direct supervisor who is responsible for the team and the results should conduct this pre-trip meeting. The agenda for this meeting should include a review of the purpose of the trip and the expected results. Have a plan for everyone and for all the work objectives. Other items that should be covered would include the chain of command, the schedule, the cost and expense issues, and an exchange of phone numbers for emergency contacts. Review what to do if someone misses the plane, etc.
On arrival, check in with the key Client contact person and the jobsite construction manager. Safety is the first and most important step of the actual site visit. Make sure that every member of the team has received the site-specific safety training. Know and understand the emergency warning system and the evacuation routes. Identify and agree on a place to meet, if there is a possibility of getting separated.
Engineers and Designers who visit a Client facility or site are expected to know the type of work they will be doing when they arrive and should be prepared to take prompt action to address that work. They are also expected to have with them the tools and supplies required for their jobs.
Standard safety clothing and personal protective equipment (PPE) Requirements:
- Hard hat
- Goggles or safety glasses w/ permanent side shields (no contact lenses and no removable side shields)
- Work shoes (check, some job sites require steel toed work boots)
- Gloves
- Ear protection
- Respirator with Cartridges (When required)
- NOMEX or Equivalent flame retarding outer wear (This is sometimes optional depending on the client or type of plant)
Basic tools:
- Pencils and markers, a clip board, straightedge
- Sketch paper and Isometric forms
- 25 ft. Tape measure
Alternate tools that may be helpful
- String line, Plumb Bob, and String Level (Used for measurements)
- Stopwatch (Used for checking frequency of events)
- Medical type Stethoscope (Used for listening for unusual noises inside of pipes)
- Camera (Requires Client approval and pass)
The team should not expect to borrow any tools or supplies from the Client. If a new requirement for tools or supplies is identified, after arrival at the site, the team should arrange to rent or purchase the item and turn in the cost on an expense report. An exception may be made if the required item is unusual and or very costly and the client has the item available.
Once in the field and trained in the site safety criteria, the team is ready to go to work. Everyone should go about the work in a prompt and professional manner. Where possible, fieldwork should be done by two person teams. The people on each team should check each other’s work as the work progresses. They should review their list of activities and tasks as they proceed. Review the trip plan. It’s better to get too much information thus insuring you do not miss something. Remember that this job site may be thousands of miles from your home office. A return trip for one missed item could be very costly.
Check in with the home office daily or per previous instructions. Let the home office supervisor know the progress of the planned work and ask if there are any new requirements. Proceed through the list of all planned trip requirements. Perform all activities and tasks. Do no return from the job site until all planned items are complete (unless directed otherwise). It is also recommended that you check in with the site construction manager on a daily basis. There may be additional project needs that have come up. There may also be a change in some critical site condition that could effect the team safety. When leaving the job site you should check out with the construction manager and your client host.
Upon return to the office, there should be a debriefing meeting. The responsible supervisor, the project engineer (or manager) and all team members should attend. Review the purpose of the trip, the results. Review the trip plan. Did you accomplish everything that was required? If not, why not? Were there any problems? Were they solved and what were the solutions? Are there any lessons to be learned from this trip? Is another trip required? If so why? And when will the next trip be required?
Every field trip should be planned and executed in a proper and cost effective manner. If so, then the project will benefit. The individuals on the team also benefit. They gain value and a reputation for being an experienced and effective candidate for future fieldwork. Good luck and have a safe and successful trip.
Field Issues
Section V - Field Issues
A. Field trip guidelines - By: James O. Pennock
This discussion is about what to expect when you are asked to go to the field?
B. Defining Offsite Facilities for Process Plants - Contributed by Jadeep Choudary, Anita R. Legvold and James O. Pennock.
Some have asked questions such as: “What is Balance of Plant?”; “What is Offsites?” What is OSBL?” and “What needs to be considered when a project includes Offsites.” The purpose of this document is to aid in answering this type of question.
A. Field trip guidelines - By: James O. Pennock
This discussion is about what to expect when you are asked to go to the field?
B. Defining Offsite Facilities for Process Plants - Contributed by Jadeep Choudary, Anita R. Legvold and James O. Pennock.
Some have asked questions such as: “What is Balance of Plant?”; “What is Offsites?” What is OSBL?” and “What needs to be considered when a project includes Offsites.” The purpose of this document is to aid in answering this type of question.
The Problem with Piping "Lift-off"
B: The Problem with Piping "Lift-off"
By: CAEPIPE (visit http://sstusa.com )
Contemporary commercial piping analysis programs deal differently with the problem of apparent lift-off of an operating pipe at a rod hanger or a one-way vertical support, such as a pipe on a support rack. A few programs provide error messages; others show a vertical movement with a possible increase in sustained (weight) stress (see NOTE below for CAEPIPE). A proper understanding of the standard piping design practice is the key to correct interpretation of these results from different programs. Such standard piping design practice was generally understood when the sustained and flexibility analysis rules were introduced in the 1955 Edition of the ASME B31 Code for Pressure Piping.
The problem with lift-off is compounded by the intention of the piping analysis being performed - whether the intent is to design new or revamp existing piping or the intent is to analyze as-built. The intention of the various sections of ASME B31 Code (B31.1, B31.3, etc.) is to provide guidance for new construction. Note, since the publication of the 1935 Edition of ASME B31.1 (which included the predecessor of B31.3 as a chapter, Paras. 101.6 and 121.4 and their predecessor paras.) state:
Piping shall be carried on adjustable hangers or properly leveled rigid hangers or supports, and suitable springs...
Hangers used for the support of piping, NPS 2½ (NPS 2 in 1935 edn.) and larger, shall be designed to permit adjustment after erection while supporting the load.
While not quite as explicit, the current ASME B31.3 Para. 321.1.1 states:
The layout and design of piping and its supporting elements shall be directed toward preventing... piping stresses in excess of those permitted by in this Code;... unintentional disengagement of piping from its supports;... excessive piping sag in piping requiring drainage slope;...
These paragraph excerpts define standard practice in piping design. That is, during operation, it is neither the intention of the code nor standard practice to allow piping to lift-off. Piping is normally designed to be supported in the operating condition. The means to achieve this is through proper adjustment of the supports during operation. This is important in piping because unadjusted supports will permit the pipe to sag and create locations in steam or condensable gas piping where condensates can collect or concentrate. And it is especially important for piping operating above 800 degF, where unadjusted supports will allow the pipe to permanently deform (creep) over time.
Small gaps are inevitable in actual construction because of fabrication and installation tolerances and would normally be closed by support adjustments. But, so long as the pipe is prevented from significant lateral movement, small gaps below pipe during operation (¼ inch and less in moderate size piping) may be tolerable because the weight analysis is a very simplified and conservative method that the ASME B31 codes use to guard against collapse. Stresses caused by takeup of a small gap below the pipe could even be considered expansion or building settlement type stresses and thus would not need to be considered in the weight analysis. Weight analysis with the intent of designing pipe normally considers all the weight supports perform their intended function. Any significant gaps determined by analysis could either indicate that a support is not required, or that adjacent supports need to be modified, or that an alternate means of support is needed, e.g., a variable or constant spring should be used.
However, if the purpose of an analysis is not to design a new or revamp an old piping system, but to evaluate an as-built and maintained piping system, small gaps may have more significance in as much as they would indicate that the pipe support system may not be acting as designed and maintained. A lack of or improper adjustment of the supports in the operating condition may cause lift-off at rigid supports. Improperly designed or adjusted or maintained or degraded variable or constant spring supports may cause lift-off, too.
The interpretation of the results of the analysis of as-built piping systems need not necessarily conform to the rules of the ASME B31 codes. Remember, the rules in the B31 codes are required for new construction, not the evaluation of existing piping. It is understood that a greater factor of safety is required for the design process because the pipe and its components are not yet available to be measured and materials confirmed, as well as the knowledge of how the piping is to be actually used. The interpretation of the analysis results of as-built piping may be able to take advantage of what the actual piping dimensions and materials are and how the piping has been operated. Competent engineering judgement based on knowledge of the intent of the respective ASME B31 codes must then become part of the evaluation process.
For the reasons noted, it is important to distinguish between the design and analysis of piping. If designing, certain assumptions are normally made with regard to whether the piping is supported in the operating condition. Such assumptions might include tolerating a small gap at a given support but realizing that the installation of the given support will require adjustment. Alternately, a larger gap at the given support may require support relocation to be effective or the selection of a different type of support, most typically a constant or variable spring. If merely analyzing existing piping, no assumptions need be made regarding supports acting and analysis gaps may become important considerations. That said, however, the analyst must realize that the piping analysis model is a very idealized estimation of the as-built piping and for the analysis results to be meaningful, the analyst needs to consider how well the results correlate with the actual performance of the in-situ piping.
NOTE: In case of lift-off, CAEPIPE will show a gap and possibly increased sustained stresses. The user must interpret the gaps according to whether the user is designing new or revamping existing piping or is analyzing an existing condition.
By: CAEPIPE (visit http://sstusa.com )
Contemporary commercial piping analysis programs deal differently with the problem of apparent lift-off of an operating pipe at a rod hanger or a one-way vertical support, such as a pipe on a support rack. A few programs provide error messages; others show a vertical movement with a possible increase in sustained (weight) stress (see NOTE below for CAEPIPE). A proper understanding of the standard piping design practice is the key to correct interpretation of these results from different programs. Such standard piping design practice was generally understood when the sustained and flexibility analysis rules were introduced in the 1955 Edition of the ASME B31 Code for Pressure Piping.
The problem with lift-off is compounded by the intention of the piping analysis being performed - whether the intent is to design new or revamp existing piping or the intent is to analyze as-built. The intention of the various sections of ASME B31 Code (B31.1, B31.3, etc.) is to provide guidance for new construction. Note, since the publication of the 1935 Edition of ASME B31.1 (which included the predecessor of B31.3 as a chapter, Paras. 101.6 and 121.4 and their predecessor paras.) state:
Piping shall be carried on adjustable hangers or properly leveled rigid hangers or supports, and suitable springs...
Hangers used for the support of piping, NPS 2½ (NPS 2 in 1935 edn.) and larger, shall be designed to permit adjustment after erection while supporting the load.
While not quite as explicit, the current ASME B31.3 Para. 321.1.1 states:
The layout and design of piping and its supporting elements shall be directed toward preventing... piping stresses in excess of those permitted by in this Code;... unintentional disengagement of piping from its supports;... excessive piping sag in piping requiring drainage slope;...
These paragraph excerpts define standard practice in piping design. That is, during operation, it is neither the intention of the code nor standard practice to allow piping to lift-off. Piping is normally designed to be supported in the operating condition. The means to achieve this is through proper adjustment of the supports during operation. This is important in piping because unadjusted supports will permit the pipe to sag and create locations in steam or condensable gas piping where condensates can collect or concentrate. And it is especially important for piping operating above 800 degF, where unadjusted supports will allow the pipe to permanently deform (creep) over time.
Small gaps are inevitable in actual construction because of fabrication and installation tolerances and would normally be closed by support adjustments. But, so long as the pipe is prevented from significant lateral movement, small gaps below pipe during operation (¼ inch and less in moderate size piping) may be tolerable because the weight analysis is a very simplified and conservative method that the ASME B31 codes use to guard against collapse. Stresses caused by takeup of a small gap below the pipe could even be considered expansion or building settlement type stresses and thus would not need to be considered in the weight analysis. Weight analysis with the intent of designing pipe normally considers all the weight supports perform their intended function. Any significant gaps determined by analysis could either indicate that a support is not required, or that adjacent supports need to be modified, or that an alternate means of support is needed, e.g., a variable or constant spring should be used.
However, if the purpose of an analysis is not to design a new or revamp an old piping system, but to evaluate an as-built and maintained piping system, small gaps may have more significance in as much as they would indicate that the pipe support system may not be acting as designed and maintained. A lack of or improper adjustment of the supports in the operating condition may cause lift-off at rigid supports. Improperly designed or adjusted or maintained or degraded variable or constant spring supports may cause lift-off, too.
The interpretation of the results of the analysis of as-built piping systems need not necessarily conform to the rules of the ASME B31 codes. Remember, the rules in the B31 codes are required for new construction, not the evaluation of existing piping. It is understood that a greater factor of safety is required for the design process because the pipe and its components are not yet available to be measured and materials confirmed, as well as the knowledge of how the piping is to be actually used. The interpretation of the analysis results of as-built piping may be able to take advantage of what the actual piping dimensions and materials are and how the piping has been operated. Competent engineering judgement based on knowledge of the intent of the respective ASME B31 codes must then become part of the evaluation process.
For the reasons noted, it is important to distinguish between the design and analysis of piping. If designing, certain assumptions are normally made with regard to whether the piping is supported in the operating condition. Such assumptions might include tolerating a small gap at a given support but realizing that the installation of the given support will require adjustment. Alternately, a larger gap at the given support may require support relocation to be effective or the selection of a different type of support, most typically a constant or variable spring. If merely analyzing existing piping, no assumptions need be made regarding supports acting and analysis gaps may become important considerations. That said, however, the analyst must realize that the piping analysis model is a very idealized estimation of the as-built piping and for the analysis results to be meaningful, the analyst needs to consider how well the results correlate with the actual performance of the in-situ piping.
NOTE: In case of lift-off, CAEPIPE will show a gap and possibly increased sustained stresses. The user must interpret the gaps according to whether the user is designing new or revamping existing piping or is analyzing an existing condition.
The Designer, Stress Problems and Stress Training
A: The Designer, Stress Problems and Stress Training
By: James O. Pennock
Stress related technical and execution problems in the design of process plant piping are complex and must be addressed properly. There will be some Piping Designers, Stress Engineers and others who read this and say that they agree. Others may say that they do not agree. Others will just not know one way or the other. This discussion, while not covering solutions to every potential problem, is intended only to highlight some of the most common stress related factors and designer training needs
There are five basic factors that influence piping and therefore piping stress in the process plant. There is temperature, pressure, weight, force and vibration. These factors will come in many forms and at different times. Stress problems become all the more complex because two or more of these will exist at the same time in the same piping system. The main objective of the focus when dealing with problems related to piping systems is not normally the pipe itself. In a very high percentage of the time it is not the pipe that is the weakest link. Note this: the pipe is normally stronger and/or less vulnerable to damage than what the pipe is connected to. Pumps are just one examples of equipment to which pipes are routinely connected. Misalignment problems caused by expansion (or contraction) in a poorly designed system can result in major equipment failure. Equipment failures can lead to the potential for fire, plant shutdown and loss of revenue. At this point it should be emphasized that the success (or failure) of the plant’s operation, years down the road can and will depend on what is done up front by all the members of the design team during the design stage. An important point to remember, “While analysis cannot create a good design, it can confirm a good design” (Improved Pump Load Evaluation,” Hydrocarbon Processing, April 1998, By: David W. Diehl, COADE Engineering Software, Inc Houston, TX). On the other hand, proper analysis will identify bad design and potential problems in a piping system design.
Stress Related Design Factors
Temperatures in piping systems may range from well over 1000o F (537.8 C) on the high side to below -200 o F (-128.8 C) on the low side. Each extreme on the temperature scale and everything in between brings its own problems. There will also be times when both high and low temperatures can occur in the same piping system. An example of this would be in piping that is installed in an arctic environment. The piping is installed outdoors where it is subjected to -100 o F (-73.3 C) over the arctic winter. Six to nine months later it is finally commissioned started up and may operate at five or six hundred degrees.
The problems that temperature causes is expansion (or contraction) in the piping system. Expansion or contraction in a piping system is an absolute. No matter what the designer or the stress engineer does they cannot prevent the action caused by heat or cold. Expansion or contraction in a piping system it self is not so much a problem. As we all know if a bare pipe was just lying on the ground in the middle of a dry barren desert it will absorb a lot of heat from just solar radiation. In the hot sun piece of pipe can reached 150 o F (65.5 C). The pipe will expand and with both ends loose it would not be a problem. However, when you connect the pipe to something, even if only one end is connected you may begin to have expansion related problems. When the pipe is anchored or connected to something at both ends you absolutely will have expansion induced problems. Expansion induced problems in a piping system is stress. There are a number of ways to handle expansion in piping systems. Flexible routing is the first and by far the cheapest and safest method for handling expansion in piping systems. The other way is the use of higher cost and less reliable flexible elements such as expansion joints.
Stress will exist in every piping system. If not identified and the proper action taken, stress will cause failure to equipment or elements in the piping system itself. Stress results in forces at equipment nozzles and at anchor pipe supports. Two piping configurations with the same pipe size, shape, dimensions, temperature and material but with different wall schedules (sch. 40 vs. sch. 160) will not generate the same stress.
Force in piping systems is not independent of the other factors. Primarily, force (as related to piping systems) is the result of expansion (temperature) and/or pressure acting on a piping configuration that is too stiff. This may cause the failure of a pipe support system or it may cause the damage or failure of a piece of equipment. Force, and the expansion that causes it, is best handled by a more flexible routing of the piping. Some people suggest that force can be reduced by the use of expansion joints. However we must remember that for an expansion joint to work there must be an opposite and equal force at both ends to make the element work. This tends to compound the problem rather than lessen it.
Pressure in piping systems also range from the very high to the very low. Piping systems with pressure as high as 35,000 psi in some plants are not unusual. On the other hand piping systems with pressures approaching full vacuum are also not unusual. The pressure (or lack of) in a piping system effects the wall thickness of the pipe. When you increase the wall thickness of the pipe you do two things. First, you increase the weight of the pipe. Second, you increase the stiffness of the pipe thus the stress intensification affecting forces. Increasing the wall thickness of the pipe is the primary method of compensating for increases in pressure. Other ways, depending on many factors include changing to a different material. With low or vacuum systems there are also other ways to prevent the collapse of the pipe wall. Among these the primary method is the addition of stiffening rings. Stiffing rings may be added internally or externally depending on the commodity type and the conditions.
Weight in a piping system is expressed normally as dead load. The weight of a piping system at any given point is made up of many elements. These include the weight of the pipe, the fittings, the valves, any attachments, and the insulation. There is also the test media (e. g. hydrotest water) or the process commodity whichever has the greater specific gravity. Piping systems are heavy, period. Everybody involved in the project needs to understand this and be aware that this weight exists and it needs to be supported. Ninety-nine times out of a hundred this weight will be supported from a structural pipe support (primary pipe support system) of some kind. However there are times when the piping (weight) is supported from a vessel or other type of equipment.
Vibrations will also occur in piping systems and come in two types. There is the basic mechanical vibration caused by the machines that the piping is connected to. Then, there is acoustic (or harmonic) vibration caused by the characteristics of the system itself. Typically the only place severe vibrations will be found is in piping connected to equipment such as positive displacement reciprocating pumps or high pressure multi-stage reciprocating compressors and where there is very high velocity gas flows.
All of the issues listed above that a piping system is exposed to need to be covered in a company specific or company sponsored piping designer, stress-related training program. This piping designer, stress-related training should be done at the department level, early in the designer’s career and prior to the start of the project. Unfortunately however this is not always the case.
By definition, the role of the piping designer is to design the plant piping systems. This means design all of the system. Design all of the system means that the piping designer shall define the proper routing of each and every pipeline required for the project. This includes each and every inline component (pipe, valves, fittings, flanges, instruments, etc.), every online component (anchors, guides, hangers, etc.). It includes the definition of any attached piece of equipment and the definition of every support point. To do this and do it properly the designer must know about piping stress issues and know what to do about them. The designer is responsible for a lot and so they need to know a lot.
Is there any risk involved to the company or the project in not doing this stress related designer training? Yes! First, a designer who is naïve about the cause and effect of stress related problems would not be able to recognize the symptoms and will burn a lot of budget hours and create bad designs. Second, bad designs are subject to the ‘domino effect’ when the need for corrective action is finally identified and taken then other lines get “pushed” and then modifications to them are required. Third, when the bad design does get to the stress engineer for analysis there is the potential for repeated recycle and a serious delay in the design issue schedule.
Designer Stress Training
What does the piping designer need to know? Piping design is more than just knowing how to turn on the computer, how to find the piping menus and the difference between paper space and model space. So, appropriately, what else does the designer need to know about piping design besides how to connect a piece of pipe to a fitting?
Here is a list of some of the most basic of things that a good piping designer should know. Thinking about every one of these items should be as natural as breathing for a good piping designer.
• Allowable pipe spans – All designer need to know and understand the span capabilities of pipe in the different schedules for a wide variety of common piping materials. When a new project introduces a new material with severely reduced span capabilities; supplemental training may be required.
• Expansion of pipe – All designers must understand that they need to treat a piping system as though it is alive. It has a temperature and that temperature causes it to grow and move. That growth and movement must be allowed for and incorporated in the overall design. Not just of that specific line but for all other lines close by. The process of expansion in a pipe or group of pipes will also exert frictional forces or anchor forces on the pipe supports they come in contact with.
• Routing for flexibility – The piping designer must understand how to route pipe for flexibility. Routing for flexibility can normally be achieved in the most natural routing of the pipeline from its origin to its terminus. Routing for flexibility means (a) do not run a pipe in a straight line from origin to terminus and (b) building flexibility into the pipe routing is far cheaper and more reliable than expansion joints.
• Weight and loads (live loads and dead loads) – The piping designer needs to understand the effects of weight and loading. They need to know and understand that everything has a weight. They need to be able recognize when there is going to be a concentrated load. They need to have access to basic weight tables for all the standard pipe schedules, pipe fittings, flanges, valves for steel pipe. They also need to have the weight tables for other materials or a table of correction factors for these other materials vs. carbon steel. They need to be able to recognize when downward expansion in a piping system is present and is adding live loads to a support or equipment nozzle.
• Equipment piping – The piping designer needs to know the right and the wrong way to pipe up (connect pipe to) different kinds of equipment. This includes pumps, compressors, exchangers, filters or any special equipment to be used on a specific project.
• Vessel piping – The piping designer also needs to understand about the connecting, supporting and guiding of piping attached to vessels (horizontal or vertical) and tanks. They need to know that nozzle loading is important and does have limitations.
• Rack piping – The designer needs to understand that there is a logical approach to the placement of piping in (or on) a pipe rack. It does not matter how wide or how high the rack or what kind of plant, the logic still applies. Starting from one or both outside edges the largest and hottest lines are sequenced in such a manner that allows for the nesting of any required expansion loops. The spacing of the lines must also allow for the bowing effect at the loops caused by the expansion.
• Expansion loops – The designer needs to understand and be able to use simple rules and methods for sizing loops in rack piping. This should include the most common sizes, schedules and materials.
• Cold spring/Pre-spring – Designers should understand the basics rules of cold spring and pre-spring. They need to understand what each one is along with when to and when not to use each.
Piping Designer or Piping Drafter
Any piping designer that has this type of training, this type of knowledge and then consistently applies is indeed a piping designer. He or she will also be a more valuable asset to their company and to themselves in the market place. On the other hand anyone who does not know or does not apply the knowledge about these issues while doing piping work is nothing more than a piping drafter or a CAD operator.
By: James O. Pennock
Stress related technical and execution problems in the design of process plant piping are complex and must be addressed properly. There will be some Piping Designers, Stress Engineers and others who read this and say that they agree. Others may say that they do not agree. Others will just not know one way or the other. This discussion, while not covering solutions to every potential problem, is intended only to highlight some of the most common stress related factors and designer training needs
There are five basic factors that influence piping and therefore piping stress in the process plant. There is temperature, pressure, weight, force and vibration. These factors will come in many forms and at different times. Stress problems become all the more complex because two or more of these will exist at the same time in the same piping system. The main objective of the focus when dealing with problems related to piping systems is not normally the pipe itself. In a very high percentage of the time it is not the pipe that is the weakest link. Note this: the pipe is normally stronger and/or less vulnerable to damage than what the pipe is connected to. Pumps are just one examples of equipment to which pipes are routinely connected. Misalignment problems caused by expansion (or contraction) in a poorly designed system can result in major equipment failure. Equipment failures can lead to the potential for fire, plant shutdown and loss of revenue. At this point it should be emphasized that the success (or failure) of the plant’s operation, years down the road can and will depend on what is done up front by all the members of the design team during the design stage. An important point to remember, “While analysis cannot create a good design, it can confirm a good design” (Improved Pump Load Evaluation,” Hydrocarbon Processing, April 1998, By: David W. Diehl, COADE Engineering Software, Inc Houston, TX). On the other hand, proper analysis will identify bad design and potential problems in a piping system design.
Stress Related Design Factors
Temperatures in piping systems may range from well over 1000o F (537.8 C) on the high side to below -200 o F (-128.8 C) on the low side. Each extreme on the temperature scale and everything in between brings its own problems. There will also be times when both high and low temperatures can occur in the same piping system. An example of this would be in piping that is installed in an arctic environment. The piping is installed outdoors where it is subjected to -100 o F (-73.3 C) over the arctic winter. Six to nine months later it is finally commissioned started up and may operate at five or six hundred degrees.
The problems that temperature causes is expansion (or contraction) in the piping system. Expansion or contraction in a piping system is an absolute. No matter what the designer or the stress engineer does they cannot prevent the action caused by heat or cold. Expansion or contraction in a piping system it self is not so much a problem. As we all know if a bare pipe was just lying on the ground in the middle of a dry barren desert it will absorb a lot of heat from just solar radiation. In the hot sun piece of pipe can reached 150 o F (65.5 C). The pipe will expand and with both ends loose it would not be a problem. However, when you connect the pipe to something, even if only one end is connected you may begin to have expansion related problems. When the pipe is anchored or connected to something at both ends you absolutely will have expansion induced problems. Expansion induced problems in a piping system is stress. There are a number of ways to handle expansion in piping systems. Flexible routing is the first and by far the cheapest and safest method for handling expansion in piping systems. The other way is the use of higher cost and less reliable flexible elements such as expansion joints.
Stress will exist in every piping system. If not identified and the proper action taken, stress will cause failure to equipment or elements in the piping system itself. Stress results in forces at equipment nozzles and at anchor pipe supports. Two piping configurations with the same pipe size, shape, dimensions, temperature and material but with different wall schedules (sch. 40 vs. sch. 160) will not generate the same stress.
Force in piping systems is not independent of the other factors. Primarily, force (as related to piping systems) is the result of expansion (temperature) and/or pressure acting on a piping configuration that is too stiff. This may cause the failure of a pipe support system or it may cause the damage or failure of a piece of equipment. Force, and the expansion that causes it, is best handled by a more flexible routing of the piping. Some people suggest that force can be reduced by the use of expansion joints. However we must remember that for an expansion joint to work there must be an opposite and equal force at both ends to make the element work. This tends to compound the problem rather than lessen it.
Pressure in piping systems also range from the very high to the very low. Piping systems with pressure as high as 35,000 psi in some plants are not unusual. On the other hand piping systems with pressures approaching full vacuum are also not unusual. The pressure (or lack of) in a piping system effects the wall thickness of the pipe. When you increase the wall thickness of the pipe you do two things. First, you increase the weight of the pipe. Second, you increase the stiffness of the pipe thus the stress intensification affecting forces. Increasing the wall thickness of the pipe is the primary method of compensating for increases in pressure. Other ways, depending on many factors include changing to a different material. With low or vacuum systems there are also other ways to prevent the collapse of the pipe wall. Among these the primary method is the addition of stiffening rings. Stiffing rings may be added internally or externally depending on the commodity type and the conditions.
Weight in a piping system is expressed normally as dead load. The weight of a piping system at any given point is made up of many elements. These include the weight of the pipe, the fittings, the valves, any attachments, and the insulation. There is also the test media (e. g. hydrotest water) or the process commodity whichever has the greater specific gravity. Piping systems are heavy, period. Everybody involved in the project needs to understand this and be aware that this weight exists and it needs to be supported. Ninety-nine times out of a hundred this weight will be supported from a structural pipe support (primary pipe support system) of some kind. However there are times when the piping (weight) is supported from a vessel or other type of equipment.
Vibrations will also occur in piping systems and come in two types. There is the basic mechanical vibration caused by the machines that the piping is connected to. Then, there is acoustic (or harmonic) vibration caused by the characteristics of the system itself. Typically the only place severe vibrations will be found is in piping connected to equipment such as positive displacement reciprocating pumps or high pressure multi-stage reciprocating compressors and where there is very high velocity gas flows.
All of the issues listed above that a piping system is exposed to need to be covered in a company specific or company sponsored piping designer, stress-related training program. This piping designer, stress-related training should be done at the department level, early in the designer’s career and prior to the start of the project. Unfortunately however this is not always the case.
By definition, the role of the piping designer is to design the plant piping systems. This means design all of the system. Design all of the system means that the piping designer shall define the proper routing of each and every pipeline required for the project. This includes each and every inline component (pipe, valves, fittings, flanges, instruments, etc.), every online component (anchors, guides, hangers, etc.). It includes the definition of any attached piece of equipment and the definition of every support point. To do this and do it properly the designer must know about piping stress issues and know what to do about them. The designer is responsible for a lot and so they need to know a lot.
Is there any risk involved to the company or the project in not doing this stress related designer training? Yes! First, a designer who is naïve about the cause and effect of stress related problems would not be able to recognize the symptoms and will burn a lot of budget hours and create bad designs. Second, bad designs are subject to the ‘domino effect’ when the need for corrective action is finally identified and taken then other lines get “pushed” and then modifications to them are required. Third, when the bad design does get to the stress engineer for analysis there is the potential for repeated recycle and a serious delay in the design issue schedule.
Designer Stress Training
What does the piping designer need to know? Piping design is more than just knowing how to turn on the computer, how to find the piping menus and the difference between paper space and model space. So, appropriately, what else does the designer need to know about piping design besides how to connect a piece of pipe to a fitting?
Here is a list of some of the most basic of things that a good piping designer should know. Thinking about every one of these items should be as natural as breathing for a good piping designer.
• Allowable pipe spans – All designer need to know and understand the span capabilities of pipe in the different schedules for a wide variety of common piping materials. When a new project introduces a new material with severely reduced span capabilities; supplemental training may be required.
• Expansion of pipe – All designers must understand that they need to treat a piping system as though it is alive. It has a temperature and that temperature causes it to grow and move. That growth and movement must be allowed for and incorporated in the overall design. Not just of that specific line but for all other lines close by. The process of expansion in a pipe or group of pipes will also exert frictional forces or anchor forces on the pipe supports they come in contact with.
• Routing for flexibility – The piping designer must understand how to route pipe for flexibility. Routing for flexibility can normally be achieved in the most natural routing of the pipeline from its origin to its terminus. Routing for flexibility means (a) do not run a pipe in a straight line from origin to terminus and (b) building flexibility into the pipe routing is far cheaper and more reliable than expansion joints.
• Weight and loads (live loads and dead loads) – The piping designer needs to understand the effects of weight and loading. They need to know and understand that everything has a weight. They need to be able recognize when there is going to be a concentrated load. They need to have access to basic weight tables for all the standard pipe schedules, pipe fittings, flanges, valves for steel pipe. They also need to have the weight tables for other materials or a table of correction factors for these other materials vs. carbon steel. They need to be able to recognize when downward expansion in a piping system is present and is adding live loads to a support or equipment nozzle.
• Equipment piping – The piping designer needs to know the right and the wrong way to pipe up (connect pipe to) different kinds of equipment. This includes pumps, compressors, exchangers, filters or any special equipment to be used on a specific project.
• Vessel piping – The piping designer also needs to understand about the connecting, supporting and guiding of piping attached to vessels (horizontal or vertical) and tanks. They need to know that nozzle loading is important and does have limitations.
• Rack piping – The designer needs to understand that there is a logical approach to the placement of piping in (or on) a pipe rack. It does not matter how wide or how high the rack or what kind of plant, the logic still applies. Starting from one or both outside edges the largest and hottest lines are sequenced in such a manner that allows for the nesting of any required expansion loops. The spacing of the lines must also allow for the bowing effect at the loops caused by the expansion.
• Expansion loops – The designer needs to understand and be able to use simple rules and methods for sizing loops in rack piping. This should include the most common sizes, schedules and materials.
• Cold spring/Pre-spring – Designers should understand the basics rules of cold spring and pre-spring. They need to understand what each one is along with when to and when not to use each.
Piping Designer or Piping Drafter
Any piping designer that has this type of training, this type of knowledge and then consistently applies is indeed a piping designer. He or she will also be a more valuable asset to their company and to themselves in the market place. On the other hand anyone who does not know or does not apply the knowledge about these issues while doing piping work is nothing more than a piping drafter or a CAD operator.
Piping Stress for the Piping Designer
Section IV - Piping Stress for the Piping Designer
A. Stress Problems and Designer Stress Training - By: James O. Pennock
This discussion is an introduction to the problems found in piping caused by thermal expansion and dead weight, their relationship to the overall piping arrangement and the type of stress related training required for the piping designer.
B: The Problem with Piping "Lift-off" - By CAEPIPE
Contemporary commercial piping analysis programs deal differently with the problem of apparent lift-off of an operating pipe at a rod hanger or a one-way vertical support, such as a pipe on a support rack
A. Stress Problems and Designer Stress Training - By: James O. Pennock
This discussion is an introduction to the problems found in piping caused by thermal expansion and dead weight, their relationship to the overall piping arrangement and the type of stress related training required for the piping designer.
B: The Problem with Piping "Lift-off" - By CAEPIPE
Contemporary commercial piping analysis programs deal differently with the problem of apparent lift-off of an operating pipe at a rod hanger or a one-way vertical support, such as a pipe on a support rack
Pipe Supports, Part - 2
A: Pipe Supports, Part - 2
By: James O. Pennock
Pipe supports as we stated in Part 1 (of Pipe Supports) is a much more complex subject than the term would first suggest. We also want to make it clear that there are many ways that errors can be made when designing or selecting pipe supports this includes the various secondary pipe supports.
In Part - 1, we saw a chart that described some of the many different types of secondary pipe support devices. In this, Part - 2 of Pipe Supports we are going to focus on specific data required to properly size, qualify and select a support.To do this we will look at one specific device. The specific device we will focus on is the Hanger Rod.
You will remember that in Part - 1 we said there are three basic types of Hanger Rod support devices: (type 1) beam-to-pipe, (type 2) pipe-to-pipe and (type 3) beam-to-beam (or trapeze). They all have three major components, a top connection component, middle or connector component and a bottom component. For the type 1 Hanger the top component normally connects to a structural beam. The connector component is normally steel rod. The bottom component is normally a pipe clamp. We also said that the danger with the design of these items is in the lack of knowledge of some of the people doing the design. They do not know how to calculate all the actual dead and live loading that the Hanger will support. Then they choose the wrong type or strength of component for the intended load.
In order to bring attention to some of the potential problems lets take a hypothetical piping configuration and plant situation for study. We will look at two cases. We will use the same configuration with different conditions for each case.
Case #1
Let's take the following as an example scenario for the basis for our discussion.
>> The project is a process plant in a multi-story structure
>> The line is 12", standard weight carbon steel pipe located in a lower level of the structure
>> The line will carry a process liquid with a specific gravity of .85
>> The line is subject to hydrotest
>> The line is not insulated
>> The piping travels horizontal north in a well supported manner, then after crossing the last normal pipe support (support 'a') it travels 40 feet, then drops down (3'-0") and turns east (right) with two elbows (fitting-to-fitting) and travels another 40 feet to the next normal support (support 'b').
>> There are no additional horizontal support beams available at or near the turn point and at the exact piping elevation.
>> The closest steel available as a possible support point is 24" deep major equipment support beam located 6'-0" (top-of-pipe to bottom-of-beam) above the pipe and 4'-0" from the pipe drop.
It is logical and factual that structural support 'a' will carry one half of the pipe load of the north-south run. And the structural support 'b' will carry half pipe load of the east-west run. However, the L-shaped "dog-leg" in this scenario is obviously excessively overspanned and the pipe will be over stressed. The piping designer must provide some type of additional support at or near the corner. Because of the availability of the overhead beam a hanger rod is chosen as the best possible and most economical method of support for the pipe.
We must now look at the factors so we can choose the correct Hanger Rod assembly. The factors include all the weight to be supported.
The component weights are as follows:
>> 20'-0" of pipe in the north-south run (1/2 the 40' run)
>> 20'-0" of pipe in the east-west run (1/2 the 40' run)
>> Two 90 degree elbows
>> 43 lineal feet of hydrotest water in the 12" Standard Weight pipe
With this information the next step is a simple look-up of the correct data.
Case #1-12" Standard Weight, Carbon Steel Pipe
Pipe Weight Fitting Weight Insulation Weight Water Weight Total Weight
1984 lbs. 246 lbs. 0 2107 lbs 4337 lbs
We now have what we need to select a hanger rod assembly to support our pipe. There are two ways that this can be done. First, the designer can use the "pick-and-choose" or "do-it-your-self ' method. This is the process of picking up a hanger parts catalog and then selects each individual piece and part. The hope is that the designer knows what they are actually doing.
The second method is that we select from a pre-packaged Hanger Rod assembly that fits our need. One that comes complete with all the proper and matched pieces and parts. The term "pre-packaged hanger assembly" also means that the assembly has been "tag named," has been pre-designed, pre-engineered, pre-qualified and fully documented including the related needs for the applicable computer aided design system, material procurement and installation.
The assembly we need for our "Case #1 includes the following:
(All components and load data are taken from "PTP" Piping Technology and Products online catalog, see pipingtech.com)
Load Capacity*
>> Figure 110, Eye Rod (Welded), Size 1" 4960 lbs.
>> Figure 20, Welded Beam Attachment, Size #8 (for 1" Rod) 4900 lbs.
>> Figure 40, Weldless Eye Nut, Size #2 for 1" threaded Rod 4960 lbs.
>> Figure 80, Heavy Three-Bolt Pipe Clamp, for 12" pipe 7000 lbs.
>> Beam attachment welds ¼" fillet, 2 sides 12000lbs.
* It is normal practice for components of this type to be designed with a plus 50% safety factor. The safety factor is not to be considered as available when making a selection.
**The Beam Attachment is 3" on each side, ¼" attachment fillet weld 1" long is rated @ 2000 lbs. Per inch.
We now compare our pipe weights against the Hanger Rod load capacity data and see that (not using any of the safety factor) the Hanger' weakest link is the Welded Beam Attachment (4900 lbs.) but it is more than enough for our piping needs (4337 lbs.).
If we were using the "pick-and-choose" method then the designer must indicate the hanger in the design then identify each and every piece and part. The detailed part identification is required for proper procurement and installation.
If we use the "pre-package" method the designer is only required to indicate the hanger and the item name or tag number (example: HR-1-12".) All the procurement and installation details are included in the hanger documentation.
Now Case #2
Later someone else has a similar problem. They had seen what was done by another designer with the Case #1 problem and decided they would just copy it and callout for the same Hanger Rod Assembly. Why not? They too had a 12" line. They had the same configuration. And, they also had the same span distances. No problem, right? However, all things were in fact not the same.
So what was different?
Case #2
>> The project is also a process plant in a multi-story structure
>> The line is 12", Schedule 160 carbon steel pipe located in a lower level of the structure
>> The line will carry a process liquid with a specific gravity of .85
>> The line is subject to hydrotest
>> The line is insulated with 3" of Calcium Silicate
>> The piping travels horizontal north in a well supported manner, then after crossing the last normal pipe support (support 'a') it travels 40 feet, then drops down (3'-0") and turns east (right) with two elbows (fitting-to-fitting) and travels another 40 feet to the next normal support (support 'b').
>> There are no additional horizontal support beams available at or near the turn point and at the exact piping elevation.
>> The closest steel available as a possible support point is 24" deep major equipment support beam located 6'-0" (top-of-pipe to bottom-of-beam) above the pipe and 4'-0" from the pipe drop.
With this information we look-up of the correct data.
Case #2, 12" Schedule 160, Carbon Steel Pipe
Pipe Weight Fitting Weight Insulation Weight Water Weight Total Weight
6412 lbs. 794 lbs. 528 lbs 1462 lbs 9196 lbs
We see here that the total load to be actually carried by the Case #2 hanger is more than twice the safe capacity any of the components included in the original Hanger Rod. This will not work! This is an example of the type of errors that result when there is a lack of thinking or laziness on the part of the piping designer.
All of the items identified, as Secondary Pipe Support Systems are subject to this same kind of miss-design and miss-use. It is incumbent on the piping designer to become trained and knowledgeable about these issues.
Having identified the need for the hanger in the case study above and selected the correct hanger is not the end of the piping designers responsibility. That hanger is carrying a load and the top of that hanger is attached to a steel beam. The load is being transferred to that beam. That hanger and the pipe it is carrying is an abnormal load added to that beam. It is a load that the structural engineer would not normally be aware of. It is the piping designer's responsibility to document that loading and advise the proper member of the structural engineering group. That beam may be a very large beam and is at or very near it's safe design limit. You might think "Oh it is okay, it can carry my pipe" However, you are not a structural engineer and this is not your decision to make. Whenever an abnormal piping load is added to a structural beam (steel or concrete) the structural group must be advised.
By: James O. Pennock
Pipe supports as we stated in Part 1 (of Pipe Supports) is a much more complex subject than the term would first suggest. We also want to make it clear that there are many ways that errors can be made when designing or selecting pipe supports this includes the various secondary pipe supports.
In Part - 1, we saw a chart that described some of the many different types of secondary pipe support devices. In this, Part - 2 of Pipe Supports we are going to focus on specific data required to properly size, qualify and select a support.To do this we will look at one specific device. The specific device we will focus on is the Hanger Rod.
You will remember that in Part - 1 we said there are three basic types of Hanger Rod support devices: (type 1) beam-to-pipe, (type 2) pipe-to-pipe and (type 3) beam-to-beam (or trapeze). They all have three major components, a top connection component, middle or connector component and a bottom component. For the type 1 Hanger the top component normally connects to a structural beam. The connector component is normally steel rod. The bottom component is normally a pipe clamp. We also said that the danger with the design of these items is in the lack of knowledge of some of the people doing the design. They do not know how to calculate all the actual dead and live loading that the Hanger will support. Then they choose the wrong type or strength of component for the intended load.
In order to bring attention to some of the potential problems lets take a hypothetical piping configuration and plant situation for study. We will look at two cases. We will use the same configuration with different conditions for each case.
Case #1
Let's take the following as an example scenario for the basis for our discussion.
>> The project is a process plant in a multi-story structure
>> The line is 12", standard weight carbon steel pipe located in a lower level of the structure
>> The line will carry a process liquid with a specific gravity of .85
>> The line is subject to hydrotest
>> The line is not insulated
>> The piping travels horizontal north in a well supported manner, then after crossing the last normal pipe support (support 'a') it travels 40 feet, then drops down (3'-0") and turns east (right) with two elbows (fitting-to-fitting) and travels another 40 feet to the next normal support (support 'b').
>> There are no additional horizontal support beams available at or near the turn point and at the exact piping elevation.
>> The closest steel available as a possible support point is 24" deep major equipment support beam located 6'-0" (top-of-pipe to bottom-of-beam) above the pipe and 4'-0" from the pipe drop.
It is logical and factual that structural support 'a' will carry one half of the pipe load of the north-south run. And the structural support 'b' will carry half pipe load of the east-west run. However, the L-shaped "dog-leg" in this scenario is obviously excessively overspanned and the pipe will be over stressed. The piping designer must provide some type of additional support at or near the corner. Because of the availability of the overhead beam a hanger rod is chosen as the best possible and most economical method of support for the pipe.
We must now look at the factors so we can choose the correct Hanger Rod assembly. The factors include all the weight to be supported.
The component weights are as follows:
>> 20'-0" of pipe in the north-south run (1/2 the 40' run)
>> 20'-0" of pipe in the east-west run (1/2 the 40' run)
>> Two 90 degree elbows
>> 43 lineal feet of hydrotest water in the 12" Standard Weight pipe
With this information the next step is a simple look-up of the correct data.
Case #1-12" Standard Weight, Carbon Steel Pipe
Pipe Weight Fitting Weight Insulation Weight Water Weight Total Weight
1984 lbs. 246 lbs. 0 2107 lbs 4337 lbs
We now have what we need to select a hanger rod assembly to support our pipe. There are two ways that this can be done. First, the designer can use the "pick-and-choose" or "do-it-your-self ' method. This is the process of picking up a hanger parts catalog and then selects each individual piece and part. The hope is that the designer knows what they are actually doing.
The second method is that we select from a pre-packaged Hanger Rod assembly that fits our need. One that comes complete with all the proper and matched pieces and parts. The term "pre-packaged hanger assembly" also means that the assembly has been "tag named," has been pre-designed, pre-engineered, pre-qualified and fully documented including the related needs for the applicable computer aided design system, material procurement and installation.
The assembly we need for our "Case #1 includes the following:
(All components and load data are taken from "PTP" Piping Technology and Products online catalog, see pipingtech.com)
Load Capacity*
>> Figure 110, Eye Rod (Welded), Size 1" 4960 lbs.
>> Figure 20, Welded Beam Attachment, Size #8 (for 1" Rod) 4900 lbs.
>> Figure 40, Weldless Eye Nut, Size #2 for 1" threaded Rod 4960 lbs.
>> Figure 80, Heavy Three-Bolt Pipe Clamp, for 12" pipe 7000 lbs.
>> Beam attachment welds ¼" fillet, 2 sides 12000lbs.
* It is normal practice for components of this type to be designed with a plus 50% safety factor. The safety factor is not to be considered as available when making a selection.
**The Beam Attachment is 3" on each side, ¼" attachment fillet weld 1" long is rated @ 2000 lbs. Per inch.
We now compare our pipe weights against the Hanger Rod load capacity data and see that (not using any of the safety factor) the Hanger' weakest link is the Welded Beam Attachment (4900 lbs.) but it is more than enough for our piping needs (4337 lbs.).
If we were using the "pick-and-choose" method then the designer must indicate the hanger in the design then identify each and every piece and part. The detailed part identification is required for proper procurement and installation.
If we use the "pre-package" method the designer is only required to indicate the hanger and the item name or tag number (example: HR-1-12".) All the procurement and installation details are included in the hanger documentation.
Now Case #2
Later someone else has a similar problem. They had seen what was done by another designer with the Case #1 problem and decided they would just copy it and callout for the same Hanger Rod Assembly. Why not? They too had a 12" line. They had the same configuration. And, they also had the same span distances. No problem, right? However, all things were in fact not the same.
So what was different?
Case #2
>> The project is also a process plant in a multi-story structure
>> The line is 12", Schedule 160 carbon steel pipe located in a lower level of the structure
>> The line will carry a process liquid with a specific gravity of .85
>> The line is subject to hydrotest
>> The line is insulated with 3" of Calcium Silicate
>> The piping travels horizontal north in a well supported manner, then after crossing the last normal pipe support (support 'a') it travels 40 feet, then drops down (3'-0") and turns east (right) with two elbows (fitting-to-fitting) and travels another 40 feet to the next normal support (support 'b').
>> There are no additional horizontal support beams available at or near the turn point and at the exact piping elevation.
>> The closest steel available as a possible support point is 24" deep major equipment support beam located 6'-0" (top-of-pipe to bottom-of-beam) above the pipe and 4'-0" from the pipe drop.
With this information we look-up of the correct data.
Case #2, 12" Schedule 160, Carbon Steel Pipe
Pipe Weight Fitting Weight Insulation Weight Water Weight Total Weight
6412 lbs. 794 lbs. 528 lbs 1462 lbs 9196 lbs
We see here that the total load to be actually carried by the Case #2 hanger is more than twice the safe capacity any of the components included in the original Hanger Rod. This will not work! This is an example of the type of errors that result when there is a lack of thinking or laziness on the part of the piping designer.
All of the items identified, as Secondary Pipe Support Systems are subject to this same kind of miss-design and miss-use. It is incumbent on the piping designer to become trained and knowledgeable about these issues.
Having identified the need for the hanger in the case study above and selected the correct hanger is not the end of the piping designers responsibility. That hanger is carrying a load and the top of that hanger is attached to a steel beam. The load is being transferred to that beam. That hanger and the pipe it is carrying is an abnormal load added to that beam. It is a load that the structural engineer would not normally be aware of. It is the piping designer's responsibility to document that loading and advise the proper member of the structural engineering group. That beam may be a very large beam and is at or very near it's safe design limit. You might think "Oh it is okay, it can carry my pipe" However, you are not a structural engineer and this is not your decision to make. Whenever an abnormal piping load is added to a structural beam (steel or concrete) the structural group must be advised.
Pipe Supports, Part - 1
A: Pipe Supports, Part - 1
By: James O. Pennock
The subject, "Pipe Supports" is a much more complex subject than the term suggests. There are so many situations that a pipe can find itself in and in every case it will need to be supported. Pipe supports is a general term that actually is split into two families. There is what I call the primary pipe support systems, and then there are the secondary pipe support systems.
The primary pipe supports systems are those supports that are a part of the infrastructure and fall under the prime responsibility of the structural department. The secondary pipe support systems are more a part of the piping systems and as such fall under the prime responsibility of the piping department. You notice I used the words 'prime responsibility' with each of these there is still a cross over responsibility to provide proper, accurate and timely information and then action.
Primary Pipe Support Systems
As noted above the primary pipe supports are a part of the infrastructure. This is true of most all projects. For simplicity the emphasis here will focus on "Grass Root" or new construction plants. These primary pipe supports systems may also be referred to as piperacks, pipeways, pipe alleys. These support systems may be major or minor and they may be overhead or sleeper pipe racks. It is important to understand that even though they are called pipe racks they support and carry more than just piping. These other items may include the cables for electrical and instrumentation services.
For clarification, overhead pipe racks are elevated to the point where you can walk and/or drive under the supported piping. Sleepers or sleeper ways are low to the ground so there is no passage under the supported piping.
Pipe racks (overhead or sleeper) are normally established and sized early in the preliminary engineering phase of a project. This time of the project is normally called the plant development phase or the plot plan development phase. Once they are established and sized they are one of the first things the structural department can work on. The terms 'establish' and 'size' requires a lot of wisdom and work.
The wisdom and work means thinking one, two or three years into the future and deciding where (location) the primary pipe support systems will run. Other critical elements include the configuration, height, width, spacing and the materials of construction/fabrication method. Let's take these elements one at a time.
» Location - In order to set the location of the primary pipe support systems the total plant layout must be established. This means that all the various disciplines must have a very good idea what equipment is required and it's size. The "Plot Plan" must be reviewed by all the key people on the project and then approved by the client.
» Configuration - This is the selection of "fit-for-purpose." Each main run, minor run and branch run must be looked at to determine its configuration. Will it be an overhead rack or a sleeper way? Will each be single deck (layer) or multiple deck? Will the support be a single column ("T") support or multi-column support? How many columns? A second part of the configuration issue effects pipe racks in the process units themselves. This is the question of whether or not the pipe rack will support equipment such as Air Coolers (Fin Fans). Another part of configuration is the issue of intersections. Poor planning on this issue can cause problems later with the piping.
» Height - How high should each run of rack be? Should they be elevated or low sleepers. The sleepers are concrete with an imbedded steel plate on the top. For sleepers, they need to be off the ground to allow for maintenance and drainage also to prevent corrosion. For elevated multi-level racks what should the separation be? For elevated racks you must plan the height and the separation of the whole system together. A key element in the determination of separation is the line sizes to be carried on the racks.
» Width - This requires a detailed study of the total piping systems for the whole plant based on pipe rack routing. In the past, a study (called a "Transposition") was done to, as best you could, account for each line on each pipe rack. From this study, a berth sequence was established and the line spacing set. A percentage was added as an error factor and then the clients "future" reserve was added. This then constituted the minimum rack width. The final width would be set after all racks were "sized" and then some might be rounded up in width for consistence based on the materials of construction/fabrication method.
» Spacing - This issue can be addressed after the transposition has been completed. The transposition identifies all the rack piping from the largest to the smallest From this the average line size for each leg of the rack system can be established. With the pipe size information (largest, smallest and average pipe size) the number and spacing of the pipe support bents can be set. A cost tradeoff is evaluated and made between more pipe supports spaced closer together or fewer pipe supports and some sort of intermediate support system.
» Materials of construction/fabrication method - What materials are the pipe racks to be made of and what will be the fabrication method? Pipe racks can be bare steel, steel w/a concrete encasement (fireproofing), reinforced concrete or a combination. The steel can be steel structural shapes or pipe shape. The concrete fireproofing can be cast in place onto (or around) the steel columns and beams or it can be pre-cast onto the columns and beams prior to installation. The reinforced concrete pipe supports can also be cast in place or pre-cast then field erected. The space requirement dimensions for a reinforced concrete column or beam is about twice that of bare steel.
The piping design group on the project (at the company where I came from) was the lead group in all of the above issues except the last one, materials of construction/fabrication method. This issue was properly the responsibility of the structural department, construction and the client. There is no doubt that economics, the jobsite location, labor and material availability played a part. Piping, however must know what the materials of construction/fabrication method will be because it can affect one or more of the other issues.
Secondary Pipe Support Systems
The secondary pipe support systems are a broad family of devices with two branches and actually include more than just supports. The two branches are defined as (a) "engineered" devices and (b) "miscellaneous" pipe support devices.
The term "engineered" pipe supports relates to devices that are non-static, one-of-a-kind, location and condition specific. They are identified at the time the need is recognized and then designed and engineered for that specific need. Constant support spring hangers and snubbers are just two of the devices in this category. The piping stress engineer is the party/person who is responsible for the engineering of these. However, the piping designer working in the specific area has a shared responsibility.
The term "miscellaneous" pipe support refers to a broad array of devices that includes items such as Anchors, Base Supports, Cradles, Dummy Support Legs, Guides, Hanger Rods, Pick-ups, Shoes, Trunnions, etc. All companies have their own operating methods and may not use a different approach to miscellaneous pipe support devices. Some may allow each piping designer to pick and choose pieces and parts from various catalogs to design their own pipe supports. Others may use a more organizational approach and "pre-engineer" these supports.
The term "pre-engineer" means that the various devices are an existing company standard that may be used on the project. Secondary support devices typically have multiple or repetitive point of use subject to similar conditions. Having these devices "pre-engineered" and available to the piping designer on the project saves money, provides consistency of design, and results in a safer design. The configurations, hardware and materials have already been established, the load calculations have been performed (and are on file). There is also an "If-then" selection key and criteria established (If you have "X" support problem, then you can/must use "Y" support device). The extensive use of computers and plant design software makes this approach more viable. Having these support devices "pre-engineered" and documented allows for the inserting of the item's specific electronic symbol required for model generation and document (plans, elevations and isometrics) extraction.
Secondary pipe support devices
(Item name, purpose and frequency of use)Name Purpose Frequency
Anchors Prevent the movement of the pipe line normally in a pipe rack High
Base Anchors Prevent any movement of a piping assembly normally at grade Low
Base Guides Allows only vertical movement (up or down) of piping assemblies at grade Low
Base Supports Provides support under piping assemblies normally at grade High
Cradles Provides protection for cold insulation when crossings a pipe support in pipe racks High for cold service
Directional Anchor Restricts the movement of a pipe line to a specific direction pipe racks High
Dummy Support Legs Provides added length to a pipeline for the purpose of support. Not restricted to only pipe rack usage High
Field Supports A catchall term sometimes used by a piping designer that includes any type of non-infrastructure support.
These items are not location specific. High
Guides Provides restraint to keep a pipe line in place in horizontal pipe racks or vertical pipe racks
in buildings or up tall equipment High
Gussets Provides added reinforcement for small (fragile) branch connections on a larger header or pipe See note #1
Hanger Rods A wide verity of top-down pipe supports situations, not location specific. High
Hold Downs Prevents or controls mechanical vibration in piping systems. See note #2
Load Distribution Pads Provides additional mass for thin wall pipe at a point of concentrated stress loading.
This item is not location specific. Low
Pick-ups Provides support of pipes from other pipes or overhead beams and is not location specific. Moderate
Shoes Provides "mini-supports for lines with hot insulation normally only used only at pipe support points High
Trunnions Provides load-carrying points for vertical pipelines most often used to support pipes attached to tall vertical
vessels or hung from tall structures. Low
Note #1 - This item is normally used only for (a) services subject to heavy vibration such as at reciprocating compressors or (b) services that contain highly hazardous or toxic material.
Note #2 - This item is normally only used for the suction and discharge piping at reciprocating compressors.
Now, lets look at and discuss each of these "miscellaneous" or "pre-engineered" devices. The description for these items is based on my own experience. Others will no doubt have other and even better ways. Everyone is encouraged to create "a better mouse trap."
Anchors
The anchoring of a pipe in place can be achieved in a number of ways. An anchor will normally require some additional material regardless of the line size. You cannot just weld a pipe to a pipe support. For some small lines in the right situations you can use "U" bolts over the pipe (tack-welded to the pipe) and through-bolted to a bare steel pipe support. Another way for small line sizes (2" and 3") uses 1-1/2" angle iron 6" long. Weld one leg of the angle iron (horizontal) flat to the top of the pipe support with the other (vertical) leg against the pipe. Stitch weld (1" fillet weld on 5" centers) to the vertical leg to the pipe. For larger lines use a pipe guide to restrain the side-to-side movement and add a piece of steel ("T" or channel) to the bottom of the pipe (or shoe) at the pipe support to restrict longitudinal. Anchors will be required for both bare (uninsulated) pipe and insulated pipe. The requirements for anchors for cold insulated and hot insulated pipe is different.
Base Anchors
This will occur most often at control valve manifolds (or stations) situated close to grade or a platform. Base anchors are simply a stub of pipe (dummy leg) attached to the lower portion of an elbow and extended to grade (or platform). A square steel plate is welded flat to the pipe. The plate may have holes in it and be cinch-anchored to the paving or welded to platform steel. The sizing of the "pipe leg" can be the same as for Dummy Legs.
Base Guides
This item is constructed of the material and methods as the base anchor except that the bottom plate is not bolted or welded down. For this item angle iron strips are installed on two opposite sides (depending on desired movement) to control the direction.
Base Supports
This is another name for one of the items that sometimes falls under the name Field Support. This item also has a dummy leg type pipe extension (or stub) welded down from an elbow. However, the bottom end if the stub is threaded using a straight (conduit) thread machine. A straight thread, conduit coupling in then used to make height adjustments to the support. When this is required for high cost piping materials that require post weld heat treating the stub is shortened and added in the shop. The balance of the stub is added in the field from carbon steel. Another variation of this is restricted to small diameter piping. For this a 3'-0" (1 meter) length of 3"x3" steel angle is welded to a 6"x6" plate. Holes are drilled in the angle at the proper elevation and a "U" bolt secures the pipe to the angle.
Cradles
This device is normally fabricated from carbon steel that is shaped to fit the outside diameter of cold insulation. The potential number of sizes for this item can be vast. The sizing requirements are based on (a) the pipe size, (b) the insulation thickness, (c) the load bearing capability of the insulation, (d) the length of the required cradle and (e) the thickness of the cradle material. The pipe size, the insulation thickness and the load bearing capability should be easy to understand. The length if the cradle is influenced by questions such as: Does this line require an anchor at this cradle? What kind of pipe supports do we have at the point of this cradle? How much thermal movement will this line "see" at the point of this cradle? All of these items effect the cradle length. If there is to be an anchor at this cradle and the forces are substantial then the cradle thickness may need to be increased.
Directional Anchor
This item could also be called a Directional Guide and is most often associated with hot piping. This item is designed to allow for thermal movement in a specific axis. The design may require longitudinal movement or it may require side-to-side movement of a line. This item has two versions, one for longitudinal movement and a second for the side-to-side movement. Remember this most often occurs in hot piping. Hot piping also requires shoes to elevate the line and the insulation above the pipe support. So we have a pipe, a hot pipe, already on a shoe. Now, to allow for longitudinal movement we simply add (weld) Guides to the top (steel) surface of the pipe support. To allow for side-to-side movement in the pipe we DO NOT ADD GUIDES. We add two pieces piece of steel ("T" or channel) to the bottom of the pipe shoe, one on each side of the pipe support with a small (1/4") gap to avoid binding.
Dummy Support Legs - (or Dummy Legs)
This is simply a piece of pipe extended from an elbow to provide support when a pipe line enters or leaves a pipe rack short of a support and is left improperly support. A stub or length of pipe sized to carry the load is welded to the elbow and extended beyond the support. The length and the wall schedule of the pipe extension are a rather complex formula based on the parent line size and the total load. The total load is based on the distance (indirection of flow) from the last support to the drop, the distance of the drop, the distance from the drop to the next support, the weight of any insulation plus the weight of the hydrotest water or commodity which ever is greater.
Field Supports
This "catch-all" term is used to describe a simple piece of steel angle or channel welded to a column or beam intended to provide a support point for a pipe. As mentioned above (Base Support), this term is also used for the support under control valve stations and pump suction or discharge piping.
(The term "Field Support" (or F.S.) is seen on old drawings from existing plants of years ago. It was used on drawings with only a simple symbol indicating a location. This may have occurred when the piper got lazy or did not know enough about pipe supports. The intention was for the installation contractor "Field" to do what ever they chose to do with whatever material that was available.)
Guides
Guides are predominantly in elevated pipe racks or sleepers to keep the pipes in their assigned berth. Guides are most often short lengths of properly sized steel angle welded to the pipe support on each side of each pipe. For small lines using small angle the angle is installed with the point up, like a pyramid. For larger uninsulated lines with larger angle one leg of the angle is flat on the support and the other is vertical. For the installations of guides care must be taken by thew installers to leave a small gap between the pipe and the angle to avoid binding. Because of the close spacing of the pipes in a rack guides are attached to alternate pipe bents in staggered fashion.
Gussets
This is a simple piece of angle steel welded or clamped to a header pipe and to a (small) branch to prevent breakage due to vibration or other action. There are some locations and services where the use of gussets is highly recommended.
These are:
1. Suction and discharge piping of reciprocating compressors and pumps
2. Lines in mixed phase flow subject to slug flow or surge
3. Lines in hydrogen service
4. Lines in toxic service (category "X" or "M")
5. Branches in piping low to grade (or platforms) that may be used as a step by operators
Hanger Rods
These devices are one of the most dangerous items used in the piping field. In many if not most cases they are not properly "designed". Hanger Rods, Rod Hangers and Pipe Hangers all terms for the same device. There are three basic types of Hanger support devices: (type 1) beam-to-pipe, (type 2) pipe-to-pipe and (type 3) beam-to-beam (or trapeze). In general they all have three components, a top connection component, a connector component and a bottom component. For the type 1 Hanger the top component normally connects to a structural beam. The connector component is normally steel rod. The bottom component is normally a pipe clamp. For the type 2 Hanger the top component is also a pipe clamp. Other components are the same as type 1. For the type 3 Hanger there are two top connector components and two connector rods. The bottom component is a piece of steel angle or channel sized to span the distance and carry the intended load.
The danger with the design of these items is in the lack of knowledge of the people doing the design. They do not know how to calculate all the actual dead and live loading that the Hanger will support. Then they choose the wrong type or strength of component for the intended load.
Hold-Downs
These items are a combination of clevises, steel shapes, bolts and compression washers. The are used to hold down the piping on the suction and discharge of reciprocating compressors and pumps. Normally this type of piping is low to the ground and supported on sleepers. The hold-down is a bridge assembly over the pipe and welded to the sleeper steel plate. The combination of clevises, steel shapes bolts and compression washers exert tension on the pipe to suppress vibration.
Load Distribution Pads
This is simply a 120 degree section of pipe about 18" long. The Pad is cut from the same material as the subject line. The Pad is opened up a little to fit the pipe O. D. and then welded to the pipe at the required location.
Pick-ups
This is a set of devices used to provide intermediate support for small diameter piping that will not span the existing distance. Its use is normally restricted to locations where the small size pipelines run parallel to one or more large diameter pipelines. This is also used to save the cost in time and material from adding a formal (primary) structural pipe support. This is simply a length of properly sized, steel angle and one or more "U" bolts. The angle is cut long enough to span under both the supported and the supporting lines. The "U" bolts are sized based on the large pipes that will be doing the supporting.
Shoes
This device is required to raise a hot insulated off the structural support surface. The reason for this is to prevent damage to the insulation as the pipe expands as it heats up and shrinks as it cools down. For pipe sizes 3" thru 10" a simple inverted "T" shoe with a flat bottom plate and one (single) vertical plate should be used. For pipe sizes 12" thru 18" a shoe with a flat bottom plate and two (double) vertical plates should be used. For pipe sizes 20" and larger consideration should be given to the addition of a Load Distribution Plate (see above) where thin wall pipe may exist. The material for pipe shoes will normally be carbon steel. However, where the pipeline is an exotic material this would cause a weld of dissimilar metals to exist where the shoe is attached to the pipe. For shoes used on exotic materials only the bottom plate is carbon steel. The (single or double) vertical plates are made of the same material as the pipe. For piping that requires post weld heat treating (PWHT) after fabrication the shoes must be added by the shop. Some company's (engineering and client) will also require the use of shoes (with the Load Distribution Pad) for all uninsulated 24" and larger piping where the pipe wall is below a certain limit.
Trunnions
For this device a vertical pipeline will have two (2) stub pipes attached horizontally to opposite sides of the pipe. One end of these stub pipes is shaped to fit the O.D. of the vertical pipe the other end is normally square cut. The shaped end of the stubs are welded to the vertical pipe with a full penetration (*) fillet weld. When used on a pipe attached to and supported from a vertical vessel the vessel department supplies the primary support. Coordination of size, type, elevation, orientation, etc. between the piping designer and the vessel group is required. When used on a pipe attached to and supported from a vertical structure the structural department supplies the primary support. Coordination of size, type, elevation, location, etc. between the piping designer and the structural group is required.
(*) This full penetration refers to the wall thickness of only the stub pipes not the vertical pipe.
The recommended practice for all of these secondary pipe support devices is to determine what is needed. Start out with items that are found to have consistent and repetitive use within the company's past projects. Document each device complete with parts list and installation instructions. (Documenting also includes the updates required for any electronic design system database, AutoCAD, PDS, PDMS or other) Qualify each device by the specific use criteria based on pipe size, load limitations and application. Define the selection criteria for each based on the qualification criteria. Then train all the piping designers, stress engineers, material group and construction contractors on the responsibility, purpose, use, application and limitations.
What about responsibility? Who is responsible for pipe supports or the supporting of the piping? Some may say, "That it is the structural groups responsibility." That is only partly true. They are only responsible for providing a support of the size; shape and strength based on information given to them. If nobody tells them to put a pipe support (of a specific size, shape and loading) in a specific location they are not going to do it. So, who is responsible for doing the telling? The piping designer is responsible for the piping, which means all the piping and all aspects of all the piping. The piping designer is responsible for telling the structural group what is required for all primary pipe support systems. And, the piping designer is also responsible for telling the structural group when a secondary pipe support device will be attached to and impose a load on a structural member.
There are of course other opinions on this subject and there are no doubt questions and more that can be discussed. The other opinions I will warmly accept. And, as for the questions, please ask. If you don't ask you will never give others a chance to offer answers.
Pipe Supports, Part - B, Will discuss data requirements and the process for the selection and qualification of typical pipe supports.
By: James O. Pennock
The subject, "Pipe Supports" is a much more complex subject than the term suggests. There are so many situations that a pipe can find itself in and in every case it will need to be supported. Pipe supports is a general term that actually is split into two families. There is what I call the primary pipe support systems, and then there are the secondary pipe support systems.
The primary pipe supports systems are those supports that are a part of the infrastructure and fall under the prime responsibility of the structural department. The secondary pipe support systems are more a part of the piping systems and as such fall under the prime responsibility of the piping department. You notice I used the words 'prime responsibility' with each of these there is still a cross over responsibility to provide proper, accurate and timely information and then action.
Primary Pipe Support Systems
As noted above the primary pipe supports are a part of the infrastructure. This is true of most all projects. For simplicity the emphasis here will focus on "Grass Root" or new construction plants. These primary pipe supports systems may also be referred to as piperacks, pipeways, pipe alleys. These support systems may be major or minor and they may be overhead or sleeper pipe racks. It is important to understand that even though they are called pipe racks they support and carry more than just piping. These other items may include the cables for electrical and instrumentation services.
For clarification, overhead pipe racks are elevated to the point where you can walk and/or drive under the supported piping. Sleepers or sleeper ways are low to the ground so there is no passage under the supported piping.
Pipe racks (overhead or sleeper) are normally established and sized early in the preliminary engineering phase of a project. This time of the project is normally called the plant development phase or the plot plan development phase. Once they are established and sized they are one of the first things the structural department can work on. The terms 'establish' and 'size' requires a lot of wisdom and work.
The wisdom and work means thinking one, two or three years into the future and deciding where (location) the primary pipe support systems will run. Other critical elements include the configuration, height, width, spacing and the materials of construction/fabrication method. Let's take these elements one at a time.
» Location - In order to set the location of the primary pipe support systems the total plant layout must be established. This means that all the various disciplines must have a very good idea what equipment is required and it's size. The "Plot Plan" must be reviewed by all the key people on the project and then approved by the client.
» Configuration - This is the selection of "fit-for-purpose." Each main run, minor run and branch run must be looked at to determine its configuration. Will it be an overhead rack or a sleeper way? Will each be single deck (layer) or multiple deck? Will the support be a single column ("T") support or multi-column support? How many columns? A second part of the configuration issue effects pipe racks in the process units themselves. This is the question of whether or not the pipe rack will support equipment such as Air Coolers (Fin Fans). Another part of configuration is the issue of intersections. Poor planning on this issue can cause problems later with the piping.
» Height - How high should each run of rack be? Should they be elevated or low sleepers. The sleepers are concrete with an imbedded steel plate on the top. For sleepers, they need to be off the ground to allow for maintenance and drainage also to prevent corrosion. For elevated multi-level racks what should the separation be? For elevated racks you must plan the height and the separation of the whole system together. A key element in the determination of separation is the line sizes to be carried on the racks.
» Width - This requires a detailed study of the total piping systems for the whole plant based on pipe rack routing. In the past, a study (called a "Transposition") was done to, as best you could, account for each line on each pipe rack. From this study, a berth sequence was established and the line spacing set. A percentage was added as an error factor and then the clients "future" reserve was added. This then constituted the minimum rack width. The final width would be set after all racks were "sized" and then some might be rounded up in width for consistence based on the materials of construction/fabrication method.
» Spacing - This issue can be addressed after the transposition has been completed. The transposition identifies all the rack piping from the largest to the smallest From this the average line size for each leg of the rack system can be established. With the pipe size information (largest, smallest and average pipe size) the number and spacing of the pipe support bents can be set. A cost tradeoff is evaluated and made between more pipe supports spaced closer together or fewer pipe supports and some sort of intermediate support system.
» Materials of construction/fabrication method - What materials are the pipe racks to be made of and what will be the fabrication method? Pipe racks can be bare steel, steel w/a concrete encasement (fireproofing), reinforced concrete or a combination. The steel can be steel structural shapes or pipe shape. The concrete fireproofing can be cast in place onto (or around) the steel columns and beams or it can be pre-cast onto the columns and beams prior to installation. The reinforced concrete pipe supports can also be cast in place or pre-cast then field erected. The space requirement dimensions for a reinforced concrete column or beam is about twice that of bare steel.
The piping design group on the project (at the company where I came from) was the lead group in all of the above issues except the last one, materials of construction/fabrication method. This issue was properly the responsibility of the structural department, construction and the client. There is no doubt that economics, the jobsite location, labor and material availability played a part. Piping, however must know what the materials of construction/fabrication method will be because it can affect one or more of the other issues.
Secondary Pipe Support Systems
The secondary pipe support systems are a broad family of devices with two branches and actually include more than just supports. The two branches are defined as (a) "engineered" devices and (b) "miscellaneous" pipe support devices.
The term "engineered" pipe supports relates to devices that are non-static, one-of-a-kind, location and condition specific. They are identified at the time the need is recognized and then designed and engineered for that specific need. Constant support spring hangers and snubbers are just two of the devices in this category. The piping stress engineer is the party/person who is responsible for the engineering of these. However, the piping designer working in the specific area has a shared responsibility.
The term "miscellaneous" pipe support refers to a broad array of devices that includes items such as Anchors, Base Supports, Cradles, Dummy Support Legs, Guides, Hanger Rods, Pick-ups, Shoes, Trunnions, etc. All companies have their own operating methods and may not use a different approach to miscellaneous pipe support devices. Some may allow each piping designer to pick and choose pieces and parts from various catalogs to design their own pipe supports. Others may use a more organizational approach and "pre-engineer" these supports.
The term "pre-engineer" means that the various devices are an existing company standard that may be used on the project. Secondary support devices typically have multiple or repetitive point of use subject to similar conditions. Having these devices "pre-engineered" and available to the piping designer on the project saves money, provides consistency of design, and results in a safer design. The configurations, hardware and materials have already been established, the load calculations have been performed (and are on file). There is also an "If-then" selection key and criteria established (If you have "X" support problem, then you can/must use "Y" support device). The extensive use of computers and plant design software makes this approach more viable. Having these support devices "pre-engineered" and documented allows for the inserting of the item's specific electronic symbol required for model generation and document (plans, elevations and isometrics) extraction.
Secondary pipe support devices
(Item name, purpose and frequency of use)Name Purpose Frequency
Anchors Prevent the movement of the pipe line normally in a pipe rack High
Base Anchors Prevent any movement of a piping assembly normally at grade Low
Base Guides Allows only vertical movement (up or down) of piping assemblies at grade Low
Base Supports Provides support under piping assemblies normally at grade High
Cradles Provides protection for cold insulation when crossings a pipe support in pipe racks High for cold service
Directional Anchor Restricts the movement of a pipe line to a specific direction pipe racks High
Dummy Support Legs Provides added length to a pipeline for the purpose of support. Not restricted to only pipe rack usage High
Field Supports A catchall term sometimes used by a piping designer that includes any type of non-infrastructure support.
These items are not location specific. High
Guides Provides restraint to keep a pipe line in place in horizontal pipe racks or vertical pipe racks
in buildings or up tall equipment High
Gussets Provides added reinforcement for small (fragile) branch connections on a larger header or pipe See note #1
Hanger Rods A wide verity of top-down pipe supports situations, not location specific. High
Hold Downs Prevents or controls mechanical vibration in piping systems. See note #2
Load Distribution Pads Provides additional mass for thin wall pipe at a point of concentrated stress loading.
This item is not location specific. Low
Pick-ups Provides support of pipes from other pipes or overhead beams and is not location specific. Moderate
Shoes Provides "mini-supports for lines with hot insulation normally only used only at pipe support points High
Trunnions Provides load-carrying points for vertical pipelines most often used to support pipes attached to tall vertical
vessels or hung from tall structures. Low
Note #1 - This item is normally used only for (a) services subject to heavy vibration such as at reciprocating compressors or (b) services that contain highly hazardous or toxic material.
Note #2 - This item is normally only used for the suction and discharge piping at reciprocating compressors.
Now, lets look at and discuss each of these "miscellaneous" or "pre-engineered" devices. The description for these items is based on my own experience. Others will no doubt have other and even better ways. Everyone is encouraged to create "a better mouse trap."
Anchors
The anchoring of a pipe in place can be achieved in a number of ways. An anchor will normally require some additional material regardless of the line size. You cannot just weld a pipe to a pipe support. For some small lines in the right situations you can use "U" bolts over the pipe (tack-welded to the pipe) and through-bolted to a bare steel pipe support. Another way for small line sizes (2" and 3") uses 1-1/2" angle iron 6" long. Weld one leg of the angle iron (horizontal) flat to the top of the pipe support with the other (vertical) leg against the pipe. Stitch weld (1" fillet weld on 5" centers) to the vertical leg to the pipe. For larger lines use a pipe guide to restrain the side-to-side movement and add a piece of steel ("T" or channel) to the bottom of the pipe (or shoe) at the pipe support to restrict longitudinal. Anchors will be required for both bare (uninsulated) pipe and insulated pipe. The requirements for anchors for cold insulated and hot insulated pipe is different.
Base Anchors
This will occur most often at control valve manifolds (or stations) situated close to grade or a platform. Base anchors are simply a stub of pipe (dummy leg) attached to the lower portion of an elbow and extended to grade (or platform). A square steel plate is welded flat to the pipe. The plate may have holes in it and be cinch-anchored to the paving or welded to platform steel. The sizing of the "pipe leg" can be the same as for Dummy Legs.
Base Guides
This item is constructed of the material and methods as the base anchor except that the bottom plate is not bolted or welded down. For this item angle iron strips are installed on two opposite sides (depending on desired movement) to control the direction.
Base Supports
This is another name for one of the items that sometimes falls under the name Field Support. This item also has a dummy leg type pipe extension (or stub) welded down from an elbow. However, the bottom end if the stub is threaded using a straight (conduit) thread machine. A straight thread, conduit coupling in then used to make height adjustments to the support. When this is required for high cost piping materials that require post weld heat treating the stub is shortened and added in the shop. The balance of the stub is added in the field from carbon steel. Another variation of this is restricted to small diameter piping. For this a 3'-0" (1 meter) length of 3"x3" steel angle is welded to a 6"x6" plate. Holes are drilled in the angle at the proper elevation and a "U" bolt secures the pipe to the angle.
Cradles
This device is normally fabricated from carbon steel that is shaped to fit the outside diameter of cold insulation. The potential number of sizes for this item can be vast. The sizing requirements are based on (a) the pipe size, (b) the insulation thickness, (c) the load bearing capability of the insulation, (d) the length of the required cradle and (e) the thickness of the cradle material. The pipe size, the insulation thickness and the load bearing capability should be easy to understand. The length if the cradle is influenced by questions such as: Does this line require an anchor at this cradle? What kind of pipe supports do we have at the point of this cradle? How much thermal movement will this line "see" at the point of this cradle? All of these items effect the cradle length. If there is to be an anchor at this cradle and the forces are substantial then the cradle thickness may need to be increased.
Directional Anchor
This item could also be called a Directional Guide and is most often associated with hot piping. This item is designed to allow for thermal movement in a specific axis. The design may require longitudinal movement or it may require side-to-side movement of a line. This item has two versions, one for longitudinal movement and a second for the side-to-side movement. Remember this most often occurs in hot piping. Hot piping also requires shoes to elevate the line and the insulation above the pipe support. So we have a pipe, a hot pipe, already on a shoe. Now, to allow for longitudinal movement we simply add (weld) Guides to the top (steel) surface of the pipe support. To allow for side-to-side movement in the pipe we DO NOT ADD GUIDES. We add two pieces piece of steel ("T" or channel) to the bottom of the pipe shoe, one on each side of the pipe support with a small (1/4") gap to avoid binding.
Dummy Support Legs - (or Dummy Legs)
This is simply a piece of pipe extended from an elbow to provide support when a pipe line enters or leaves a pipe rack short of a support and is left improperly support. A stub or length of pipe sized to carry the load is welded to the elbow and extended beyond the support. The length and the wall schedule of the pipe extension are a rather complex formula based on the parent line size and the total load. The total load is based on the distance (indirection of flow) from the last support to the drop, the distance of the drop, the distance from the drop to the next support, the weight of any insulation plus the weight of the hydrotest water or commodity which ever is greater.
Field Supports
This "catch-all" term is used to describe a simple piece of steel angle or channel welded to a column or beam intended to provide a support point for a pipe. As mentioned above (Base Support), this term is also used for the support under control valve stations and pump suction or discharge piping.
(The term "Field Support" (or F.S.) is seen on old drawings from existing plants of years ago. It was used on drawings with only a simple symbol indicating a location. This may have occurred when the piper got lazy or did not know enough about pipe supports. The intention was for the installation contractor "Field" to do what ever they chose to do with whatever material that was available.)
Guides
Guides are predominantly in elevated pipe racks or sleepers to keep the pipes in their assigned berth. Guides are most often short lengths of properly sized steel angle welded to the pipe support on each side of each pipe. For small lines using small angle the angle is installed with the point up, like a pyramid. For larger uninsulated lines with larger angle one leg of the angle is flat on the support and the other is vertical. For the installations of guides care must be taken by thew installers to leave a small gap between the pipe and the angle to avoid binding. Because of the close spacing of the pipes in a rack guides are attached to alternate pipe bents in staggered fashion.
Gussets
This is a simple piece of angle steel welded or clamped to a header pipe and to a (small) branch to prevent breakage due to vibration or other action. There are some locations and services where the use of gussets is highly recommended.
These are:
1. Suction and discharge piping of reciprocating compressors and pumps
2. Lines in mixed phase flow subject to slug flow or surge
3. Lines in hydrogen service
4. Lines in toxic service (category "X" or "M")
5. Branches in piping low to grade (or platforms) that may be used as a step by operators
Hanger Rods
These devices are one of the most dangerous items used in the piping field. In many if not most cases they are not properly "designed". Hanger Rods, Rod Hangers and Pipe Hangers all terms for the same device. There are three basic types of Hanger support devices: (type 1) beam-to-pipe, (type 2) pipe-to-pipe and (type 3) beam-to-beam (or trapeze). In general they all have three components, a top connection component, a connector component and a bottom component. For the type 1 Hanger the top component normally connects to a structural beam. The connector component is normally steel rod. The bottom component is normally a pipe clamp. For the type 2 Hanger the top component is also a pipe clamp. Other components are the same as type 1. For the type 3 Hanger there are two top connector components and two connector rods. The bottom component is a piece of steel angle or channel sized to span the distance and carry the intended load.
The danger with the design of these items is in the lack of knowledge of the people doing the design. They do not know how to calculate all the actual dead and live loading that the Hanger will support. Then they choose the wrong type or strength of component for the intended load.
Hold-Downs
These items are a combination of clevises, steel shapes, bolts and compression washers. The are used to hold down the piping on the suction and discharge of reciprocating compressors and pumps. Normally this type of piping is low to the ground and supported on sleepers. The hold-down is a bridge assembly over the pipe and welded to the sleeper steel plate. The combination of clevises, steel shapes bolts and compression washers exert tension on the pipe to suppress vibration.
Load Distribution Pads
This is simply a 120 degree section of pipe about 18" long. The Pad is cut from the same material as the subject line. The Pad is opened up a little to fit the pipe O. D. and then welded to the pipe at the required location.
Pick-ups
This is a set of devices used to provide intermediate support for small diameter piping that will not span the existing distance. Its use is normally restricted to locations where the small size pipelines run parallel to one or more large diameter pipelines. This is also used to save the cost in time and material from adding a formal (primary) structural pipe support. This is simply a length of properly sized, steel angle and one or more "U" bolts. The angle is cut long enough to span under both the supported and the supporting lines. The "U" bolts are sized based on the large pipes that will be doing the supporting.
Shoes
This device is required to raise a hot insulated off the structural support surface. The reason for this is to prevent damage to the insulation as the pipe expands as it heats up and shrinks as it cools down. For pipe sizes 3" thru 10" a simple inverted "T" shoe with a flat bottom plate and one (single) vertical plate should be used. For pipe sizes 12" thru 18" a shoe with a flat bottom plate and two (double) vertical plates should be used. For pipe sizes 20" and larger consideration should be given to the addition of a Load Distribution Plate (see above) where thin wall pipe may exist. The material for pipe shoes will normally be carbon steel. However, where the pipeline is an exotic material this would cause a weld of dissimilar metals to exist where the shoe is attached to the pipe. For shoes used on exotic materials only the bottom plate is carbon steel. The (single or double) vertical plates are made of the same material as the pipe. For piping that requires post weld heat treating (PWHT) after fabrication the shoes must be added by the shop. Some company's (engineering and client) will also require the use of shoes (with the Load Distribution Pad) for all uninsulated 24" and larger piping where the pipe wall is below a certain limit.
Trunnions
For this device a vertical pipeline will have two (2) stub pipes attached horizontally to opposite sides of the pipe. One end of these stub pipes is shaped to fit the O.D. of the vertical pipe the other end is normally square cut. The shaped end of the stubs are welded to the vertical pipe with a full penetration (*) fillet weld. When used on a pipe attached to and supported from a vertical vessel the vessel department supplies the primary support. Coordination of size, type, elevation, orientation, etc. between the piping designer and the vessel group is required. When used on a pipe attached to and supported from a vertical structure the structural department supplies the primary support. Coordination of size, type, elevation, location, etc. between the piping designer and the structural group is required.
(*) This full penetration refers to the wall thickness of only the stub pipes not the vertical pipe.
The recommended practice for all of these secondary pipe support devices is to determine what is needed. Start out with items that are found to have consistent and repetitive use within the company's past projects. Document each device complete with parts list and installation instructions. (Documenting also includes the updates required for any electronic design system database, AutoCAD, PDS, PDMS or other) Qualify each device by the specific use criteria based on pipe size, load limitations and application. Define the selection criteria for each based on the qualification criteria. Then train all the piping designers, stress engineers, material group and construction contractors on the responsibility, purpose, use, application and limitations.
What about responsibility? Who is responsible for pipe supports or the supporting of the piping? Some may say, "That it is the structural groups responsibility." That is only partly true. They are only responsible for providing a support of the size; shape and strength based on information given to them. If nobody tells them to put a pipe support (of a specific size, shape and loading) in a specific location they are not going to do it. So, who is responsible for doing the telling? The piping designer is responsible for the piping, which means all the piping and all aspects of all the piping. The piping designer is responsible for telling the structural group what is required for all primary pipe support systems. And, the piping designer is also responsible for telling the structural group when a secondary pipe support device will be attached to and impose a load on a structural member.
There are of course other opinions on this subject and there are no doubt questions and more that can be discussed. The other opinions I will warmly accept. And, as for the questions, please ask. If you don't ask you will never give others a chance to offer answers.
Pipe Supports, Part - B, Will discuss data requirements and the process for the selection and qualification of typical pipe supports.
Pipe Supports
Section III - Pipe Supports
A. Pipe Supports - Part 1, By: James O. Pennock
This is a discussion about the two basic categories of pipe supports (the primary pipe support systems, and the secondary pipe support systems).
B. Pipe Supports - Part 2, By: James O. Pennock
This is a discussion about the data requirements and the process of selection and qualification for the typical secondary pipe supports.
A. Pipe Supports - Part 1, By: James O. Pennock
This is a discussion about the two basic categories of pipe supports (the primary pipe support systems, and the secondary pipe support systems).
B. Pipe Supports - Part 2, By: James O. Pennock
This is a discussion about the data requirements and the process of selection and qualification for the typical secondary pipe supports.
Vertical Vessel Orientation
C-II: Vertical Vessel Orientation
By: James O. Pennock
The following article was prompted by questions from a young piping designer. He wrote:
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Hi
I am getting ready to do my first vessel nozzle orientation. The vessel is a Stripper Tower (a). Can you help me? First, what are the things I have to take into consideration? Second, what are the key steps in the process for doing a vessel nozzle orientation?
Regards
XXXXXXXXXXXX
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(a)The name/function of the vessel has been changed.
For your first question: "What are the things I have to take into consideration?"
The answer to this question is very simple; you must take everything in to consideration. Everything is important! Someone may tell you that some things do not matter but this is not true, everything matters.
You need to consider the following:
a) Timing: Vessel orientation is normally the only equipment related layout activity that can be done without specific input from a vendor. All of the information required for vessel orientation is generated on the project in the form of P&ID data and project standards. It is also one of the few activities that will feed one or more other downstream groups whose work is critical to the project schedule. With this in mind this activity can and should be started as soon as the P&ID reaches "Approved-For-Design" (AFD) status. Te vessel orientation activity can be started manually or on basic 2D CAD before the 3D PDS data base is fully loaded and checked. There is some logic to doing this activity manually or in 2D CAD because of the amount of trial and error required to finally achieve an acceptable and approved orientation. Once the orientation is approved and the PDS data base is ready the 3D model can be built with no recycle.
b) The Plot Plan (Note 1): The plot plan is required to identify the location of the vessel and its related equipment. The related equipment includes the equipment that feeds the vessel (is up-stream) and also the equipment that the vessel feeds (is down-stream). It shows and locates adjacent, non-related equipment. It also shows adjacent structures that may support the related up-stream or down-stream equipment. It also indicates the plant features such as pipe racks, operating aisles, maintenance access areas and the direction of Plant North.
c) The project foundation criteria: Vertical vessels normally sit on an octagon pad foundation with the top of grout at EL101' - 0" (high point of finished paving = EL 100' - 0"). You need to have and understand the type and elevation of the foundation for this vessel.
d) The P&ID's (Note 1): The P&ID's are required to show the process streams that connect to the Stripper Tower and its related equipment. In my experience P&ID's are much like the pages in a book. Some equipment (the heater) starts or shows on sheet one P&ID the story continues with the key item (the Stripper Tower, Thermosyphon Reboiler and Bottoms Pumps) showing on sheet two and then continues to some conclusion (the overhead condensers) on sheet three. You will need all three process system P&ID's. The Stripper Tower P&ID will show a graphic of the column along with all the piping connecting to the vessel. There will also be a data block at the top of the page. This data block should include the vessel number, the vessel name and the basic size. It will also indicate the design temperature and the insulation requirements (if any). The graphic of the vessel should also indicate the basic type of internals (Trays or Packing). If the internals are Trays then the number of trays should be indicated. The trays just above or just below where a line is connected should be numbered. If the internals are some form of packing then the extent of the packing beds should be indicated.
e) The project Line List (Note 1): The line List is required to give you specific and critical key data about the lines such as the Line Number, line class, maximum operating temperature and insulation requirements,
f) The project Piping Material Specifications (Note 1): The Piping Material Specifications are required to give you the data about metallurgy and any specifics about fittings, flanges, valves or requirements for PWHT (post weld heat treatment).
g) The Vessel Drawing (Note 2): The vessel drawing at this time will most likely be marked "Preliminary." It will give you; the inside diameter (I.D.), the tangent-to-tangent shell length, the shape of the top and bottom heads and the skirt height. This drawing should also have a table showing all the nozzles with the basic information such as: identification, quantity, and size, flange rating, the elevation above (or below) the bottom tangent line for each nozzle, the purpose for the nozzle and any special instructions. The vessel drawing needs to also indicate where the internals start and end inside the vessel.
h) The Internals (Note 2) (Trays or Packing) A tower can have a number of different types and configurations of internals. It may be Trays or it may be some form of Packing.
- Trays: If you have Trays then you need to know: the number of trays, the spacing of the trays, the number of passes for the trays (1-pass, 2-pass, 3-pass etc.). You also need to know if there are any "draw sumps," baffles or other special features.
- Packing: You need to know the number of "Beds," the depth of the beds and the method of installing and removing the packing material. You also need to know and understand about the type of feed distributor(s) to be used. You need to know about the packing discharge nozzles.
For the purpose of this article we will assume we have 35 single pass trays.
i) The Thermosiphon Reboiler data sheet (Note 1): This will give you the preliminary size and type information. The P&ID indicates that this vessel has a vertical Thermosiphon reboiler fitted to it. Some discussion should normally take place to determine the optimum tube length and the proper support elevation and support method.
j) The project Vessel Platform Standards (Note 1): This will give you the required information about the minimum vertical spacing between platforms. It will also give you specific details about platform supports and how to make the openings where pipes must pass through a platform. This drawing will (or should) also give you specifics about handrails.
k) The project Vessel Ladder Standards (Note 1): This drawing will give you all the required information about ladder construction and more important the limits for the maximum vertical run for a single ladder.
l) The project Vessel Nozzle Standards (Note 1): This will give you all the normal options for un-reinforced and reinforced nozzles. It may also show you some options for internal nozzle piping.
m) The project Vessel Davit Standards (Note 1): A davit is a small device permanently mounted on the vessel that acts as a crane for lifting heavy objects such as tray sections.
n) The project Vessel Pipe Support and Guide Standards (Note 1): These are devices attached to a vessel that support and/or guide the vertical runs of pipe. This drawing also defines the minimum distance from the outside of a vessel shell to the back of an adjacent pipe. Where I came from this was called the "L" dimension. The "L" dimension was normally 12" (adjusted as required for insulation) The maximum was 20" without a special design. The key was to have a minimum of 7" clear between two co-existing insulations. These supports and guides also require a wider than normal line spacing in the vertical plane as the lines go up or down a vessel. This is mainly due to the configuration of the Trunnion (Note 3) support attached to the pipe and the pipe clamp used for the guide.
o) The project Piping and Vessel Insulation Specification (Note 1): From this document you will get the thickness of the insulation needed for the pipes and vessel at the operating temperature.
(Note 1): These items are normally created by your company for the project and should be "Approved for Design" (AFD) quality documents. This means that they have been through all of the proper in-house reviews and checks and have then been approved by the Company and the Client for use in the design of the work.
(Note 2): These documents will initially come from the project Vessel Engineer. They will normally be marked "Preliminary" until they receive and process your orientation drawings. Later you may receive the vessel fabricator's detail drawings for "Squad Check" (review and approval).
(Note 3) For more information about a Trunnion support see www.pipingdesigners.com look under Training and Secondary Pipe Supports
There may be other documents that are required due to a specific company's method of operation.
The next things you need to consider is; functionality, safety, operation, maintenance and constructability.
Functionality: No matter what, this vessel must do its job. You must know and understand what that intended job is. You do not need to be a process engineer but you should be involved in the review of the P&ID for this specific vessel. You need to hear what the critical issues are relating to this vessel and the connected piping. If your company does not include piping in the formal review of the P&ID's then you need to seek out the process engineer and ask him or her to explain the function, key points and any critical issues relating to this vessel.
Safety: This is the other important issue relating to vessel orientation. The operation must be able to be done in a safe manner. The same must be said for both maintenance and constructability. To achieve this goal the locations of nozzles relative to the placement and arrangement of the ladders and platforms must be carefully considered. The travel path (access and egress) must be arranged so the main travel path cannot be blocked by open manholes, scaffolding, tools, tray parts, valves or piping. The basic rule here; a: ladder #1 comes up with a side step-off (right or left) on to platform #1. Then b: there is a minimum rest space equal to one ladder width. Then c: the next ladder (#2) continues up to the next platform. Platform #1 can continue beyond ladder #2 around the vessel to provide access to nozzles and manholes. This arrangement does not impede or obstruct the clear path for rapid escape from the vessel for anyone from a higher elevation. Other safety issues include one or more skirt access openings located near grade which should be located with clear access. There will also be four or more skirt vents located high near the skirt-to-vessel attachment which also should not be blocked.
Operation: Process plants need to be operated. Most operation is concentrated around valves and instruments. These items must be accessible. Accessible means reachable. This reachable is conditional. Nozzles with a nominal size of 2' (NPS) and smaller can be reachable from a ladder or from a platform. Nozzles 3" (NPS) and larger shall be reachable on a platform. In this context the from means that the object is not more than 18" (one arms length) from the ladder or platform and the on means the object must be fully inside the platform. There is normally only one exception to this rule. That is for valves or nozzles that are located less than 20 feet from grade and can be accessed with scaffolding or a "Man-Lift".
Maintenance: All the accessibility issues that apply for operations also apply for maintenance. In addition don't block access to manholes with control valve assemblies or other piping. Make sure the Electrical and Instrument people don't locate a panel or a transmitter assembly in the operations or maintenance access ways.
Constructability: This vessel needs to be erected and therefore it will need Lifting Lugs. These are normally very large steel shapes with "eyes" welded to the top head. They will normally not interfere with your orientation, however you should check to make sure.
Your second question: "What are the key steps in the process for doing a column nozzle orientation?"
The key steps in the process are:
(You may choose for some reason to do something in a different order, but this is how I think I would do it. It should be noted that I like to be able to have all things numbered from the bottom up. This includes trays, nozzles, ladders, platforms, etc. However, sometimes due to company preference or the tray manufacturer standards the trays are numbered from the top down.)
1. Data collection - Collect a copy of all the drawings listed above. Make a folder file (or a stick file) to keep them in. Mark all the drawings "Stripper Tower Orientation Master" (STOM). This STOM file is your justification for everything you do or did. If anyone has reason to question why you did what you did then you have a file of the source material you based the work on. It is your responsibility to use the proper information and to properly file and incorporate changes from all new revisions when received.
2. P&ID conditioning - Take your STOM P&ID and pick-up any marks from the Project Master copy. From time to time as you work, go back and recheck the Project Master P&ID for any new marks (i.e.: line size changes, additions, deletions, etc.). Study the Stripper Tower and identify all the related equipment and all connecting lines. Study the lines for valves and instrumentation.
3. Plot Plan conditioning - Take the STOM Plot Plan and with a yellow high-lighter identify the Stripper Tower and all the related equipment. Related equipment means that which is directly connected by pipe to the Stripper Tower. I prefer to work with Plant North up or towards the top of the paper (CAD screen). When I do a vessel orientation I consider the pipeway to be in "front" of the vessel. I call the maintenance area the "back" of the vessel or equipment row. For the purpose of my instruction here I am going to assume that 0º is "up" and "up" is north. Maintenance is on the north (back) side and the pipe way is on the south (front) side.
4. Prepare preliminary elevation - Manually or by CAD, create a scale drawing of the vessel elevation (side view) Locate the bottom tangent line and in phantom (dotted line) the bottom head. Accurately locate the top tangent line from the bottom tangent line and draw in the top head. We will assume that this vessel is a skirt supported vessel and that the skirt is 20 ft high. (If not skirt supported then Leg or Lug supported will require optional considerations that we can discuss if applicable.) At the bottom accurately create the skirt (vessel support). Check with the Structural department and find out how high the foundation is for this vessel. Make sure they give you the top of grout (TOG) not just top of concrete. They are not the same. I will assume that the TOG is EL. 101' - 0." Now indicate the high point of finished paving (HPFP). I will assume that the HPFG is EL. 100' - 0." Now from this HPFP line, draw a light line to indicate the projects minimum head clearance.
5. Prepare preliminary plans - Manually or by CAD, create a scale drawing of a number of plan views. The plan views will be where you will do most of your work so make one for each ten feet +/- (3 to 4 meters) of vertical elevation ending with one above and showing the very top platform. These starter plans should have crossed center lines and the actual I.D. of the vessel. (We are using 8' - 0" for this article). Mark the location of Plant North on each mini-plan. Normally plant north is the same as 0 degrees on the vessel shell. East is 90 degrees, South is 180 degrees and all additional orientation is clockwise from north and 0 degrees. Don't worry about the O.D. or the wall thickness. Now, look at the platform drawing and get the clearance from the vessel shell and the inside edge of a platform. Draw a very light circle (different color and/or layer) on each mini-plan to indicate where the inside edge of a platform might be. Now draw another very light circle 3'-0" (1meter +/_) more in diameter to indicate where the outside of a platform might be. These are not real platforms yet they are just guide lines to remind you of platforms as you do other work. Now mark the "Front" (pipeway side) of the vessel and the "Back" (maintenance side) of the vessel.
6. Thermosiphon Reboiler: The Reboiler for our sample vessel has a 42" shell, 24 ft fixed tube (vertical mount) shell and tube exchanger. The shell side is high temperature steam. The tube side is the process fluid from the bottom of the tower which enters at the bottom end of the reboiler. The process vapor exits the top end of the reboiler and returns to the tower below tray #1. The placement and support of the Thermosiphon Reboiler is the next thing we should cover. Because of the plot plan placement of our Stripper Tower the Thermosiphon Reboiler will be mounted directly to the tower at the 270 degree point. It will have a knee braced cantilevered support that is attached to the vessel. The exchanger needs to be supported so the top tube sheet is at the same level as the high liquid level inside the vessel.
7. Bottoms section baffle - Because of the way this vessel works there is a baffle dividing the bottom section of the tower. The baffle can not be on the centerline of the vessel because the reboiler feed nozzle is centered on the bottom head. Therefore the baffle must be offset to miss that nozzle connection. The height of the baffle is the same as the "High Liquid Level." All of the liquid that comes off the downcomer from tray #1 goes into the "large" side of the bottom section. It then goes through the reboiler and returns to the vessel as vapor. Excess liquid from the "large" side overflows the baffle and becomes the "Bottoms" and is drawn off by the bottoms pumps. The connection for the bottoms nozzle "B" is on the "small" side of the baffle.
8. Check for nozzle continuity - Look at the STOM P&ID and the table of nozzles on the vessel drawing. They should match in number and size. In pencil mark each line connecting to the P&ID vessel with the nozzle number from the vessel nozzle table. Do they match in number? Do they match is size? If not, go see the Process Engineer and ask for clarification.
(Sample) Stripper Tower Nozzle Table
The bottom tangent line elevation = 121' - 0"
The top tangent line elevation = 232' - 8"# Name or Function Size (NPT) Rating Dimension (from tangent line) Elevation (plant datum) Comments
V1 Vapor Out 14" 300# RF 113' - 6" 234' - 6"
V2
PSV 6" 300# RF 113' - 6" 234' - 6"
V3 Vent 4" 300# RF 113' - 6" 234' - 6"
R Reflux 6" 300# RF 106' - 6" 227' - 6" w/internal pipe
F Feed 8" 300# RF 73' - 0" 194' - 0" w/internal pipe
B Bottoms 10" 300# RF 7' - 0" 117' - 3"
D1 Drain 6" 300# RF 8' - 0" 116' - 2" nozzle on nozzle B
D2 Drain 6" 300# RF 8' - 2" 115' - 9" nozzle on nozzle N1
N1 Reboiler Feed 14" 300# RF 7' - 0" 116' - 9"
N2 Reboiler Return 16" 300# RF 29' - 3" 150' - 3"
M1 Manhole #1 24" 300# RF 2' - 0" 123' - 0"
M2 Manhole #2 24" 300# RF 73' - 0" 194' - 0"
M3 Manhole #3 24" 300# RF 107' - 0" 228' - 0"
S1 Steam Out 2" 300# RF 0' - 6" 121' - 6"
S2 Steam Out 2" 300# RF 71' - 6" 192' - 6"
S3 Steam Out 2" 300# RF 105' - 6" 226' - 6"
L1 & L2 Level Gage Bridle 2" 300# RF
0' - 6"
25' - 0"
121' - 6"
146' - 0"
L3 & L4 Level Transmitter 2" 300# RF
0' - 6"
25' - 0"
121' - 6"
146' - 0"
T1 Temperature Element 1" 300# RF 30' - 0" 151' - 0"
T2 (Ditto) 1" 300# RF 72' - 0" 193' - 0"
T3 (Ditto) 1" 300# RF 107' - 0" 228' - 0"
P1 Pressure Element 1" 300# RF 28' - 0" 149' - 0"
P2 (Ditto) 1" 300# RF 74' - 0" 195' - 0"
P3 (Ditto) 1" 300# RF 108' - 0" 229' - 0"
9. Check for nozzle temperature - You now have all the nozzles connected or identified to its specific line. Now look at the line list and fine the maximum operating temperature for each of the flowing lines (feed and main outlet lines). Don't worry about vents and drain. In pencil, mark these temperatures onto the STOM P&ID at the point where the line connects to the vessel. You now have the vessel identified, the line from somewhere connecting to the vessel, you have the connection point identified with a nozzle number and you have a temperature at that nozzle.
10. Locate nozzle elevations - Based on the elevation for each nozzle (given in the Nozzle Table on the Vessel Drawing) locate all the nozzles on the scale vertical view (side view) of the vessel. Most of these flowing lines will be above the bottom tangent line. What this means is that all things connected to the nozzles above the bottom tangent line will grow up when the vessel is hot and in full operation. Only four of the nozzles are located below the bottom tangent line and these nozzles (and their attached piping) below the bottom tangent line will grow down when the vessel is hot and in full operation.
11. Establish temperature zones - The next step is to calculate the incremental and total vertical growth of the vessel. The incremental growth means the growth for a specific section of the vessel. Trayed vessels do not have the same operating temperature from bottom to the top. They have a graduated temperature. You may be asking what temperature you use for this operation. DO NOT USE THE VESSEL DESIGN TEMPERATURE. The vessel design temperature may be something like 500 degrees F. If you use this number along with the height of the vessel and the coefficient of expansion for the vessel metallurgy you would end up with a total expansion that would be incorrect. You look at the temperatures you marked for each of the Flowing lines. You take two adjacent Flowing nozzles that have a temperature. Let's say we take the Feed nozzle and the Bottoms Out nozzles. (I am assuming there are no other flowing nozzles between these two nozzles. If there are then make the appropriate adjustment). These two nozzles and their temperatures form a zone. You add their two temperatures together and divide the answer by 2 to get an average temperature for the zone (example: (475 degrees F and 395 degrees F)/2 = 435 degrees F). You use this 435 degrees F figure for the maximum operating temperature along with the zone length and the coefficient for the vessel shell material for the calculation of the incremental expansion. Do the same for each set of flowing nozzles and calculate the incremental expansion for each zone. The overhead vapor line temperature may be as low as 180 degrees F. Somewhere lower down the vessel there is another flowing nozzle with its operating temperature. This forms the top zone in the group. For talking purposes let's say we have five zones. Let's say that Zone one expands a total of 1", Zone two expands ¾". Zone three expands ½", Zone four expands ½" and Zone five expands ¼" for a total of 3". You need to mark each of the incremental expansions at the appropriate place. Now take each of the incremental expansions and add them together as you progress up the vessel. Part of Zone one is below the support point so some of the expansion grows up and some of it grows down. Because of this let's say that the top of Zone one only grows up 5/8" during operation. The top of Zone two grows up a total of 1-3/8". Zone three grows up a total of 1-7/8". The top of Zone four grows up a total of 2-3/8'. And the top of Zone five grows up a total of 2-5/8". You also need to mark each of the accumulated expansions at the appropriate place. You now have a basis for the preliminary pipe flexibility work you will do later.
12. Locate manholes - We have three manholes and they are only used during maintenance. These manholes will be the hinged type and for our situation they will all open to the right. They are identified as M#1 (bottom section) through M#3 (top section). They are not used or needed during operations. So Manholes should normally be located on the "back" side of the vessel. This is logical and it works 90% of the time. One of the times it does not hold true is for the lower shell manhole when there is a vertical Thermosiphon reboiler attached to the back of a vessel. So you can start with all of our Manholes on the back centerline of the vessel. This may not be the final location but it is a starting point. From the bottom of the vessel M#1 is in what is called the "surge" section. There are (normally) no internals in this section. So if we need to we can locate M#1 at any orientation. M#3 is in the very top section above the top tray so it also has few limits to its orientation. Manhole M#2 is located between trays at a maximum spacing of (say) twenty trays. In our case M#2 is on tray #19. The side manholes need to enter on a tray, not behind the downcomer.
13. Steam out nozzles: Along with each manhole there will also be a steam out nozzle. This nozzle will be fitted with a valve which will be blind flanged. During shut-down the blind flange is removed and a flanged spool with a steam coupling will be installed. Prior to any entry into the vessel the steam will be turned on for 12 to 24 hours to remove (steam-out) hydrocarbons. The steam-out nozzle will be located in close proximity to the manhole. The recommended placement for the steam-out connections on our vessel will be to the right and 1' - 6" below the manhole center line.
14. Set tray orientation - As we said above, we have 35 single pass trays. Tray #1 is 35' - 10" above the bottom tangent line of the tower and tray #35 is 104' - 10" above the bottom tangent line. Since we have trays that have only a single pass (downcomer) then we have almost 270 degrees of orientation with which we can place the manholes. However that 270 degrees of orientation needs to be in the right quadrant. If the excluded part of that circle is centered on 0 degrees (North) then we need to ask if that manhole can move up one tray or down one tray. If we have trays that are two pass or three pass then we need to find ways to orient the manholes, nozzles and trays so they co-exist. We have located all our manholes on the maintenance (north) side centerline at 0 degrees. We will then place the orientation of the trays on an East/West center line. We then insure that we adjust the vertical location of the manholes (up or down one tray) to enter on to a tray.
Up to this point you have doing the very important background work that is required before you can do the actually vessel orientation. Next you need to locate the nozzles, determine where the pipes will travel up or down the vessel and establish the support and guide points for each line. As you do that you also need to establish the ladder and platform requirements to provide proper access for operation and maintenance.
So let's move on to the next task.
15. Nozzle placement - As we stated before large nozzles need to be accessible "on" a platform. So keep that in mind as you proceed. Start with the nozzles at the top of the vessel and work down. Here is a key to remember, the line (up-or-down the vessel) and the nozzle do not need to be at the same bearing point. By this I mean that the line up-or-down the vessel can be at one point, say 196 degrees, and then wrap around the vessel to where the nozzle is on the other side of the vessel say at 315 degrees. The line would rise up the vessel and then turn horizontal to go around the vessel. It would then turn vertical again, go through the platform required for nozzle access and then enter the nozzle. This allows the nozzle to be "on" a platform but the line does not penetrate all the other platforms. Nozzles "F" and "R" on this vessel might be done using this method. The other lines from the "V1' nozzle and the PSV can simply drop down the vessel at the most convenient point. The lines to and from the Thermosiphon Reboiler will connect almost fitting to fitting with no valves. The bottoms line to the pumps is also a simple routing and might exit the vessel skirt at the 90 or 180 degree point depending on where the pumps are located. Instrument connections need to be placed so they perform their function and so they are accessible from a ladder or a platform. They do not normally extend far from the vessel shell thus do not cause an obstruction so with care they may be positioned on the vessel in the space between two ladders.
16. Pipe Supports - Each line that travels up or down the vessel will need one or more pipe supports. Lines that travel up-or-down the vessel at the same bearing point as the nozzle only need one pipe support. For side mounted nozzles this support will be located a short distance below the top elbow. For top mounted nozzles the support will be located a short distance below the vessel top weld seam. Lines that travel up-or-down the vessel at a different bearing point as the nozzle need to be considered for two supports. One below the nozzle elbow and a second support below the elbow where the line drops down the vessel.
17. Pipe Guides - Each line that travels up or down the vessel will need to be considered for pipe guides. The two factors in determining the number of guides a line requires is the wind force at the jobsite and the length of vertical travel. Some lines require only one guide and others require more than one pipe guide. Each line that travels up-or-down the vessel normally turns (elbows) horizontal at some lower elevation. The bottom guide should not be placed closer than 50 pipe diameters above this elbow. Other guides for a line may be spaced by taking the elevation of the support (at the top of the line drop) and then deduct the elevation of the bottom guide. The space remaining is then considered for one or more additional guides. Guides should be spaced every 20 to 30 feet.
18. Ladder placement - All of the ladders should be placed in the same general quadrant of the vessel. It is simple to work out the minimum spacing from one ladder to another. As stated before the minimum space between two ladders should be equal to one ladder (measured at the center of the cage). So if the ladder (with cage) is 2'-6" +/- wide then the space between two ladders is also 2'-6"+/-. This makes the center to center between two ladders 5'-0"+/-. Most of the ladders on this vessel can be in the quadrant from 45 degrees to 135 degrees. For a vessel 8' - 0" in diameter this would mean:
- Ladder #1 would be at 135 degrees
- Ladder #2 would be at 90 degrees
- Ladder # 3 would be at 45 degrees.
- Ladder #4 is back at 135 degrees.
- Ladder #5 is at 90 degrees and
- Ladder #6 is at 45 degrees.
- There will be a ladder #7 on this vessel which we will discuss when we talk about platforms.
19. Platforms - Platforms are the next thing to be defined. Platform # Dimension from tangent line (in feet) Project Elevation (in feet)
#1 1' - 0" 120' - 0"
#2 24 - 0" 145' - 0"
#3 45' - 0" 166' - 0"
#4 70 - 0" 191'- 0"
#5 90 - 0" 211'- 0"
#6 103 - 0" 224'- 0"
#7 113 - 0" 234'- 0"
#2a 19 - 0" 140' - 0"
#2b 27' - 0" 148' - 0"
Platform #1 would start at the step-off from ladder #1 (135 degrees) and wrap around the vessel (counter clock wise) to about the 350 degree point, beyond Manhole #1.
Platform #2 would start at the step-off from ladder #2 (90 degrees) and wrap around the vessel (counter clock wise) to ladder # 7 located at 315 degrees. Ladder #7 goes both up and down to provide access to two auxiliary platforms #2a and #2b. These small maintenance platforms provide access to the head flange of the reboiler and to nozzle N2. They must be sized to meet the criteria that the nozzle and head flange is "on" the platform.
Platform #3 would start at the step-off from ladder #3 and wrap around the vessel (clock wise) to and under ladder #4 at 135 degrees.
Platform #4 would start at the step-off from ladder #4 and wrap around the vessel (counter clock wise) to about the 315 degree point for access to Manhole #2 and to provide maintenance access for nozzle "F".
Platform #5 would start at the step-off from ladder #5 and provide a minimum platform (counter clock wise) for access to ladder #6
Platform #6 would start with a side step-off from mid way up ladder # 6 and wrap around the vessel (counter clock wise) to about the 315 degree point for access to Manhole #3 and to provide maintenance access to nozzle "R".
Platform #7 is a "Top" platform supported from the vessel head. This platform must be sized to allow space for the piping off the vessel head, access to the Davit and room for maintenance people to work during turn-around.
The imaginary vessel we have been discussing above is really a very simple vessel. After you read all of this you may think that vertical vessel orientation is very complex. You are right! However, I think vessel orientation is also the most fun there is in all of piping design.
For those of you who may want to try this vessel as a trial run I say give it a shot. Please feel free to E-mail me at (jopennock@netscape.net) when you start and maybe I can offer some suggestions.
Good luck to all of you who get a chance to do an actual vertical vessel orientation.
By: James O. Pennock
The following article was prompted by questions from a young piping designer. He wrote:
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Hi
I am getting ready to do my first vessel nozzle orientation. The vessel is a Stripper Tower (a). Can you help me? First, what are the things I have to take into consideration? Second, what are the key steps in the process for doing a vessel nozzle orientation?
Regards
XXXXXXXXXXXX
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(a)The name/function of the vessel has been changed.
For your first question: "What are the things I have to take into consideration?"
The answer to this question is very simple; you must take everything in to consideration. Everything is important! Someone may tell you that some things do not matter but this is not true, everything matters.
You need to consider the following:
a) Timing: Vessel orientation is normally the only equipment related layout activity that can be done without specific input from a vendor. All of the information required for vessel orientation is generated on the project in the form of P&ID data and project standards. It is also one of the few activities that will feed one or more other downstream groups whose work is critical to the project schedule. With this in mind this activity can and should be started as soon as the P&ID reaches "Approved-For-Design" (AFD) status. Te vessel orientation activity can be started manually or on basic 2D CAD before the 3D PDS data base is fully loaded and checked. There is some logic to doing this activity manually or in 2D CAD because of the amount of trial and error required to finally achieve an acceptable and approved orientation. Once the orientation is approved and the PDS data base is ready the 3D model can be built with no recycle.
b) The Plot Plan (Note 1): The plot plan is required to identify the location of the vessel and its related equipment. The related equipment includes the equipment that feeds the vessel (is up-stream) and also the equipment that the vessel feeds (is down-stream). It shows and locates adjacent, non-related equipment. It also shows adjacent structures that may support the related up-stream or down-stream equipment. It also indicates the plant features such as pipe racks, operating aisles, maintenance access areas and the direction of Plant North.
c) The project foundation criteria: Vertical vessels normally sit on an octagon pad foundation with the top of grout at EL101' - 0" (high point of finished paving = EL 100' - 0"). You need to have and understand the type and elevation of the foundation for this vessel.
d) The P&ID's (Note 1): The P&ID's are required to show the process streams that connect to the Stripper Tower and its related equipment. In my experience P&ID's are much like the pages in a book. Some equipment (the heater) starts or shows on sheet one P&ID the story continues with the key item (the Stripper Tower, Thermosyphon Reboiler and Bottoms Pumps) showing on sheet two and then continues to some conclusion (the overhead condensers) on sheet three. You will need all three process system P&ID's. The Stripper Tower P&ID will show a graphic of the column along with all the piping connecting to the vessel. There will also be a data block at the top of the page. This data block should include the vessel number, the vessel name and the basic size. It will also indicate the design temperature and the insulation requirements (if any). The graphic of the vessel should also indicate the basic type of internals (Trays or Packing). If the internals are Trays then the number of trays should be indicated. The trays just above or just below where a line is connected should be numbered. If the internals are some form of packing then the extent of the packing beds should be indicated.
e) The project Line List (Note 1): The line List is required to give you specific and critical key data about the lines such as the Line Number, line class, maximum operating temperature and insulation requirements,
f) The project Piping Material Specifications (Note 1): The Piping Material Specifications are required to give you the data about metallurgy and any specifics about fittings, flanges, valves or requirements for PWHT (post weld heat treatment).
g) The Vessel Drawing (Note 2): The vessel drawing at this time will most likely be marked "Preliminary." It will give you; the inside diameter (I.D.), the tangent-to-tangent shell length, the shape of the top and bottom heads and the skirt height. This drawing should also have a table showing all the nozzles with the basic information such as: identification, quantity, and size, flange rating, the elevation above (or below) the bottom tangent line for each nozzle, the purpose for the nozzle and any special instructions. The vessel drawing needs to also indicate where the internals start and end inside the vessel.
h) The Internals (Note 2) (Trays or Packing) A tower can have a number of different types and configurations of internals. It may be Trays or it may be some form of Packing.
- Trays: If you have Trays then you need to know: the number of trays, the spacing of the trays, the number of passes for the trays (1-pass, 2-pass, 3-pass etc.). You also need to know if there are any "draw sumps," baffles or other special features.
- Packing: You need to know the number of "Beds," the depth of the beds and the method of installing and removing the packing material. You also need to know and understand about the type of feed distributor(s) to be used. You need to know about the packing discharge nozzles.
For the purpose of this article we will assume we have 35 single pass trays.
i) The Thermosiphon Reboiler data sheet (Note 1): This will give you the preliminary size and type information. The P&ID indicates that this vessel has a vertical Thermosiphon reboiler fitted to it. Some discussion should normally take place to determine the optimum tube length and the proper support elevation and support method.
j) The project Vessel Platform Standards (Note 1): This will give you the required information about the minimum vertical spacing between platforms. It will also give you specific details about platform supports and how to make the openings where pipes must pass through a platform. This drawing will (or should) also give you specifics about handrails.
k) The project Vessel Ladder Standards (Note 1): This drawing will give you all the required information about ladder construction and more important the limits for the maximum vertical run for a single ladder.
l) The project Vessel Nozzle Standards (Note 1): This will give you all the normal options for un-reinforced and reinforced nozzles. It may also show you some options for internal nozzle piping.
m) The project Vessel Davit Standards (Note 1): A davit is a small device permanently mounted on the vessel that acts as a crane for lifting heavy objects such as tray sections.
n) The project Vessel Pipe Support and Guide Standards (Note 1): These are devices attached to a vessel that support and/or guide the vertical runs of pipe. This drawing also defines the minimum distance from the outside of a vessel shell to the back of an adjacent pipe. Where I came from this was called the "L" dimension. The "L" dimension was normally 12" (adjusted as required for insulation) The maximum was 20" without a special design. The key was to have a minimum of 7" clear between two co-existing insulations. These supports and guides also require a wider than normal line spacing in the vertical plane as the lines go up or down a vessel. This is mainly due to the configuration of the Trunnion (Note 3) support attached to the pipe and the pipe clamp used for the guide.
o) The project Piping and Vessel Insulation Specification (Note 1): From this document you will get the thickness of the insulation needed for the pipes and vessel at the operating temperature.
(Note 1): These items are normally created by your company for the project and should be "Approved for Design" (AFD) quality documents. This means that they have been through all of the proper in-house reviews and checks and have then been approved by the Company and the Client for use in the design of the work.
(Note 2): These documents will initially come from the project Vessel Engineer. They will normally be marked "Preliminary" until they receive and process your orientation drawings. Later you may receive the vessel fabricator's detail drawings for "Squad Check" (review and approval).
(Note 3) For more information about a Trunnion support see www.pipingdesigners.com look under Training and Secondary Pipe Supports
There may be other documents that are required due to a specific company's method of operation.
The next things you need to consider is; functionality, safety, operation, maintenance and constructability.
Functionality: No matter what, this vessel must do its job. You must know and understand what that intended job is. You do not need to be a process engineer but you should be involved in the review of the P&ID for this specific vessel. You need to hear what the critical issues are relating to this vessel and the connected piping. If your company does not include piping in the formal review of the P&ID's then you need to seek out the process engineer and ask him or her to explain the function, key points and any critical issues relating to this vessel.
Safety: This is the other important issue relating to vessel orientation. The operation must be able to be done in a safe manner. The same must be said for both maintenance and constructability. To achieve this goal the locations of nozzles relative to the placement and arrangement of the ladders and platforms must be carefully considered. The travel path (access and egress) must be arranged so the main travel path cannot be blocked by open manholes, scaffolding, tools, tray parts, valves or piping. The basic rule here; a: ladder #1 comes up with a side step-off (right or left) on to platform #1. Then b: there is a minimum rest space equal to one ladder width. Then c: the next ladder (#2) continues up to the next platform. Platform #1 can continue beyond ladder #2 around the vessel to provide access to nozzles and manholes. This arrangement does not impede or obstruct the clear path for rapid escape from the vessel for anyone from a higher elevation. Other safety issues include one or more skirt access openings located near grade which should be located with clear access. There will also be four or more skirt vents located high near the skirt-to-vessel attachment which also should not be blocked.
Operation: Process plants need to be operated. Most operation is concentrated around valves and instruments. These items must be accessible. Accessible means reachable. This reachable is conditional. Nozzles with a nominal size of 2' (NPS) and smaller can be reachable from a ladder or from a platform. Nozzles 3" (NPS) and larger shall be reachable on a platform. In this context the from means that the object is not more than 18" (one arms length) from the ladder or platform and the on means the object must be fully inside the platform. There is normally only one exception to this rule. That is for valves or nozzles that are located less than 20 feet from grade and can be accessed with scaffolding or a "Man-Lift".
Maintenance: All the accessibility issues that apply for operations also apply for maintenance. In addition don't block access to manholes with control valve assemblies or other piping. Make sure the Electrical and Instrument people don't locate a panel or a transmitter assembly in the operations or maintenance access ways.
Constructability: This vessel needs to be erected and therefore it will need Lifting Lugs. These are normally very large steel shapes with "eyes" welded to the top head. They will normally not interfere with your orientation, however you should check to make sure.
Your second question: "What are the key steps in the process for doing a column nozzle orientation?"
The key steps in the process are:
(You may choose for some reason to do something in a different order, but this is how I think I would do it. It should be noted that I like to be able to have all things numbered from the bottom up. This includes trays, nozzles, ladders, platforms, etc. However, sometimes due to company preference or the tray manufacturer standards the trays are numbered from the top down.)
1. Data collection - Collect a copy of all the drawings listed above. Make a folder file (or a stick file) to keep them in. Mark all the drawings "Stripper Tower Orientation Master" (STOM). This STOM file is your justification for everything you do or did. If anyone has reason to question why you did what you did then you have a file of the source material you based the work on. It is your responsibility to use the proper information and to properly file and incorporate changes from all new revisions when received.
2. P&ID conditioning - Take your STOM P&ID and pick-up any marks from the Project Master copy. From time to time as you work, go back and recheck the Project Master P&ID for any new marks (i.e.: line size changes, additions, deletions, etc.). Study the Stripper Tower and identify all the related equipment and all connecting lines. Study the lines for valves and instrumentation.
3. Plot Plan conditioning - Take the STOM Plot Plan and with a yellow high-lighter identify the Stripper Tower and all the related equipment. Related equipment means that which is directly connected by pipe to the Stripper Tower. I prefer to work with Plant North up or towards the top of the paper (CAD screen). When I do a vessel orientation I consider the pipeway to be in "front" of the vessel. I call the maintenance area the "back" of the vessel or equipment row. For the purpose of my instruction here I am going to assume that 0º is "up" and "up" is north. Maintenance is on the north (back) side and the pipe way is on the south (front) side.
4. Prepare preliminary elevation - Manually or by CAD, create a scale drawing of the vessel elevation (side view) Locate the bottom tangent line and in phantom (dotted line) the bottom head. Accurately locate the top tangent line from the bottom tangent line and draw in the top head. We will assume that this vessel is a skirt supported vessel and that the skirt is 20 ft high. (If not skirt supported then Leg or Lug supported will require optional considerations that we can discuss if applicable.) At the bottom accurately create the skirt (vessel support). Check with the Structural department and find out how high the foundation is for this vessel. Make sure they give you the top of grout (TOG) not just top of concrete. They are not the same. I will assume that the TOG is EL. 101' - 0." Now indicate the high point of finished paving (HPFP). I will assume that the HPFG is EL. 100' - 0." Now from this HPFP line, draw a light line to indicate the projects minimum head clearance.
5. Prepare preliminary plans - Manually or by CAD, create a scale drawing of a number of plan views. The plan views will be where you will do most of your work so make one for each ten feet +/- (3 to 4 meters) of vertical elevation ending with one above and showing the very top platform. These starter plans should have crossed center lines and the actual I.D. of the vessel. (We are using 8' - 0" for this article). Mark the location of Plant North on each mini-plan. Normally plant north is the same as 0 degrees on the vessel shell. East is 90 degrees, South is 180 degrees and all additional orientation is clockwise from north and 0 degrees. Don't worry about the O.D. or the wall thickness. Now, look at the platform drawing and get the clearance from the vessel shell and the inside edge of a platform. Draw a very light circle (different color and/or layer) on each mini-plan to indicate where the inside edge of a platform might be. Now draw another very light circle 3'-0" (1meter +/_) more in diameter to indicate where the outside of a platform might be. These are not real platforms yet they are just guide lines to remind you of platforms as you do other work. Now mark the "Front" (pipeway side) of the vessel and the "Back" (maintenance side) of the vessel.
6. Thermosiphon Reboiler: The Reboiler for our sample vessel has a 42" shell, 24 ft fixed tube (vertical mount) shell and tube exchanger. The shell side is high temperature steam. The tube side is the process fluid from the bottom of the tower which enters at the bottom end of the reboiler. The process vapor exits the top end of the reboiler and returns to the tower below tray #1. The placement and support of the Thermosiphon Reboiler is the next thing we should cover. Because of the plot plan placement of our Stripper Tower the Thermosiphon Reboiler will be mounted directly to the tower at the 270 degree point. It will have a knee braced cantilevered support that is attached to the vessel. The exchanger needs to be supported so the top tube sheet is at the same level as the high liquid level inside the vessel.
7. Bottoms section baffle - Because of the way this vessel works there is a baffle dividing the bottom section of the tower. The baffle can not be on the centerline of the vessel because the reboiler feed nozzle is centered on the bottom head. Therefore the baffle must be offset to miss that nozzle connection. The height of the baffle is the same as the "High Liquid Level." All of the liquid that comes off the downcomer from tray #1 goes into the "large" side of the bottom section. It then goes through the reboiler and returns to the vessel as vapor. Excess liquid from the "large" side overflows the baffle and becomes the "Bottoms" and is drawn off by the bottoms pumps. The connection for the bottoms nozzle "B" is on the "small" side of the baffle.
8. Check for nozzle continuity - Look at the STOM P&ID and the table of nozzles on the vessel drawing. They should match in number and size. In pencil mark each line connecting to the P&ID vessel with the nozzle number from the vessel nozzle table. Do they match in number? Do they match is size? If not, go see the Process Engineer and ask for clarification.
(Sample) Stripper Tower Nozzle Table
The bottom tangent line elevation = 121' - 0"
The top tangent line elevation = 232' - 8"# Name or Function Size (NPT) Rating Dimension (from tangent line) Elevation (plant datum) Comments
V1 Vapor Out 14" 300# RF 113' - 6" 234' - 6"
V2
PSV 6" 300# RF 113' - 6" 234' - 6"
V3 Vent 4" 300# RF 113' - 6" 234' - 6"
R Reflux 6" 300# RF 106' - 6" 227' - 6" w/internal pipe
F Feed 8" 300# RF 73' - 0" 194' - 0" w/internal pipe
B Bottoms 10" 300# RF 7' - 0" 117' - 3"
D1 Drain 6" 300# RF 8' - 0" 116' - 2" nozzle on nozzle B
D2 Drain 6" 300# RF 8' - 2" 115' - 9" nozzle on nozzle N1
N1 Reboiler Feed 14" 300# RF 7' - 0" 116' - 9"
N2 Reboiler Return 16" 300# RF 29' - 3" 150' - 3"
M1 Manhole #1 24" 300# RF 2' - 0" 123' - 0"
M2 Manhole #2 24" 300# RF 73' - 0" 194' - 0"
M3 Manhole #3 24" 300# RF 107' - 0" 228' - 0"
S1 Steam Out 2" 300# RF 0' - 6" 121' - 6"
S2 Steam Out 2" 300# RF 71' - 6" 192' - 6"
S3 Steam Out 2" 300# RF 105' - 6" 226' - 6"
L1 & L2 Level Gage Bridle 2" 300# RF
0' - 6"
25' - 0"
121' - 6"
146' - 0"
L3 & L4 Level Transmitter 2" 300# RF
0' - 6"
25' - 0"
121' - 6"
146' - 0"
T1 Temperature Element 1" 300# RF 30' - 0" 151' - 0"
T2 (Ditto) 1" 300# RF 72' - 0" 193' - 0"
T3 (Ditto) 1" 300# RF 107' - 0" 228' - 0"
P1 Pressure Element 1" 300# RF 28' - 0" 149' - 0"
P2 (Ditto) 1" 300# RF 74' - 0" 195' - 0"
P3 (Ditto) 1" 300# RF 108' - 0" 229' - 0"
9. Check for nozzle temperature - You now have all the nozzles connected or identified to its specific line. Now look at the line list and fine the maximum operating temperature for each of the flowing lines (feed and main outlet lines). Don't worry about vents and drain. In pencil, mark these temperatures onto the STOM P&ID at the point where the line connects to the vessel. You now have the vessel identified, the line from somewhere connecting to the vessel, you have the connection point identified with a nozzle number and you have a temperature at that nozzle.
10. Locate nozzle elevations - Based on the elevation for each nozzle (given in the Nozzle Table on the Vessel Drawing) locate all the nozzles on the scale vertical view (side view) of the vessel. Most of these flowing lines will be above the bottom tangent line. What this means is that all things connected to the nozzles above the bottom tangent line will grow up when the vessel is hot and in full operation. Only four of the nozzles are located below the bottom tangent line and these nozzles (and their attached piping) below the bottom tangent line will grow down when the vessel is hot and in full operation.
11. Establish temperature zones - The next step is to calculate the incremental and total vertical growth of the vessel. The incremental growth means the growth for a specific section of the vessel. Trayed vessels do not have the same operating temperature from bottom to the top. They have a graduated temperature. You may be asking what temperature you use for this operation. DO NOT USE THE VESSEL DESIGN TEMPERATURE. The vessel design temperature may be something like 500 degrees F. If you use this number along with the height of the vessel and the coefficient of expansion for the vessel metallurgy you would end up with a total expansion that would be incorrect. You look at the temperatures you marked for each of the Flowing lines. You take two adjacent Flowing nozzles that have a temperature. Let's say we take the Feed nozzle and the Bottoms Out nozzles. (I am assuming there are no other flowing nozzles between these two nozzles. If there are then make the appropriate adjustment). These two nozzles and their temperatures form a zone. You add their two temperatures together and divide the answer by 2 to get an average temperature for the zone (example: (475 degrees F and 395 degrees F)/2 = 435 degrees F). You use this 435 degrees F figure for the maximum operating temperature along with the zone length and the coefficient for the vessel shell material for the calculation of the incremental expansion. Do the same for each set of flowing nozzles and calculate the incremental expansion for each zone. The overhead vapor line temperature may be as low as 180 degrees F. Somewhere lower down the vessel there is another flowing nozzle with its operating temperature. This forms the top zone in the group. For talking purposes let's say we have five zones. Let's say that Zone one expands a total of 1", Zone two expands ¾". Zone three expands ½", Zone four expands ½" and Zone five expands ¼" for a total of 3". You need to mark each of the incremental expansions at the appropriate place. Now take each of the incremental expansions and add them together as you progress up the vessel. Part of Zone one is below the support point so some of the expansion grows up and some of it grows down. Because of this let's say that the top of Zone one only grows up 5/8" during operation. The top of Zone two grows up a total of 1-3/8". Zone three grows up a total of 1-7/8". The top of Zone four grows up a total of 2-3/8'. And the top of Zone five grows up a total of 2-5/8". You also need to mark each of the accumulated expansions at the appropriate place. You now have a basis for the preliminary pipe flexibility work you will do later.
12. Locate manholes - We have three manholes and they are only used during maintenance. These manholes will be the hinged type and for our situation they will all open to the right. They are identified as M#1 (bottom section) through M#3 (top section). They are not used or needed during operations. So Manholes should normally be located on the "back" side of the vessel. This is logical and it works 90% of the time. One of the times it does not hold true is for the lower shell manhole when there is a vertical Thermosiphon reboiler attached to the back of a vessel. So you can start with all of our Manholes on the back centerline of the vessel. This may not be the final location but it is a starting point. From the bottom of the vessel M#1 is in what is called the "surge" section. There are (normally) no internals in this section. So if we need to we can locate M#1 at any orientation. M#3 is in the very top section above the top tray so it also has few limits to its orientation. Manhole M#2 is located between trays at a maximum spacing of (say) twenty trays. In our case M#2 is on tray #19. The side manholes need to enter on a tray, not behind the downcomer.
13. Steam out nozzles: Along with each manhole there will also be a steam out nozzle. This nozzle will be fitted with a valve which will be blind flanged. During shut-down the blind flange is removed and a flanged spool with a steam coupling will be installed. Prior to any entry into the vessel the steam will be turned on for 12 to 24 hours to remove (steam-out) hydrocarbons. The steam-out nozzle will be located in close proximity to the manhole. The recommended placement for the steam-out connections on our vessel will be to the right and 1' - 6" below the manhole center line.
14. Set tray orientation - As we said above, we have 35 single pass trays. Tray #1 is 35' - 10" above the bottom tangent line of the tower and tray #35 is 104' - 10" above the bottom tangent line. Since we have trays that have only a single pass (downcomer) then we have almost 270 degrees of orientation with which we can place the manholes. However that 270 degrees of orientation needs to be in the right quadrant. If the excluded part of that circle is centered on 0 degrees (North) then we need to ask if that manhole can move up one tray or down one tray. If we have trays that are two pass or three pass then we need to find ways to orient the manholes, nozzles and trays so they co-exist. We have located all our manholes on the maintenance (north) side centerline at 0 degrees. We will then place the orientation of the trays on an East/West center line. We then insure that we adjust the vertical location of the manholes (up or down one tray) to enter on to a tray.
Up to this point you have doing the very important background work that is required before you can do the actually vessel orientation. Next you need to locate the nozzles, determine where the pipes will travel up or down the vessel and establish the support and guide points for each line. As you do that you also need to establish the ladder and platform requirements to provide proper access for operation and maintenance.
So let's move on to the next task.
15. Nozzle placement - As we stated before large nozzles need to be accessible "on" a platform. So keep that in mind as you proceed. Start with the nozzles at the top of the vessel and work down. Here is a key to remember, the line (up-or-down the vessel) and the nozzle do not need to be at the same bearing point. By this I mean that the line up-or-down the vessel can be at one point, say 196 degrees, and then wrap around the vessel to where the nozzle is on the other side of the vessel say at 315 degrees. The line would rise up the vessel and then turn horizontal to go around the vessel. It would then turn vertical again, go through the platform required for nozzle access and then enter the nozzle. This allows the nozzle to be "on" a platform but the line does not penetrate all the other platforms. Nozzles "F" and "R" on this vessel might be done using this method. The other lines from the "V1' nozzle and the PSV can simply drop down the vessel at the most convenient point. The lines to and from the Thermosiphon Reboiler will connect almost fitting to fitting with no valves. The bottoms line to the pumps is also a simple routing and might exit the vessel skirt at the 90 or 180 degree point depending on where the pumps are located. Instrument connections need to be placed so they perform their function and so they are accessible from a ladder or a platform. They do not normally extend far from the vessel shell thus do not cause an obstruction so with care they may be positioned on the vessel in the space between two ladders.
16. Pipe Supports - Each line that travels up or down the vessel will need one or more pipe supports. Lines that travel up-or-down the vessel at the same bearing point as the nozzle only need one pipe support. For side mounted nozzles this support will be located a short distance below the top elbow. For top mounted nozzles the support will be located a short distance below the vessel top weld seam. Lines that travel up-or-down the vessel at a different bearing point as the nozzle need to be considered for two supports. One below the nozzle elbow and a second support below the elbow where the line drops down the vessel.
17. Pipe Guides - Each line that travels up or down the vessel will need to be considered for pipe guides. The two factors in determining the number of guides a line requires is the wind force at the jobsite and the length of vertical travel. Some lines require only one guide and others require more than one pipe guide. Each line that travels up-or-down the vessel normally turns (elbows) horizontal at some lower elevation. The bottom guide should not be placed closer than 50 pipe diameters above this elbow. Other guides for a line may be spaced by taking the elevation of the support (at the top of the line drop) and then deduct the elevation of the bottom guide. The space remaining is then considered for one or more additional guides. Guides should be spaced every 20 to 30 feet.
18. Ladder placement - All of the ladders should be placed in the same general quadrant of the vessel. It is simple to work out the minimum spacing from one ladder to another. As stated before the minimum space between two ladders should be equal to one ladder (measured at the center of the cage). So if the ladder (with cage) is 2'-6" +/- wide then the space between two ladders is also 2'-6"+/-. This makes the center to center between two ladders 5'-0"+/-. Most of the ladders on this vessel can be in the quadrant from 45 degrees to 135 degrees. For a vessel 8' - 0" in diameter this would mean:
- Ladder #1 would be at 135 degrees
- Ladder #2 would be at 90 degrees
- Ladder # 3 would be at 45 degrees.
- Ladder #4 is back at 135 degrees.
- Ladder #5 is at 90 degrees and
- Ladder #6 is at 45 degrees.
- There will be a ladder #7 on this vessel which we will discuss when we talk about platforms.
19. Platforms - Platforms are the next thing to be defined. Platform # Dimension from tangent line (in feet) Project Elevation (in feet)
#1 1' - 0" 120' - 0"
#2 24 - 0" 145' - 0"
#3 45' - 0" 166' - 0"
#4 70 - 0" 191'- 0"
#5 90 - 0" 211'- 0"
#6 103 - 0" 224'- 0"
#7 113 - 0" 234'- 0"
#2a 19 - 0" 140' - 0"
#2b 27' - 0" 148' - 0"
Platform #1 would start at the step-off from ladder #1 (135 degrees) and wrap around the vessel (counter clock wise) to about the 350 degree point, beyond Manhole #1.
Platform #2 would start at the step-off from ladder #2 (90 degrees) and wrap around the vessel (counter clock wise) to ladder # 7 located at 315 degrees. Ladder #7 goes both up and down to provide access to two auxiliary platforms #2a and #2b. These small maintenance platforms provide access to the head flange of the reboiler and to nozzle N2. They must be sized to meet the criteria that the nozzle and head flange is "on" the platform.
Platform #3 would start at the step-off from ladder #3 and wrap around the vessel (clock wise) to and under ladder #4 at 135 degrees.
Platform #4 would start at the step-off from ladder #4 and wrap around the vessel (counter clock wise) to about the 315 degree point for access to Manhole #2 and to provide maintenance access for nozzle "F".
Platform #5 would start at the step-off from ladder #5 and provide a minimum platform (counter clock wise) for access to ladder #6
Platform #6 would start with a side step-off from mid way up ladder # 6 and wrap around the vessel (counter clock wise) to about the 315 degree point for access to Manhole #3 and to provide maintenance access to nozzle "R".
Platform #7 is a "Top" platform supported from the vessel head. This platform must be sized to allow space for the piping off the vessel head, access to the Davit and room for maintenance people to work during turn-around.
The imaginary vessel we have been discussing above is really a very simple vessel. After you read all of this you may think that vertical vessel orientation is very complex. You are right! However, I think vessel orientation is also the most fun there is in all of piping design.
For those of you who may want to try this vessel as a trial run I say give it a shot. Please feel free to E-mail me at (jopennock@netscape.net) when you start and maybe I can offer some suggestions.
Good luck to all of you who get a chance to do an actual vertical vessel orientation.
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