[PIPING ENGINEERING 101] - PIPING DESIGN

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What is a P&ID?

A P&ID, or Piping and Instrumentation Diagram, is a detailed diagram used to illustrate all processes within a plant or industrial facility. It serves as a crucial tool for engineers, operators, and maintenance personnel to comprehend the layout and operation of a system. Typically, P&IDs incorporate symbols representing mechanical equipment, piping, valves, instruments, sensors, controls, cable lines, hydraulics, and more.

What is Piping Design?

Piping design involves translating P&IDs into the actual layout of piping systems used in facilities. It depicts how pipes will be arranged, how they will connect with other equipment, and specifies the piping components to be used.

What considerations are needed on piping design?

1. Safety: Ensure easy escape routes and prevent fire hazard
2. Maintainability & Operability: Ensure easy equipment access for operator and maintenance personnel
3. Cost: Ensure economical layout to optimizing material usage
4. Constructability: Ensure easy erection and on-site fabrication space.
5. Other: Effective tie-in and drain locations, conditions around the site boundaries, future expansion project area.

Understanding Piping Components:

Based on: ASME B31.3 Table 326.1 Component Standards

1. Joints: connection

• Welded Joints: Connect components by welding the edges together. (For High Pressure/High Temperature/Big Bore/Hydrogen this type is preferable)
• Flanged Joints: Connect components via flanges bolted together, usually with a gasket for a tight seal.
• Threaded Joints: Connect components by screwing them together using matching threaded ends.
• Spigot & Socket Joint: Connect components by inserting one component's end into the inside of another component's end.
• Solvent Cement Joint: Connect components using solvent/chemical allows the material to fuse to itself
• Heat Fusion Joint: Connect components using heating two components to a designated temperature, and then fuse them together by application of the required force

2. Pipes: convey fluid

• Seamless: Manufactured by extruding billets, without welded seams.
• Welded: Manufactured by rolling metal sheets, welded longitudinally or spirally.
• Forged: Manufactured by forging metal, shaped through compressive forces.
• Casted: Manufactured by casting molten metal, poured into molds.

3. Fittings: altering flow

Rule of Thumb: One pipe diameter spacing or 3" minimum between each welded fittings.

• Elbows 45°, 90°, 180° (long radius, short radius, reducing, mittered): Alter the flow direction in a piping system.
• Tees (equal tee, reducing tee): Split or combine flow in a piping system.
• Crosses: Provide four-way connections to split or combine flow in multiple directions.
• Stub-in: Branching without tees.
• Stub-in reinforcement/Olets (weldolet, sockolet, thredolet, latrolet, elbolet, nippolet, sweepolet, insert, brazolet, couplet): Provide branching from larger pipes to smaller ones.
• Caps & plugs: Seal the ends of pipes.
• Reducers (concentric, eccentric FOT/FOB): Connect pipes of different diameters.
• StubEnd: Connects dissimilar piping materials.
• Couplings (full, half): Connect two straight pieces of pipe of the same diameter.
• Nipple (close, head): Connect two other fittings or pipes.
• Union: Allow easy disconnection of pipes for maintenance or replacement.
• Hex Head (plug & bushing): Ensure a leak-tight seal in a piping system, tightened or loosened with a wrench or socket.
• Reducing Insert (type 1, 2, 3): Enable the use of standard socket-weld fittings to create various combinations of pipe line reductions.

4. Flanges: connect piping

• Flange Face Types: Flat Face (FF), Raised Face (RF), Ring Type Joint (RTJ), Tongue and Groove, and Male and Female faces.
• Pipe-to-Flange Connection Types: Weld Neck, Socket Weld, Slip On, Threaded, and Lap Joint.
• Special Flange Types: Including Oriface, Blind, Reducing, Expanding, Split, Puddle, Elbow, and Square flanges.
• Ratings: Forged (150#, 300#, 400#, 600#, 900#, 1500#, 2500#), Cast (25#, 125#, 250#, 800#)

4. Gaskets: a mechanical seal

• Full-Face Gasket used for flat-face (FF) flange
• Flat-Ring Gasket used for raised-face (RF) flange
• RTJ (Ring Type Joint) Gasket used for ring-type-joint (RTJ) flanges.

5. Fasteners: join/secure materials together.

• Bolts and Nuts: Threaded fasteners with a head on one end, designed to be used with nuts to secure parts together.
• Studs: Threaded rods that can be used for both ends of the connection to fasten components together.
• Washers: Thin discs placed between the bolt head or nut and the surface to distribute load and prevent damage

6. Valves: regulating fluid flow.

• Gate Valve: For on/off control.
• Globe Valve: Offers fine control, suitable for throttling.
• Ball Valve: Provides quick on/off control with low friction loss.
• Butterfly Valve: Offers quick operation with low pressure drop, ideal for large-diameter pipes.
• Check Valve: Prevents backflow automatically.
• Plug Valve: Offers tight shut-off and minimal leakage.
• Needle Valve: Provides precise flow control.
• Pinch Valve: Effective shut-off for abrasive or corrosive fluids.
• Diaphragm Valve: Uses a flexible diaphragm for flow regulation.
• Piston Valve: Offers tight shut-off, suitable for high-pressure applications.
• Solenoid Valve: Rapid on/off operation, commonly used in automation.
• Control Valve: Regulates flow, pressure, or temperature based on control system signals
• Pressure Safety Valve: Releases excess pressure to protect equipment.
• Vacuum Relief Valve: Low pressure devices specifically designed to protect equipment from excessive vacuum pressure.

7. Specialty Items: special purpose piping components

• Heat Tracing: Maintains or raises pipe temperature to prevent freezing or maintain process temperature.
• Steam Traps: Remove condensate and non-condensable gases from steam systems while preventing steam loss.
• Strainer and Filter: Removes solid particles from fluids using a mesh or perforated screen.
• Angle Piston Valve: Uses a piston to control flow, typically at an angle to the pipe.
• Flame Arrestor (Detonation & Deflagration): Prevents flame propagation in piping systems, preventing explosions.
• Flexible Hose: Absorbs vibrations or accommodates changes in position, allowing for movement or flexibility.
• Quick Coupling: Enables fast and easy connection and disconnection of piping components.
• Sight Glass: Allows visual observation of fluid flow in a piping system.
• Static Mixer: Blends or mixes fluids with stationary mixing elements.
• Grit/Sand Trap: Removes grit or sand particles from fluid flow.
• Liquid Trap: Separates liquid from a gas or vapor stream.
• Air Release Vacuum Breaker: Releases trapped air to prevent vacuum formation.
• Bug Screen: Prevents insects or debris from entering the system.
• Chemical Injection Systems: Inject chemicals for purposes like corrosion inhibition or water treatment.
• Insulation Joints/Flanges/Kits: Provide thermal insulation and prevent galvanic corrosion.
• Bursting Discs: Rupture at predetermined pressure to relieve excess pressure.
• Sample Cooler: Cools fluid samples for analysis or testing.
• Valve Interlock: Prevents valve operation unless another valve is in a specific position.
• Quick Release Coupling: Allows rapid release of connected components.
• Oblique Connection: Connects at an angle to accommodate space constraints.
• Corrosion Coupon/Probe: Monitors corrosion rates over time.
• Expansion Joints: Compensate for thermal expansion or contraction.
• Fabricated/Special Forged Items and Nozzles: Custom-made according to customer drawings.
• Test Plugs: Temporarily seal openings for pressure testing or maintenance.
• Ball Joints: Allow movement in multiple directions, accommodating thermal expansion or vibration.
• Fire Hydrant: Provides water for firefighting purposes.

8. Pipe Coating & Insulation:

• Painting/Coating: Protective material applied to prevent corrosion, abrasion, or chemical damage.
• Galvanizing: Coating with zinc to protect from corrosion.
• Wrapping: Additional protection against corrosion, abrasion, or mechanical damage.
• Insulation: Reduces heat loss/gain, maintains temperature, prevents condensation.
• Cathodic Protection: Prevents corrosion by applying direct current.
• Acoustic Foam: Reduces noise transmission.
• Open Mesh Metal: Protects personnel from physical contact or injury.

9. Support: Components used to support and stabilize piping systems.

• Pipe Hangers: Suspend piping from beams or ceilings.
• Pipe Shoes: Support pipes and prevent excessive movement or vibration.
• Pipe Clamps: Secure pipes to walls, beams, or other structures.
• Pipe Saddles: Cradle and secure pipes, distributing their weight.
• Spring Hangers: Absorb vertical movement or vibration.
• Variable/Constant Spring Hangers: Accommodate varying loads and movements.
• Clevis Hangers: U-shaped hangers for easy pipe adjustment.
• Beam Clamps: Attach piping directly to steel beams.
• Riser Clamps: Support vertical pipes or risers.
• Guide Supports: Prevent lateral movement or buckling.
• Anchor Supports: Prevent displacement due to thermal expansion.
• Sway Braces: Absorb lateral movement or vibration.
• Trunnion Supports: Support heavy or large-diameter pipes.
• Slide Plates: Allow for thermal expansion or contraction.
• Cushion Supports: Absorb shock and vibration.
• U-Bolt Clamps: Secure pipes with a U-shaped bolt.
• Pipe Rollers: Guide movement during thermal changes.
• Cardel/Wear Pad: Stabilize pipes and prevent sagging.

How to do piping design?

1. Understand project specifications/requirements and review P&ID.
2. Visiting site for surveying tie-in locations and existing plant layout as per P&ID.
3. Checking equipment size (data sheet) and determining horizontal spacing & headroom.
4. Plan area for heavy equipment access, drop zones, site fabrication, maintenance & operation.
5. Routing piping layout and avoids obstacle.
6. Drawing equipment layout and piping plan.
7. Drawing piping isometric.
8. Review and validate the design through pipe stress analysis.

What is the standard code for Piping Design?

1. Pressure Piping & Pipeline: ASME B31 - Power Piping, Fuel Gas Piping, Process Piping, Transport Piping, Refrigeration Piping, Gas Piping, Building Service, Slurry Transportation, Hydrogen Piping and Pipelines
2. Component Standards: ASME B31.3 - Table 326.1 Component Standards
3. Water Treatment: AWWA - American Water Works Association
4. Pipe Spacing: ASME B16.47 - Large Diameter Steel Flanges
5. Pipe Spacing: ASME B16.5 - Pipe Flanges and Flanged Fittings
6. Equipment Spacing: PNC00003 - Process Unit and Offsites Layout Guide
7. Equipment Spacing: OISD 118 - Layout For Oil and Gas Installations
8. Equipment Spacing: NFPA 30 - Flammable and Combustible Liquids Code
9. Electrical Spacing: API 500 - Location for Electrical Installation
10. Ladders: PIP STE05501 - Fixed Ladders Design Guide

What is software used by Piping Designer?

Piping designer need to do drawing from piping database as per P&ID. This is example of software that can do drawing from piping database:

• AutoCAD 2D
• AutoCAD Plant 3D
• Intergraph Smart Plant 3D
• AVEVA Plant Design Management System (PDMS)