Knowing Pipe Stress Analysis is an engineering activity that focuses on evaluating the stresses, deformations, and forces within a piping system.
Knowing Pipe Stress Analysis
Knowing Pipe Stress Analysis is an engineering activity that focuses on evaluating the stresses, deformations, and forces within a piping system. It plays a vital role in ensuring the safe and reliable operation of piping systems in various industries, including oil and gas, petrochemical, power generation, and more. The Objectives of Pipe Stress Analysis focus to Stress Analysis of Critical piping systems is performed to ensure the following objectives.
Structural Integrity:
Design adequacy for the pressure of the carrying fluid.
Failure against various loading in the life cycle. Limiting piping stresses below code allowable.
Operational Integrity:
Limiting nozzle loads of the connected equipment within allowable values.
Avoiding leakage at flanged joints.
Limiting sagging & displacement within allowable values.
Optimal Design:
Avoiding excessive flexibility and high loads on supporting structures. Aim towards an optimal design for both piping and structure.
Basic Concepts of Piping Stress Analysis
Piping Components
Pipe stress analysis considers various components like pipes, fittings, valves, and supports. Understanding the properties and behavior of these components is crucial for accurate analysis.
- Pipes: Different materials, sizes, and schedules are used for pipes, and they exhibit specific stress-strain behaviors.
- Fittings and Valves: These components introduce stress concentrations and affect the overall behavior of the system.
- Supports: Supports and restraints are essential for controlling pipe movements and distributing loads.
Load Types
Pipe systems experience several load types, including:
- Static Loads: Steady-state conditions like internal pressure, deadweight, and thermal expansion.
- Dynamic Loads: Transient events such as water hammer, relief valve discharge, and seismic activity.
- Thermal Loads: Temperature variations causing thermal expansion and contraction.
Stress-Strain Relationships
Pipe stress analysis relies on understanding the stress-strain relationship of materials. Key concepts include:
- Elasticity: Materials return to their original shape when the load is removed within their elastic limit.
- Plasticity: Beyond the elastic limit, materials deform irreversibly.
- Creep: Slow, time-dependent deformation under constant load and elevated temperature.
Governing Codes and Standards for Pipe Stress Analysis
Codes and Standards specify minimum requirements for safe design and construction (i.e. provide material, design, fabrication, installation, and inspection requirements.). Following are the codes and standards used for Piping stress analysis of process piping:
- ASME B31.3: Process Piping Code
- ASME B31.1: Power Piping Code
- Centrifugal Pumps: API 610
- Positive Displacement Pumps: API 676
- Centrifugal Compressors: API 617
- Reciprocating Compressors: API 618
- Steam Turbines: NEMA SM23/ API 612
- Air Cooled Heat Exchanger: API 661
- Fired Heaters: API 560
- Flat Bottom Welded Storage Tanks: API 650
- Heat Exchangers: TEMA/ Vendor-Specific.
- Vessel/Column: Vendor-Specific/ ASME Sec VIII
- ASME B 31.4/ASME B 31.8: Pipeline Stress Analysis
- ISO 14692: GRE/GRP/FRP Piping Stress Analysis
- ASME B31.4: Pipeline Transportation Systems for Liquid Hydrocarbons and Other Liquids
- ASME B31.8: Gas Transmission and Distribution Piping Systems
- EN 13480: European standard for metallic industrial piping
- API 570: Inspection, repair, alteration, and rerating of in-service piping systems
