ASME B31.3, Process Piping.
ASME B31.3 is the American Society of Mechanical Engineers code governing pressure piping in petroleum refineries, chemical plants, pharmaceutical plants, paper mills, textile mills, semiconductor plants, and cryogenic plants. The code defines the materials acceptable for piping service, the design rules for pressure and temperature, the welding and fabrication requirements, the inspection and testing requirements, and the required documentation, line list, isometric drawings, weld map, hydrotest records. It is one of seven sections in the ASME B31 Code for Pressure Piping. B31.1 covers power piping, B31.4 covers liquid-pipeline transportation, B31.8 covers gas transmission and distribution.
What ASME B31.3, Process Piping means.
B31.3 is the most widely cited piping code in chemical and petrochemical engineering. It is updated on a 2-year cycle. The current edition is B31.3-2022. The code is structured into chapters covering design, materials, fabrication and assembly, examination, inspection, testing, and high-pressure piping. The fluid service category, Category D for low pressure, low temperature, Category M for hazardous, Category K for high pressure under Chapter IX, Normal Fluid Service for ordinary service, Severe Cyclic for fatigue-prone determines which design and examination requirements apply. The code is referenced by U.S. Federal regulations, OSHA PSM piping requirements and by state piping inspection requirements. International equivalents include EN 13480, Europe, JIS B 8210, Japan.
What are the B31.3 fluid service categories.
Category D covers fluid services where the gauge pressure does not exceed 150 psig, the temperature is between -29°C and 186°C, and the service is not lethal or highly toxic. The design and inspection rules are relaxed. Category M covers fluids that are lethal upon escape, highly toxic gases, certain hazardous liquids. The rules are tightened, more inspection is required, and material restrictions apply. Category K covers high-pressure piping above the normal B31.3 limits. The code provides a separate chapter, Chapter IX. Severe Cyclic Service applies to piping subject to thousands of significant pressure or temperature cycles. Fatigue analysis is required. The default category for chemical and petrochemical service is Category O, Ordinary unless one of the other categories applies.
What does the piping spec, pipe class carry.
A piping spec, pipe class is a document maintained by the engineering contractor or operating company that translates B31.3 requirements into specific pipe components for a given service. The piping spec specifies the pipe material and schedule per nominal size, the flange rating and material, the gasket type, the valve construction, body, trim, packing, and acceptable fittings. A piping spec is identified by a short code, A1A, B2C, D3E, etc. That appears on the line number. The combination of pipe spec, service, and process conditions determines whether the line meets B31.3 design requirements.
What does the line list carry per B31.3.
The line list is the project register of every named pipe spec on the P&ID set. Each row carries the line number, nominal size, schedule, pipe spec, material, service, design pressure, design temperature, insulation, tracing, and the connected-equipment references at each end. The line list is referenced by the piping detailer for isometric drawings, by the stress engineer for flexibility and support design, by the inspector for pressure-test scoping, by the fabricator for material takeoff, and by operations for the lifetime piping integrity management plan.
Common questions
What is the difference between B31.1 and B31.3.
Does B31.3 require post-weld heat treatment, PWHT.
What is the difference between B31.3 and API 570.
Does the pipe class designation come from B31.3.
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