ASME B31.3
Process Piping Code
ASME B31.3 (Process Piping) is the international code governing design, fabrication, inspection, and testing of process piping in refineries, petrochemical plants, fertiliser plants, gas processing facilities, and chemical plants. ASME B31.3 is the foundational piping code referenced on virtually every EPC project worldwide and forms the basis for piping material specifications, stress analysis, and integrity management.
Full Definition
ASME B31.3 (Process Piping) is the international code published by the American Society of Mechanical Engineers covering the design, fabrication, inspection, examination, and testing of process piping systems. The code addresses metallic and non-metallic piping handling fluids in process service (Category D, M, Normal, and High Pressure) across refineries, petrochemical plants, chemical plants, gas processing facilities, and pharmaceutical plants. ASME B31.3 is one of the broader ASME B31 family (B31.1 Power Piping, B31.4 Liquid Pipelines, B31.8 Gas Transmission). Every EPC project produces a Piping Material Specification (PMS) keyed to ASME B31.3 service categories. See the piping MTO extraction page for the Pathnovo product that handles ASME B31.3 piping deliverables.
Context & Detail
ASME B31.3 fluid service categories
ASME B31.3 classifies piping by fluid service category. Category D: non-flammable, non-toxic, low pressure (under 150 psig), low temperature. Category M: toxic services where a single exposure can cause serious harm. Normal Fluid Service: most refinery and petrochemical process piping. High Pressure Fluid Service: piping above 21 MPa (3,000 psig). Each category has progressively stricter design, fabrication, examination, and testing requirements.
Design and stress analysis
ASME B31.3 design requirements cover wall thickness calculation (Section 304), allowable stress per material at design temperature, flexibility analysis for thermal expansion (Section 319), reinforcement of branch connections (Section 304.3), and pressure-temperature ratings. Stress analysis software (CAESAR II, AutoPIPE, ROHR2) computes flexibility and supports per ASME B31.3 Section 319 requirements for every process piping line.
Fabrication and inspection
ASME B31.3 Section 327-329 covers welding requirements (welder qualification per ASME Section IX, welding procedure specifications), heat treatment, and examination per service category. NDE requirements: radiographic examination for Normal Fluid Service (typically 5% spot), 100% for Category M and High Pressure, plus visual examination, dye penetrant, and ultrasonic where specified. Hydrostatic testing at 1.5x design pressure per Section 345.
Piping Material Specification (PMS)
Every EPC project produces a Piping Material Specification keyed to ASME B31.3 service categories. The PMS specifies material grade (carbon steel, low-alloy steel, stainless steel, duplex stainless, copper-nickel), thickness schedule, fitting class, valve class, gasket type, bolting material, and insulation per service class. ASME B31.3 forms the regulatory backbone for the PMS.
EPC Usage
- 01
Every greenfield refinery, petrochemical plant, fertiliser plant, and gas processing facility produces piping deliverables under ASME B31.3 scope. The Piping Material Specification (PMS) and stress analysis reports are foundational engineering deliverables.
- 02
Indian PSU refineries operate piping systems totaling 200,000-1,000,000 metres of process piping under ASME B31.3. Periodic inspection, repair, and replacement cycles draw on ASME B31.3 design data.
- 03
Petrochemical plants handling Category M toxic services (chlorine, hydrogen sulphide, ammonia, ethylene oxide) follow ASME B31.3 Category M requirements with stricter design, fabrication, and inspection cycles.
- 04
Sour service piping per NACE MR0175 / ISO 15156 combines ASME B31.3 with NACE requirements for hydrogen sulphide exposure. Sour service material selection and hardness control are critical.
- 05
High pressure ammonia and hydrogen services (urea synthesis, refinery hydrocracking) follow ASME B31.3 High Pressure Fluid Service requirements with 100% radiographic examination and tighter material control.
- 06
EPC contractors (L&T, Tata Projects, Toyo, KBR, Engineers India Limited) producing ASME B31.3 piping deliverables use the PMS as the procurement reference and stress analysis as the construction reference.
How Pathnovo Handles It
Pathnovo's piping MTO extraction product extracts piping material take-off from scanned and PDF isometric drawings without requiring a 3D model. Output is keyed to ASME B31.3 piping material specifications: line numbers, pipe sizes, materials per PMS, fittings per spec, valves per spec, and bolting per gasket class. Combined with MTR traceability, every delivered pipe and fitting traces back to the ASME B31.3 PMS, the heat number, and the regulatory regime. Used by Indian EPC contractors and PSU refineries for greenfield piping deliverables and brownfield revamp scope. See the weld schedule generation page for the ASME B31.3 weld and NDE deliverables.
Frequently Asked Questions
What is ASME B31.3?
ASME B31.3 (Process Piping) is the international code published by the American Society of Mechanical Engineers covering design, fabrication, inspection, and testing of process piping at refineries, petrochemical plants, chemical plants, gas processing facilities, and pharmaceutical plants. Every EPC project references ASME B31.3 for the Piping Material Specification (PMS).
What are the ASME B31.3 fluid service categories?
ASME B31.3 categorises piping by fluid service. Category D: non-flammable, non-toxic, low pressure (under 150 psig). Category M: toxic services with high-harm exposure. Normal Fluid Service: most refinery and petrochemical piping. High Pressure Fluid Service: above 21 MPa (3,000 psig). Each category has progressively stricter design, fabrication, examination, and testing requirements.
How does ASME B31.3 differ from ASME B31.1?
ASME B31.1 (Power Piping) covers piping for steam, water, and condensate at power generation plants. ASME B31.3 (Process Piping) covers piping at refineries, petrochemical plants, chemical plants, gas processing, and pharmaceutical plants. The two codes share the broader ASME B31 framework but address different industries with different design and inspection requirements.
What NDE does ASME B31.3 require?
NDE requirements depend on fluid service category. Normal Fluid Service: typically 5% spot radiographic examination plus 100% visual. Category M and High Pressure: 100% radiographic examination. Plus dye penetrant, magnetic particle, and ultrasonic examination where specified by the PMS or project requirements. Hydrostatic testing at 1.5x design pressure per Section 345.
What is the Piping Material Specification (PMS)?
The Piping Material Specification (PMS) is the EPC project document keyed to ASME B31.3 service categories. The PMS specifies material grade, thickness schedule, fitting class, valve class, gasket type, bolting material, and insulation for every piping service class on the project. ASME B31.3 forms the regulatory backbone for the PMS.
Can Pathnovo handle ASME B31.3 piping deliverables?
Yes. Pathnovo's piping MTO extraction product extracts piping material take-off keyed to ASME B31.3 PMS from scanned and PDF isometric drawings without requiring a 3D model. Output traces every pipe, fitting, valve, and bolt back to the PMS, the heat number, and the regulatory regime.
Is ASME B31.3 used in India?
Yes. ASME B31.3 is the foundational process piping code used in India alongside IS, BS, and IBR codes. Indian PSU refineries, petrochemical plants, and gas processing facilities reference ASME B31.3 directly in piping material specifications. IBR-scoped piping additionally complies with Indian Boiler Regulations 1950.
Related Pages
Piping MTO Software
ASME B31.3 piping material take-off from scanned isometrics.
MTO from Isometric Drawings
Extract piping MTO without a 3D model, ASME B31.3 PMS-keyed.
Weld Schedule & NDE Plan
ASME B31.3 + AWS D1.1 weld schedule and NDE plan automation.
MTR Traceability Software
Mill test report traceability for ASME B31.3-compliant piping.
ASME Section VIII Standard
Pressure vessel design code complementing B31.3.
IBR Compliance Software
Indian Boiler Regulations 1950 compliance for IBR-scoped piping.
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