Valve Standard Reference
ASME B31.3
AmericanProcess Piping
ASME B31.
Overview — ASME B31.3
ASME B31.3 is the process piping code that governs the design, materials, fabrication, assembly, testing, and inspection of piping within the property limits of facilities that process, store, or handle chemical, petroleum, pharmaceutical, textile, and similar products. It specifies the requirements for all piping components — including valves — and establishes the design basis, examination, and test categories (Normal fluid, Category D, Category M, High Pressure, etc.). Virtually all process plant valve procurement references B31.3.
Scope
Covers all piping systems within process plant battery limits: chemical plants, refineries, pharmaceutical plants, food processing facilities, and semiconductor fabs. Applies to all fluid services including normal (water, steam, hydrocarbons), Category D (non-flammable, non-toxic, T ≤ 186°C, P ≤ 1035 kPa), Category M (highly toxic), and High Pressure (>ASME B16.5 Class 2500).
Applicable Valve Types
All valve types used in process piping
Applicable Pressure Classes
Key Requirements — ASME B31.3
Valve materials must conform to ASME B16.34 pressure-temperature ratings for the service
Valves must bear ASME/ANSI pressure class markings (Class 150 through 2500)
End connection facing must match the piping flange facing (RF, FF, RTJ)
Valve testing per manufacturer's standard (minimum API 598 equivalent)
Weld end valves must be installed per ASME B31.3 welding procedure qualification
Branch connections using valves must be rated for the design pressure
Positive Material Identification (PMI) required for alloy steel and stainless valves in critical service
Testing Requirements — ASME B31.3
Hydrostatic leak test of piping system after installation
Individual valve test certificates per API 598 / ISO 5208
Documentation Required for ASME B31.3 Compliance
ASME B16.34 compliance marking on valves
Material Test Reports (MTR) per EN 10204 3.1
Valve pressure test certificates
ASME B31.3 piping system test records
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