Valve Standard Reference
ASME B16.5
AmericanPipe Flanges and Flanged Fittings NPS 1/2 through NPS 24 Metric/Inch Standard
ASME B16.
Overview — ASME B16.5
ASME B16.5 is the fundamental flange standard that establishes pressure-temperature (P-T) ratings, materials, dimensions, tolerances, marking, and testing requirements for flanged fittings and flanged valves in sizes NPS ½" through NPS 24". It defines seven pressure classes (150 through 2500) across 33 material groups, making it the universal reference for valve end flange selection and procurement worldwide. Any valve with flanged ends ordered for ASME-governed piping systems must comply with B16.5 for proper mating.
Scope
Covers raised face (RF), ring-type joint (RTJ), flat face (FF), and tongue-and-groove flanged valves and fittings, NPS ½" through NPS 24", in all standard ASME pressure classes. Applies to carbon steel, alloy steel, and stainless steel body materials across seven pressure classes.
Applicable Valve Types
Ball Valves — flanged end
Gate Valves — flanged end
Globe Valves — flanged end
Butterfly Valves — double-flanged
Check Valves — flanged end
Plug Valves — flanged end
Applicable Pressure Classes
Key Requirements — ASME B16.5
Seven pressure classes defined: Class 150, 300, 600, 900, 1500, and 2500
Thirty-three material groups (1.1 through 3.3) each with its own P-T rating table
Class 150 WCB carbon steel rated 285 psi at ambient; Class 2500 rated 4500 psi
Flange facing options: raised face (RF), flat face (FF), ring-type joint (RTJ), tongue-and-groove
Bolting dimensions and bolt circle specified per class and nominal size
Material marking on flange body: material designation, pressure class, size, heat code
Hydrostatic shell test per manufacturer's standard (minimum 1.5× rated pressure)
End flange dimensions must match piping flanges for leak-free bolted assembly
Testing Requirements — ASME B16.5
Shell hydrostatic test: 1.5× rated pressure per class and material group
Flange facing dimensional inspection to B16.5 tolerances
Positive material identification (PMI) for alloy and stainless steel flanges
Documentation Required for ASME B16.5 Compliance
ASME B16.5 compliance marking on valve body flange
Material Test Reports (MTR) per EN 10204 3.1
Pressure-temperature rating data sheet referencing B16.5 material group
Hydrostatic test certificate
Related Standards
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