What pressure classes does ASME B16.5 cover for gate valves?

ASME B16.5 covers Class 150, Class 300, Class 600, Class 900, Class 1500, Class 2500.

Standard Specification

ASME B16.5 Gate Valves

What ASME B16.5 requires for gate valves — applicability, key and testing requirements, the alternative standards, and compliant supply with full certification.

What does ASME B16.5 require for gate valves?

ASME B16.5 (Pipe Flanges and Flanged Fittings NPS 1/2 through NPS 24 Metric/Inch Standard, American Society of Mechanical Engineers (ASME)) sets the design, material and testing requirements for gate valves in its scope. 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.

Applicable Pressure Classes

Class 150Class 300Class 600Class 900Class 1500Class 2500

Key Requirements

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