Standard Specification

ASME B16.34 Butterfly Valves

What ASME B16.34 requires for butterfly valves — applicability, key and testing requirements, the alternative standards, and compliant supply with full certification.

What does ASME B16.34 require for butterfly valves?

ASME B16.34 (Valves - Flanged, Threaded, and Welding End, American Society of Mechanical Engineers (ASME)) sets the design, material and testing requirements for butterfly valves in its scope. ASME B16.34 is the foundational pressure-temperature rating standard for industrial valves. It defines the maximum allowable working pressure (MAWP) for valves at any given temperature, based on valve pressure class (150 to 4500) and body material group. Almost every industrial valve purchased globally references ASME B16.34 - it is the starting point for pressure-temperature compliance of any process valve.

Applicable Pressure Classes

Class 150Class 300Class 600Class 900Class 1500Class 2500Class 4500

Key Requirements

Minimum wall thickness of body and bonnet based on pressure class and material group
Pressure-temperature (P-T) rating tables: every combination of class and material has a defined MAWP at each temperature
End-to-end dimensional requirements for flanged, threaded, and weld-end valves
Weld-end bevel dimensions per ASME B16.25
Material compliance: each material assigned to a Group (1.1, 1.2, 1.3, 1.13, 2.1, 2.2, 3.1, 3.2, etc.) with separate P-T tables
Examination requirements: mandatory hydrostatic and leakage testing per B16.34 Table 5
Marking requirements: stamping with class, material, pressure, and body markings