API 609 Historical

This standard covers design criteria, face-to-face dimensions, pressure-temperature ratings, and examination and test requirements for cast iron, ductile iron, bronze, carbon steel, and alloy steel butterfly valves that provide tight shutoff in the closed position and are suitable for flow regulation. Two categories of butterfly valves are included:

Category A. Cold working pressure (CWP) rated butterfly valves that normally have a concentric disc and seat. (See Table 1 for face-to-face dimensions.)

Category B. Pressure-temperature rated butterfly valves whose seat rating may be less than their body rating and that have an offset seat and either an eccentric or a concentric disc configuration. (See Table 2 for face-to-face dimensions.)

The valve sizes covered are NPS 2-48 for Category A valves and NPS 3-24 for Category B valves, corresponding to nominal pipe sizes in ASME B36.10M, with pressure ratings up to and including ASME Class 600 (see Tables 1 and 2).

Valve configurations are limited to lug and wafer types with facings that permit installation between ASME, API, and MSS flanges that conform to the standards and specifications listed in 1.2 (see Figure 1).

The bolting options for lug- and wafer-type valves are shown in Figure 1.

When fire-tested valves are specified by the purchaser, steel valves meeting the requirements of API Standard 607 shall be furnished.