API STD 609-2021 PDF Download

1.1 This standard covers design, materials, face-to-face dimensions, pressure-temperature ratings, and examination, inspection, and test requirements for gray iron, ductile iron, bronze, steel, nickel-based alloy, or special alloy butterfly valves.

1.2 The following two categories of butterfly valves are included:

a) Category A—Manufacturer’s rated cold working pressure (CWP) butterfly valves, usually with a concentric disc and seat configuration. Sizes covered are NPS 2 to NPS 60 for valves having ASME class 125 or class 150 flange bolting patterns.

b) Category B—ASME class and pressure-temperature-rated butterfly valves that have an offset seat and either an eccentric or a concentric disc configuration. Sizes covered are listed below:

• for lug and wafer, class 150 and 300: NPS 2 to NPS 60;
• for lug and wafer, class 600: NPS 3 to NPS 60;
• for double-flanged short and long pattern, class 150, 300, and 600: NPS 3 to NPS 60;
• for butt-welding ends, class 150, 300 and 600: NPS 3 to 60;

1.3 Valve configurations include double-flanged, lug- and wafer-type with facings that permit installation between ASME and MSS flanges and butt-welding ends. Configurations conform to the standards and specifications listed in Section 2. Typical valve construction and nomenclature for valve parts are shown in Annex C.