API STD 609: 2021 [paper]

API STD 609 – Butterfly Valves: Double-flanged, Lug- and Wafer-type, and Butt-welding Ends, 2021

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.

The following two categories of butterfly valves are included:

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.

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;