API 609:2021 pdf download.Butterfly Valves: Double-flanged, Lug- and Wafer-type, and Butt-welding Ends.
API 609 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 class150 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；API 609:2021 pdf download