API 609 Eccentric Butterfly Valve, ASTM A995 5A, 6, 8 Inch

API 609 is a specification developed by the American Petroleum Institute (API) for "Butterfly Valves: Double Flanged, Lug- and Wafer-Type". This specification covers the design, materials, testing, and performance of butterfly valves used in the petroleum, petrochemical, and natural gas industries. An eccentric butterfly valve is a type of butterfly valve that has the stem offset from the center of the disc. This design allows for a more efficient flow of fluid through the valve, as well as better sealing performance. The API 609 specification covers eccentric butterfly valves in addition to other types of butterfly valves.