This Standard Practice covers dimensions, design, testing, and marking requirements for butterfly valves. Further reference should be made to the MSS SP-68.
This Standard Practice covers two types of butterfly valves:
Type I – Valves for tight shut-off (Tested per Section 10.2.1)
Type II– Valves permitting seat leakage (See Section 10.2.2)
This Standard Practice covers flangeless (wafer-type), single flange (lug-type), and flanged end valves in size NPS 1½ through NPS 72, along with grooved end valves, and shouldered end valves, with pressure ratings in accordance with the requirements of Sections 3 and 4.