本标准实施规程涵盖蝶阀的尺寸、设计、测试和标记要求。应进一步参考MSS SP-68。本标准实施规程涵盖两种类型的蝶阀:I型-紧密关闭阀（根据第10.2.1节进行测试）II型-允许阀座泄漏的阀门（见第10.2.2节）。本标准实施规程涵盖尺寸为NPS 1？至NPS 72的法兰端、单法兰（凸耳型）和无法兰（对夹型）阀门，以及槽端阀和带肩端阀，压力额定值符合第3节和第4节的要求。

This Standard Practice covers dimensions, design, testing, and marking requirements for butterflyvalves. 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 flanged-end, single-flange (lug-type), and flangeless (wafer-type) valves in size NPS 1¿ 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.