API 6D Butterfly Valve Series 815/ 830 ; Pipeline butterfly valve PN20 (2 1/2"-60") PN50 (3"-36") API 6D,API Q1,ASME,ISO900 API 6D Butterfly valve 815 / 830API 6D Pipeline Butterfly valve Certificates:API 6D,API Q1,ASME standard,ISO9001,ISO14001 etc. Application:City gate station,long pipelines,power plant,oil field gas fuel power plant,gas turbine power plant etc.