API flange standard and API 6A 500010000 Blind Flange

api5000Surface, Underwater Safety, and Boarding Shutdown Valves Background Products covered by API 6A include surface safety valves (SSV), underwater safety valvesAPI has specified weld necks for many 6BX flanges, and not done so for many others, but API has provided the basis for determining the dimensions of a 6BX integral flange that the manufacturer may attach to a