api5000class API 5000 API 10000 API 15000 AA, BB, CC PSL 1 PSL 2 PSL 2 DD, EE, FF PSL 1 PSL 2 PSL 3 HH PSL 3 PSL 3 PSL 3 Our extensive experience in manufac-turing valves for wellheadAPI 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