api5000API 6A TYPE 6B 5000 PSI Blind pipe flanges are used to seal the end of a piping system or pressure vessel openings to prevent flow.API 6A TYPE 6B 5000 PSI Blind flanges are mainlyAPI 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