api5000API 5000 (Class 1500) Connection Types Performance Requirement API 6A Flange Means; Studded; Bolted; PR1; PR2; American Petroleum Institute; Coating Types Of API STD 6A Hh10,000 PSI - Type 6BX API 6A - Table E.4 . Nominal size of Flange: Maximum Bore: Outside Diameter of Flange: Max. Chamfer