api5000API 6A Type 6B 5000 PSI Weld Neck Flanges are generally used in hh pressure applications, where hot or cold temperatures exist. These steel API 6A weld neck flanges10,000 PSI - Type 6BX API 6A - Table E.4 . Nominal size of Flange: Maximum Bore: Outside Diameter of Flange: Max. Chamfer