AMSE B16.5 Flange

Flammable and explosive high-pressure pipelines in petrochemical industry require weld neck flanges Petrochemical pressure pipeline components are used to connect or assemble pressure bearing and sealed pipeline system components, including pipes, fittings, flanges, gaskets, fasteners, valves, joints, hoses, traps, filters, separators, etc. Among them, flammable and explosive high-pressure pipelines require forged weld neck flanges.   Seals for flammable and explosive high-pressure pipelines in petrochemical industry include flange sealing surfaces, flange gaskets, and fasteners. The flange sealing surface forms include flat face (FF), raised face (RF), ring joint face (RTJ), tenon groove, special groove, etc. The flange gasket includes flat gasket, spiral wound gasket (with inner and outer rings), and metal gasket (oval, octagonal).     High quality butt welded flanges should meet the following requirements: 1.No defects such as cracks, shrinkage, slag inclusion, and cold-lap; 2.The depth of rust, dents, and other mechanical damage should not exceed the negative deviation of wall thickness allowed by the product standard; 3.The machining accuracy and roughness of threads, sealing surfaces, and grooves should meet the requirements of the design documents or product standards; 4.The weld seam should be well formed and smoothly transition to the base metal, without defects such as cracks, lack of fusion, and incomplete penetration; 5. Metal bellows expansion joints, spring supports and hangers, and other shipping parts or positioning pin blocks should be complete and free of looseness.       The compliance of flanges, blind flanges, and stub end can be determined through the following visual inspections: a) The sealing surface should be flat and free of rust and radial scratches; b) The outer edge of the flange and flange cover should have a permission mark; c) The product standard number, nominal size, nominal pressure, material, and sealing surface type code should match the quality certificate.       Standard class rating of flanges According to the different nominal pressure ratings of valves, flanges with different pressure ratings are configured in pipeline flanges. Several commonly used flange pressure ratings are classified according to international standards According to ASME B16.5, steel flanges have 7 pressure ratings: Class150-300-400-600-900-1500-2500 (corresponding to Chinese standard flanges with PN0.6, PN1.0, PN1.6, PN2.5, PN4.0, PN6.4, PN10, PN16, PN25, PN32Mpa ratings)