Summary of Technical Requirements for Pressure Vessels (VII)

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For pressure vessels containing highly permeable media, the following requirements are mandatory: 01 For vessels holding highly permeable media that pose a moderate level of hazard, their pipe flanges must comply with the specifications set out in the HG/T 20592–HG/T20635 series of standards; in addition, necked butt-welded flanges, metal wound gaskets with reinforcement rings, and high-strength studs of specialized grade should be used. 02 Packing box type heat exchangers shall not be used. For pressure vessels filled with ammonia, the following requirements are mandatory: 01 For ammonia containers, their pipe flanges must comply with the specifications set out in the HG/T 20592–HG/T 20635 series of standards; welded neck flanges, metal wound gaskets with reinforcement rings, and high-strength studs of special grade should be used in such assemblies. 02 Packing box type heat exchangers shall not be used. 03 Ball tanks storing liquid ammonia should undergo post-weld heat treatment. 04 Corrosion margin of liquid ammonia spherical tank: C2 ≥ 3 mm.