The design standards for check valves are based on the requirements of GB/T12236 standard: the structural length is GB/T12221 standard, the flange standard is HG/T20592 standard, the wall thickness standard is GB/T12224, and the pressure test standard is GB/T26480 standard; The nominal diameter includes DN15-DN50, and the nominal pressure includes 1.6MPa-2.5MPa-4.0MP.