The main failure mode of pipe flange connection is leakage. Leakage is related to many factors such as the type of seal structure, the rigidity of the connected parts, the performance of the seal, operation and installation. As the main component of flange connection, gasket plays an important role in sealing. Therefore, while revising the steel pipe flange standard, the gasket standard for the pipe flange is also revised accordingly. (1) The type of gasket HG pipe flange (European system) retains the non-metallic flat gasket, wound gasket, metal toothed composite gasket, flexible graphite composite gasket, PTFE coated gasket in the HGJ pipe flange standard Gasket types such as metal ring gaskets and metal ring gaskets, in addition, a new gasket type of metal clad gaskets has been added. This gasket is mainly used in the oil refining industry with high temperature. (2) Scope of application According to various gaskets, materials and actual sealing performance, as well as the matching flange structure type, main parameters and sealing surface type, the nominal pressure and service temperature (upper limit) of the seven gaskets in this standard are determined. and the nominal diameter range shown in the table below