| Gasket is the core component of flanged connection system,and its mechanical properties have a great influence on the sealing performance of flanged system.Compression-resilience property is the main mechanical property of gasket,which affects the reliability of flange sealing.Currently,the composite serrated gasket with nonmetal covered has been widely used in petrochemical industry and other industries,but the study on its mechanical behavior is limited,so it is necessary to study the compression-resilience property of the composite serrated metal gasket.Firstly,using test method to study that the compression-resilience properties of composite serrated metal gaskets,which are the combination of four kinds of stainless skeleton materials(304,304 L,316,316L)and two kinds of non-metallic overburden(Flexible graphite and Polytetrafluoroethylene(PTFE)).Two loading modes are designed: cyclic and repeated load-unload at room temperature.The research shows that the compressibility is from the biggest to the smallest metal skeleton materials are in order: 304 L,304,316 L,316.The rebound ratio of the gaskets are from the biggest to the smallest metal skeleton materials:316,316 L,304,304 L.The compressibility of flexible graphite gaskets is higher than that of PTFE gaskets.The rebound ratio of 304 and 304 L skeleton materials and flexible graphite composite gaskets are lower than that of PTFE composite gaskets,the rebound ratio of 316 and 316 L skeleton materials and flexible graphite composite gaskets are higher than that of PTFE composite gaskets.Comparison of cyclic load-unload and direct loading to design load test results,the gasket compression ratio and resilience ratio of two methods are basically identical.In the repeated load-unload test,it was found that the compression ratio of gaskets decrease with the increase of test times,while the rebound ratio increase,the trend of increase or decrease is relatively gentle.Finite element simulation on composite gaskets with four kinds of stainless skeleton materials and flexible graphite.The simulation results have a high degree of consistency with the tendency of compression-resilience property under normal temperature test.Under high temperature,simulating compression-resilience property of gaskets with four kinds of stainless skeleton material,it can be found that there exists difference.Compression-resilience property of 316 gasket is the best,followed by 304 gasket,mechanical properties of 304 L gasket and 316 L gasket are poor in high temperature.Bolt pre-tightening force and medium pressure are fixed,under high temperature,numerical simulation on stress changes of stainless skeleton material and flexible graphite composite gasket with four types.The stress distribution of gasket is uniformed along the circumferential direction and increases gradually along the radial direction from the inside to the outside.The performance of compression-resilience affect the uniformity of surface of the gasket stress distribution.316 gasket has a good compression resilience,so the stress distribution on the surface of the gasket is more uniform,compared with the other three stainless materials,its effective sealing area is larger,with the increase of ambient temperature,the inner and outer stress attenuation degree of 316 gasket is small. |
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