Performance Analysis Of MMC Gasket And Calculation Of Bolt Pre Tightening Force

With the development of modern industry,especially in the petrochemical industry and the atomic energy industry,the working environment has put forward higher requirements for the flange connection seal.In order to meet the low leakage for a long time in the working environment of high temperature,high pressure,pressure and temperature fluctuation,a new MMC gasket is invented by absorbing advantages of bimetal seal corrugated composite gasket and nuclear grade graphite gasket.The main contributions of this paper are as follows:First of all,the new type of gasket is processed to test its mechanical properties and sealing performance.The research results show that the compression-recovery performance of the new gasket is influenced slightly by temperature.Along with the rise of temperature,the compression rate increases and the rebound rate decreases.In the case of metal to metal contact,the contact stress of the gasket increases sharply,the compression rebound curve is approximately linear and the limiting ring is used to bear the excess bolt load.The leakage rate of gasket is relatively large before flange contact gasket,then the leakage rate remain stable,therfore it has good sealing performance.If the bolt load is reduced,the limiting ring will be used to compensate the loss of gasket stress and the leakage of MMC gasket still remain stable.Secondly,according to the characteristics of the new gasket flange connection and referring to the prC EN/TS1591-3 flange connection design method proposed by the European Union,the calculation of the preload for this new gasket is studied.Although this method is just a draft,it provides a theoretical basis for the design and calculation of the new gasket flange connection.Finally,ANSYS is used to analyze the structure,steady state and transient-structure coupling analysis of the new gasket flange connection to study the sealing performance of new gasket under different working conditions.The results show that the MMC gasket has the ability of self sealing,the limiting ring is used to bear the extra bolt load after the case of MMC.The decrease of the gasket stress is caused by the internal pressure fluctuation in the steady state temperature field,but the reduced value is very small,which indicates that the MMC gasket can adapt to the pressure fluctuation.No matter the heating process,temperature fluctuations or cooling p rocesses in transient analysis,the temperature of the inner side of the gasket is greater than that of the outer,the pressure stress of gasket remains stable and can meet the sealing requirement,which indicates that this new gasket can adapt to temperature fluctuation.