| Gasket is an important sealing element in flange bolt connection system.When a proper pre-tightening force is applied,the gasket is compressed and rebounds to fill the gap between the flanges,blocking the fluid leakage channel to prevent leakage,and completely seal the system.Compression resilience is an important mechanical property that reflects the sealing performance of gaskets.Compressibility reflects the ability of gaskets to compensate for flange surface defects,and r esilience reflects the ability of the gasket to adapt to chan ges in pressure and temperature.Among the many types of gaskets,the tooth-shaped metal gasket with a covering layer has many advantages such like the good sealing performance,wide adaptability of preload,good thermal cycle adaptability,easy to use,and reusability compared with other gaskets.The tooth-shaped metal gasket with a covering layer can also be used in low-temperature environments,but there is still a lack of research on the compression resilience of such gaskets in low-temperature environments.Therefore,this paper uses a combination of experiment and numerical simulation to evaluate the compression resilience of this kind of gasket.Put the gaskets composed of different non-metal covering layers(flexible graphite,PTFE)and tooth-shaped metal rings(304,304 L,316,316L)of different materials at low temperature(-30,-80,-130℃)environment.Study the effect of gasket material on its performance.The test results show that the elastic recovery properties of flexible graphite and four kinds of stainless steel composite gaskets are basically similar at the same temperature.Compared with gaskets made of different nonmetallic materials,it can be found that the compression resilience of flexible graphite composite gaskets is generally better than that of PTFE composite gaskets.In addition,it is found from the test data that,temperature changes will not lead to regular changes in the performance of gasket materials,we cannot derive a law of changes in the mechanical properties of gaskets based on temperature changes.Both flexible graphite and PTFE composite gaskets can be used in low temperature environments,and the performance of the same gasket will not change significantly at different low temperatures.The repeated use of the gasket will result in a decrease in the compression rate of the gasket,an increase in the rebound rate,and gradually stabilize.It is recommended that gaskets should not be reused in applications with high tightness requirements.The finite element simulation of normal temperature environment and low temperature environment was performed on ga skets composed of different tooth-shaped metal rings and flexible graphite non-metallic coatings,and the compression resilience performance was studied.The research results show that the compression resilience curve of this type of gasket is close,indic ating that the compression resilience performance is basically similar.It is consistent with the compression rebound curve trend of the gasket obtained in the test.The compressive resilience curves of gaskets at different temperatures are basically the s ame,with only slight differences.When the displacement of the gasket is the same,the stress value of the low temperature environment is greater,so when the stress is the same,the compression rate of the gasket will decrease.We can conclude that the decrease in temperature will increase the hardness of the gasket material,decrease the compression rate,and increase the rebound rate.Finally,the difference between the simulation results and the test results shows that the results of the two research m ethods have the same trend.However,due to the fact that the friction coefficient of the material and the performance parameters have not changed during the simulation process,and the stress-strain relationship of graphite is not accurate.There are cert ain differences in the data. |
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