| The toothed metal gasket with flexible graphite coating(referred to as graphite tooth gasket)has the advantages of high strength,good resilience and good sealing effect.In this paper,the influence of gasket compression resilience on sealing performance at low temperature is studied,and the relationship between gasket compression deformation and leakage rate is established.Through the combination of experiment and numerical simulation,the influence of low temperature on the sealing performance of bolt flange connection is studied and analyzed.The main research contents are as follows :(1)The graphite gasket was studied based on the porous medium leakage model.Combined with JIS B 2490,it is found that there is no single value correspondence between gasket stress and leakage rate,so is gasket compression deformation and gasket stress,while there is a single value correspondence between gasket compression deformation and leakage rate.Based on this,a leakage rate prediction model of graphite tooth gasket based on gasket compression deformation under uniform compression is established.(2)The compression resilience performance of graphite gasket was tested and compared with finite element analysis.Through the compression resilience performance test of graphite tooth gasket at low temperature(-30 °C,-80 °C and-130 °C),the distribution of gasket compression deformation under different working conditions is obtained,and the compression resilience performance of graphite tooth gasket at low temperature is simulated by finite element method.It is found that the error between the finite element simulation results and the test results is within 5 %,which can provide reference for the same type of test in the future.Based on the test and simulation data,the influence of the change of the gasket compression resilience performance on the sealing performance is analyzed by the leakage rate prediction model based on the gasket compression deformation.It is found that as the temperature decreases,the gasket compression deformation decreases,resulting in the gasket leakage rate increases with the decrease of temperature.By comparing the experimental and simulated leakage rate models,it is found that the calculated simulated leakage rate is larger than the experimental leakage rate.(3)The influence of stress distribution on the sealing performance of graphite gasket at low temperature is analyzed.For the bolted flange connection structure with gasket in nonuniform compression state,a finite element analysis model was established to study the influence of gasket stress distribution on sealing performance under low temperature conditions,and the sealing performance of non-uniform compression and uniform compression gaskets was compared and analyzed.The results show that the lower the temperature is,the smaller the effective stress of the gasket is,which leads to the decrease of the compression deformation and the increase of the leakage rate of the gasket.The leakage rate of the flange connection of the gasket in the non-uniform compression state is much larger than that of the gasket in the uniform compression state.Through the above research on the sealing performance of graphite tooth gaskets under low temperature conditions,it provides an important reference for how to ensure good sealing of pressure equipment using graphite tooth gaskets at low temperature in the future. |
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