Research On The Sealing Performance Of The Metal Lens Gaskets

The lens gaskets are widely used in the synthesis of urea nitrogen and deep-sea equipment.The sealing reliability of the metal lens gaskets is directly related to the operation of the equipment,the safety of workers,the loss of economy,the pollution of the environment and so on.The sealing surface of the metal lens gasket is the two spherical,and the sealing form is the plane to area sealing.After the preloads,it changes to area to area sealing,and the width of the contact surface will change with the force on the contact surface.The understanding of width and stress distribution of contact surface is still not clear in engineering.So this paper launches the research on the sealing performance of the lens gaskets.We firstly built an experimental setup to measure the width of contact surface under different preloads and study the leakage of the sealing performance test.Then we calculated the contact width by using the two-dimensional Hertz contact theory,linear elastic and elastic-plastic calculation methods of the FEA software ANSYS.We compare the different kinds of results according to the calculation methods.Then the FEA software ANSYS is also used to analyze the sealing performance of the operating condition of the lens gaskets.Finally we analyze several common calculation methods of the metal lens gaskets by two specific examples.After discussing the existing problems deeply during the calculation,we can obtain conclusions as below:(1)We found that the test data are in good agreement with the elastic-plastic FEA results.And the test data are also relatively close to the calculated results according to the formula in EN1334.3-G when the value of Qmax is equal to 2 times of the lens gaskets' yield strength.(2)The stress distribution on the surface contact of the lens gasket is approximately a parabolic distribution.When the surface contact pressure is more than 2 times of the lens gaskets' yield strength,the difference of contact stress and the distribution width between the linear elastic FEA results and the elastic-plastic FEA results is getting more and more obvious.And the bifurcation point of them is located at a point when the maximum Hertz contact stress is equal to 2 times of the lens gaskets' yield strength.(3)When the internal medium is nitrogen,the value of preloads of the lens gasket which is calculated based on the common method of the lens gasket in engineering is less than that of the PVRC standard T2 level.The gasket coefficient y and m calculated by the test results are larger than that of the standard specification.