金属石墨缠绕垫片蠕变对法兰接头密封性能的影响

Influence of Gasket Creep on Flange Joint Sealing Performance

法兰接头在高温环境中工作时,接头各个部件的蠕变松弛会加剧,然而在法兰接头的研究中,大多没有考虑垫片的蠕变松弛。以金属石墨缠绕垫片为例,在不同温度及不同初始密封比压情况下进行蠕变松弛性能试验;将试验结果进行拟合得到垫片蠕变松弛性能计算公式,将其代入法兰接头变形协调方程中,计算得到接头蠕变2年的螺栓力随时间的变化情况。使用ANSYS软件建立法兰接头有限元模型,并计算不同部件蠕变2年所造成的螺栓力的松弛情况。理论计算结果与有限元计算结果相近,表明建立的理论模型可用于接头螺栓力松弛的评估。研究结果表明:初始密封比压相同时,温度越大则垫片的蠕变量越大,温度相同时,初始密封比压越大则垫片的蠕变量越大;垫片蠕变对法兰接头有显著影响,在一些情况下仅垫片蠕变就能使螺栓力下降40%,因此垫片蠕变对法兰接头的影响不能忽略。

When the flange joint works in a high temperature environment,the creep relaxation of each part of the joint is intensified.However,the creep relaxation of gaskets is mostly not considered in the study of flange joints.The creep relaxation performance test of metal-graphite spiral wound gaskets at different temperatures and different initial sealing specific pressures was carried out.By fitting the experimental results,the calculation formula for the creep relaxation performance of the gasket was obtained,and by substituting into the flange joint deformation coordination equation,the change of bolt force with time in 2 years of joint creep was obtained by calculation.The finite element model of the flange joint was established by ANSYS software the relaxation of the bolt force caused by the creep of different parts for 2 years was calculated.The theoretical calculation results are similar to the finite element calculation results,which indicates that the established theoretical model can be used for evaluating the joint bolt force relaxation.The research results indicate that when the initial sealing pressure is the same,the higher the temperature,the greater the creep deformation of the gasket.When the temperature is the same,the larger the initial sealing pressure,the greater the creep deformation of the gasket.The creep of gaskets has a significant impact on flange joints,and in some cases,only gasket creep can reduce bolt force by 40%.Therefore,the effect of gasket creep on flange joints cannot be ignored.