Research On Partial Self-tightening Seals Of Metal Lens Gasket Jointed With Flangs

Metal lens gaskets belong to the gaskets of partial radial self-tightening sealing ability.Self-tightening capability of the lenticualr gaskets directly determines sealing performance of the bolted flang jointed with a lenticular gasket.In this paper,Hertz contact theory is applied to deduce the relations between contact width as well as maximum contact pressure of the gaskt and the load of the bolts.Self-tightening coefficients of the lenticular gasket is defined based on the mathematical model of the maximum contact pressure and preload force of the lenticular gasket connected by the bolted flange.The bolts,flangs and gaskt are considered as integral assembly.The stiffness of the bolted flang and gasket are introduced to define the self-tightening coefficients of the lenticular gasket when the relationship between deformation and stress of the assembly.Therotical fomula of the stiffness of gaskets is solved through the elasticity theory.The microstructure of the face-turned surfaces of the gaskts is studied,and is used to caculate the micro-leakage.Thermodynamic simulation is introduced to analyze the effect of temperature on the bolted flang joints with a lenticular gasket.A model for sealing test device is disigned to verify the theoretical results.The theoretical results indicate that self tightening capability of metal lens gasket and the member stiffness are relevant;we must ensure that the ratio of member stiffness and metal lens gasket stiffness is greater than a certain value,can make the lens gasket has the self-tightening capability completely.Thermodynamic analysis shows that the fluid templeture increases make the connection between the gasket and the flangs more closely.The sealing test not only verify the formula of gaskets' contact width and the minimum sealing bolt load,but also verify the when the maximum contact pressure reachs the yield strength of gasket the fluid can be sealed.