Strength And Sealing Analysis Of Flange At High Temperature With Metal Serrated Gasket

Bolted flange connection system is widely used in petrochemical equipment,which acts as a sealing connection,and it is the weak link of integrity and tightness of piping system.At present,the flange system with metal graphite spiral gasket has been studied both domestic and foreign,the research on the metal serrated gasket flange is less,therefore,the reasonable design of metal serrated gasket flange is of great significance to the safe operation of various types of petrochemical devices.In this paper,the bolt flange connection system of the gas compressor in the coking plant is taken as the research object,failure analysis of fracture gasket.Due to the existence of stress concentration during the processing of the gasket,the bolt preloading force uneven during the installation process,the superposition of the assembly stress and the high temperature thermal stress during the service process,causes the brittle fatigue fracture of the gasket.Finite element analysis of flange with metal serrated gasket,based on ANS YS nonlinear finite element method,using three-dimensional isoparametric discrete bolt flange joints,considering the non-linearity of the contact,three finite element model of metal gasket flange is established.Firstly,analyzed the steady temperature field of flange bolt,get the steady-state temperature distribution of flange.Flange temperature gradually decreases from the inner surface to the outer surface.Secondly,the minimum preload is guaranteed by the internal pressure and temperature of the gasket when the gasket reached the initial sealing condition.Due to the influence of preload,the flange has a certain deflection,resulting in uneven stress distribution of the gasket.The deflection angle of the flange is less than the deflection angle specified by ASME,flange strength and sealing performance to meet the requirements;The deformation and stress distribution of bolted flange connection system is similar to that of the pre tightening condition,and the flange strength and sealing performance meet the requirements.Under the operating condition,with the influence of temperature load,the flange of the overall stress and displacement is significantly higher than that of the pre tightening condition and pressure condition,the thermal expansion bolt also increases significantly.After assessment,the strength and sealing performance of the bolt flange system still meet the requirements.