Abstract:The sealing performance of selftightening wedge seal of ultrahigh pressure vessel was analyzed according to 〖JP2〗the Mises yield criterion by using the finite element method.The plasticity rule according to multilinear kinematic hardening〖JP〗 was adopted for the material of the wedge seal ring,while the plasticity rule according to bilinear kinematic hardening was adopted for the materials of vessel and others.The stress distributions of the seal system under the conditions of preloading and working were obtained by numerical simulation,and the stress was linearized by subdividing the stress into primary stress,secondary stress and peak stress,then the reliability of the seal and the safety of the system were evaluated according to the characteristics of different types of stress.The results show that the stress variation of the wedge seal ring is small between the preloading and working conditions,so that the seal performance can be ensured.The resource of the sealing force experiences the processes of preload,preload and work pressure,and the work pressure itself.The primary stress of the vessel is membrane stress,whereas the screw thread at the end of the vessel undertakes the bend stress,therefore,the stress need to be evaluated according to the corresponding stress limits.