Effect of Pressure-Dependent Deformation of Safety Valve Disc on Sealing Performance

Abstract In nuclear power plant and other important industrial facilities, the safety valve is a key safety protection device, and its sealing performance is directly related to the safety of the system. The contact pressure between the disc and the valve seat can significantly affect the sealing performance of the safety valve. The disc will deform under the high pressure and large spring force, which can affect the contact state of the sealing surface, leading to the deterioration of sealing performance. The safety valve applied to nuclear power plant is often spring-loaded safety valve, the seal of which is mainly in the form of mechanical face seal, and the valve disc shape is mainly round plate. However, the effective sealing width in the working condition often deviates significantly from the designed sealing surface width. The reduction of the effective sealing width also directly leads to the decline of the sealing performance of the safety valve, and then increases the risk of leakage of the safety valve. Therefore, based on Reissner thick plate theory, the safety valve disc is simplified into a thick plate model, and the force under high pressure is simplified into a mechanical calculation model, and then the calculation formula of the effective sealing width is derived. According to the above formula, the effective sealing width at different pressures is calculated quantitatively. At the same time, according to the static structure simulation, the effective width of the safety valve simulation under high pressure is also obtained to verify the accuracy of the calculation results. The effect of different working pressure on the effective sealing width is also studied. The study found that the larger the internal medium pressure, the smaller the effective sealing width. This study can provide reference for the seal evaluation of the safety valve under high pressure and the design optimization of the sealing surface of the safety valve.