Abstract:Because of the complex conditions of deepsea,the working condition of the sealing structure is very unstable.So,it is difficult to study the sealing performance with traditional design methods based on experience or classical mechanics theories.Based on the deepsea conditions,a deepsea ball valve with a valve rod of double sealed construction and bolted fixed ball valve seat was designed.By using the finite element numerical simulation software,and choosing three paths in the surface of valve seat to substitute the whole surface,the deformation regularity of the valve was studied under complex conditions of the external pressure of water and the internal pressure of medium.The seal performance of valve seat was analyzed and the relationship between deformation and sealing pressure was summarized.It is found that the relationship between seat deformation and sealing pressure is different at different paths.The deformation of the ends of the seat is independent of the sealing pressure,and the deformation of the middle part of the seat is opposite to that of the sealing pressure.Reducing the radial thickness of the seat can increase the sealing specific pressure and make the distribution of the specific pressure on the sealing surface more uniform,and when the thickness is small,the increase of the sealing specific pressure is faster.Based on the study above,the size of the valve seat was optimized by reducing the radial thickness of the valve seat,which makes the sealing specific pressure distribution of the valve seat more uniform and conforms to the sealing evaluation criteria of the valve.