Abstract:
Taking the plug valve as the research object, calculation model of the contact surfaces was established based on the deformation coupling model between the set screw of the plug valve and the cock. A leak identification algorithm for sealing surface considering fatigue cumulative damage of sealing surface asperities of plug valve was established by analyzing the microscopic contact of the plug valve’s sealing surfaces which are constructed by auto-correlation function. Taking plug valve F-2 ISO-STANDARD (1″) as the research example, the variation of plug valve fatigue life is numerically studied with the change of the number of tightening cycles of the set screw. It was shown that the life expectancy of the sealing surface of the plug valve was decreased with the increase of the numbers of screw tightening cycles, and was increased with the sealing surface roughness at the same tightening cycles. And the life expectancy of the sealing surface of the plug valve was decreased with the increase of the plug compression force, and was decreased with the sealing surface roughness at the same plug compression. The fatigue life of the sealing surface of plug valve was increased with the increase of the ratio of fluid pressure amplitude in the pipe, and was decreased with the increase of the limit pressure amplitude of the fluid in the pipe. The fatigue life of the sealing surface was first increased and then decreased with the increase of the average pressure of the fluid in pipe. This research provides a new method for the prediction of the fatigue life of the valve sealing surface, based on the fluctuation of fluid pressure in the pipe.