Study on Seal Performance of Globe Valve with Conical Seat.

Abstract

Concerning the seal performance of a globe valve with conical seat, the authors have investigated the effects of surface roughness, roundness and seat angle difference between disc and seat ring. In order to estimate leak rate, theoretical calculations have been carried out supposing plastic deformation of asperities, while seal tests have been conducted using test pieces prepared by the same process as practical ones. The results of calculation were consistent with the experimental results, and combined effects of some factors were found. For example, it was shown that the roundness of a conical seat has a large influence on the seal performance compared with surface roughness, and there exists an optimum roughness which minimizes the leak rate for each roundness. It was also confirmed that the leak rate decreases as the seat angle difference becomes large except for in the case of very light stem force.