An Investigation on Leakage Rate of Hard Sealing Ball Valve

With the rapid development of industries, hard sealing ball valves are increasingly adopted in extreme working conditions, especially for the advantage of high sealing performance. However, current research works on ball valves are lack of leakage rate prediction, which is an important issue. In this paper, a typical hard sealing ball valve is selected as the research object. Mathematical equations for sealing pressure are derived on both fixed and floating ball valves. The sealing pressure on the hard sealing side of the ball valve is analyzed, and the accuracy of the theoretical equation is verified. Meanwhile, the relationship between sealing performance factor and sealing pressure is fitted, and a prediction method of hard sealing ball valve is proposed, and also is validated experimentally. Results indicate that the sealing pressure obtained from the theoretical equation is conservative, as the actual pressure on the sealing surface exhibits a U-shaped distribution. The sealing performance factor varies with sealing pressure according to a piecewise function. It increases in the form of a power function when the pressure is less than 110 MPa and decreases in the form of a quadratic function when the pressure is higher than 110 MPa. The R2 of the fitting equation is greater than 0.98%. Furthermore, the theoretical predictions are consistent with the experimental results in magnitude, confirming the reliability of the proposed prediction method. When the roughness is below 0.2, further reduction in the roughness has little effect on the sealing performance. Both roughness and sealing pressure should be considered comprehensively to enhance sealing performance. This work can benefit the leakage rate prediction and further study for the sealing performance improvement of hard sealing ball valves.