Analysis and Optimization for the Sealing Performance of Ultra-High Pressure Solenoid Valves in Low-Temperature Environments

The sealing performance of ultra-high-pressure solenoid valves faces significant challenges, particularly under low-temperature conditions. Due to the difference in thermal expansion coefficients between the valve seat and the sealing tube, combined with material contraction at low temperatures, the bolt preload decreases, and consequently the contact force on the sealing surface and the average sealing specific pressure are reduced. This may result in an average sealing specific pressure falling below the required sealing specific pressure, causing leakage and failure of the ultra-high-pressure solenoid valve. To address this problem, this study utilizes theoretical and simulation analysis to examine the preload status in low-temperature environments and the causes of sealing failure in ultra-high-pressure solenoid valves. A corresponding optimization scheme is proposed, which involves increasing the torque from 120 N·m to 130 N·m and applying sealant to the threaded connection to enhance the sealing performance of the ultra-high-pressure solenoid valve. Following the increase in tightening torque and the application of thread sealant, the helium leakage rate at −40 °C is significantly reduced. Specifically, at a test pressure of 87.5 MPa, the helium leakage rate decreases from 1.6×10−5 mbar·L/s to approximately 1.4×10−6 mbar·L/s. At test pressures of 1.4 MPa and 10 MPa, the leakage rate is approximately 3.0×10−7 mbar·L/s. Experimental verification shows that the proposed solution can significantly enhance the sealing reliability of ultra-high-pressure solenoid valves under extreme operating conditions.