Experimental and simulation study on the sealing performance of rubber O-rings exposed to hydrogen conditions

Abstract

As the key link of pure hydrogen and hydrogen-doped pipeline system, rubber O-ring sealing element is of great significance for the safe and efficient transportation of pipeline. The variation law of leakage rate of rubber O-ring under various factors such as preload, sealing ring size, hydrogen pressure and hydrogen blending ratio was explored from a macro perspective through experiments, and the mechanical properties of rubber materials under hydrogen permeation conditions were further studied from a micro perspective through simulation. The results show that: (1): Under the condition of hydrogen permeation, with the increase of preload torque, the leakage rate of the sealing system shows a trend of decreasing first and then increasing. When the diameter of the O-ring is constant, the leakage rate tends to increase linearly with the increase of the inner diameter, and the sealing performance is weak. With the increase of hydrogen pressure, the gas leakage rate decreases exponentially. The hydrogen blending ratio is negatively correlated with the leakage rate, and increasing the hydrogen blending ratio will promote the sealing performance. (2) Under the condition of hydrogen permeation, the contact stress of the rubber O-ring increases linearly with the increase of hydrogen pressure. Substituting it into the leakage rate formula, it is found that the leakage rate decreases, which is consistent with the experimental conclusion, but the pressure rise will also increase the Mises stress, and cause the volume of the O-ring outside the extrusion groove to increase, accelerating the sealing failure. The increase of hydrogen blending ratio will increase the contact stress and reduce the Mises stress, but the effect is not obvious. (3) A theoretical formula of hydrogen leakage rate with multiple independent variables and single dependent variable is established. Suggestions on the selection of flange seals and the application of process operation parameters in hydrogen environment are put forward, which provides theoretical support for the safe transportation of pure hydrogen or hydrogen-doped natural gas pipelines.