Gas Sealing Performance Research Of The Sealing Ring

The sealing device is widely used in industrial equipment. The leakage will cause economic losses, waste of energy and pollution of environment in petroleum industry, chemical industry, aerospace and navigation industry. If the sealed gas is poisonous or corrosive, the leakage may result in serious accidents, which impacts on people’s personal safety. Many accidents have happened due to the poor sealing performance, which yield huge economic and life losses. In the aerospace systems, the sealing technology is particularly important. Hence, how to achieve the best sealing performance with the minimum economic cost is a long-term goal. This work explores the gas sealing problem between the valve’s connecting surfaces and small O-ring with the reciprocating piston movement, with an application to a project, in order to provide the theoretical foundation for investigating key pipelines’sealing parts in a new type of equipments.Due to the roughness on an actual surface, the gaps always exist between the contact surfaces. From a micromechanical point of view, this work simulates the rough surface and generates the Gauss distribution with different amplitudes. According to the basic theory of the average flow model, we explore the mechanisms governing the leakage rate by considering the effects of pressure, temperature, texture direction, air viscosity and air density.The finite element software is used to analyze the structural integrity of the valve of the pipelines such that the influence of the external environment on the thermal stress, Mises stress, contact stress and axial deformation of the sealing ring could be evaluated. We also study the effects of temperature, pressure, texture direction and screw bolt force on the sealing performance of the valve. As a result, we draw some conclusion that:(1) making the texture direction perpendicular to the leakage direction can reduce the leakage rate; (2) choosing the suitable screw bolt force can reduce the leakage rate; (3) the leakage rate decreases with the increase of the temperature and the decrease of the pressure.To research the sealing performance of the pipelines, we also perform the high pressure dynamic sealing experiment for the small O-ring with the reciprocating piston movement. Experimental results show that the leakage rate of the O-ring with 1 mm amplitude and 5 Hz frequency piston reciprocating motion is 2×10-4 Pa·m3/s, which is almost equal to the static leakage rate when the pressure is 20 MPa. In addition, we find that the safety life of the O-ring with reciprocating piston movement is about 20 hours after which the O-ring friction is continuously increased, and the wave shape becomes bad because of heat expansion. As a result, the O-ring would wear and tear seriously.