Failure analysis on rubber sealing structure of mandrel hanger and improvement in extreme environments

Abstract

In view of the failure of the sealing structure of mandrel hanger under high pressure and extreme temperature environment, according to the sealing structure characteristics and application requirements of conventional mandrel hanger, based on the principle of the minimum sealing pressure ratio of metal sealing surface and the constitutive model of rubber material, the advantages and disadvantages of three conventional sealing structures are analyzed and compared. Based on the heat conduction theory and the energy conservation equation of thermal coupling, the transient temperature field model of the hanger seal structure is established. The heat transfer analysis and thermo-mechanical coupling calculation of the new metal seal structure are carried out at extreme temperature. The results show that the contact pressure on the double U and single U sealing rings is greater than 140 MPa at extreme temperature, which meets the principle of minimum sealing pressure ratio. The temperature distribution law of the conventional rubber structure under the temperature and pressure load is analyzed, and the reason of early failure of rubber is found. The mandrel hanger of full metal sealing structure is used in the field. The mandrel hanger of full metal have been tested for more than 20 times of gas pressure. The pressure is stable and the sealing effect is good. The test results show that this new structure has the advantages of good seal performance.