Effects of Friction Coefficient on Structure and Sealed Integrity of Expandable Casing Joint with Metal-to-metal Seal

During the expansion process, the structure and sealed integrity of a new type expandable casing joint with metal sealing were explored by the finite element explicit dynamic analysis method, the nonlinear analysis is used in the expansion process of metal sealing joint of expansion casing under different friction coefficients between expansion cone and inner wall of expansion casing, while the key technical parameters such as effective stress, residual stress and contact force on the sealing surface of the expandable casing joint were obtained. When the expansion process is over, the V on Mises peak stress and residual stress increase with the rise of the friction coefficient. In order to maintain the structural integrity of the joint, the friction coefficient should be controlled below 0.12. Stress is focused on the thread teeth in the expansion process, and the residual peak stress is concentrated at the root of internal thread after expansion. Increasing the friction coefficient moderately is beneficial to increase the contact force between sealing surfaces after expansion, and thus to improve the sealing performance of the joint. Considering the structure and sealed integrity of the joint, the friction coefficient should be controlled at about 0.1. The results of the paper research had reference value for the design of expandable casing joint with metal sealing structure.