Creep Behavior of Metal-to-Metal Contact Bolted Flanged Joint

Metal to Metal contact (MMC) bolted flange joint, which appears between gasket centering ring and flange facing, is widely used in nuclear and petrochemical industry for severe conditions. Compared to the floating type joints, the gasket outer metal ring is compressed after bolt-up and the stored energy can compensate the loss of residual gasket stress due to internal pressure, bending moment and creep, resulting in a low leakage. As it is difficult to assess the flanged joint integrity affected by creep analytically, a three-dimensional nonlinear finite element model is developed to highlight the creep behaviour of MMC flanged joint under different load cases at elevated temperature. The results show that MMC flanged joint can reduce the unloading effects due to creep and a suitable preload is recommended.