FEM Stress Analysis of Bolted Flange Joints in Elevated Temperature Service Condition

Abstract

Performance of a bolted flange joint (BFJ) is characterized mainly by its ‘strength’ and ‘sealing capability’. How to keep the ‘strength’ and ‘sealing capability’ for the BFJ serving at elevated temperature is a difficult problem in engineering applications. The variations of bolt stress and gasket contact stress play an important role on the structural integrity and sealing performance of BFJ in the bolt-up, pressurization and heat-up stages. In this paper, a three-dimensional elastic-plastic finite element model has been developed to investigate the performance of joint under combined internal pressure and elevated temperature. The thermal-structural coupling method has been used to analyze the variations of axial bolt force, maximum blot stress and gasket contact stress under steady-state and transient thermal loadings. The effects of internal pressure, temperature as well as the heating rate on the variations of bolt load, bolt stress and gasket contact stress have been evaluated. The results show that the maximum bolt stress increases while average gasket contact stress decreases with increasing the temperature under steady-state thermal loading. Besides, when the transient thermal loading is considered, heating rate has a significant effect on the maximum bolt stress and gasket contact stress. This research will contribute to the design of BFJ subjected to elevated temperature.