Study on strength and sealing of a bolted flange joint under complex working conditions

Abstract

Abstract Bolted flange joints are widely used in petrochemical equipment and pipelines, while the problem of its leakage is a serious threat to the environment and safety. In order to study the strength and sealing of the bolted flange connection, a three-dimensional finite element model of the bolted flange joint with a flexible graphite spiral wound gasket is developed by using APDL in ANSYS. Considering the nonlinear compression rebound constitutive relation of gasket material, the indirect coupling method of temperature and structure is used to simulate the whole process of the bolted flange joint from installation to maintenance. The stresses of the flange, bolt and gasket under different operated conditions are investigated in detail. The results show that the stress distribution of the bolted flange joint is not uniform along the circumference due to the tightening sequence of bolts. The stress of each part of the bolted flange joint changes slightly under pressure condition, but the stress distribution is greatly affected by high temperature and creep at high temperature for 1000 hours. And the possibility of leakage of the bolted flange connection is increased with the application of transient cooling and heating up and additional bending moment and torque. After the application of various loads in turn, the bolted flange joint is likely to leak on the tension side.