Finite Element Analysis on the Contact Stress of Class 600 Flange Joints

Flange joint to provide a seal is constructed by inserting a gasket between the two flanges and fastening them with bolts. Among various types of gaskets, the ring gaskets, known as the RTJ, are mostly used in offshore oil and gas pipelines and are designed to work under extremely high pressure. They are solid rings of metal in different cross sections like oval, round, octagonal etc. Since the performance of flange joint is determined by the strength and sealing capability, it is necessary to conduct the research for the behavior characteristics and the contact pressure between the flange and the gasket, in order to investigate whether the joint is able to play a role under the given conditions. In this study, stress analysis of CLASS 600 flange joints specified in ASME 16.5, which are widely used in the industry, was carried out in order to obtain the useful information about the contact mechanism of flange joints. First, the contact forces and stress levels after the gasket was bolted up in the flange were examined for five models, and then the changes in the behavior characteristics and the contact force due to internal pressure were investigated to compare with the previous results.