<p>Bolted flange joints are widely implemented in various fields of the industry, such as oil and gas, nuclear and power plant fields, due to their simplicity in installation and operation as well. However, the most challenging concern about their application is the leakage tightness of the joint problem that is not addressed by current ASME code flange designs and it can affect the level of safety of the industrial plants due to their potential human and environmental risks. This study develops an analytical approach to evaluate the connection of the different types of pressure vessel heads to the flange body. The proposed approach is based on cylinder theory and circular beam on elastic foundation method to obtain different significant parameters such as flange rotation, contact stress between gasket and flange body and determining the stress concentration area by considering discontinuity effects. In this study, all results are calculated in bolt-up and pressurization stages. To this point, several types of shell connections such as hemispherical, conical, dish and cylinder are compared together in the same loading condition in bolt-up and pressurization stages. As a matter of fact, the flange rotation and contact stresses between the gasket and the flange body may affect the leak rate of the bolted flange joint during the bolt-up and pressurization stages. On the other hand, the integrity problem of the bolted flange joints is another concern that should be taken into account by determining the points with high-stress concentration to avoid the occurrence of plastic failure. In this research, all types of heads are connected to the raised-face flanges ring without the hub. Moreover, to support the analytical approach, various types of shell connections are modelled in FEM software to validate the above-mentioned parameters in ANSYS simulation. It is worth mentioning that in this paper, the gasket nonlinear unloading behaviour is simulated to investigate the gasket deformation by considering its realistic characteristic. Finally, the tangential, as well as the longitudinal stresses of the inside and outside radius of the head in bolt-up and pressurization stages, are compared by the analytical and numerical methods for all the above-mentioned types of heads. The purpose of this comparison is to identify the effect of the changes in the geometry of the head on the rate of stresses in the junction of the head and the flange body by considering the same operating pressure and head and flange dimensional condition.</p>

Stress Analysis of Bolted Flange Joints With Different Shell Connections

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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