FEM Stress Analysis and Sealing Performance Evaluation in Pipe Flange Connections with Gaskets Subjected to External Bending Moments

Abstract

The stresses in a pipe flange connection with a gasket subjected to an internal pressure and an external bending moment are analyzed taking account the non-linearity and hysteresis of a spiral wound gasket and a joint sheet gasket by using an elasto-plastic finite element method (FEM). The effects of the internal pressure and the external bending moment on the contact gasket stress distributions are examined. Leakage tests were also conducted using an actual pipe flange connection with a gasket under an external bending moment. As a result, a difference in the new gasket constants is substantial between the PVRC values and the estimated values when the external bending moment is applied to the connection. The hub stress and variation in axial bolt force were also measured. Fairly good agreements are found between the calculated and experimental results. In addition, a method for determining the bolt preload in the pipe flange connection under the external bending moment is demonstrated for a given tightness parameter.