Stress analysis and an estimation of the sealing performance in pipe flange connections with spiral wound gasket subjected to internal pressure

The stresses of a pipe flange connection with a spiral wound gasket under internal pressure are analyzed taking account a non-linearity and a hysteresis of the gasket by using axisymmetric theory of elasticity and finite element method (FEM). The leakage tests were also conducted using the actual pipe flange connections with spiral wound gaskets. Using the contact stress distribution of the pipe flange connections with 3″ nominal diameter under internal pressure, the values of the new gasket constants proposed by PVRC are estimated by taking account the changes in the contact stress. A difference in the new gasket constants is substantial between the PVRC values and the estimated results, which are obtained by using the initial clamping stress. However, the difference is small between the PVRC values and the estimated values which are obtained by using the actual gasket stress. In addition, a method for determining the bolt preload for a given tightness parameter is demonstrated. The obtained results for the pipe flange connection are in a fairy good agreement with those obtained by PVRC procedure.