Stresses in Teflon-filled spiral wound gaskets in flange joints are analysed by an axisymmetric finite-element method using micromechanical models constructed based on layer geometry. The constituents of the gasket are represented by hyperelastic and elasto-plastic material models. The inplane and bending stiffness and the non-linearity of the gasket are considered through micromechanical modelling. The micromechanical model is validated with experimental data available in the literature. An improved gasket stress distribution across the width of the gasket is obtained under different bolt preloads and internal pressures. At lower bolt preloads, only half of the gasket is effective for sealing. The results are compared with the average gasket stress model results with bolt axial force.

The effect of external bending on flange joints in pipelines, pressure vessels, and pressure vessel nozzles is significant and difficult to assess. In the current work, the sealing performance of a gasketed flange joint under external bending has been studied by using a threedimensional finite element analysis, considering the non-linear material behaviour of the gaskets. Spiral wound gaskets and non-metallic gaskets with various sealing materials are considered. Results show that the allowable bending moment on a flange joint depends on the tightness required, type of gasket, and its deformation characteristics. Gaskets with elastomeric sealing materials show good performance against leakage under external bending.

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