Micromechanical modelling and gasket stress evaluation in flange joints under bolt load and internal pressure

Abstract

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.

Deformation and Stresses Generated on The Bolted Flange Joint Assembly and The Grayloc Clamp Connector at Elevated Temperatures

“…Furthermore, the gasket stresses are higher on the outer part of the gasket, which is expected because of the increasing proximity to the bolts (Do, 2011). This effect is more pronounced for higher values of initial bolt preload, as indicated in Mathan and Prasad (2009) also studied the gasket stresses across the radial-width of the gasket, as illustrated in Figure 2-7. An initial bolt preload, ranging from 25 kN to 40 kN was applied on the gasket in the bolting-up stage.…”

“…However, a sharp elastic recovery zone exists near the end of the unloading curve as shown in Figure 2-1, and this information is lost in linearizing the unloading curve. Mathan and Prasad (2009) recovery during unloading when compared to experimental results. Mathan and Prasad (2009) attribute the discrepancies between the micromechanical model and the experimental p-c curve to the presence of voids in the actual gasket material.…”

“…Mathan and Prasad (2009) recovery during unloading when compared to experimental results. Mathan and Prasad (2009) attribute the discrepancies between the micromechanical model and the experimental p-c curve to the presence of voids in the actual gasket material. By assuming perfect contact between the metal and the filler in the micromechanical model, the voids present in an actual semi-metallic gasket are ignored.…”

“…Researchers have analysed the external loads applied to gaskets in different ways. Bouzid and Derenne (2002), Krishna et al (2007) and Mathan and Prasad (2009) considered the influence of internal pressure and initial bolt preload applied on the gasket on a BFJA at room temperature. Bouzid and Nechache (2005) extended this pressure analysis to study the influence of high spatially-uniform thermal loadings.…”

“…The raised-faces of the flange reduce the contact area with the gasket to lower the initial bolt preload required to seat the gasket. Abid et al ( ), Hwang (1994, Krishna et al (2007), and Mathan and Prasad (2009) modelled the flanges as an elastic-plastic and isotropic material.…”