Stress Analysis and Design of Bolted Flange Connections Under Internal Pressure

Abstract

In the present paper, the gasket stress distributions, hub stress and a variation in axial bolt force in bolted gasketed pipe flange connections under internal pressure are analyzed using elasto-plastic FEM taking into account the nonlinearity of gasket behavior. Non-asbestos spiral wound gaskets were employed. The effect of nominal flange diameter is examined on the gasket contact stress distributions, the hub stress and the variation in axial bolt force (the load factor) is examined. Using the obtained gasket contact stress distribution and the fundamental data of the relationship between gasket compressive stress and gasket leak rate according to JIS B 2490, a method for predicting the leak rate is demonstrated. Experiments to measure the amount of leakage, the hub stress and the variation in axial bolt force when the joint is under internal pressure were carried out. The numerical results of the leak rate, hub stress and the load factor are in a fairly good agreement with the measured results. Then, a method is demonstrated for determining the bolt preload under given conditions, that is, taking into account assembly efficiency, leak rate and internal pressure In addition, bolt preload is determined using the actual gasket contact stress which can be estimated using the value of the load factor. As a design example, the procedure for determining the bolt preload in 3″ and 20″ nominal diameter pipe flange connections is shown for the allowable leak rate of 1.0−3Pa • m3/s. The results are validated by the experiments.

Bolted fibre-reinforced polymer flange joints for pipelines: A review of current practice and future challenges

“…The variation of the nominal diameter of bolted flange connection has an effect on the flange performance and is considered as a key to optimise the design. Omiya et al [33] has studied stress analysis of flange joint using Elasto-Plastic (EP) FEA and ASME method. They have found that the hub stress with larger diameter is smaller than that with a smaller diameter.…”

“…On the other hand, increasing the pre-stress bolts has a positive effect on the longitudinal displacement to prevent the leakage. Omiya et al [33] proposed a new method of calculating the preload bolt by taking into account the allowable leak rate and the scattered bolt preloads.…”

“…It is also apparent from the results that the TF spiral wound gasket has the least variations in the contact stress distributions whereas the GF spiral wound gasket has an opposite trend. Omiya et al [33] have studied the influence of non-linear characteristics of non-asbestos and asbestos spiral wound gaskets (SWG) on the sealing performance. Contact stress distribution has been calculated and the leak rate has been examined.…”

“…On the other hand, increasing the pre-stress bolts has a positive effect on the longitudinal displacement to prevent the leakage. Omiya et al 33 proposed a new method of calculating the preload bolt by taking into account the allowable leak rate and the scattered bolt preloads. In addition, previous studies 41,42 have clarified that the internal pressure has insignificant influence on the pre-bolt load, in contrast, the maximum allowable internal pressure largely depends on the axial bolt force.…”

Study on the effect of gasket thickness for bolted gearbox flange joint

“…Factor of safety is calculated by analysis method. Omiya et al [4] analyzed the gasket stress distributions, stress in the hub and a variation in axial bolt force in bolted gasketed pipe flange connections under internal pressure. Kapgate et al [5] analyzed deformation, contact pressures, slippage during preload and failure stresses as bolted joints are subjected to preload, shear and bending loads.…”