| Gasket-Bolt joint is one of detachable connections that is widely used in pressure pipe and vessel. As a transition part of this joint, gasket is closely pressed by two opposite surfaces on the two ends of adjacent pipes, which provides the necessary sealing for pipe connection and its performance shall influence the reliability of pipe connection. In this paper, finite element method (FEM) is implemented to make a numerical analysis to connection system on the conditions of varying internal pressures and temperatures. The study contents are as following:1. The tensile strength, compressing recovery, medium resistance and sealing of non-asbestos gasket are further studied.2. Based on the nonlinear viscoelasticity of non-asbestos gasket, a creep relaxation model on room temperature is proposed, then, an experiment is carried on to verify the correctness of this model. Results show that this model can predict the mechanical properties of non-asbestos gasket on room temperature. Furthermore, the relationship between stress amount and gasket thickness is revealed in this model.3. A three-dimensional mechanical model and heat transfer model of Gasket-Bolt joints were built, concerning material nonlinearity and contact nonlinearity.4. The temperature field and stress field of Gasket-Bolt joint system are simulated and studied using ABAQUS software. In this simulation, the results proclaim:a) the temperature distribution on bolt, flange and gasket; b) the relationship between flange rotating angle and bolt, gasket stress; c) the stress distribution on the gasket in circumferential and radial direction; d) the influence on stress from temperature distribution on the coupling condition. Performance of a flange joint is characterized mainly by its ’strength’ and ’sealing capability’. A number of analytical and experimental studies have been conducted to study these characteristics under internal pressure loading. However, with the prevalence and application of high temperature and pressure equipment, an increased performance demand for the joint is requested. The present design codes do not address the effects of temperature on the structural integrity and sealing ability. The ’strength’ and ’sealing capability’ of the bolt-flange joint on the condition of high temperature and pressure is studied in this paper to determine the safe operating conditions or the actual joint load capacity. These consequences at some extents have a guiding significance on the ’strength’ and ’sealing capability’ design of the Gasket-Bolt joint. |
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