Flange connection is of high strength and sealability and thus it is widely used in petrochemical e-quipment and pipeline. The finite element (FEM) model of the connection which consists of flange, gasket and bolt was established according to the FEM principle. An analysis of the stress and strain of flange was conducted with the FEM software. The effects of bolt' s pre-tightening force and medium pressure on the flange stress, strain and seal-ability were studied. The analysis shows that the greater the bolt' s pre-tightening force, the bigger the flange' s Von Mises stress, contact stress and deformation. When the pre-tightening force is greater than 140 kN, plastic deformation occurs near the bolt hole of flange plate. The contact stress of flange face in the pre-tightening state is greater than that in operation. The greater the medium pressure, the bigger the flange' s Von Mises stress value and the smaller the contact stress on flange face.%法兰连接具有较高的强度和密封性,被广泛地用于石油化工设备和管道中.依据有限元原理,建立了由法兰、垫片和螺栓组成的连接有限元模型,并在有限元软件中对法兰的应力、应变进行了分析,研究了螺栓预紧力、介质压力对法兰应力、应变和密封性能的影响.分析结果表明,螺栓的预紧力越大,法兰的Von Mises应力、接触应力和变形量就越大；当螺栓预紧力大于140 kN时,法兰盘的螺栓孔附近发生塑性变形；预紧状态下的法兰面接触应力大于工作中的接触应力；介质压力越大,法兰的Von Mises应力值越大,法兰面上的接触应力越小.
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