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法兰接头作为压力容器和管道的一种可拆性连接结构，在化工、石油化工及其它工业部门中都得到了广泛的应用。随着人们对安全和环境的关注不断提高。对法兰接头在强度与紧密性方面的可靠性要求也在不断提高，同时法兰分析对研究者来说也是一个很大的挑战，其研究难点在于：法兰接头中存在材料和结构等多种非线性；必须考虑接头各元件间的相互作用，把接头当成一个系统来分析；接头的强度和紧密性也不能割裂开来进行分析。正是由于上述这些情况，使得法兰接头分析在国际上一直是一个很活跃的研究课题综合考虑了不同因素对系统整体结构完整性和紧密性的影响，结论如下：
法兰接头系统中应力水平较高的位置在几何形状不连续处。这是由于几何形状的不连续在此处产生了边缘应力，使其具有值得关注的应力强度。法兰接头中螺栓受到轴向拉应力在加内压过程中由于密封垫片上的压紧应力发生松弛而基本持稳定；但在此加内压过程中，由于法兰环弯曲作用的不断加大，螺栓所受弯曲应力也不断增加，所以在法兰接头的分析和设计时不仅要对螺栓受到的轴向拉应力而且要对其受到的弯曲应力都给予重视。垫片的预紧压紧压力在预紧阶段沿着径向的分布是不均匀的；垫片的残余压紧压力在加内压阶段沿着径向的分布会变得更不均匀的；而沿周向的分布由于螺栓较密和法兰较厚而在预紧和加压阶段基本上都是均匀的。在垫片的外环方向存在着具有较高残余压紧压力的闭合环带，它们对接头的紧密性有非常关键的作用。随着内压升高，环状密封带区域的宽度由内向外不断变窄，而介质也不断由内向外渗透侵入垫片密封面中，当内压介质到达垫片外侧时，法兰接头发生泄漏。
Flange joint as pressure vessels and pipes of a detachable connection structure, in the chemical, petrochemical and other industrial sectors have been widely used. As people focus on the safety and the environment improved. The flange joint strength and tightness in terms of reliability requirements are also rising, while flange of the researcher is also a great challenge, the research difficulty is: flange joint structure exists in many materials and kind of nonlinear; must consider the joint interaction between the various components, the joint as a system analysis; joint strength and tightness can not be separated for analysis. It is precisely because of these circumstances, make joint analysis of flange international has been a very active research topic of the different factors taken into account the overall structural integrity of the system and the impact of tightness, the following conclusions: Flange joint system, the location of high stress level geometry discontinuity. This is because the geometry of discontinuities in the edge of the stress created here, it is worth noting the stress intensity. Bolt flange joints under axial tensile stress in the course of the internal pressure increases due gasket compressive stress occurs on the relaxation and basic support and stability; but in the process of internal pressure increases, due to the constant bending and flange to increase , bolt bending stresses also suffered increasing, so the analysis and design of flange joints not only on the bolt when subjected to axial tensile stress and bending stress are subjected to its attention. Gasket compression preload preload phase along the radial pressure distribution is uneven; gasket compression pressure of the residual phase in the increase in pressure along the radial distribution becomes more unequal; and week due to the distribution along the bolt and flange thicker than the dense and the pressure in the preload phase are basically uniform. In the direction of the existence of the outer ring gasket with high residual compression stress of the closed ring, the close of their joints have a crucial role. As the inner pressure, ring seal with a width of from inside to outside the region continue to narrow, and media have been penetrated from the inside out penetration gasket sealing surface, when the internal pressure medium to reach outside the gasket, the flange joint leak.