Integrity Analysis Of MTM Flexible Graphite Gasket Bolted Flange Joint

Since the1970s,due to solving the engineering problems the traditional gasket can hardly deal with the advances of Metal-to-Metal (MTM) gasket were highlighted. Flexible graphite gasket is one representative of MTM gaskets. Flexible graphite gasket is often applied in the field of nuclear plant and Steam-electric power plant needing special sealing requirement. For the excellent performance of the material and the structure, the gasket is paid more and more attentions. Main contents in this paper are summarized as follows:1.According to the principle of MTM, FEA software were used to establish2D model of flexible graphite gasket to analyze the performance of flexible graphite gasket. The mechanical status and discipline of change in the combined conditions of different gasket pressure,temperature and the internal pressure were studied.2.According to the structure characteristic of MTM gasket, Normal flange of NPS4Class1500in ASME B16.5was taken as an example. Numerical analysis was done by building3D FEA model. Effects of preload, internal pressure and bending moment on joint were studied. The stress distribution of gasket and mechanism of bending moment was gained.3.Flange stress strength was assessed by stress analysis design method. Bolt failure criterion was proposed based on bolt bending stress and axial extension stress.4.The effects of main flange geometric parameters related to metal-to-metal contact area on the joint performance were studied. The less ideal metal-to-metal contact area provides the better sealing performance of joint. The larger ideal metal-to-metal contact area provides the larger capacity of suffering loads.The results of analysis can provide valuable reference to production, manufacturing and usage of flexible graphite gasket.