The Analysis Of Bolt Flange 3-d Finite Element And Tightness

The bolt flanged fittings is an important sealing joint structure in petrochemical field. As a result of various conditions, the joint is easy to leak, resulting in seal failure. In 2001 according to statistics showed that all leak occurred in the position of the Bolt and flange's connection about 17%, which can be seen that tightening of the flange and bolts to ensure the safe operation of pressure vessels has a very important role. The paper to the bolt flanged fittings 's finite element analysis and the tightness analysis, may provide the theory reference for the reasonable flanged joint design, reduces leak during the operation of this equipment, ensure the safety operation.The paper taken the bolt flanged fittings of the tubular heat exchanger entrained tube plate as the research object, used the standard high neck flange for equipment (JB/T4703-2000) to take the Benchmark flange of the analysis, and considered the nonlinear properties of Gasket materials and the contact relation between each element (one kind of nonlinear relations), taken the bolt, the flange, the tube plate, the gasket and so on ten kind of parts as a whole structure, carried on the static analysis using the ANSYS finite element analysis software to it, studied the geometric dimensions and load to influence overall intensity and tightness of the bolt flanged fittings. In the paper the bolt flanged fittings entrained the actual tube plate in the Tubular heat exchanger simplified as without holes solid equivalent tube plate through Flange design specification of the ASMEBPVC of the ASME, and compared the finite element calculation results with GB151 design specification formula calculation results, finally demonstrated that radial maximum stress value of the tube plate center and standard calculated value are relatively consistent.Through to the bolt flanged fittings 's finite element analysis, demonstrated finally: When pre-tight and intrinsic pressure operating mode, the whole of the bolt flanged fittings and the various elements' stress distribution tendency are similar, along with intrinsic pressure enlarging, various spots' stress intensity increases, the flange and bolt's distortion also increases. Bolts by axial tensile stress, nuts contacting flange ring by compressive stress, has caused stress concentration, and the flange link has the tendency which opens from inside to outside. Because of the discontinuous of geometrical shape, the flange link and the flange neck attachment point presents the stress concentration when pre-tight, the flange neck and joint of the shell cover presents the stress concentration when the intrinsic pressure, but affects the region to be small.Because of the complex structure, the Various influence factors, Multiple nonlinear existing, adopting the finite element numerical analysis technology, hopefully makes the quantitative analysis to the intensity and tightness of the bolt flange fitting's.