Study On The Reliablity Of Bolted Flanged Joint Under Petrochemical Extrem Condition

In this paper, the integrity and sealing property of bolted flanged joint are analysed and evelatuated under different conditions, such as preloading condition, pressurization condition, high temperature condition and creep condition. The effects of sudden stop and redrive, cooling rate and gaske type on the bolted flanged joint’s sealing property are investigated.Based on the finite element model conducted by ANSYS, the bolted flanged joint is analysed. Only 1/28 model of the flanged joint is built due to the cyclic symmetry. The highly nonlinear properties including gasket compression-rebounce property, material nonlinearity and contact between flange and nut are considered in the process of calculation.The result of thermal-mechanical coupled analysis shows that the stress of flanged joint increases with the occurrence of temperature. The stress of bolt decreases and redistributes with the consideration of creep for flange and bolt. The effect of creep on bolted flanged joint can not be ignored, which may leads to the sealing failure and leak accident. The result of transient analysis shows that displacement, stress and deflection angle increase under sudden stop and drive condition. Flange deflection will be severer repeated stop and drive codition, which may increases the possibilities of leakage and strength faliure. The effects of different gasket type on bolted flanged joint’s sealing property are different, heat tight operation should be considered whether to be needed according to the specified situation.Extreme conditions such as high temperature condition, creep consition and abruptly stop and drive condition have a profound impact on the integrity and sealing property, resulting in the flanged joint in complex stress and stress wave state, increasing the trend of leakage, should be avoided. Appropriate cooling rate and gasket type should be choosed according to the actual requirements to reduce the trend of leakage. The research results have important engineering significance on the selection of flanged joint and control of process of stop and drive in petrochemical plant.