Failure Analysis Of Ultrahigh Pressure Polyethylene Equipment Tube

Ultrahigh pressure polyethylene reaction tube is one of key equipment in the polyethylene production plant, the reaction tube can safe operation is directly related to the plant output value, profits and personal and property safety, has been the subject of attaches great importance. With the development of science and technology and industrial production, the ultra-high pressure polythene reactor operating conditions become more complex and demanding, frequent intermittent operation or start, shutdown and operation in the process of pressure wave and pulse and periodic variations of temperature, these factors will lead to repeated alternating stresses.In addition to consider static load, the risk of fatigue damage is also considered. According to statistics, more than 75% of the damage in the operation of the pressure vessel is caused by fatigue, of which more than 40% are caused by fatigue crack growth, so the fatigue damage of all countries are very seriously.The research of this paper is aimed at the ultrahigh pressure polyethylene reaction tube of a petrochemical plant. The theoretical analysis and experimental analysis are carried out according to the actual working conditions of the reaction tube. Based on the actual performance of the material, the residual stress is calculated by the optimization model theory, and the influence of the mean stress on the crack growth rate is considered. And the finite element analysis of high pressure polyethylene pipe was carried out by ANSYA software. The material of macro and micro analysis, the ultimate combination of simulation and the actual research to find out the failure cause of the high pressure polyethylene pipe:corrosion lead to the initiation of cracks on the outer surface of; periodic fluctuation of the internal pressure of parking is the major impetus of crack propagation; autofrettage residual stress has a certain degree of attenuation, the anti-fatigue ability of the super high pressure pipe decreased. Finally, according to the reasons for the failure to put forward some preventive measures.