| Vessels and equipments used in petrochemical industry, power generation, aviation and aerospace and so on usually work under situation of high temperature and high pressure. Because of their complex work condition, the credible life prediction of the vessels and equipments is critical for the save production.In the thermal power plants, boilers and steam pipe work under high temperature and cyclic loading, their typical failur is fatigue, creep and creep—fatigue interaction damage of material.The steam pipe of P91 steel used in the boiler was choosed as the object, the main researches are as follows:Finite element analysis was carried out for straight pipe,90°elbows and union tee made from P91 steels the distribution of stress in the pipe was described. Influence of ovality and temperature variation on the maximum stress of steam pipe was discussed. All of them provide a reference for corporation to evaluate the life and reduce the stress of pipeline.Experiments of fatigue, creep and creep—fatigue interaction were carried out for P91 steel. Based on the experiment results, the properties of P91 steel, such as creep curve, fatigue curve, creep—fatigue damage map and etc., were obtained. Based on the numerical results and experimental data, the life of straight pipe and 90°elbows of steam pipeline for Ninghai power plant were evaluated by both enduring strength method and creep—fatigue damage map. Assessment indicated that the steam pipe evaluated are running safely and still have a long residual life. |
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