Research On The Reliability Of The Friction Welded Joints In Power Plants Boiler Serpentine Pipe

The research on the reliability of the friction welded joints in boiler serpentine pipe has been carried out in this paper. (1)Based on reliability theory, the approach and specification of accelerated life test for friction welded joints in boilerserpentine pipe are provided. The correctness of the specification and concordance of the failure mechanism of the friction welded joints on the different combined stress levels are verified by high-temperature internal pressure burst duration testwith accelerated life senses for a large number new friction welded joints of 15CrMo steel and by the test results analysis. (2)With the specification the mathematicalmodel with reliability indices which is used to calculate residual life for the friction welded joints of 12Cr1MoV steel having worked 132000 hours is set up. With the help of this model, the residual life of the new and old friction welded joints are predicted. The results illustrate that the friction welded joints are reliable during the design life and the quality of the friction welding procedure is stable. (3)Theexpression of the acceleration coefficient combined with the temperature and stress accelerated life test and the transformation of reliability functions between different combined stress levels are researched. Through double variables variance analysis for test data, it is known that the interaction between temperature and stress can be ignored. On this assumption, it is put forward that combined acceleration coefficient in double stress accelerated life test is the product of each accelerated stresscoefficient. The quality of friction welded joints in serpentine pipe is a decisive factor for the power plants boiler safe and reliable work. The reliability of friction welded joints has been studied by means of accelerated life test. The reliability indices have been increased. The mathematical model with reliability indices, which is used to calculate residual life for welded joints having been worked for a long time, has been set up. It is of economical and social benefit to prolong the safe working life of II 哈尔滨理工大学工学硕士学位论文power plants boiler and reduce the accidents which are caused by welded jointsfailure, and for reasonable maintenance project to be worked out.