Failure analysis of a thermocouple protection tube in a steam-entering pipe of a steam turbine
A stainless steel thermal couple protection tube in a steam-entering pipe at the front of a steam turbine fractured after three months in service. This paper presents a failure analysis of the tube. The fracture surface of the tube is observed and investigated using scanning electron microscope (SEM). The steam flowing conditions are simulated using computational fluid dynamics (CFD) and the inherent frequency of the tube is calculated using finite element method. Results show that the cracks initiated from both the inside surface and the outside surface of the tube and then grew through the tube wall due to fretting and normal fatigue. The crack propagation was caused mainly by cyclically undulated pressure caused by the flow of the over-heated steam in the pipe. The inherent frequency of the tube was found to be close to that of the steam pressure variation in the pipe, which speeded up the fatigue crack propagation in the tube due to sympathetic vibration. Methods for improving the life of the tube are proposed.
Thermocouple protection tube Finite element method Fretting fatigue CFD Vibration
Deming Fang Shuihua Zheng Changjiang Huang Ying Li
Institute of Process Equipment and Control Engineering, The MOE Key Laboratory of Mechanical Manufacture and Automation, Zhejiang University of Technology, Hangzhou 310032, China
国际会议
国际断裂力学2007年会(Fracture Mechanics and Applications 2007)
长沙
英文
273-276
2007-11-01（万方平台首次上网日期，不代表论文的发表时间）