600MW机组省煤器爆管原因

Causes of economizer tube explosion in 600 MW unit

某600 MW机组省煤器发生爆管事故,采用宏观观察及壁厚测量、磁粉检测、化学成分分析、力学性能测试、金相检验、扫描电镜及能谱分析等方法分析爆管原因。结果表明:弯管外表面磨损严重及腐蚀造成壁厚减薄量过大,并且爆裂弯管处圆度超标,在内压膜应力的作用下,弯管外弯复圆过程会产生较大的弯曲应力和拉应力,故弯管外弯部位表面承受的应力进一步增大,使剩余壁厚无法承受内部介质的压力,从而造成爆管事故。

A 600 MW unit economizer tube burst accident occurred.The causes of tube burst were analyzed by means of macroscopic observation and wall thickness measurement,magnetic particle detection,chemical composition analysis,mechanical property test,metallographic examination,scanning electron microscope and energy spectrum analysis.The results show that the outer wall of the bent pipe was seriously worn and the wall thickness reduction caused by corrosion was too large,and the roundness of the burst bent pipe exceeded the standard.Under the action of internal pressure film stress,the outer bending and rerounding process of the bent pipe would cause large bending stress and tensile stress,which further increased the stress on the wall of the outer bending part of the bent pipe,so that the remaining wall thickness could not withstand the internal medium pressure,resulting in a burst accident.