某电厂1号锅炉发生主蒸汽管道泄漏,管道泄漏部位为炉顶主蒸汽对空排气门法兰与主蒸汽联箱中间焊缝位置,经对管道焊缝及母材的无损检测、理化分析和管道系统的支吊架检查,确认本次泄漏主要原因为主蒸汽管道支吊架设置不合理造成应力集中且主蒸汽管道对空排气门使用频次过高,导致主蒸汽管道的焊接接头受循环应力作用,在长周期循环应力的作用下焊接接头在熔合区出现疲劳裂纹,裂纹又经过扩展导致此次管道泄漏.本文从主蒸汽管道支吊架设置不合理引起焊管道集中,分析焊接接头开裂原因,并针对此类管道焊缝无损检测工艺提供了相应措施.%A leakage of main steam pipeline happened to the No.1 boiler in a power plant,the pipeline leakage site was the weld joint location between the main steam pipeline exhaust valve flange on boiler roof and the main steam header.Through the non-destructive testing of the pipeline weld,the physicochemical analysis of weld and base metal and the supports and hangers inspection of the pipe system,the major cause of this leakage was the stress concentration caused by the unreasonable setting of the main steam pipeline's supports and hangers.In addition,the usage frequency of main steam pipeline exhaust valve was too high,causing the weld joint subjected to cyclic stress effect.Fatigue crack appeared in the fusion zone of the weld joint under the effect of long-periodic cyclic stress,and the crack extended which led to this pipeline leakage.In this paper,the cracking cause of weld joint was analyzed from the welded pipe concentration caused by unreasonable setting of main steam pipeline's supports and hangers,and corresponding measures were proposed for such pipeline weld joint non-destructive testing technology.
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