针对某电厂亚临界机组运行过程中低温过热器SA210C管发生的泄漏原因进行了失效分析, 并提出了改进措施。结果表明: 低温过热器管在弯管加工时造成了弯管外侧机械损伤, 经火焰校正、锤击后演变为显微裂纹, 显微裂纹在外界环境和材料内部应力的综合作用下发生扩展, 引起管道泄漏; 断口形貌呈现出疲劳特征。建议在管道弯管加工时应确保接触面的平整, 弯管后火焰校正及锤击工艺要合理, 弯管使用前采用超声导波技术进行检验。

The reasons for leakage of the low temperature superheater pipe SA210C in subcritical units for a thermal power plant were analyzed and the relevant improvement was given to avoid the similar failure. The results show mechanical damages caused in the process of pipe bending evolved into the microcracks after flame correction and hammering. These microcracks propagated under the combining effects of external environment and internal stress, resulting in the failure of pipe. A fatigue characteristic could be found in fracture morphology. In process of pipe bending the contact surface should keep neat and the processes of flame correction and hammer for the bended pipe were reasonable, the ultrasonic guided wave inspection technology was suggested to apply before this type pipe were used.