燃煤电厂低温过热器新旧管焊缝轴向裂纹分析

Analysis on the Axial Crack of Weld Joint of the New-Old Low Temperature Superheater Tube in a Coal-fired Power Plant

某燃煤电厂低温过热器新管与旧管对接的焊缝在水压试验中发现存在泄漏,通过对泄漏位置的宏观形貌、金相组织和力学性能进行检验,分析讨论造成低温过热器管泄漏的原因,针对该类型缺陷提出了一些针对性的措施。结果表明:管道加工变形过程中形成了端部贯穿性裂纹,并在后期配管时两端盲区缺陷未割除干净。提出的措施可以为锅炉受热面管检修质量管理提供参考。

To solve the problem of the leakage in the weld joint between the new and old low temperature superheater tube found during water pressure test in a coal-fired power plant, analyses and discussions were conducted on the leakage reason of the low temperature superheater through the test of macroscopic morphologies, microstructure and mechanical properties for the leakage sample. After which, corresponding countermeasures were proposed for this type of defect. Results show that the penetrating end crack is formed in the process of tube machining deformation, while the defects in the blind areas at the both ends are not completely removed in later tube selecting. The proposed countermeasures can serve as a reference for the quality management of the heat transfer tubes in boilers.