国内某电厂引进型350 MW亚临界锅炉运行1.2×10⁵ h后在进行水压试验时，其三级再热器T91钢管道在定位滑块焊接处出现多处泄漏失效现象。对其中两根发生泄漏的T91钢管进行割管取样，通过宏观分析、化学成分分析、力学性能试验、金相检验、扫描电镜以及能谱分析等方法，对其泄漏原因进行了分析。结果表明：焊接工艺执行不当，造成T91钢管在焊接定位滑块时局部管壁被焊穿，同时焊缝中存在气孔等缺陷，是导致其在水压试验时发生泄漏失效的主要原因。

For an imported 350 MW subcritical boiler of a power plant in China, multiple leakage failure phenomenon occured to the third stage reheater T91 steel tubes at the slider welding positions during hydraulic test after operation for 1.2×10⁵ h. Two typical leakage tubes were cut and the leakage reasons were analyzed by means of macroscopic analysis, chemical composition analysis, mechanical property test, metallographic examination, scanning electron microscope and energy spectrum analysis and so on. The results show the improper welding process resulted in local tube wall burn-through and pore defect when welding sliders, which was the main reason for the leakage of the T91 steel tubes during hydraulic test.