350 MW亞臨界機組T91鋼再熱器管泄漏失效分析

350 MW亞臨界機組T91鋼再熱器管泄漏失效分析Failure Analysis on Leakage of T91 Steel Reheater Tubes in a 350 MW Subcritical Power Unit

國內某電廠引進型350 MW亞臨界鍋爐運行1.2×105 h后在進行水壓試驗時，其三級再熱器T91鋼管道在定位滑塊焊接處出現(xiàn)多處泄漏失效現(xiàn)象。對其中兩根發(fā)生泄漏的T91鋼管進行割管取樣，通過宏觀分析、化學成分分析、力學性能試驗、金相檢驗、掃描電鏡以及能譜分析等方法，對其泄漏原因進行了分析。結果表明：焊接工藝執(zhí)行不當，造成T91鋼管在焊接定位滑塊時局部管壁被焊穿，同時焊縫中存在氣孔等缺陷，是導致其在水壓試驗時發(fā)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.

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