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利用故障树失效分析方法,从设计、制造、安装、运行等角度出发,对某超(超)临界锅炉水冷壁管泄漏事故可能性原因进行排除性分析,分析工作包括设计复核、运行参数检查、宏观形貌、断口形貌、显微组织分析、化学成分分析、室温拉伸性能试验、硬度试验等。结果表明:失效部件在设计、制造、运行方面无问题,水冷壁泄漏的直接原因为宽大的H型鳍片角焊缝裂纹扩展至水冷壁管。H型鳍片与水冷壁弯管的角焊缝质量差,存在未焊透、气孔、缩孔等缺陷,导致角焊缝的强度降低、局部应力集中、冷却效果差,在长期服役中过早形成裂纹。根据失效分析结果,给出了缺陷处理建议。
Based on the design, manufacture, installation and operation of the fault tree failure analysis, the author analyzes the possible causes of water wall tube leakage accident in a supercritical (super) critical boiler. The analysis includes design review, operation parameter check, Macroscopic morphology, fracture morphology, microstructure analysis, chemical composition analysis, tensile properties at room temperature test, hardness test. The results show that there is no problem in the design, manufacture and operation of the failed components. The direct cause of the water wall leakage is that the crack of the fillet welds in the wide H-shaped fins extends to the water-cooled tube. H-shaped fins and water wall elbow fillet weld quality is poor, there is no penetration, porosity, shrinkage and other defects, resulting in reduced strength of fillet weld, local stress concentration, cooling effect is poor, too early in the long service Crack formation. According to the result of failure analysis, the advice of defect disposal is given.