高温过热器爆管失效分析

Burst Failure Analysis of Pipe in High Temperature Superheater

锅炉高温再热器使用150000 h后发生爆管,通过对高温再爆管情况进行现场调研,并对管样进行宏观检查、力学性能试验、金相及硬度试验、壁厚及管径测量等分析。结果表明:失效管样金相组织中珠光体完全球化,碳化物已呈链状分布,从而导致其力学性能明显下降;内外壁氧化皮厚度测量结果均已超过相关标准要求。高温再热器出口联箱弯头爆管原因为:材质老化导致材料力学性能下降,材料内部产生微裂纹,由于弯头处应力较大,裂纹扩展至壁厚减薄,当壁厚减薄至不满足工况需要时,发生爆管。

After working for 150000 h,a pipe in the high-temperature reheater of a boiler burst.In order to find out the failure cause,field investigation,macroscopic inspection,mechanical properties testing,metallographic examination,hardness testing,and wall thickness and diameter measurement were carried out.The results show that the pearlite in the failed tube-like metallographic structure is completely globalized,and the carbides have been distributed in a chain shape,which resulting in a significant decrease in mechanical properties.The measurement results of the inner and outer wall oxide scale thickness exceed the relevant standard requirements.The burst reasons of the elbow pipe of the outlet header of the high temperature reheater are as follows:the aging of the material led to the deterioration of the mechanical properties of the material and the occurrence of micro-cracks in the material.Due to the larger stress at the elbow,the crack expanded,resulting in the thinning of the wall thickness.When the wall thickness was thinned enough,the pipe burst.