对一起电站锅炉主蒸汽管道流量装置裂爆事故的技术分析

Technical analysis on a ruptured accident of flow device of main steam pipe of power plant boiler

在某电厂蒸汽管道所使用的流量装置发生裂爆事故后,对事故现场进行资料核查,并对事故流量计进行外观检查、金相分析、材料成分分析和微观形貌分析。焊缝宏观检查发现存在严重的焊缝不连续、未焊透、未熔合、夹渣、弧坑裂纹等缺陷,这些缺陷遍布整个焊缝。扫描电镜和金相分析发现破断焊缝断口上有典型的脆性沿晶开裂特征,并伴有沿晶次裂纹。对流量计与主蒸汽管道安装位置焊缝的金相分析发现此处焊缝微观组织合理。

After the crack explosion accident occurred in the flow device being used in the steam pipeline of a power plant,the data check on the accident site,appearance check,metallographic analysis,material composition analysis and micro morphology analysis of the accident flowmeter were carried out.The macro inspection of the weld found that there were serious weld discontinuities,incomplete welding,incomplete fusion,slag inclusion,arc pit cracks and other macro defects,these defects throughout the whole weld.The fracture of broken welds was tested by sem and metallographic analysis.It was found that there were typical characteristics of brittle intergranular cracking and intergranular subcracks.The result of metallographic analysis shows that the microstructure of the weld between the installation position of the flowmeter and main steam pipe is reasonable.