大型化工设备中蒸汽异径管的失效分析及对策

Failure Analysis and Countermeasures on Reducer Pipe in Steam System of Chemical Plant

在蒸汽系统中,其管配件长期在高温高压的环境下服役,对于异径管来说还会受到流体的不规则冲刷等问题,容易发生早期失效。文章就某化工设备蒸汽系统中异径管的腐蚀失效开展研究,其在使用不到两年的时间内就发生了严重腐蚀,部分甚至出现了穿孔。为了确定失效的根本原因对其进行了系统性分析,包括材质分析、腐蚀凹坑的宏微观分析、水质分析和腐蚀产物分析。结果表明,点蚀与流体冲刷的交互作用是导致管壁腐蚀的根本原因。此外,点蚀坑在流体作用下形成漩涡冲刷,进一步加剧凹坑尺寸,最终导致腐蚀穿孔的发生。最后提出了相应的解决对策,以防类似事故的再次发生。

The pipe fittings of steam system serviced in high temperature and high pressure environments,and for reducer pipe,it would also be subject to irregular fluid erosion and other problems,which were prone to early failure.This paper studied the reducer pipe corrosion in steam system of one specialty chemical plant,which had been severely corrroded and even perforated in less than two years after put into service.The systematic failure analysis was conducted to determine the root cause of the failure,including material analysis,macro and micro analysis of the corrosion pits,water quality analysis and corrosion product analysis.It was identified that the interaction between pitting and erosion was the root cause.In addition,the pitting pits was aggravated under the effect of vortex erosion inside the corrosion pits,and eventually leading to the occurrence of perforation.Finally,the countermeasures were proposed for prevention of reoccurrence of similar cases.