X42输油管道泄漏分析

Failure Analysis of Leakage of X42 Line Pipe

利用力学性能检测、无损探伤、腐蚀坑形貌观察和XRD相分析等研究手段,对X42输油管道试压泄露原因进行系统分析。分析结果表明:X42输油管道具有良好的强韧性能,各项力学性能指标满足管线标准要求;X42管道4点钟至8点钟位置管道内部腐蚀严重,存在明显的管道存蓄水腐蚀特征,并在管道内壁6点钟位置发现有多处点蚀坑;点蚀坑电镜分析和腐蚀产物分析表明,点蚀坑位置存在较高浓度的Cl^-,点蚀坑形貌表现为典型的Cl^-诱发小孔腐蚀特征。因此,X42管道试压泄漏是由于铺设后的管道内残留含较高浓度Cl^-的积水,积水中的Cl^-诱发孔蚀所导致。建议已完成铺设但未投用的油气管道,在封存前应进行充分排水和干燥处理,避免类似事故的发生。

The leakage cause of X42 line pipe was investigated by mechanical properties testing,nondestructive testing and SEM observation on corrosion pits and X-ray diffraction（ XRD） analysis. Experimental results show that X42 line pipe has outstanding combination of strength and toughness,and the properties meet the requirement. Obvious corrosion features can be found at the 4o＇clock to 8 o＇clock region of the inner surface,and several corrosion pits can be found at the 6 o＇clock. Energy spectrum analysis and phase analysis of XRD show there were a high content of chloride ions at the corrosion pits,and the pits displayed the typical small-hole corrosion characteristics. Therefore,it can be assumed that the pipe leakage is due to a large amount of residual water containing high-concentration chloride ions. The chloride ions resulted in pitting corrosion and final leakage under test pressure. It is suggested that those line pipes that have been laid but not put into service should be fully drained to avoid the occurrence of similar accidents.