化工厂316L输送管道失效原因分析

Failure Analysis of 316L Pipeline in Chemical Plant

材质为316L不锈钢的半成品柴油输送管道在水平段底部出现快速腐蚀,9个月出现5次泄露。通过宏观分析、化学成分检测、力学性能测试、金相分析、腐蚀产物物相分析、腐蚀介质有害相分析、腐蚀产物分析等方法,对管道失效原因进行分析。结果表明:不锈钢管线腐蚀属于氧腐蚀及点蚀;氧化铁等腐蚀产物或杂质随介质在管线底部流动,对管线底部形成线状冲刷磨损,破坏了钝化膜的保护作用,造成管线底部率先腐蚀;腐蚀环境中Cl^-极易破坏不锈钢表面的钝化膜,形成坑蚀,成为孔蚀延伸的活性中心。

Rapid corrosion occurred to a semi-finished diesel pipeline made of 316L stainless steel at the bottom of the horizontal section,for 5 times within 9 months.The causes for the pipeline failure were analyzed by macroscopic analysis,chemical composition analysis,mechanical properties testing,metallographic analysis,corrosion product phase analysis,harmful phase analysis of corrosive media,and corrosion product analysis.The results show that the corrosion of the stainless-steel pipeline is oxygen corrosion and pitting corrosion.Corrosion products or impurities such as iron oxides flowed along the bottom of the pipeline with the media,leading to linear erosion wear on the bottom of the pipeline and damaging the protective effect of passivating film.As a result,the bottom of the pipeline was first corroded.Chlorine ions inthe corrosion environment can easily destroy the passivating film on the surface of stainless steel,forming pitting corrosion and becoming the active center of hole corrosion extension.