顺丁橡胶装置溶剂管线腐蚀泄漏原因分析及防腐对策

Analysis of the Causes of Corrosion and Leakage of Solvent Pipeline and Corrosion Countermeasures of Cis-Butadiene Rubber Plant

某石化公司的顺丁橡胶装置发现溶剂管道出现了腐蚀穿孔问题。为了找到管道失效的根本原因,对腐蚀管道进行了取样,并进行了宏观检查、化学成分分析、硬度测量、金相组织分析、微观形貌分析以及腐蚀产物能谱分析等检验与分析。结果显示,管道的化学成分、力学性能及金相组织均符合要求。然而,微观形貌分析发现腐蚀区域呈现沿晶选择性腐蚀,能谱结果显示腐蚀区域含有较高量的氟元素。综合考虑到腐蚀主要发生在焊缝附近,焊缝的凸起和沟槽会在该区域形成涡流和低压区,导致管道内上层气相区的氢氟酸(HF)浓度过高,从而对管壁组织变化区域产生选择性晶间腐蚀。因此可以判断氢氟酸(HF)腐蚀是导致溶剂管道腐蚀穿孔的根本原因。针对管道失效原因,提出了在焊接施工、工艺操作和材质升级方面的建议措施,以避免和预防类似失效,从而提高设备的安全性。

Corrosion perforation is found in the solvent line of a petrochemical company's cis-butadiene rubber plant.In order to find the root cause of the pipe failure,the corroded pipe is sampled,inspected,and analyzed by macro inspection,chemical composition analysis,hardness measurement,metallurgical organization analysis,microscopic morphology analysis,and corrosion product energy spectrum analysis.The results show that the chemical composition,mechanical properties and metallographic organization of the pipe meet the requirements.However,the micro-morphological analysis showes that the corrosion area is selective corrosion along the crystal,and the energy spectrum results showes that the corrosion area contained a high amount of fluorine elements.Considering that the corrosion mainly occurs in the vicinity of the weld seam,the bumps and grooves of the weld seam will form eddy currents and low-pressure zones in the region,which will lead to the high concentration of hydrofluoric acid(HF)in the upper gas phase region in the pipeline,thus causing selective intergranular corrosion in the region of tissue changes in the pipe wall.Therefore,it can be judged that hydrofluoric acid(HF)corrosion is the root cause of corrosion perforation of solvent pipelines.Suggested measures in welding design,process operation and material upgrading are proposed for the causes of pipe failure to avoid and prevent similar failures and thus improve the safety of the equipment.