工艺冷凝液管线泄漏原因分析

Cause Analysis of Process Condensate Pipeline Leakage

某化工装置工艺冷凝液管线在服役过程中多处发生泄漏。泄漏管线宏观检查和无损检测结果表明,泄漏集中在焊缝及周边母材区域。采用化学成分分析检验、金相组织分析、断口形貌分析、腐蚀产物形貌及成分分析等方法对泄漏部位裂纹及腐蚀坑进行检测检验,结合管内工艺流体特性进行综合分析,认为管线内壁附着物下产生的酸性环境是导致管壁发生点腐蚀的根本原因,介质中Cl-在腐蚀坑内不断富集,裂纹在应力作用下萌生、扩展及开裂是导致管线泄漏的主要原因,同时提出了预防和减少管线泄漏的建议措施。

The process condensate pipeline of a chemical plant was found to have leaks in many places during its service.The results of the macroscopic inspection and nondestructive testing of the leaked pipeline show that the leakage was concentrated in the weld seam and surrounding base metal area.The chemical composition analysis,metallographic structure analysis,fracture morphology analysis,corrosion product morphology and composition analysis were used for detection analysis of cracks and corrosion pits at leakage sites.According to the comprehensive analysis of the characteristics of the process fluid in the pipe,it is believed that the acidic environment generated under the attachments on the inner wall of the pipeline is the root cause of pitting corrosion on the pipe wall.Cl-is constantly enriched in the corrosion pit,and the initiation,expansion,and cracking of cracks under the action of stress are the main reasons.Precautions are proposed to lower down pipeline leakage.