连续重整装置再生单元电加热器管束腐蚀开裂失效分析

Corrosion and Cracking Failure Analysis of Electric Heater Tube Bundles in Regeneration Unit of Continuous Reformer

基于对连续重整装置再生单元失效电加热器的宏观检验、无损检测及理化分析结果,结合生产工艺状况及设备结构存在的腐蚀环境,参考有关金属材料失效机理经验理论,对电加热器管束腐蚀开裂的原因进行综合失效分析。结果表明,SS321不锈钢加热管开裂机理为氯化氢应力腐蚀开裂,加热管金属组织中形变马氏体的存在对应力腐蚀开裂起到了促进作用,腐蚀介质来源于设备结构设计不当引起的微量氯化氢及水在加热管局部的冷凝聚集。

The cause of corrosion and cracking of electric heaters in regeneration unit of continuous reformer was analyzed comprehensively.These conclusions were obtained through macro inspection,non-destructive testing,physical and chemical analysis of failed electric heaters,combined with the production process conditions and the corrosive environment of the equipment structure,according to the empirical theory about the failure mechanism of metal materials.The results show that the cracking mechanism of SS321 stainless steel heating tube is hydrogen chloride stress corrosion cracking.At the same time,the presence of deformed martensite in the metal structure of the heating tube promotes stress corrosion cracking.The corrosive medium comes from the condensation and accumulation of traces of hydrogen chloride and water in the heating pipe due to the improper design of the equipment structure.