三聚氰胺装置一吸塔泄漏事故分析

Leakage Accident Analysis of First Absorption Column in Melamine Unit

三聚氰胺装置一吸塔使用过程中发生裂纹泄漏。为研究其断裂类型和影响因素,对断口进行了宏观和微观形貌分析,发现在焊接热影响区的敏化区发生混合型(晶间型和穿晶型同时存在)应力腐蚀破裂。通过一吸塔内介质分析、铁素体检测、材料硬度检测、磁性检测和裂纹形态分析,判定开裂失效是敏化后的S30408不锈钢(奥氏体+形变诱导马氏体)在含有硫化氢的潮湿环境中产生的应力腐蚀破裂。

First absorption column of a melamine unit was found cracking in the process of using. In order to study the cracking types and influence factors, the fracture analysis of macroscopic profile and microstructure was performed to study, it was found stress corrosion cracking（SCC） in the welding heat sensitizing area, this SCC include IGSCC and TGSCC. Through analysis of medium in the absorption column ＆ ferrite material ＆ material hardness ＆ material magnetism ＆ cracking types, it was decided： the cracking was the stress corrosion cracking, that the cracking reason was SCC of S30408 stainless steel（austenitic ＋deformation induced martensite） working in the environment of wet hydrogen sulfide.