Abstract:

Shortly after the start-up of a 1 000 MW steam turbine, the No. 2 closed tube expansion joint of the middle and low-pressure cylinder burst suddenly, and the turbine was forced to shut down. The blasting area of the bellows expansion joint was studied through salt deposit chemical analysis, metallographic examination, SEM and EDS analysis. Results showed that a large amount of salt and abnormal water deposit at the bottom of the bellows expansion joint, which provided chloride ion corrosion environment. As the material of 316L stainless steel was sensitive to the above environment, stress corrosion cracking of the expansion joint was finally triggered by combing with the action of stress.

Key words: steam turbine, expansinon joint, salt accumulation, stress corrosion, chloride ion

摘要：

某1 000 MW汽轮机启动后不久，中低压缸导汽管2^#膨胀节突然发生爆破，被迫紧急停运。通过对波纹管膨胀节爆破部位进行积盐化学分析以及金相检查、SEM和能谱分析，查明膨胀节底部大量积盐和异常积水提供了氯离子腐蚀环境，其与316L不锈钢敏感材质和应力共同作用，导致膨胀节发生应力腐蚀破裂。

关键词: 汽轮机, 膨胀节, 积盐, 应力腐蚀, 氯离子

CLC Number: 

• TG17