低压蒸汽过热器换热管应力腐蚀开裂案例分析

Analysis of Stress Corrosion Crack Occurred in Tubes in Low Pressure Steam Superheater

某项目投产运行一段时间后,低压蒸汽过热器多次发生泄漏。通过水压试验找到泄漏位置,割取换热管进行失效分析,得出泄漏产生的原因:奥氏体不锈钢换热管发生了起源于管外侧的点蚀和应力腐蚀裂纹,并向内壁扩展,最终导致换热管泄漏。

Leakages were occurred in low-pressure steam superheater leaked for several times after the plant had been put into operation for a period of time.The leakage location was found by hydrostatic test.By failure analysis of the heat exchange tubes the cause of the leakage was obtained that was pitting corrosion and stress corrosion cracks initiating from the outside of the austenitic stainless steel tube and spreading to the inner wall finally resulted in leakage.