Abstract: In case of a certain flash steam condenser，cracks are found at the end of the stainless steel heat-exchanger pipe as welded onto the pipe plate.The cracks are analyzed by means of scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy（EDS），and then the crack type is identified as intergranular fracture，and a significant presence of Cu in the cracking area is also found. Furthermore，the stress distribution in the welded joint is simulated by using the Abaqus software，revealing a peak Mises stress of 246.75 MPa at the pipe end. Additionally，the temperature-field simulation shows that the temperature exceeds 1 083 ℃ at the pipe end during the welding. Combining actual welding process and operation，the main causes for the said pipe end crack are identified，i.e.，the“Cu contamination”at the tube end proper，and the stress concentration. To prevent reoccurrence of such problem，it is recommended to properly process the inner side of the pipe end during the machining operation so as to reduce stress concentration，and to eliminate the source of Cu contamination.