Corrosion Failure Causes of 2205 Tube Bundle in a Bottom Reboiler of a Condensate Stabilization Tower

The failure of cracking appeared on 2205 duplex stainless steel heat exchange tube bundle in a bottom reboiler of a condensate stabilization tower. The failure causes were analyzed systematically by macroscopic inspection, chemical composition and microstrcture inspection, residual stress test, fracture analysis and stress corrosion test. The results show that the failure location of the heat exchange tube bundle was mostly concentrated in the U-shaped area, and most cracks were circumferential. There was residual tensile stress in the U-shaped area of the failed tube bundle, whose maximum value reached 262 MPa. Obvious cleavage and quasi-cleavage features and secondary cracks could be seen on the fracture surface. The failure cause of the tube bundle was chloride stress corrosion cracking, which related to high temperature, salt formation and oxygen.