Failure Analysis of Tees on Heat Exchanger Inlet

The cracking failure of a hydrogenation heat exchanger tee has been analyzed. The failure mechanism of the tee can be described as the stress corrosion cracking (SCC) of austenitic stainless steel, through the investigation of manufacturing and service history, the analysis of the macro-morphology and the crack morphology, the composition analysis, the metallographic analysis, the energy-dispersive spectroscopy (EDS) and numerical simulation. The analysis results show the presence of chloride and sulfur, which provides the medium condition for SCC. Also, the residual stress and the working stress in the weld zone provide the tensile stress condition for SCC.