Failure Analysis of a Welded 316L Stainless-Steel Stack with Premature Damage Due to Stress-Corrosion Cracking

This study analyzed the premature failure of a stainless-steel stack obtained from a mining company. The stack was manufactured using ASTM A240 Type 316L stainless steel. After one year of its service, massive leakages and cracks were observed near the welds. Following a visual examination of the stack, a representative sample was extracted and analyzed using visual and radiographic inspection, metallographic examination, scanning electron microscopy, energy-dispersive spectrometry, optical emission spectrometry, ferrite number analysis, and leak testing. Furthermore, corrosion mechanisms and the sequence of events leading to failure were determined. Two different mechanisms were identified: acid dew point corrosion caused by the condensation of H₂SO₄ and HCl at the inner walls of the chimney, followed by stress-corrosion cracking near the welded joints.