Microbiologically influenced corrosion of welded AISI 304 stainless steel pipe in well water

This work analyzes the premature corrosion failure of a welded AISI 304 stainless steel (SS) pipe network in well water (WW) for 6 months. Laboratory tests were performed to analyze the corrosion behavior and to identify and distinguish the genera of bacteria. Pipe specimens were analyzed using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, open circuit potential, cyclic potentiodynamic polarization, and electrochemical impedance spectroscopy. Physicochemical properties of WW in the AISI 304 SS pipe presented positive Langelier saturation index, indicating the formation of corrosion scales. In welded 304 austenitic SS, the chromium depletion both in HAZ and in weld-metal leads to preferential anodic dissolution. The biofilm electrochemical activity produces oxygen concentration cells and the acid metabolic products induce preferential MIC, thus leading to pit formation on the HAZ of the weld. Biodiversity analysis of bacteria by next generation sequencing was carried out in corroded AISI 304 SS pipes and different genera of bacteria were identified.