Microbiologically Influenced Corrosion in an Oxidizing KMnO ₄ Transfer Pipeline: Role of Biofilm‐Induced Anaerobic Microenvironments in Premature Failure

In this study, Premature leakage of a stainless‐steel pipeline used to transfer a 4% potassium permanganate (KMnO 4 ) solution was investigated to identify the degradation mechanism responsible for the failure after a short service period. Visual inspection revealed tubercle formation and deposit accumulation on the inner pipe surface, while scanning electron microscopy (SEM) analysis showed localized corrosion features, including micro‐pitting and tunnel‐like cavities beneath biofilm layers. SEM‐EDS analysis detected sulfur‐rich corrosion products within the deposits and pit interiors, suggesting sulfide formation possibly associated with microbiologically influenced corrosion. The observed corrosion mechanism is consistent with microbial sulfate reduction coupled with electrochemical iron dissolution, leading to iron sulfide deposition and localized under‐deposit corrosion. The study demonstrates that biofilm formation can create localized anaerobic microenvironments that enable microbiologically influenced corrosion (MIC), even in oxidizing KMnO 4 transfer systems, providing new insights into MIC risks in chemical‐handling pipelines.