Corrosion behavior and mechanism of carbon steel influenced by interior deposit microflora of an in-service pipeline

• Published in: Bioelectrochemistry (Amsterdam, Netherlands) Vol. 132; p. 107406
• Main Authors: Su, Hong, Tang, Ruohao, Peng, Xiaowei, Gao, Aiguo, Han, Yejun
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.04.2020; Elsevier BV
• Subjects: 16S rRNA sequencing; Bacterial corrosion; Biofilms; Carbon - chemistry; Carbon steel; Carbon steels; Cementite; Charge transfer; Corrosion; Corrosion mechanisms; Corrosion products; Corrosion resistance; Direct electron uptake; EIS; Electrochemical impedance spectroscopy; Electrochemistry; Electrodes; Electron transfer; Gene sequencing; Iron carbonate; Killed steels; Microbial activity; Microbiologically influenced corrosion; Microbiota - genetics; Microflora; Minimum inhibitory concentration; Oil and gas fields; Open circuit voltage; Pitting (corrosion); Polarization; RNA, Ribosomal, 16S - genetics; rRNA 16S; Spectroscopy; Steel; Steel - chemistry; Submerging; Surface analysis (chemical); Polarization; Microbiologically influenced corrosion; Carbon steel; Direct electron uptake; 16S rRNA sequencing; EIS
• ISSN: 1567-5394; 1878-562X
• DOI: 10.1016/j.bioelechem.2019.107406

•Deposited microflora on steel pipe inner wall caused severe pitting.•Charge transfer resistance increased for the first 45 days and decreased rapidly thereafter.•Final biofilm microbes significantly accelerated the cathodic reaction.•Genus Methanobacterium dominated the final biofilm community. Investigation of carbon steel corrosion influenced by in-situ microbial communities can provide reliable information about microbiologically influenced corrosion (MIC) in the oil and gas field. Here, we investigated the 90-day corrosion behavior of Q235 carbon steel influenced by interior deposit microflora of an in-service pipeline using open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS). Linear sweep voltammetry (LSV), 16S rRNA gene sequencing, and surface analysis were used to comprehensively analyze the corrosion mechanisms. The results indicated that OCP was decreased while the charge transfer resistance (Rct) was increased, and that steel corrosion was inhibited during the first 45 days. Subsequently, OCP was significantly increased while Rct was rapidly decreased, and steel corrosion was enhanced. After 90-day immersion, severe pitting corrosion with a maximum pit depth of 89.6 μm occurred on the steel surface. Viable microbes in the final biofilm significantly increased the cathodic current. Iron carbonate, chukanovite and cementite were identified as the main corrosion products on the steel surface. Methanobacterium dominated the final biofilm community. These observations indicate that the corrosion mechanism of the final biofilm can be explained by extracellular electron transfer MIC in which microbes corrode steel by direct electron uptake.