Microbiologically Influenced Corrosion of Carbon Steel Exposed to Anaerobic Soil

• Published in: Corrosion (Houston, Tex.) Vol. 57; no. 9; pp. 815 - 828
• Main Authors: Li, S.Y., Kim, Y.G., Jeon, K.S., Kho, Y.T., Kang, T.
• Format: Journal Article
• Language: English
• Published: Houston, TX NACE International 01.09.2001; NACE
• Subjects: Ammeters; Analytical methods; Applied sciences; Bacteria; Bacterial corrosion; Biofilms; Carbon steel; Carbon steels; Cathodic protection; Corrosion; Corrosion environments; Corrosion mechanisms; Corrosion prevention; Corrosion products; Corrosion rate; Corrosion resistance; Corrosion tests; Current measurement; Electric conductivity; Electrical resistivity; Electrochemical impedance spectroscopy; Electrochemistry; Electrode polarization; Electron microscopy; Energy dispersive spectroscopy; Environmental factors; Exact sciences and technology; Hydrogen production; Hydrogen sulfide; Hydrogen sulphide; Iron sulfides; Light polarization; Localized corrosion; Metals. Metallurgy; Microbiology; Minimum inhibitory concentration; Moisture; Moisture content; Organic carbon; Oxidation; Polarization; Polls & surveys; Redox reactions; Scanning electron microscopy; Soil; Soil investigations; Soil water; Soils; Spectroscopy; Spectrum analysis; Steel; Sulfate reduction; Sulfate-reducing bacteria; Sulfates; Sulphate reduction; Sulphides; Surveying; Thin films; Total organic carbon; Water content; Corrosion rate; Sulfate-reducing bacteria; Corrosion mechanism; Carbon steel; Bacterial corrosion; Soil corrosion
• ISSN: 0010-9312; 1938-159X
• DOI: 10.5006/1.3280616

ABSTRACTMicrobiologically influenced corrosion (MIC) of plain carbon steel in anaerobic soil was investigated using field survey, the electrochemical polarization technique, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), a thin-film electrical resistance (ER) probe, and galvanic current measurement. The field survey revealed that the risk of MIC could be predicted by the analysis of environmental parameters such as soil resistivity, water content, the content of total organic carbon, reduction-oxidation potential, and the content of sulfate with the consideration of the effectiveness of cathodic protection (CP). From the results of conventional electrochemical experiments, it is evident that the presence and therefore the activity of sulfate-reducing bacteria (SRB) alter the corrosion mechanism of steel by the production of hydrogen sulfide (H2S) and iron sulfide (FeS) film on the steel surface, which reduces the polarization resistance and therefore increases the corrosion rate. SRB-induced MIC is a localized corrosion accompanying the breakdown of the biogenic FeS film. This fact is confirmed by SEM/EDS analysis and thin-film ER probe testing. The localized corrosion rate by SRB after the rupture of the sulfide film can be obtained by the zero-resistance ammeter (ZRA) technique and is comparable to that reported in field conditions.Microbiologically influenced corrosion (MIC) is the term used for the phenomenon in which corrosion is initiated and/or accelerated by the activities of microorganisms. MIC is widely recognized in various industrial fields. Microorganisms are especially abundant in soil, which means they can influence the corrosion behavior of buried metal structures such as pipelines. Buried pipeline is designed to have a lifetime of ~ 30 years to 50 years. Continuous inspection and maintenance are required to secure this lifetime and reliability. For this purpose, protective organic coating and cathodic protection (CP) are applied. Despite these protection measures, failure cases of underground pipelines caused by corrosion have been continuously reported. MIC has been identified as one of the major causes of corrosion failures of underground pipelines.1 The first MIC case was identified by von Wohlzogen Kühr and van der Vlugt in 1934,2 where sulfate-reducing bacteria (SRB) resulted in the failure of cast iron pipes buried in anaerobic soil. Since this observation, numerous works have been written concerning the effect of bacteria (including SRB). According to a recent survey performed by the authors, corrosion of underground gas transmission