Effect of Concentration and Temperature of Ethanol in Fuel Blends on Microbial and Stress Corrosion Cracking of High-Strength Steel

Localized environments in fuel grade ethanol (FGE) transportation systems, where conditions are suitable for growth, may allow for microbiologically influenced corrosion (MIC) of steel components. Interstate pipeline transportation of ethanol fuels increases the potential impact of a MIC related failure. A laboratory MIC investigation is presented to evaluate the potential for increased susceptibility of linepipe steels to MIC when low concentrations of ethanol are present. This research is supported by a microbiological field survey of FGE infrastructure. Acetic acid producing bacteria (APB) and a sulfate-reducing bacterial (SRB) consortium are isolated from a failed storage tank used to capture ethanol spillage and runoff water at a fueling terminal. Electrochemical corrosion testing and electron microscopy are applied to study MIC of API X52 and API X70 linepipe steels by these isolated bacteria. Electrochemical techniques including open circuit potential (OCP), polarization resistance (PR), and electrochemical impedance spectroscopy (EIS) evaluate corrosion kinetics and electrochemical properties of the steel-solution interface. Scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) are applied to study corrosion products and morphology. Qualitative MIC models are presented to explain corrosion mechanisms operating in the experimental systems. A multi-specimen four-point bend testing (MSBT) method is developed to screen for crack initiation and reductions in mechanical properties due to microbially influenced embrittlement. Electrochemical corrosion data indicate acceleration of steel corrosion rates due to SRB in ethanol and acetic acid environments. Localized corrosion is identified on API X52 and X70 steels exposed to APB and on API X70 exposed to SRB. Neither cracking nor reduction of mechanical properties was identified on either steel in either environment.

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  • Corporate Authors:

    Colorado School of Mines

    1500 Illinois Street
    Golden, CO  United States  80401

    National Institute of Standards and Technology

    100 Bureau Drive
    Gaithersburg, MD  United States  20899-8615

    iCorrosion, LLC


    Pipeline and Hazardous Materials Safety Administration

    Department of Transportation
    East Building, 2nd Floor, 1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Jain, Luke
    • Mishra, Brajendra
    • Olson, David L
    • Spear, John R
    • Williamson, Chase
    • Weeks, Timothy
    • Sowards, Jeff
    • Kane, Russell D
  • Publication Date: 2012-2


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 109p

Subject/Index Terms

Filing Info

  • Accession Number: 01640830
  • Record Type: Publication
  • Contract Numbers: DTPH56-08-T-000014
  • Files: TRIS, ATRI, USDOT
  • Created Date: Jul 10 2017 10:57AM