Ethanol fuel production and consumption is expected to increase significantly in the near future. Existing pipeline infrastructure could be repurposed to transport ethanol and other biofuels from production sources, such as those located in the Midwest, to end users across the country. The effects of ethanol fuel, including its ability to harbor corrosion-inducing microbiological life, are not well established in relation to degrading the fatigue properties of pipeline materials. Experiments were performed to evaluate crack growth behavior of pipeline steels in several ethanol environments. The environments included a simulated fuel grade ethanol and an ethanol-water solution inoculated with a microbiological species (Acetobacter aceti) isolated from industrial ethanol storage tanks. Fatigue crack growth rates of API 5L X52 and X70 pipeline steels were determined as a function of the stress intensity amplitude (Δ_K) during exposure to the various ethanol environments. Significant increases in fatigue crack growth rate were found above approximately 17 MPa*m^1/2 and 20 MPa*m^1/2 during testing of X52 and X70 in simulated fuel grade ethanol, respectively. Fatigue crack growth rates were increased by two orders of magnitude during testing of X52 and X70 in ethanol-water solutions inoculated with acetic acid producing bacteria. Concurrent research suggested that glutaraldehyde may be an effective biocide for controlling acid producing bacteria in pipelines. The data presented is useful for reliability models to ensure safe ethanol fuel transport.
Conference Dates: July 31-August 5, 2011
Conference Location: La Quinta, CA
Conference Title: DoD Corrosion Conference 2011
Pub Type: Conferences
acid producing bacteria, biofuel, fuel grade ethanol, fatigue crack growth, microbiologically influenced corrosion, pipeline steel, X52, X70