At a conference this week,* NIST researchers presented new experimental evidence that bacteria that feed on ethanol and produce acid boosted fatigue crack growth rates by at least 25 times the levels occuring in air alone.
The NIST team used a new biofuels test facility to evaluate fatigue-related cracking in two common pipeline steels immersed in ethanol mixtures, including simulated fuel-grade ethanol and an ethanol-water solution containing common bacteria, Acetobacter aceti. Ethanol and bacteria are known to cause corrosion, but this is the first study of their effects on fatigue cracking of pipeline steels.
"We have shown that ethanol fuel can increase the rate of fatigue crack growth in pipelines," NIST postdoctoral researcher Jeffrey Sowards says. "Substantial increases in crack growth rates were caused by the microbes. These are important data for pipeline engineers who want to safely and reliably transport ethanol fuel in repurposed oil and gas pipelines."
Ethanol, an alcohol that can be made from corn, is widely used as a gasoline additive due to its oxygen content and octane rating. Ethanol also can be used as fuel by itself in modified engines. The NIST tests focused on fuel-grade ethanol.
The tests were performed on X52 and X70 pipeline steels, which are alloys of more than a dozen metals. Simulated fuel-grade ethanol significantly increased crack growth at stress intensity levels found in typical pipeline operating conditions, but not at low stress levels. The cracking is related to corrosion. The X70 steel, which is finer-grained than X52, had lower rates of crack growth at all stress levels. This was expected because larger grain size generally reduces resistance to fatigue. In the bacteria-laden solutions, acid promoted crack growth at stress intensity levels found in typical pipeline operating conditions.
Preliminary tests also suggested that glutaraldehyde, a biocide used in oil and gas operations, may help control bacterial growth during ethanol transport.
The findings are the first from NIST's biofuels test facility, where material samples are installed in hydraulic test frames and subjected to load cycles while immersed in fuel inside a transparent polymer tank. Fatigue crack growth and other properties are observed over a period of up to 10 days. NIST staff expect to continue and possibly expand the research to other potential biofuels such as butanol or biodiesel.
Collaborators at the Colorado School of Mines provided the bacteria, which were isolated from industrial ethanol storage tanks. The research was supported by the U.S. Department of Transportation.
* J.W. Sowards, T.D. Weeks, J.D. McColskey, C. Williamson, L. Jain and J.R. Fekete. Effect of ethanol fuel and microbiologically influenced corrosion on the fatigue crack growth behavior of pipeline steels. Presented at DOD Corrosion Conference 2011, La Quinta, Calif., August 1, 2011.
Laura Ost | EurekAlert!
ADIR Project: Lasers Recover Valuable Materials
21.07.2017 | Fraunhofer-Institut für Lasertechnik ILT
High-tech sensing illuminates concrete stress testing
20.07.2017 | University of Leeds
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....
A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...
Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision
Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...
21.07.2017 | Event News
19.07.2017 | Event News
12.07.2017 | Event News
21.07.2017 | Earth Sciences
21.07.2017 | Power and Electrical Engineering
21.07.2017 | Physics and Astronomy