Growing interest in the use of alternative fuels has led to an increase in production of fuel grade ethanol (FGE), necessitating an efficient method of transportation for this biofuel. Occurrences of stress corrosion cracking (SCC) of pipeline steels in FGE have spurred studies toward understanding the phenomenon of this environmentally assisted cracking and corrosion. Prior work in simulated fuel grade ethanol (SFGE) has shown that water, chloride ions, dissolved oxygen, and acidity are all major factors in the promotion of SCC of pipeline steel. In this study, passive film characteristics and passivation kinetics of X65 pipeline steel in different FGE environments are explored. Results of scratch tests performed to compare passivation kinetics of X65 steel in FGE environments containing chloride, oxygen, and water are presented in this paper. Scratch tests and electrochemical measurements aided in characterization of passive layer formation, while scanning electron microscope (SEM) imaging and energy dispersive spectroscopy (EDS) of FGE-exposed steel coupons helped identify passive layer composition and elucidate passive film characteristics and corrosion product composition.

Subject
Electric current, Films, Steel surfaces, Water, Simulated fuel grade ethanol, Aqueous environments, Pipelines, Stress, Film formation, Steel, Ethanol, Stress corrosion cracking, Chloride stress corrosion cracking
Keywords:
Stress corrosion cracking, biofuel, fuel grade ethanol, pipeline steel, X65, scratch test, passivation kinetics
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2011
Association for Materials Protection and Performance (AMPP)
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