A mathematical approach was taken in order to describe the pitting process in CO2 corrosion. The hypothesis established was based on a unidirectional pit model which involved nineteen species, one of them (Fe2+) being diffused from the bottom of the pit. Using numerical methods, a prediction of corrosion rates in the pit, concentrations of the species in the pit and pH profile were determined. The average corrosion pitting rate from CO2 was found by calculating the corrosion rate at various pit depths.

Sulfate reducing bacteria (SRB) on carbon steel has been studied by determining the role of bacteria in conjunction with localized CO2 corrosion. The influence of temperature, pH, sodium chloride, acetates and sulfates has been analyzed and modeled in a program that calculates CO2 pitting corrosion rates including the reduction from sulfate to sulfide due to SRB. This bacteria metabolism produces acetate and hydrogen ions which increases the CO2 pitting corrosion rates. The increased corrosion rate from the bacteria is expressed as a percent enhancement above the CO2 corrosion model value.

Subject
Pits, Fluxes, Ions, Corrosion rate, Sulfates, Sodium chloride, Pitting corrosion rates, Acetates, Corrosion modeling, Bacteria, Sulfate ions, Pitting, Chemical reactions
Keywords:
Modeling bacteria corrosion, sulfate reducing bacteria (SRB), CO2 corrosion prediction, pitting corrosion
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2008
Association for Materials Protection and Performance (AMPP)
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