A pitting model has been developed which provides an explanation of why acetates affect CO2 pitting corrosion. The pitting diffusion model is based on the diffusion of iron ions from the bottom to the top of the pit. To maintain electro-neutrality, negatively charged ions must migrate into the pit. For the pit to continue propagating, it must be more acidic at its bottom than at the top. The model has shown how acetates allow this to happen.

The new model can be used to predict if CO2 pitting corrosion will occur provided parameters such as temperature, salt concentration, in-situ pH and acetate concentration are known. A method is presented which allow for the calculation of in-situ pH from laboratory information.

Subject
Acids, Pits, Water, Ions, Salts, Corrosion rate, Acetates, Acidity, Ion concentrations, Corrosion modeling, Salt concentration, Pitting, Chemical reactions
Keywords:
CO2 pitting corrosion, acetic acid, acetates, salt, in-situ pH
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2010
Association for Materials Protection and Performance (AMPP)
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