DEVELOPMENT OF A PREDICTIVE MODEL FOR ACTIVATION-CONTROLLED CORROSIONOF STEEL IN SOLUTIONS CONTAINING CARBON-DIOXIDE

Corrosion of steel in carbon dioxide (CO2)-containing solutions is con sidered a chemical reaction-controlled process. A corrosion rate equat ion was derived on the basis of fundamental reaction rate theory and c ompared to empirically determined relationships reported in the litera ture. The predictive equation was developed as a function of pH, parti al pressure of CO2 (P-CO2), and temperature, The equation. allows the inclusion of other variables, such as flow, impurities, inhibitors, an d steel microstructure, through the reaction constant. The application limit for this equation extends to the point where corrosion becomes diffusion-controlled as a result of the formation of stable corrosion products on the steel surface.