An Electrochemical Model for Prediction of CO₂ Corrosion Available to Purchase

A predictive model of CO₂ corrosion, based on modelling of individual electrochemical reactions occurring in a water - CO₂ system, is presented. The model takes into account the following electrochemical reactions: hydrogen ion reduction, carbonic acid reduction, direct water reduction, oxygen reduction and anodic dissolution of iron. The required electrochemical parameters in the model such as: exchange current densities and Tafel slopes for different reactions are determined from experiments conducted in glass cells. In those experiments the corrosion process was monitored with the following electrochemical measuring techniques: polarisation resistance, potentiodynamic sweep, electrochemical impedance in addition to weight loss measurements. The model has been calibrated for two different mild steels over a wide range of parameters: t = 20 - 80°C, pH 3 - 6, p(CO₂)= 0 - 1 bar, ω=0 - 5000 rpm. In its present stage of development the model applies for the case of uniform corrosion with no protective films present.

Performance of the model is validated by comparing the predictions with results from independent loop experiments. The predictions made with the present model were also compared with performance of other CO₂ corrosion prediction models. Compared to the previous largely empirical models, the present model gives a much clearer picture of the corrosion mechanisms and of the effect of key parameters.