Effect of temporal variability of operating parameters in corrosion modelling for natural gas pipelines subject to uniform corrosion

In practice, the operating parameters of a natural gas pipeline change continuously within an uncertain range, yet this temporal variability is seldom considered in corrosion modelling. Most of the time it is due to the limitation of the corrosion predictive model itself as many of them are data-driven. Therefore, this paper proposes a physics-based corrosion predictive model that predicts the time-dependent corrosion rate. The model was developed mainly for uniform corrosion in natural gas pipelines made of mild steels and subjected to aqueous H2S/CO2 environment. Experimental data was used to validate the proposed corrosion model in terms of pH, flow velocity, temperature, and partial pressure of H2S. Also, the influence of time-varying operating parameters on the corrosion predictions was studied. It was found that the variability of the operating parameters has a significant impact on the long-term corrosion predictions as compared with the case without considering such variabilities.