A Mechanistic Model of Top-of-the-Line Corrosion

A mechanistic model is developed to predict the general corrosion rate at the top of a gas pipeline. This model covers the three main processes involved in the Top of the Line Corrosion (TLC) phenomena: the dropwise condensation, the behavior of the chemistry in the condensed water and the corrosion at the steel surface. The dropwise condensation process is modeled based on the heat and mass transfer theory and is used to predict the condensation rate. The breakdown of species concentrations in the droplet is established through the main thermodynamic and chemical equilibrium. The general corrosion rate is predicted using the kinetics of the electrochemical reactions at the steel surface and by taking into account the mass transfer and chemical reactions occurring inside the droplet. Finally, the accuracy of the predictions of the model is evaluated by comparison with experimental data.