Localized CO2 corrosion on mild steel is always associated with the partial breakdown of a protective
corrosion product scale such as iron carbonate. The scale breakdown can happen for a variety of reasons
many of them related to fluid flow. It is hypothesized that following the scale damage, a galvanic effect
is established between the scale covered surface (cathode) and the scale free surface (anode) leading to
propagation of localized attack.