Efficiency Criterion of Corrosion Inhibitors of Carbon Steel in Seawater

A criterion of the efficiency evaluation of corrosion inhibitors of metallic samples in aqueous solutions was proposed for the first time.The criterion was derived based on calculating the limit of ratio value of the resistivity of carbon steel sample in inhibited seawater (ρins) to the resistivity of the carbon steel sample in blank seawater (ρs). In other words, the criterion; lim (ρins/ρs) =1 will determine the efficiency of the corrosion inhibitor in the seawater when ρins becomes equal (decreases) to ρs  as a function of time of the exposure of the sample to the inhibited seawater. This criterion is not only can be used to determine the efficiency of different corrosion inhibitors, but also, the criterion can be used to determine the efficiency of corrosion inhibitors with a wide range of concentrations in different aqueous solutions. In addition, the criterion can be applied under diverse test conditions with a predetermined period of inhibitor’s dosages.  Key Words: Efficiency of corrosion inhibitors; Resistivity; Carbon steel; Seawate