Investigating the Effect of Ethylcellulose Nanofibres on Cathodic Disbondment of Polyurethane Coatings on Steel Pipelines

Typically polyurethane coatings are used to protect oil and gas transmission pipelines against corrosion. In order to increase the protection efficiency and prevent corrosion problems, the pipelines are cathodically protect. The major problem of the polymeric coatings under cathodic protection is reducing the adhesion of the coating at the interface with the metal surface, and as a result, the cathodic disbondment of the coating, due to the formation of corrosion products as well as the accumulation of hydrogen in the interface would be occurred. In this study, to improve the resistance against the cathodic disbondment of the polyurethane coating, before applying the polyurethane coating on the metal surface, a layer of ethylcellulose nanofibers has been applied on an API X52 steel substrates. In order to compare the cathodic disbondment of the ethylcellulose nanofibers /polyurethane nanocomposite coatings with polyurethane coating, ASTM G8-96 method at different time intervals has been used and the disbondment of the coatings has been calculated. In addition, electrochemical impedance spectroscopy analysis has been used at different interval times on coated specimens. The results obtained revealed that the ethylcellulose nanofibers /polyurethane nanocomposite coatings is more resistance to cathodic disbondment compared to polyurethane coating.