Evaluation of the cathodic disbondment resistance of pipeline coatings - A review

For coated pipelines with cathodic protection, cathodic disbondment has been recognized as the main cause of coating degradation. A thorough understanding of the cathodic disbondment mechanism, a proper evaluation of the coating resistance to disbondment as well as a precise monitoring of the cathodic protection level would minimize the occurrence of cathodic disbondment and help to maintain a pipeline's long-term integrity. This paper first reviews the various mechanisms proposed in the literature for cathodic disbondment. To provide useful guidance for selecting pipeline coating systems, cathodic disbondment test methods (categorized as standard test methods or modified test methods) that have been developed over the past two decades are then critically reviewed. In-situ techniques for assessing cathodic disbondment of coatings, especially those having promise for field applications, are also discussed. Finally, a brief discussion on the mitigation of cathodic disbondment and the associated corrosion is presented.