Critical Evaluation of International Cathodic Disbondment Test Methods

Protective coatings are normally used together with cathodic protection to protect the steel structures in buried or submerged. services.  The coating cathodic delamination resistance is always on the top of the coating property list required by end users. A large number of international standard test methods for cathodic delamination are available to evaluate the resistance to cathodic disbondment.  No universal agreement on the use of which test standard to run the test.  Most times, the standard test methods are modified to run the test.  Since the specimen geometrical parameters and test parameters will all affect test results.  The test results obtained from different cathodic disbondment test methods may vary significantly.  NACE has formed a Technical Exchange Group, TEG #349x to study the effect of different parameters on the test results and document the results to be used for the development of a new international standard to be used reliably by international community to assess coating cathodic disbondment resistance.  Specimen configuration parameters- film thickness, specimen shape (round or flat panel), test parameters,- voltage level, electrolyte composition, temperature, time, anode isolation, oxygen content etc. are all considered. This paper presents the results obtained by the committee members with the hope to develop a basis for the development of a new international standard on cathodic disbondment test method to evaluate candidate coating systems to be used in conjunction with cathodic disbondment. .