The research described in this paper was carried out with the objective of establishing any correlation between coating performance and the results of cathodic disbondment testing. Experiments were carried out using 13 coatings. Nine samples of each coating were studied in a total of 117 experiments.
The cathodic disbondment (CD) test is a well known and generally accepted laboratory test for pipeline coatings for a long time. What are we testing and what is the significance of the test? By means of basic investigations factors influencing cathodic delamination have been identified and their extent on the delamination radius has been assessed.
This paper reviews the concerns of applying excessive levels of cathodic protection current to pipelines and the need for establishing an upper potential limit. Coating disbondment, hydrogen induced stress cracks, stress corrosion cracking, hard spots and the problems associated with measurement of a true polarized pipe-to-electrolyte potential are addressed.