A number of new coatings offer the possibility for cost savings and/or improved performance. As a shielding coating, the resistance of a high-integrity three-layer coating to disbondment in damaged areas and as a function of applied cathodic potential is of interest with regard to the creation of an environment on the pipe that will support corrosion and/or cracking. The cathodic disbondment (CD) behavior of a multi-component powder coating system has been characterized under simulated field conditions (restrictive mass transport using soils), rather than the standard CSA protocol. The as-received coating displayed excellent impedance properties and minimal disbondment under normal operating conditions. Coated panels were furthermore subjected to impact damage and a hot water soak prior to the CD tests. Results showed minimal disbondment of the multi-component powder coating system over 3 to 6 months regardless of impact damage or temperature. There was some evidence that more negative potentials may increase the disbondment area over longer periods of time. However, mechanistic considerations, literature information, experimental observations and field experiences would suggest that coating disbondment might be limited when the coating is properly applied and otherwise in good condition. Longer-term experiments are required to confirm the presence of a maximum size disbondment.

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