Predicting Corrosion Under Disbonded Coating Using Modeling and Cathodic Protection Monitoring Coupon

Coating defects generally take the form of either exposed bare steel or a disbondment, where a gap is formed between a relatively intact coating and bare steel. Cathodic protection can be difficult to achieve and monitor in the disbonded regions depending on the type of coating and soil conditions. Furthermore, stress corrosion cracking occurs predominantly under disbonded coatings. This paper describes a numerical modeling approach to predict the potential and chemistry under disbonded coating. In addition, the use of a monitoring coupon to simulate pipeline disbondments is demonstrated.