Role of hydrogen and hydroxyl ion in cathodic disbondment

The most economical way of protecting pipelines is through the application of organic coatings and wrappings. To make the protection foolproof at holidays and pores, cathodic protection is also applied. At coating holidays, the pipelines act as the cathode generating hydroxyl ion and hydrogen electrochemically. Extensive studies have been carried out using samples of mild steel pipe coated with reinforced coal tar enamel coating to investigate the role of hydrogen and hydroxyl ion on cathodic disbondment. The testing material is subjected to different environmental conditions like pH, aeration and addition of different anionic species. A mechanism has been proposed to describe the individual role of hydroxyl ion and hydrogen in the process of disbondment.