What can cause disbondment in three-layer pipe coating systems?

Over the last few years, there have been many reported failures around the world in the adhesion of three-layer pipe coatings. It is debatable as to whether these adhesion failures put the pipeline at risk of corrosion, says Denis Grimshaw, of Jotun Powder Coatings A/S. However, many believe they must raise the potential for cathodic shielding. Failures fall into two main categories: adhesion failure between the FBE and the adhesive and the more serious failure between the FBE and the steel. Most failures between the FBE and the adhesive should be picked up in the standard plant quality assurance peel tests. These relate to the FBE being too reacted when the adhesive is applied, resulting in little or no bond between the FBE and the adhesive. However, some failures seen in the field relate to an aging effect, which cannot be detected in plant quality assurance testing. This is where the adhesive breaks down with the effect of water and heat, in a process known as hydrolysis.

Keywords:

Adhesion , Pipeline , Cathodic Shielding