Reclamation Information Sharing Environment (RISE)

For use of cathodic protection with the zinc-rich vinyl coating, field observations and laboratory cathodic disbondment testing suggests blistering of the vinyl coating where the cathodic protection current density is the highest, but minimal or no blistering on other areas of the structure. The hypothesis is that the blistering occurs due to excessive reaction products at the steel surface where it is being over-polarized. There is limited quantitative data to verify these claims, and the underlying mechanism that causes the blistering is complex. Further, field investigation of coating failure or damage is intrusive, expensive, and complex. So, a controlled analysis of the circumstances that produce blistering is needed to improve CP design and specification of coatings on water infrastructure. The primary objectives of this research were to: 1) Better understand the susceptibility of the vinyl zinc-rich coating system to CP and interacting factors and 2) Improve TSC design best practices and maintenance and repair recommendations with regard to use of CP with vinyl coatings. This work included a combined approach with preliminary laboratory investigation, field inspection, and a preliminary desktop review of existing datasets.