The tendency of pipeline girth weld coatings to shield cathodic protection (CP) current was studied in the laboratory. Epoxy, epoxypolyurethane, polyurethane, and wax were investigated. Results showed that the liquid coatings, when applied extra thin to accelerate the kinetics of absorption and current transmission, all disbonded by blistering, and all allowed CP current to be transmitted.
This paper begins with a brief discussion of essential properties of all pipeline coatings, and a listing of multi-layer systems designed to meet specific needs. It then focuses on special considerations regarding application parameters for multi-layer systems that use fusionbonded epoxy as the primer.