North American Refinery – Pipeline Coating Rehabilitation

A pipeline coating rehabilitation project in Mexico used Denso’s ViscoWrap HT and Viscotaq PE Outerwrap to repair aged sections of existing bitumen- and coal tar-coated line pipe. The objective was to rehabilitate difficult legacy coating systems with a solution that could be applied efficiently in the field, bond effectively to the existing coating, and provide long-term performance. A key challenge was the required SP2 surface preparation, as successful repair over coal tar coatings under this level of preparation can be difficult to achieve.

ViscoWrap HT was selected for its ability to conform to and integrate with existing coating systems through Van der Waals bonding. This allowed the repair material to tie into the original coating, creating a seamless, monolithic transition between the rehabilitation area and the existing line coating while achieving strong adhesion to the aged coal tar surface.

The rehabilitation program began in October 2011 and was carried out over a period of two years. It included 12-inch, 16-inch, and 24-inch O.D. product pipelines operating at 86°F to 140°F (30°C to 60°C). During the initial two-year program, more than 1,000,000 square feet (100,000 square meters) of the Viscotaq coating system were applied across Mexico in a wide range of field conditions, environments, and climates.

The coating repairs significantly improved the overall performance of the pipeline coating system, allowing the existing rectifiers and cathodic protection system to function normally again. Since the original application, the rehabilitation system has remained in service for more than 14 years and is now approaching 15 years of field performance. This long-term service record, combined with documented adhesion and seamless tie-in to the existing coal tar coating, confirms that ViscoWrap HT and Viscotaq PE Outerwrap are effective long-term solutions for pipeline coating rehabilitation on difficult legacy coating systems.