Comparison of international standards to evaluate field-applied pipeline girth weld coatings

Abstract

The external surfaces of all underground oil and gas pipelines are protected by polymeric coatings and cathodic protection. The polymeric coatings are classified under two types: mainline coating and girth weld coating. Most of the modern mainline coatings are applied in the mill as line pipes are made. The mainline-coated line pipes are shipped to the construction site where they are joined by welding. Over the weld joint – commonly known as girth weld – coatings are applied in the field. The mainline coating, girth weld coating, and cathodic protection all should function in a complementary fashion. The standards developed by various associations for evaluating and selecting mainline coatings were previously reviewed. In this article, three international standards for girth weld coatings developed by the Canadian Standards Association, National Association of Corrosion Engineers, and International Standards Organization have been reviewed and compared with those for mainline coatings. It should be noted that in addition to these international standards, other country-specific standards are also available.