Review of pipeline coating systems from an operator's perspective

Over the past 40 years, pipeline integrity has been maintained by the simultaneous application of protective coatings and cathodic protection (CP). There have been significant developments in pipeline coating technology over the last 30 years as the traditional coating systems such as coal tar enamel, asphalt and single- and two-layer polyethylene (PE) coatings have been replaced in favour of coatings such as single and dual layer fusion bonded epoxy and three-layer PE and polypropylene. New coating technologies inevitably bring with them new problems for pipeline operators. The present paper reviews the transition from the more traditional coating systems to the second and third generation of pipeline coatings and discusses the new challenges that pipeline operators face. The difficulties of selecting field joint coatings with similar performance to the newer mainline coating systems will also be discussed, as well as issues related to electrical interference (ac and dc) and CP shielding that have become more of a concern because of the high integrity and dielectric strength of some modern coatings. Lessons learned over the years will be reiterated, and how far the pipeline coatings industry has progressed will be reflected upon.