PICon - Pipeline Integrity

Coatings

The corrosion control system for an oil and gas pipeline consists of two parts: the external coating on the pipeline and cathodic protection (CP). The primary purpose of the coating is to protect the pipe surface from its external environment. Coatings are also increasingly used to protect the internal surface of pipelines. If the coating disbonds from the pipe, the CP system is designed to protect the pipe from corrosion.

Over the years the pipeline has been protected by various polymeric coatings. In the 1950s and 1960s, coal tar or asphalt coatings were applied. In the mid-1950s, mill-applied extruded polyethylene coatings were introduced (primarily on small-diameter pipes). From the early 1960s to the early 1980s, polyethylene tape coatings were field-applied.