ASSESSMENT OF BURIED PIPELINES COATING AND THE CASE FOR A NEW REFLECTOMETRY BASED TECHNOLOGY

Abstract

Corrosion control of buried assets usually involves a redundant shield: a coating system as a physical barrier, and a cathodic protection system as an ad hoc defense. Characterization and localization of defects in the coatings of such assets is critical, since large defects, if left unrepaired, will not only leave the asset locally prone to corrosion, but also drain and weaken the cathodic protection for the entire structure.

Electrochemical impedance spectroscopy has been used in order to study the influence of different types of defects on the insulating capabilities of coal tar coating. Experimentation and research has led the author of this thesis to design a reflectometry based method to provide both localization and characterization of such defects. In the energy industry, most pipelines consist of several parallel lines and this method makes the most of this feature in order to overcome difficulties usually associated with time domain reflectometry, specifically the quest for reliable and adaptable baselines.

The method has been tested with success in both laboratory and field conditions. The conclusion of these tests acknowledges limitations in terms of operational distance for practical applications of this technique and confirms its usefulness for the detection of coating defects as well as other features for multiple pipelines.