TransCanada Pipelines has been using fusion bond epoxy (FBE) external coatings for large diameter line pipe since the early 1980’s. Overall, this coating type, when applied in accordance to the CSA Z245.20 standard provides excellent protection and long term service life. However, some reports from the field described the periodic occurrence of blistering and disbondment of the coating. In order to understand the magnitude and causes of these phenomena, an investigative program was initiated. Laboratory tests and a program of field examinations were carried out. Some of the variables considered were: age of the coating; service temperature; cathodic protection (CP) levels; and soil type. No evidence of a pipeline integrity threat associated with fusion bond epoxy deterioration was found at any of the locations examined. Observations and correlations of coating to exposure conditions will be presented.
