Sunlight exposure is known to cause degradation in polymer coatings. However, quantitative data relating exposure to mechanical and corrosion properties is missing. Thus, it is very difficult for pipeline operators to make fair assessment of the impact of stockpiling coated pipe on project economics and pipeline integrity. As a result, a study was undertaken to quantify the effects of sunlight exposure on Fusion Bonded Epoxy (FBE) coating on stockpiled pipe. Sections of production pipe stockpiled in the southern Alberta area for the Alliance Pipeline project was selected, and a plan to evaluate the coating properties at periodic exposure intervals, to a total duration of approximately 2 years was implemented. The coating was tested at both full sunlight exposure condition (12 o’clock position) and with minimal exposure condition (6 o’clock position). The properties evaluated include residual coating thickness, cathodic disbondment, adhesion, flexibility, and impact. These tests were carried out following procedures in CSA Z245.20–98 standard. Results after 15–21 months of aging indicate that the coating with full sunlight exposure, had a reduction in thickness, flexibility and loss of gloss with chalking due to degradation of the FBE coating by the UV radiation. However, there were no significant differences for cathodic disbondment, adhesion, and impact properties compared to the 6 o’clock position.

A pipeline to bring arctic gas to southern markets requires an appropriate coating system able to withstand the rigors of northern construction and operations. A multi-layer system of fusion bond epoxy overcoated with polyethylene was selected for the mainline coating of a construction project in Northern Alberta, Canada to test out proposed arctic construction materials and practices. Coating of the girth weld area is critical to the overall coating performance. A multi-layer liquid coating system and an epoxy primer based hot melt shrink sleeve system were tested and used for coating the welds. Preliminary full-scale application trials at −48C were performed to validate the proposed field application procedures. Results of the trials and field experience will be reported.

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.