This paper represents the analysis and investigation of two pack epoxy internal lining damage on two new build 24” fuel hydrant system (FHS) pipelines. A leak in a nearby 36” irrigation line occurred during construction of the FHS and caused water flooding in the open trench containing the FHS pipelines. As a result of this, mud and water went into the FHS pipes placed in the trench. Drainage and cleaning operations were done after which the robotic inspection revealed internal lining damages such as detachment of top coat, blisters and bubbles. The cause of the lining damage was at first blamed on the water and mud ingress followed by cleaning operations (water flushing, air blowing & drying). However after detailed testing, inspection and analysis, it was confirmed that the lining was itself of poor quality. The cause of blistering and delamination in flooded and flushed FHS lines was osmotic blistering due to presence of water soluble material (salts or exudate) on the primer surface. The internal lining plant records suggest the conditions were not favorable over the entire lining application period. Very low temperatures and high humidity conditions were observed that lead to poor quality internal lining.
Fuel Hydrant System was being constructed as part of an airport expansion project. The pipelines were externally coated with 3 layers Polyethylene and internally lined with epoxy. The lining was applied in two coats with sole purpose to reduce the risk of contamination of the fuel. The girth welds were purposefully not lined during construction.
The incident started on August 2014 when one of the irrigation lines leaked and water ingress the trench where some sections of FHS pipelines were ditched. The water flooded the trench containing two 24 inch FHS pipes. This resulted in muddy water and debris accumulation to 472 meters of pipe line (Figure 1).