Abstract
Bitumen diluents with very low basic sediment and water (< 0.5%) are transported in Enbridge’s pipelines. The dissolved water and oxygen in diluents have the potential to cause corrosion in the pipeline. Due to similarity of the diluent to refined petroleum products such as gasoline, NACE TM-0172 method was carried out to qualify corrosion inhibitors for the pipeline. This method uses clear hydrocarbon product without considering the impact pipelines solids may have on the inhibitor performance. In this work we modify the NACE TM-0172 method to include the effect of solids. The pipeline solids, collected from pig trap of a diluent pipeline, were first thoroughly characterized for their physicochemical properties by several techniques. Their impact on corrosion inhibitor performance was examined by adding solids at various levels to the clear hydrocarbon. Increasing solids concentration was found to reduce the performance of the corrosion inhibitor. This reduced performance was correlated to decreased residual inhibitor concentration in the diluent, which was made possible by developing a sensitive analytical method to measure sub-ppm residual inhibitor concentration. The residual inhibitor method is expected to serve as a key performance indicator for continuous pipeline inhibitor program.
