Field observations have shown that underground transmission pipelines that share the right-of-way corridor with electric transmission lines are susceptible to AC corrosion. In the field, levels of AC interference depend on numerous conditions that are continuously changing. These conditions include significant fluctuations in AC voltage levels due to daily and seasonal changes in electrical load, soil conditions, etc. While some new devices allow continuous monitoring of suitable parameters such as AC voltage potential and/or AC corrosion current density, a systematic method to interpret the data is still lacking.
The objective of this study is to determine the effect of fluctuating AC interference phenomenon (AC interference time duration and level of AC interferences) on the corrosion risk of pipelines. This fluctuation typically represents the actual condition experienced by the pipeline but is not entirely captured or discussed in current guidelines or standards (e.g., the EN 15280:2013 standard on AC corrosion management). The goal is to develop an improved understanding and guidance which involve the balance between AC/voltages, CP levels on the pipeline systems, and their effects on coatings disbondment.
This research is currently ongoing with an expected completion date of May, 2015. The established results will be made available for standardization committees responsible for development of standards e.g. relevant CEN, NACE and ASTM committees.