Why AC voltage along pipelines can't be measured using standard closed interval surveys

January 15, 2018 Wolfgang Fieltsch

At the 2017 NACE Corrosion Conference, Stantec’s Wolfgang Fieltsch presented on AC closed interval surveys (CIS) and other common AC measurement errors


The measurement of induced AC voltages along a pipeline is a primary indicator of electrical safety hazards and AC corrosion risks under steady state operation of influencing powerlines. This paper is based on a project we were involved with in California, in which a close interval AC survey was attempted. Many companies and industry members advocate for these surveys, even though they have no proven technical merit.

Wolfgang’s paper and presentation sheds light on the error of this technique, through the combined use of basic electrical principles, computer modeling, and an assessment of close interval survey data.

The paper also addresses several other common errors that are made in field measurements to assess the AC interference risks from powerlines on pipelines, involving variability in powerline loading and gradients in the soil at mitigation locations. Conclusions and recommendations are made on how best to take these measurements and avoid the measurement errors.


The full paper is available for $20 (free for NACE members) and can be downloaded here.

About the Author

Wolfgang Fieltsch

Wolfgang Fieltsch is a NACE (National Association of Corrosion Engineers) certified cathodic protection specialist with over 18 years of experience.

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