Telluric currents: A meeting of theory and observation
- Geological Survey of Canada, Ottawa, Ontario (Canada). Geomagnetic Lab.
- CORRPRO, Calgary, Alberta (Canada)
Pipe-to-soil (P/S) potential variations resulting from telluric currents have been observed on pipelines in many locations. However, it has never teen clear which parts of a pipeline will experience the worst effects. Two studies were conducted to answer this question. Distributed-source transmission line (DSTL) theory was applied to the problem of modeling geomagnetic induction in pipelines. This theory predicted that the largest P/S potential variations would occur at the ends of the pipeline. The theory also predicted that large P/S potential variations, of opposite sign, should occur on either side of an insulating flange. Independently, an observation program was conducted to determine the change in telluric current P/S potential variations and to design counteractive measures along a pipeline in northern Canada. Observations showed that the amplitude of P/S potential fluctuations had maxima at the northern and southern ends of the pipeline. A further set of recordings around an insulating flange showed large P/S potential variations, of opposite sign, on either side of the flange. Agreement between the observations and theoretical predictions was remarkable. While the observations confirmed the theory, the theory explains how P/S potential variations are produced by telluric currents and provides the basis for design of cathodic protection systems for pipelines that can counteract any adverse telluric effects.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 669788
- Journal Information:
- Corrosion, Vol. 54, Issue 9; Other Information: PBD: Sep 1998
- Country of Publication:
- United States
- Language:
- English
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