Pipe-to-soil (P/S) potential variations resulting from telluric currents have been observed on pipelines in many locations. However, it has never been clear which parts of a pipeline will experience the worst effects. Two studies were conducted to answer this questions. Distributed-source transmission line (DSTL) theory was applied to the problem of modelling geomagnetic induction in pipelines. This theory predicted that 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 basic for design of cathodic protection systems for pipeline that can counteract any adverse telluric effects.
Telluric currents: A meeting of theory and observation
Erdströme: Ein Treffen von Theorie und Beobachtung
Corrosion, Houston ; 54 , 9 ; 751-755
1998
5 Seiten, 4 Bilder, 11 Quellen
Aufsatz (Zeitschrift)
Englisch
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