SEDL / STP / STP1056-EB / STP25287S

Measurements of IR-Drop Free Pipe-to-Soil Potentials on Buried Pipelines

Thompson, NG
President and vice-president, Cortest Columbus, Inc., Columbus, OH

Beavers, JA
President and vice-president, Cortest Columbus, Inc., Columbus, OH

Pages: 12    Published: Jan 1990

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Abstract

The purpose of this paper is to examine current interruption methods of estimating the level of polarization (off-potential) on a buried pipeline and to indicate some of the specific problems associated with field measurements. Data are reviewed that indicate the magnitude of the voltage (IR-drop) errors associated with potential measurements on buried pipelines. Oscilloscope tracings of pipe-to-soil potential waveforms are presented and a “spiking” condition is discussed which can significantly affect the ability to make an off-potential measurement at the instant of interruption. Stray currents and long-line currents, which can affect the ability to measure the level of polarization on an operating pipeline, are discussed. Methods of detecting stray currents and long-line currents are briefly presented.