L30570 Earth Current Effects on Buried Pipelines - Telluric Gradients and Their Effects

Abstract

This report is the third phase of a research program to determine the effects of earth currents on buried metallic structures such as pipelines. In the past, stray currents from direct current sources have been observed to cause severe corrosion problems. For this reason, the research program was initiated. The first phase of the program (detailed in Catalog #L30500) consisted of the develoopment of a mathematical model which simulates the conditions and the effects upon a pipeline system located in a soil environment transmitting earth current caused by a direct current system. The second phase consisted of field tests on pipelines in Ohio and Vancouver, B.C. This phase of the research program has been an effort to obtain data on the effects of natural earth currents on buried structures and to assess their possible significance.Four pipelline companies contributed data to this project. This report describes the equipment, sites, pipelines, procedures, and results. This work has shown that effects caused by telluric gradients can be observed on pipelines. However, it is concluded that these effects do not contribute significantly to corrosion.