Corrosion Rates of Buried Pipelines Caused by Geomagnetic Storms

Telluric effects associated with geomagnetic field variations cause currents to flow in buried pipelines, which present a continuing problem for monitoring cathodic protection. Protection methods involving the application of a noncorrosive coating with cathodic protection should present the circulation of erratic currents. Nevertheless, often these currents cannot be compensated. During days of high geomagnetic activity, an excess of current that cannot be drained circulates along the pipe. This effect has a strong dependence on the electrical resistivity of the host soil, produces a strong current channeling along the pipes, and increases the risk of corrosion. A method was proposed to quantify the corrosion effects over the pipelines, assuming the geomagnetic field as the external source responsible for the erratic currents. Nondisturbed fields and geomagnetic storms were modeled and pipeline currents were calculated as a function of the characteristics of the soils and pipe sizes using a numerical code previously developed.