Pipeline Corrosion

We also find induced magnetic storm currents flowing in long regional steel pipelines for oil, gas, and water (Figure 2.25). These transient currents add to those caused by a battery-like action from pipeline grounding in differing soil types and to the induced currents from man-made electrical systems. At high latitudes where the magnetic storm-time currents are strongest, the induced storm currents can cause pipes to corrode at the ever-present small holes in the protective plastic pipe coating, where the unwanted currents enter and leave the pipe (Figure 2.26). At low latitudes, corrosion engineers purposely force protective currents on pipelines in a direction that will cancel undesirable corrosive currents. The size of the protective current is established by the corrosion engineers during their scheduled pipeline maintenance visits. If the engineer's measurements are made during magnetic storm conditions, improper

FIGURE 2.25 ► During a geomagnetic storm the upper atmospheric currents at high latitudes induce unwanted disturbance currents in electric power transmission lines, telephone lines, and long oil, gas, and water pipelines.

FIGURE 2.26 ► The Alaska oil pipeline suffers enhanced corrosion caused by unwanted electric currents that are induced from the intense currents flowing in the region of the local auroras during geomagnetic storms. Geomagnetic latitude lines are shown from 60 to 70°. The central section of the pipeline, which almost parallels the latitudinal alignment of maximum auroral current flow, is particularly susceptible. Local Earth-conductivity conditions are also an important factor in the corrosion.

FIGURE 2.26 ► The Alaska oil pipeline suffers enhanced corrosion caused by unwanted electric currents that are induced from the intense currents flowing in the region of the local auroras during geomagnetic storms. Geomagnetic latitude lines are shown from 60 to 70°. The central section of the pipeline, which almost parallels the latitudinal alignment of maximum auroral current flow, is particularly susceptible. Local Earth-conductivity conditions are also an important factor in the corrosion.

and possibly harmful correction currents can be applied to the pipeline. To avoid such problems, alert engineers first obtain geomagnetic activity forecasts of quiet conditions from national space-disturbance monitoring centers before embarking on a measurement tour.

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