Technical Note: Simulated Transient Loss of Cathodic Protection for Buried Pipelines

The effect of loss of cathodic protection (CP) on steel in soil is presented for simulated (anodic) telluric currents over and above CP currents. The potential of the steel is intentionally shifted to 0 V vs. silver/silver chloride (Ag/AgCl, saturated) for 20% of the test time in a cyclic manner (with a number of different cycle times tested). It is seen that the level of corrosion experienced by the steel is dominated by the length of individual transients and not cumulative anodic exposure. The nature of the soil was found to be important, with clay soil leading to significantly more corrosion than sandy soil.