A Probabilistic Method for Estimating Rates of Pipeline Leaks and Ruptures due to Arc Faulting in Shared Utility Rights-of-Way

The probabilistic risk model estimates rates of pipe coating damage and leaks due to sustained arcing, using principles of performance-based engineering to first determine rates of lightning strikes and faults of varying intensity; then the likelihood that an arc forms given a strike or fault and properties of individual sites; and finally, the likelihood of damage conditioned on the lightning or fault intensity. Summing over all lightning and fault intensities and their occurrence frequencies allows for calculation of annual rates of arcing and damage. This model has already been applied by asset managers at electric and gas utility companies to assess risk at existing underground pipelines co-located with overhead conductors and to prioritize locations for mitigation of subsoil arcing and its consequences. Here we apply the model at a hypothetical site at which a wood pole with a grounding rod is three meters from a steel pipeline. The average annual rate of fault-initiated arcs is 6.7 × 10−4 arcs per year, about 52% higher than the average annual rate of lightning-initiated arcs, which is 4.4 × 10−4 arcs per year. Including both faultand lightning-initiated arcs, the average annual rate of coating damage is 2.0 × 10−4 incidents per year, and the average annual rate of leaks is 2.7 × 10−10 leaks per year.