DCVG (Direct Current Voltage Gradient)

DCVG is an above-ground survey technique that detects coating defects on a buried pipeline by measuring voltage gradients in the soil created by a pulsed cathodic protection current leaking through a holiday in the coating. Because it can pinpoint the location and estimate the severity of individual coating defects, it is often paired with close-interval potential surveys to prioritise which defects need excavation and repair first. It requires the cathodic protection system to be active and pulsed during the survey and is typically walked on foot along the right-of-way, which limits how much pipeline can be covered per field day.