In this method, a DC signal is imposed on the pipeline, and the DC potential gradient along the pipeline is determined through the use of a pair of electrodes separated by several feet of gradient. Readings are taken along the entire length of pipeline. A significant difference in potential between the two electrodes (steep DC voltage gradient) indicates a substantial loss of DC current and, consequently, corresponds most often to a break in the coating between the electrodes at that location.

DCVG technique has eliminated much of the skill requirements of the operators and has made the holiday detection very simple. In fact it can pinpoint holiday epicentre to within +/- 15 cm. Defect sizing can also be done in the cathodically protected pipelines. In addition, both anodic and cathodic areas can be identified.
With the help of the above survey it was possible to know exactly the location of the coating fault, quantification of holidays per kilometer and an estimation of the severity of coating damage could also be gathered.