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In surveying a pipeline, the surveyor walks the pipeline route testing for the pulsing voltage gradient at regular intervals by placing the electrodes one in front of the other at a spacing of one to two metres and parallel to the pipeline direction. As a coating fault is approached, the surveyor will observe the milli-voltmeter needle begin to respond to the pulse, pointing in the direction of current flow which is towards the coating fault location. The amplitude of the pulsing meter needle increases as the fault gradient epicentre is approached and then changes direction completely reversing and slowly decreases in amplitude as the surveyor moves away from the fault epicentre location. By retracing to where the meter changes direction, a point can be found where the meter needle shows no deflection in either direction (a null). The coating fault gradient epicentre is then sited midway between the two electrodes. This position is then marked in the soil.

The above procedure is then repeated at right angles to the first set of observations, that were made parallel to the pipeline direction, to locate a second midpoint. Where the two mid points cross in the soil above the pipeline is the gradient epicentre. This is always at or within in a 15 cm circle of the coating fault location on the pipeline buried one to two metres deep.

In order to determine various characteristics about a coating fault, such as its severity, shape, corrosion behaviour etc. various electrical measurements around the epicentre and from epicentre to remote earth are made for interpretation. If there is no CP then it is still possible to use the DCVG technique by installing a temporary CP system. Whilst it is possible to locate and determine the relative severity of coating faults, other DCVG data such as Corrosion Status, is not applicable to the native state (if under normal circumstances there was no CP then all coating faults must be considered as potential metal loss corrosion sites), but would give an indication of what would happen to the fault if a permanent CP system was installed.