Direct Current Voltage Gradient (DCVG)
This technique use to detect coating defect. DCVG technique was developed to locate coating faults, quantify the severity and measure the effectiveness of the Cathodic Protection used, without having any disturbance to the pipeline. The measurement is conducted by monitoring the voltage gradient that out of balance between two reference electrodes utilizing a specially designed millivoltmeter. The two reference electrode are placed 1.5 m apart on the soil in the voltage gradient from coating defect, one electrode adopts a more positive potential than the other, which allows the direction of current flow to established and defect to be located.