Direct Current Voltage Gradient (DCVG) surveys are a non-destructive, aboveground inspection technique for detecting and sizing coating defects on buried pipelines.

Direct Current Voltage Gradient (DCVG) surveys are a non-destructive, aboveground inspection technique for detecting and sizing coating defects on buried pipelines. By measuring DC voltage gradients at the soil surface above the pipeline, DCVG identifies coating holidays, disbondments, and damage areas that expose the pipe to external corrosion.

DCVG surveys comply with NACE SP0502 and NACE RP0472 standards and are a core component of ECDA (External Corrosion Direct Assessment) programs. Results quantify coating defect severity using the %IR classification system, helping operators prioritize excavation and repair.

DCVG is frequently combined with ACVG surveys, cathodic protection (CP) assessments, and advanced corrosion detection methods. EMPIT's CMI technology enhances DCVG findings by providing direct corrosion data beneath coating defects — distinguishing active threats from stable anomalies and reducing unnecessary excavation costs.