Description
ACVG (Alternating Current Voltage Gradient) surveys are used as an indirect inspection tool as part of the ECDA program on the line. Use of the PCM (Pipe Current Mapper) and A-Frame unit & receiver, we can locate anomalies with high accuracy. This process is very similar to the DCVG process except ACVG evaluates the coatings on pipelines by using a signal generator for alternate current. This survey is especially useful for new well coated pipes do to the high sensitivity. Also, useful in locations with congested piping such as multi-line pipe corridors, side pump stations, chemical plants because you can control the location of the signal generator and size the indication more accurately. Anomalies are classified by current direction as 3 or 4 arrow indications with severity determined by corresponding decibel readings. The higher the decibel indication once converted to a 1amp scale, the more severe the anomaly. Accuracy also depends on pipe depth and soil conditions.