![]() ![]() The current flowing from the earth towards the coating holiday is usually concentrated around the coating defect. That means it moves more or less equally in all directions, radiating towards the holiday for a short radius (three to five meters) around the holiday before achieving the steady state direction from the transmitter. The current pattern at the coating holiday is in an omnidirectional shape. In ACVG surveys, AC current is generated due to an AC voltage applied to a pipeline - which will allow current to flow from the current injection source (i.e., the ground) to coating defects in the pipeline through the earth and return back through the pipeline metal to the voltage source connection. In most cases, they require only a single operator.ACVG survey readings are digitally displayed.They can be used alongside with other techniques.They are suitable for complex piping arrangements and in congested metropolitan areas.ACVG surveys can identify shorted casings.They are less susceptible to existing or stray direct currents.They are more sensitive on top of pavement than other voltage gradient surveys.ACVG surveys work in diverse soil conditions.Here are some pros of using this technique: ACVG surveys provide readings in the form of decibels relative to one millivolt (dBmV), which is used along with other surveys to allow the operator to determine the holiday's severity class (e.g., minor, moderate, severe). ![]() They can be used as macro and micro tools to locate holidays of all sizes. ACVG surveys are highly precise and are able to accurately identify most cable breaks and holidays, including the position of anodes. ![]()
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