Correction Technology of AC Voltage Gradient for Pipeline Coating Detection

The defect quantified classification standard for buried pipeline external coatings has not been established at home and abroad. In this paper, an accurate evaluation method for external coatings was proposed by the method of calibration data of AC voltage gradient (ACVG). Based on the principle of ACVG detection, a physical model of pipeline anti-corrosion layer detection was established. Therefore, a voltage calculation formula between poles was derived. By using the calculation formula, the ACVG data were revised for the tested pipeline. By using the corrected data of AC voltage gradient, the long-distance buried pipeline layer damage can be accessed accurately.