Abstract
To eliminate the risk of AC corrosion of buried pipe lines, measurements for AC probe current density as well as conventional DC probe current density, and on and off potentials must be taken refer to criteria for AC corrosion control with steel probes. Considering this situation, the authors have developed the instrument for field use to measure AC probe current density as well as DC probe current density corresponding to protective current density, and on and off potentials. The new instrument is available that can help CP inspectors improve the reliability and efficiency of their pipe line maintenance programs. With this instrument, an increased level of safety is attained. This paper describes the basic concepts and measuring methods for the new instrument, and an example of the measurements.
