A method for in-situ measuring the corrosion rate of a corroding site on an underground metal structure buried in soil, the structure being under cathodic protection. The structure-to-soil potential at varying depths above the pipeline is measured to a depth above, but not reaching the structure. These measurements are extrapolated to obtain data representing the structure-to-soil potential at the surface of the structure under the probe. The gradient of the electrical potential at this surface is used to calculate the corrosion rate of the defect. A special probe may be used to obtain the potential measurement data.
Pavan K. Shukla; Biswajit Dasgupta