Abstract
Cathodic protection has been widely applied to protect the holidays of buried steel pipes from corrosion. Since it is difficult to measure the density of cathode current flowing directly into the holidays, buried steel pipes are controled by the density of cathode current flowing into the probes attached on the pipes. If we can estimate the density of cathode current flowing into the holidays, it is possible to repair the holidays and to control cathodic protection precisely. We have constructed a theoretical equation with potential gradient on the earth in order to estimate the density of cathode current flowing into the holiday. Experiments using simulated pipes with holidays have proven the validity of our estimation method.
