Abstract: An E-Log I field computer includes a controlled power supply, timers, and a current level stepping relay for circulating cathodic current through a buried metal structure, interrupting the current to allow the decay of residual polarization of the structure and electrolytes within the surrounding ground, and measuring the circulated current and the voltage of structure relative to the ground. The circulated current, voltage of the structure to the ground, and other parameters of interest, such as, the output voltage of the power supply are printed. Then the current level is increased by the stepping relay, and the process is repeated. When a sufficient number of readings have been taken, the data is plotted as a semi-log graph, resulting in an E-log I curve from which the corrosion current and therefore the cathodic protection voltage can be determined.

Abstract: An apparatus for locating an electrical leakage fault path relative to a cathodically protected buried pipe utilizes a conductor wire having a first end connected to the pipe and a second end wound on a reel including a level winding and distance measuring mechanism and connected to electrical signal monitoring components. An electrode in an earth cutting blade is also connected to the monitoring components and is mounted to a drafting structure for moving the blade through the earth generally over the buried pipe a sufficient depth to continuously encounter and sense electrical current indicating a flow or break in the cathodic protection of the pipe. The drafting structure includes a hitch for connection to a suitable vehicle and a regulating mechanism for controlling the depth of the blade into the earth.