Anodic Spiking: A momentary surging of potential that occurs on a pipeline when the protective current from an operating CP device is interrupted or applied. This phenomenon is the result of inductive and capacitive electrical characteristics of the system and may be incorrectly recorded as an instant-off or �on� pipe-to-electrolyte potential measurement. This effect may last for several hundred milliseconds and is usually larger in magnitude near the connection of the CP device to the pipeline. An oscilloscope or similar instrument may be necessary to identify the magnitude and duration of the spike.

Anomaly: Any deviation from nominal conditions in the external wall of a pipe, its coating, or the electromagnetic conditions around the pipe.

Coating Fault: Any anomaly in the coating, including disbonded areas and holidays.

Defect: An anomaly in the pipe wall that reduces the pressure-carrying capacity of the pipe. A physically examined anomaly with dimensions or characteristics that exceed acceptable limits.

Differential Global Positioning System (DGPS): GPS survey using differential error correction in order to obtain more accurate positioning.

ECDA Region: A section or sections of a pipeline that have similar physical characteristics and operating history and in which the same indirect inspection tools are used.

Fault: Any anomaly in the coating, including disbonded areas and holidays.

Holiday: A discontinuity (hole) in a protective coating that exposes unprotected surface to the environment.

Lateral Potential: Pipe-to-electrolyte potentials taken to either side of the pipeline a specified distance lateral to the direction of the pipe.

Pearson Survey: An aboveground survey technique used to locate coating holidays in buried pipelines. The survey compares potential gradients along the pipeline as measured between two movable electrical ground contacts. The potential gradients result from an applied AC signal leaking to earth at coating holidays.

Remote Earth (also electrically Remote): A location on the earth far enough from the affected structure that the soil potential gradients associated with currents entering the earth from the affected structure are significant.

Segment: A portion of a pipeline that is (to be) assessed using ECDA. A segment consists of one or more ECDA regions.

Side-Drain Potential: A potential gradient measured between two reference electrodes, one located over the pipeline and the other located a specified distance lateral to the direction of the pipe.