Abstract: A device for detecting dents or out of round conditions of a buried pipeline, intended to be towed by a pipeline pig, comprises two concentric annular rings, the outer ring sized to accurately fit the inner diameter of the pipeline to be inspected and having electrical contacts on its inner surface, the inner ring is supported concentric with the outer ring by chains, cables or the like and has electrical contacts on its outer surface to complete an electric circuit when the outer ring is deformed radially inwardly as it passes by a dent.

Abstract: A pipeline pig adapted to carry inspection components to determine flaws in a pipeline wall arising from corrosion, pitting, gouges, hard spots, scratches, metallurgical anomalies and dents causing out of round conditions is equipped with an accelerometer. The accelerometer is adapted to provide an electrical signal indicative of acceleration and deceleration in the direction parallel to the axis of the pipeline. By correlation of signals recorded by the flaw detection equipment with signals recorded from the accelerometer, dents may be readily identified.