Abstract: A system for mapping a surface defect in an electrically-conducting material by measuring a change in the resonance of the material includes a flexible printed circuit board and a two dimensional array of transducers printed on the flexible circuit board, wherein each element of the array includes two transducer coils in a paired arrangement. A receive circuit connected to the coils is tuned to a resonant frequency, and the transducer coils operate in a send/receive mode. In another feature of the invention, there are means for converting a change in measured resonance to a visual display of the depth and width of the surface defect.

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.