US Patent 7402999 Pulsed eddy current pipeline inspection system and method

A pulsed eddy current pipeline inspection device is provided. The pulsed eddy current pipeline inspection device comprises a plurality of stages longitudinally spaced apart from each other and adapted to move between a contracted position and an expanded position, and a plurality of sensors disposed around at least a portion of a circumference of each of the plurality of stages in the contracted position with at least one gap between sensors in each of the plurality of stages in the expanded position, the plurality of sensors being arranged such that the at least one gap in a first one of the plurality of stages is aligned with a portion of a second one of the plurality of stages that has sensors disposed thereon.