US Patent 7266992 Remote pipeline acoustic inspection

A pipe inspection apparatus comprising an acoustic source (3) for location at a first position in a pipe or pipe network, one or more acoustic or pressure detectors (4) for location at one or more positions in the pipe or pipe network, means for recording and/or displaying a signal detected by the one or more detectors following the generation of an acoustic pulse, and means for allowing the comparison of the detected signal with a predetermined reference signal, differences between the detected and reference signals being indicative of a blockage or leakage in the pipe or pipe network (10).