Patent ID: 8776558

Claim:
A method of detecting defects in a pipe wall comprising emitting ultrasonic signals from the interior of the pipe towards its wall; receiving backscattered signals from the wall, a multitude of signals being emitted and received, having their main directions distributed within a plane perpendicular to the pipe axis; processing the multitude of emitted and received signals, using an imaging process based on transmission times between emission and reception of the emitted and backscattered signals; defining a grid of grid points within the pipe wall; calculating for each grid point and for each pair of an emitting element position and a receiving element position a sound transmission time along a sound path from the emitting element position in the pair to the receiving element position in the pair, via reflection from said grid point, by choosing a set of neighboring sound transmission paths from the emitting element position to the receiving element position of the pair via said grid point, calculating the sound transmission times of the sound transmission paths and selecting the sound transmission path with the shortest travel time for the combination of the grid point and the pair; and determining for each grid point the sum of the backscatter responses determined with different ones of the pairs at the calculated sound transmission times for the pair and the grid point.