System for ultrasonically detecting defects in a pipe wall

摘要

A system for detecting defects in a pipe wall, comprises an ultrasonic transducer which is arranged for emitting, via an exit opening, ultrasonic signals from the interior of the pipe towards its wall and for receiving, via an entrance opening, backscattered signals from the wall. The system is arranged to emit and receive a multitude of signals having their main directions within a plane mainly perpendicular to the pipe axis. The openings are configured to make the ultrasonic transmission signal diverge and/or to receive back signals from a diverging range of angles over a large area of the pipe wall, by using openings with a diameter with magnitude of the wavelength of the ultrasonic signals. Sets of emitted and backscattered signals for different emission and reception positions are processed, in processing means, to form an image based on transmission times between emission and reception of backscattered signals.

主权项

1. 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.