Application of a non-invasive scheme to detect geometrical irregularities in pipelines

The purpose of the experiments performed is to investigate a non-intrasive method to detect defects in metal pipelines. An ultrasonic echo detection scheme is used. A generator produces pressure pulses that move along the pipeline. A detector monitors the pulses moving on the pipeline. Both the generator and the detector are external to the pipe and they do not need to be in contact with the pipe.

The generator is a coil wrapped around the pipe. The coil is excited with a short duration, high current pulse. The magnetic pulse generated by the current causes local compression of the pipe. This local radial compression travels along the pipe as a pulse. The detector is a capacitor formed by a copper cylinder and the pipe itself. The diameter of the pipe changes as the pressure pulse passes by. The change of the diameter of the pipe causes a voltage change of the charged capacitor, which is amplified and analyzed to find reflected waves from any discontinuities, i.e., defects due to corrosion in the pipe. The locations of the defects are found by measuring the delay of the reflected waves. Measurements have been conducted successfully and are presented.