Ultrasonic thickness measurement technique with self-calibration function

Corrosion in the pressure pipelines of nuclear reactors is a major threat to the structural safety of nuclear submarines. Online monitoring techniques are needed, rather than offline inspection techniques, owing to the special nature of nuclear reactors. The traditional ultrasonic thickness measurement technique is usually used for the offline estimation of pipe thickness, but it is difficult to use as an online monitoring technique because it requires periodic calibration. This paper proposes an ultrasonic thickness measuring technique with a self-calibration function through the introduction of a calibration block. However, the introduction of the calibration block generates trailing echoes and therefore a threaded cylindrical calibration block is designed to eliminate such trailing echoes.