Inspection Services :: Ultrasonic measuring device The measuring device uses ultrasound waves for measuring the wall thickness and inner radius of the pipe. A sound pulse is send from the transducer in the middle of the pipe towards to the pipewall. From the inner wall the sound pulse will be partially reflected back to the centre of the pipe where it will be detected by the same transducer. A part of the sound pulse will not be reflected by the inner wall but travels through the pipewall and gets reflected back from the outer pipewall. The difference in time between these reflections is a direct measurement of the wall thickness at that point.