Abstract: A system for improving the pulse-echo type of testing to determine certain parameters of tubes, such as internal diameter, external diameter, wall thickness, etc. A pair of pulses are directed transversely to the tube wall so that the transit times of the respective pulses and their reflections from a tube surface, are substantially different. From the value of the transit times associated with each pulse pair the respective parameter is derived. Inaccuracies due to undesired oscillations of the driving shaft for rotating the pulse transducer within the tube to be tested are eliminated. By means of auxiliary reflective surfaces each pair of pulses emitted from the transducer are directed transversely relative to the respective tube wall in substantially one and the same plane.

Abstract: The wall thickness of an object is measured on the basis of three consecutive rear wall reflections caused by an ultrasonic wave impinging on the front wall of the object. The time intervals between, on the one hand, the first and second rear wall reflections and, on the other hand, the second and third rear wall reflections are compared. In the event of correspondence of these time intervals, a "good" signal indicative of a true thickness value is produced. The system is adapted for a highly accurate wall thickness measurement, with the feasibility of providing an indication of the percentage of "good" measurements in sequence thereof.