Abstract: A method for determining changes in the average wall thickness or the mean radius of a pipe or tube using ultrasonic and/or magnetostrictive wave probes by analyzing the dispersive behavior of waves traveling in the tube wall volume. The method examines certain wave propagation modes and identifies a cut-off frequency that is characteristic for a particular wall thickness or tube diameter. This method permits the rapid and accurate inspection of a length of pipe or tube from a single location on the inside diameter of the pipe and permits a comparison of data gathered with similar data for the structure in its original condition. Changes in the cut-off frequency, indirectly determined by the method of the present invention are inversely related to changes in the wall thickness and/or the mean radius for the cylindrical structure. In this manner the method of the present invention provides a mechanism for determining the remaining service life for such pipes and tubes.

Abstract: An apparatus and method for directing ultrasonic and magnetostrictively generated mechanical waves from an exterior point to an interior point within a small diameter tube, pipe, or cylindrical structure. The present invention incorporates an external mechanism for generating waves in a cylindrical waveguide tube gun of a size small enough for insertion into the target tube and configured so as to maintain mechanical contact with an inside diameter of the target tube. Standard ultrasonic wave generating devices or magnetostrictive/mechanical wave generating coils are positioned on the waveguide external to the target tube and generate appropriate mechanical waves through the waveguide to a point interior to the target tube. A mechanical interface between the waveguide and the inside diameter surface of the tube is positioned and provided at a point within the target tube to transfer both the interrogating waves and the received return signal waves between the target tube and the waveguide.

Abstract: An ultrasonic apparatus and method for testing a material comprises an oscillator which generates a selected frequency in the ultrasonic range. A transducer is connected to the oscillator for applying an ultrasonic signal to the material and for receiving an echo signal back from the material. Two phase detectors are utilized one of which receives the echo signal and an in-phase oscillator signal to generate a first display signal, and the other of which receives a quadrature signal which is 90.degree. out of phase from the oscillator signal, as well as the echo signal to generate a second display signal. The first and second display signals are utilized in a visual display such as a cathode ray tube, to generate an image. The image changes according to the phase shift between the ultrasonic signal transmitted into the material and the echo signal, which, in turn, can be utilized to determine the presence and depth of a flaw or boundary in the material.