Abstract: An ultrasonic piezoelectric transducer that is operable in very high and very low temperatures. The transducer has a dual housing structure that isolates the expansion and contraction of the piezoelectric element from the expansion and contraction of the housing. Also, the internal components are made from materials having similar coefficients of expansion so that they do not interfere with the motion of the piezoelectric element.

Abstract: A method for detecting hydrogen attack by ultrasound wave velocity measurements in which ultrasound waves (e.g. longitudinal, shear, or creeping) are transmitted from one transducer to another transducer along a fixed path through a steel body such as pipe. The velocity of the ultrasound wave is determined with an accuracy of 0.1 percent from the fixed path length and the time for a wave to travel from one transducer to the other transducer. A decrease in velocity by more than two percent indicates hydrogen attack. In one embodiment, either refracted longitudinal or refracted shear waves are transmitted, and the velocities thereof are determined. In another embodiment, a creeping wave is transmitted from one transducer to the other transducer with the creeping wave including a surface wave and a subsurface wave. Travel time of the subsurface wave is measured and used with the known fixed path length in determining velocity.

Abstract: A method of monitoring the cylinder wall wear using ultrasonic phase comparison techniques is disclosed. The method comprises the steps of introducing ultrasonic waves in a cylinder wall so that the waves travel through the cylinder wall. A change in the traveling time of the ultrasonic waves traveling through the cylinder wall due to cylinder wall wear is determined. The amount of wear of the cylinder wall is calculated by multiplying the velocity of the ultrasonic waves in the cylinder wall by the traveling time change due to cylinder wall wear. The traveling time change due to cylinder wall wear is obtained by determining the actual change in travel time by a phase comparison of the traveling ultrasonic waves and adjusting the actual change in travel time to compensate for any change due to temperature variation of the cylinder wall. With this method, small changes in traveling time on the order of 10.sup.-11 second can be determined so that thickness changes due to wear on the order of 5.times.10.sup.