ECHO test Selection of Ultrasonic Transducer Focal and Water Path Lengths for Immersion Pulse-echo Testing of Cylinders

The selection procedure discussed in this paper applies to immersion pulse echo testing of cylinders This includes any arrangement of a single transducer coupled to the surface of a cylinder through a column of couplant usually water Therefore, water path indicates the distance between transducer face and cylinder surface Interference may be caused by the signal produced by the second return of the initial pulse striking and being reflected from the surface of the tested material If this signal occurs before a signal return from a target at any depth in the material it precludes the proper search for signals beyond the point where the interfering signal occurs The treatment presented in this paper shows how to select a transducer focal length, and the water path length to be employed in order to avoid such potential interference