MODEL FOR ULTRASONIC PIPE INSPECTION.

Work presented in this paper represents a first step toward establishing reliable procedures for inspecting pipe for such in-service damage problems on the outside surface as wall thinning, corrosion, graphitization and pitting. Ultrasonic pulse-echo and spectroscopy procedures are introduced as a means of locating these problems and determining the extent of damage. Signal interpretation procedures for the ultrasonic wave propagation data obtained on both time base and frequency base modes is discussed. An elastic wave computer code is used to study cylindrical stress-wave propagation in one- and two-layer structural models of flaws in pipes. In particular, an effort is made to obtain an understanding of the frequency and magnification changes associated with certain defects in cast iron pipe.