Michael Quarry introduced the work which was sponsored by EPRI. An ultrasonic lamb wave (Guided Waves) method using a shoe and a linear array comb probe was successfully used in a screening mode to find machined defects to simulate corrosion in insulation Schedule 40 steel tube. The method can easily be adapted to other pipe sizes and materials. With a linear array comb probe, modes can be generated with a wavelength equal to that to that of the distance of the elements, which gains a guided wave mode activation line with a constant slope on the dispersion curve as indicated in a figure. An easy to use fieldable equipment was developed. The technique is global, achieving full inspection coverage from a single position of the pipe, and is unaffected by supports, hangers, or insulation. It was successfully detected surface cracks and wall thinning. The reflection from defects are strongly mode and frequency depend. The sample pipes were length of 5,9,12, and 21 feet long with machined defects such as notches, flat bottom holes, and wall thinned areas. For instant wall thinning defects as 0.5'' and 0.75'' sphear ball single and 9 defects as group with 1'' spacing. The aim of future work will focus on the improvement of probes and software for defect characterization and sizing.  Guided Waves advantages by Michael Quarry  Instrument Variable Angle Beam Shoe versus Linear Array Comb |