Defect sizing in pipe using an ultrasonic guided wave focusing technique

Defect circumferential location, circumferential length and depth are studied with an ultrasonic guided wave focusing inspection technique. Differently shaped defects, such as a planar saw cut, a volumetric through-wall hole, and a volumetric spherical shape corrosion are studied. By focusing on 44 circumferential positions around the pipe at a specific distance, the maximum amplitude of the defect echo is recorded with respect to each circumferential focal position. Circumferential lengths of the planar saw cut and volumetric through-wall hole are then measured by comparing the experimental results with theoretical calculations. It is shown that this measurement technique works well with the planar saw cut and volumetric through-wall hole defects. In addition, it is shown that reflections from defects with the same cross sectional area (CSA), but different shapes, might be very different.