Localization and Sizing of Cracks in Pipe Walls Using Multimode Ultrasound Images

Defect localization and sizing are critical for assessing the structural integrity of pipelines. This work presents simple and effective imaging-based techniques for localization and sizing of surface-breaking cracks on the outer walls of liquid-filled steel pipes. Given a small set of multimode ultrasound images of a pipe section under test, we use a novel tri-sectional sliding window to localize defect features in each image, followed by establishing correspondence among potentially differing location estimates. Our approach to subsequent crack sizing incorporates similarity-driven matching of localized image patches to synthetic templates. We demonstrate the effectiveness of the proposed methods using experimental data obtained from three pipe samples imaged with an immersed 256-element probe.