Damage detection through pipe bends

Axial pipeline defects are detectable from torsional guided wave reflections through 90 deg elbows. This paper demonstrates that detection of localized damage in carbon steel pipes with a so-called standard long and very long radius elbow is possible using a single permanently installed source–receiver pair. We use dispersion imaging to determine why this is not possible in a short radius elbow pipe. Although the remote damage is detected in a standard short radius bend pipe, there is not enough signal to detect localized damage. Since pipeline bends are normally of at least standard long radius, the acoustical behavior is similar to that previously determined in straight pipes. The reflective method can thus be applied fruitfully to monitor structural health beyond industrial pipeline bends.