Long range guided wave natural focusing pipe inspection

Zhang Li, Joseph L. Rose, Mu Jing, Steven E. Ovens

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Long range ultrasonic guided wave nondestructive evaluation can be used to inspect pipelines over fairly long distances. Partial loading of transducers around the circumference leads to a non-axisymmetric energy distribution. At particular axial distances and frequencies, the ultrasonic energy is naturally focused at some spots around the circumference via constructive wave interference. This so called "natural focusing" phenomenon can be used to improve guided wave sensitivity for a defect since more energy is sent to the defect. However, defects located in other places could possibly be missed, unless we can move the natural focusing points throughout the pipe. We have done this by frequency and circumferential angle tuning for specific circumferential loading lengths. In order to utilize the natural focusing phenomenon to enhance detection sensitivity, a frequency and angle tuning (FAT) technique is employed to extend the area that is scanned by focal energy. It is observed that the natural focal points at a fixed axial distance move with frequency variation and circumferential excitation length change. In this paper, the natural focusing phenomenon with FAT is theoretically calculated and experimentally investigated. The results show that the natural focusing inspection technique can sufficiently inspect an entire pipe with FAT. Some sample inspection data is compared by applying axisymmetric excitations, FAT, and phased array focusing.

Original languageEnglish (US)
Title of host publicationProceedings of 2006 ASME Pressure Vessels and Piping Division Conference - ASME PVP2006/ICPVT-11 Conference - Pressure Vessel Technologies for the Global Community
StatePublished - 2006
EventASME PVP2006/ICPVT-11 Conference - Vancouver, BC, Canada
Duration: Jul 23 2006Jul 27 2006

Publication series

NameAmerican Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP
ISSN (Print)0277-027X


OtherASME PVP2006/ICPVT-11 Conference
CityVancouver, BC

All Science Journal Classification (ASJC) codes

  • Mechanical Engineering


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