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Circumferential higher order guided wave modes for the detection and sizing of cracks and pinholes in pipe support regions
L. Satyarnarayan, Jayaraman Chandrasekaran, Bruce W. Maxfield,
Published in
2008
Volume: 41
   
Issue: 1
Pages: 32 - 43
Abstract
The non-dispersive propagation of ultrasonic guided wave higher order modes cluster (HOMC) traveling along the circumferential direction in a hollow cylinder and its interaction with defects in pipe support regions is reported. These circumferential guided waves were generated in mild steel (MS) pipe specimens containing artificially created axial notches (simulating axial cracks) and pinholes (simulating pinhole-like defects) of different sizes in order to simulate conditions such as cracking and corrosion under pipe supports. The characteristics of these guided waves were also studied as a function of parameters related to how they were generated; namely, using: (a) 2.25 MHz linear phased array transducer, (b) 2.25 MHz conventional circular transducer and (c) 1 MHz conventional circular transducer. These higher frequency modes were explored for their ability to detect and size defects. Because of access limitations to the pipe support region in actual field testing, the transducer was always placed at a fixed circumferential position and moved axially along the length of the pipe. The defect position along the circumference was ascertained from the time of flight while the defect size was estimated using the amplitude data. The signals obtained for all three transducer configurations are compared for their ability to locate, detect and size the above-mentioned defects. It was shown that at these relatively higher frequencies, the guided wave modes exhibit small dispersion and have the ability to provide improved imaging of small size defects throughout the cross-section of the pipe. © 2007 Elsevier Ltd. All rights reserved.
About the journal
JournalNDT and E International
ISSN09638695
Open AccessNo
Concepts (13)
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    Carbon steel
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    Crack initiation
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    Damage detection
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    Parameter estimation
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    Steel corrosion
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    Transducers
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    Ultrasonic waves
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    CIRCUMFERENTIAL GUIDED WAVES
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    DEFECT SIZINGS
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    HIGHER ORDER MODES CLUSTER (HOMC)
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    HOLLOW CYLINDERS
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    PINHOLE DEFECTS
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    Crack detection