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Commercial Systems
Inspection Range
High Frequency

 Example 1
 Example 2
 Example 3

Example 1: Clamp On Pipe

The following figure shows inspection report plot in dike penetration region (top graph), photo of a clamp (left bottom), and amplified plot of clamp signal (right bottom). The inspection report was made with 64- and 150-kHz torsional mode data. The clamp signal was shown at about 2 m only in 64-kHz data. The video signal in the dotted line was plotted at the right bottom with rf signals. The clamp signal is strong at 32 kHz data, and it decreases as the frequency increases as shown in the amplified plot. The clamp signal at 150 kHz is not shown because the guided wave does not interact well with the clamp at high freqeuncy. If there is no defect in a pipe clamp, no signal is reflected from it. Therefore, 150-kHz signal indicates a defect under the clamp if its reflection is strong. The following field testing shows that the inspection range at 150 kHz is longer than that at 32 and 64 kHz if the pipeline includes tightened U-clamps. Therefore, inspection with wide frequency range, especially high frequency, is necessary to find defect in a clamp and behind it.
(W-weld, EW-elbow weld, PS- pipe support, and MsS- MsS probe generating initial pulse)

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