OmniPC Flaw Sizing Demo

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    26-May-2015
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See the video presentation: http://bit.ly/1vtsaCb Question: For precision sizing of weld flaws using OmniScan phased array inspection, which is the preferred technique: Shear wave tip diffraction or amplitude drop sizing? Answer: The decision to use shear wave tip diffraction or amplitude drop sizing is dependent on the flaw type, size, and orientation. In general, if the flaw is larger than the beam size and is near perpendicular to the beam as is typical in side wall lack of fusion, amplitude drop sizing will produce most accurate results. If the flaw is smaller than the beam size such as a crack ligament then tip diffraction will be most accurate. Sign up for our Newsletter: http://bit.ly/1sQqOyj

Transcript of OmniPC Flaw Sizing Demo

  • 1. OmniScan Tip of the Month Tip Diffraction or dB Drop for Sizing of Weld Flaws? Chris Magruder Jun 13, 2014 V4.1R8

2. Question: Precision sizing of weld flaws using phased array inspection is best achieved by which sizing technique? 1. Shear wave tip diffraction. 2. Amplitude drop sizing. OmniScan SXMX2OmniPC Tip dB Drop or Tip Diffraction? The answer to this question depends on the flaw type, size, and orientation. The intent of this presentation is to provide a general overview of length, depth, and height sizing of common flaw types and under which condition a dB drop or tip diffraction sizing technique is most beneficial. 3. OmniScan SXMX2OmniPC Tip dB Drop or Tip Diffraction? Pictured below is a two sided phased array inspection of a 25mm carbon steel weld using 5MHz .6mm pitch, 32 element phased array probes. An optimum inspection for precision sizing of weld flaws. The first indication in the C-scan is a high amplitude flaw that is detected from both sides of the weld and connected to the inner surface of the pipe. (B0) Based on the flaw location in the weld and the signal characterization of the A-scan and S-scan it can be identified with certainty as lack of fusion. 4. OmniScan SXMX2OmniPC Tip dB Drop for Length Sizing Length sizing is performed on the C-scan and B-scan using an amplitude drop sizing technique regardless of flaw type. If upfront engineering is performed on EDM notches or flaws in the same welds, the sizing can be refined to take into account all aspects of the inspection including probe frequency, beam size, focus, and pipe diameter. Where that is not necessary or practical, a -6dB, -3dB, or rapid dB drop technique is typically used. Flaw Length Sizing 5. OmniScan SXMX2OmniPC Tip dB Drop for Length Sizing cont. Length sizing is performed on the C-scan scan by placing the scan axis cursors on the extremities of the flaw using the color palette for a -6dB drop. The start and stop position are identified for a total flaw length of 29mm. 6. OmniScan SXMX2OmniPC Tip dB Drop for Length Sizing cont. Manipulation of the OmniScan color palette can assist in precision dB drop measurements as well. In the example below all data