MX2 Training Program 14D Phased Array Analysis-Depth Height Sizing

OmniScan MX2 Training Program Phased Array Analysis Flaw Depth and Height Sizing

OmniScan MX2 Training – Analysis – Flaw Depth\Height Sizing Cursors 

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In a typical weld inspection, flaw depth and height sizing is performed on the UT axis using the A-scan, B-scan, and S-scan. The three cursors used for flaw depth and height sizing are:  –  Data cursor. Used to visualize the A-scan and S-scan at a given position on the scan axis.  –  UT axis reference cursor. U(r)  –  UT axis measure cursor. U(m)

 U  T   a x i    s

Reference cursor

Reference cursor

Measure cursor

 U  T   a x i    s

Measure cursor

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OmniScan MX2 Training – Flaw Depth\Height Sizing Cursors cont. 

How many cursors are available in the OmniScan MX2 software? A. B. C. D. E.

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13 12 9 6 3

The 3 available cursors are:  –  Data cursor. (Blue)  –  Reference cursor. (Red)  –  Measure cursor. (Green)

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The data cursor appears on the S-scan, B-scan, and C-scan and is selectable for angle\focal law and scan axis position. The reference and measure cursors are linked for the group and available in each axis of each data view (UT, scan, index, and amplitude) and may be turned on or off as desired. (Display>Overlay>Cursors>Off)

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A-scan = UT vs. amplitude axis. S-scan = UT vs. index axis. B-scan = UT vs. scan axis. C-scan = scan vs. index axis or focal law.

OmniScan MX2 Training – Flaw Depth\Height Sizing Cursors cont. 

How many total cursors are available in the OmniScan MX2 software? A. B. C. D. E.

13 12 9 6 3

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OmniScan MX2 Training –Flaw Depth\Height Sizing Readings 

The readings associated with flaw depth and height sizing are:  –  U(r) Position of the reference cursor on the UT axis.  –  U(m) Position of the measurement cursor on the UT axis.  –  U(m-r) The delta between the UT axis reference and measurement cursor.

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In the ID crack example below, the UT axis red reference cursor is placed on the deepest diffracted crack tip signal (21.39mm) and the green measure cursor on the component ID (25mm). The U(m-r) reading indicates the through wall dimension of the crack. (3.61mm)

 3  .  6  1  m m

Reference cursor

Measure cursor �

OmniScan MX2 Training –Flaw Depth\Height Sizing Readings cont. 

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In the example of side wall lack of fusion (SWLF) below, the flaw through wall dimension or height was determined using a dB drop technique. The maximum amplitude position was detected on the 53.3 degree focal law at a depth of 13.58mm. Using the data cursor or color palette, the reference and measurement the UT axis cursors are positioned at -3dB of maximum for a through wall dimension of 3.64mm. Different bevel geometry will result in the need to adjust or adapt the sizing procedure to the application at hand. -3, -6 or any amplitude drop technique is dependent on a proper sensitivity calibration and data that is not saturated. Again, where height sizing of +\- 1mm is required the use of a supplemental TOFD channel is extremely helpful.

Reference cursor 3.64mm Measure cursor

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OmniScan MX2 Training – Flaw Depth\Height Sizing – Angle Resolution 

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The ability to both size and characterize flaws is dependent on the on the inspection strategy with regard to probe frequency, angle resolution (.5, 1, 2 degrees), probe aperture, beam focus (Near field), UT axis point quantity. This is especially important in a line scan from one index position where the probe cannot be skewed and repositioned for flaw signal optimization.

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OmniScan MX2 Training – Depth\Height Sizing – Angle Resolution cont. 

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The two groups below demonstrate the benefit of a high element count (32) high resolution S-scan (.2 degrees), focused beam. Both configurations detect the tip diffracted signals from both corners of the 1mm X 10mm deep notch. The ability to clearly identify the center of the energy for a precision measurement is much improved with the 32 element high angular resolution group.

5 MHz, 32 X .6mm Focus = 10 .2 degree S-scan

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5 MHz, 16 X .6mm Focus = 10 1 degree S-scan

OmniScan MX2 Training – Depth\Height Sizing – Angle Resolution cont. 

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Similarly to the UT and scan axis cursors, the index axis cursors are available for measurement of individual flaw width or multiple flaw separation. Relative readings are: I(r), I(m), and I(m-r). (40.21mm-39.21mm = 1mm) In the example below, the ability to measure the width of the notch using the diffracted corner signals is greatly improved by high element count, high S-scan angle resolution (.2 degrees), and beam focusing at the notch depth.

1mm 10mm

Index axis

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OmniScan MX2 Training – Flaw Depth\Height Sizing – Tip Diffraction 

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The shear wave dip diffraction technique is commonly used for crack detection and sizing and is not dependent on amplitude. Low level signals can indicate crack tips and in greatly assist in precision measurement, even if not noticeable in the C-scan. Move the data cursor while visualizing the S-scan and use the UT axis cursor to establish the deepest detected crack tip. (Pictured below at 7.96mm deep measured from the OD, and 4.54mm as measured from the ID)

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OmniScan MX2 Training –– Flaw Depth\Height Sizing U*I(m-r) Reading 

When the actual flaw length or diagonal dimension is required as opposed to its length and height relative to the pipe surface, scan, or UT axis, it is measured using the U*I(m-r) reading as pictured below.

U(m-r) = 7.41mm

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U*I(m-r) = 9.25mm

OmniScan MX2 Training – Flaw Depth\Height Sizing – A-scan Envelope 

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Saving the MX2 data file with the A-scan envelope enabled assists in peaking crack tips for precision measurement. Visualize the UT axis reference cursor in the S-scan positioned at 12.42mm while manipulating the data cursor on the scan axis. Find the deepest tip signal that can clearly be differentiated from background noise. With the focal law displayed on the A-scan (60.5 degrees), peak the signal using the envelope and measure with the cursor in the center of the energy. (12.42mm below) Measure the center of the energy at the peaked position. Do not attempt to read the scales. Use gate readings and cursors for precision measurements and flaw reporting.

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OmniScan MX2 Training – Flaw Depth\Height Sizing – ID Creeping Wave 

In the example below, a phased array version of a WSY creeping wave inspection was performed with a 55-72 degree S-scan on the clock (No encoder) for depth and height sizing of an ID connected crack.

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The 70 L-wave is peaked at 7.77mm in gate B for the through wall dimension of the deepest crack tip. (DB reading) CE1 (Collateral echo 1) is the mode converted shear wave signal (3070-70) that is skipping into the crack on the second leg. CE2 (Collateral echo 2) when present indicates that the crack is connected to the inner surface. Precision wedge delay calibration is necessary for precision crack tip measurement.

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10L32-A1 probe SA1N60L wedge

KK WSY and Panametrics CTS

Scan axis clock scan

L-wave crack tip signal

CE2 L-wave Crack tip signals CE1

5L64-A2 probe SA2N60L wedge

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OmniScan MX2 Training – Analysis – Flaw Depth\Height Sizing cont. 

Similarly to length sizing, where precision depth and height sizing is required, use of TOFD to compliment amplitude based phased array inspections is extremely helpful when the probe cannot be skewed and repositioned for signal optimization due to the one line scan acquisition.

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