OmniScan MX2 Training Program

Phased ArrayAmplitude Analysis

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OmniScan MX2 Training – Amplitude Analysis Overview The majority of both conventional and phased array weld inspections can be

considered “Amplitude based” inspections as opposed to time of flight applications like TOFD, corrosion mapping, and composite inspections.

Using side drilled holes (SDH) or notches of different size at different depths a reference sensitivity can be calibrated for comparison to detected flaws during the inspection. Typically to 80%.

The smaller the notch or SDH, the more gain required resulting in a more sensitive inspection and greater potential for a reject.

Amplitude analysis is dependent on the data having been acquired in accordance with the calibration and inspection rules specified in the referencing code or procedure.

The MX2 uses an 8 bit amplitude resolution (0-100%) for the digitized A-scan and a 10 bit resolution (0-200%) for the C-scan gate data and gate readings.

Modifying the gate position in analysis mode will convert 10 bit data to 8 bit data where only 0-100% amplitude is available. In other words, when you change the gate position all data between 101-200% is converted to 100% amplitude.

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OmniScan MX2 Training – Amplitude Analysis – A% Readings The A% reading is the peak amplitude detected in gate A. The A% reading is available for either the maximum peak (E as pictured

below) or first peak (D as below) detected in the gate as configured in Gate\Alarm>Gates>Parameters>Mode>Peak Selection.

The % amplitude reading is available for both gate A (Red) or gate B (Green).

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OmniScan MX2 Training – Amplitude Analysis – A% Readings cont. In the example below readings have been selected for both gate A% and

gate B%. The gate B reading is 33.7%. The reading for gate A of 86.5% also indicates with a red background that

at least one focal law in the group is saturated. Gate A in the A-scan display

is normally red, but when it flashes red\white as pictured it indicates that at least one element in the current focal law is saturated.

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OmniScan MX2 Training – Amplitude Analysis – AdBCurve Reading The AdBCurve reading calculates the difference between the peak amplitude

signal in gate A and the sizing curve level. (UT>Advanced>Reference Amplitude>Typically 80%)

This reading is available for both gate A (AdBCurve) and gate B (BdBCurve). In the below example of inadequate penetration the reference sensitivity was

calibrated to 80% amplitude using a notch in a piping calibration block. The AdBCurve reading indicates that the 99.8% amplitude signal in gate A is 1.9

dB over the reference sensitivity of 80%. A negative number would indicate below the reference curve.

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OmniScan MX2 Training – Amplitude Analysis – AdBr Reading The AdBr reading calculates the difference between the peak amplitude signal in

gate A and the reference. (UT>Advanced>Reference Amplitude>On) This reading is available for both gate A (AdBr) and gate B (BdBr). In the below example of inadequate penetration the reference sensitivity calibrated

for 80% at 18.8 dB. The AdBr reading indicates that the 144% amplitude signal in gate A is 4.2 dB over

the reference sensitivity of 80%. 26 dB (AdBr) – 18.8 dB (Ref sensitivity) – 3.0 dB (Scan sensitivity) = 4.2 dB.

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OmniScan MX2 Training – Amplitude Analysis – AdBB Reading The AdBA reading calculates the difference between the peak amplitude signal in

gate A and the gate threshold level. (Gate\Alarm>Gate>Position>Threshold>40%) This reading is available for both gate A (AdBA) and gate B (BdBB). In the below example slag is detected in gate A at 77.9% amplitude. The AdBA reading indicates that the 77.9% amplitude signal in gate A is 17.8 dB

over the gate A threshold of 10%.

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OmniScan MX2 Training – Amplitude Analysis – %(U(r)) Reading The %(U(r)) reading displays the amplitude of the signal at the position of the

reference cursor on the UT axis This reading is available for both the red reference cursor %(U(r)) and the green

measure cursor %(U(m)) on the UT axis. In the below example porosity is detected in gate A. The signal amplitude at the

position of the reference cursor on the UT axis is 71.4% amplitude.

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OmniScan MX2 Training – Amplitude Analysis – A-scan Envelope The green amplitude

envelope trace is useful for optimizing and peaking signals for both calibration and sizing.

A short stroke of the envelope function key will clear the current envelope.

A long stroke of the envelope function key will enable or disable it on the A-scan.

The envelope will refresh automatically when the current A-scan or focal law is changed.

Enve

lope

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OmniScan MX2 Training – Amplitude Analysis – Amplitude C-scan For the S-scan weld inspection, the

amplitude C-scan is defined by the vertical focal law axis and the horizontal scan axis. (Focal laws 45-70 vs. probe movement)

For each focal law, the pixel color is determined by the peak amplitude signal in gate A for that position on the scan axis. 1 pixel = 1 A-scan.

The primary function of the amplitude C-scan for weld inspection is data screening and flaw length sizing.

Scan Axis (Probe movement)

Foca

l law

s 45

-70

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OmniScan MX2 Training – Amplitude Analysis – Amplitude C-scan cont. In the amplitude C-scan below, the data point circled represents the maximum

signal detected in gate A by the 55.5 degree focal law at 269mm on the scan axis.

Is this a flaw or is it geometry? Is this an embedded or ID\OD connected flaw? Where in the weld volume does this flaw occur? Where to excavate to repair the flaw? Without visualizing the S-scan or relative 55.5 degree A-scan at 269mm it is not

possible to know the flaw type, volumetric location or depth of the flaw. Only amplitude, and scan axis position are known in the uncorrected amplitude C-scan data view.

>80%

>80%

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OmniScan MX2 Training – Amplitude Analysis – Amplitude C-scan cont.

OD weld crown geometry (2) Side wall lack of fusion (1)

1 1

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In the S-scans below are two indications that will produce the exact same pixel color in the C-scan. (55.5 degrees at 269mm on the scan axis) One is a geometric reflector from the weld crown and one is rejectable side wall lack of fusion.

Because both signal 1 and 2 are detected in gate A, it is not possible to differentiate between them without use of the S-scan or A-scan.

1 1 2

?

?2

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OmniScan MX2 Training – Amplitude Analysis – Amplitude C-scan cont. By visualizing the S-scan and A-scan that generated the amplitude C-scan pixel at

269mm it is obvious that the indication is a geometric reflector from the far side weld crown and need not be evaluated as a flaw.

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OmniScan MX2 Training – Amplitude Analysis – Amplitude C-scan cont. By visualizing the S-scan and A-scan that generated the amplitude C-scan pixel at

173mm it is obvious that the indication is SWLF and must be evaluated as a flaw. The primary indicator for flaw type characterization is the flaw’s volumetric location.

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