OmniScan MX2 Training ProgramSensitivity Calibration Wizard

All Laws

2OmniScan MX2 Training Sensitivity Calibration Wizard Overview

The MX2 sensitivity calibration wizard is designed to equalize the amplitude of all A-scans or focal laws in the group on onecalibration target. Typically an ID\OD notch or side drilled hole in a reference block.

This function is also called ACG by the ASME codes. (Angle corrected gain)

In conventional UT, sensitivity calibration is achieved by manually adjusting the gain until the reflected signal is at a predetermined amplitude, typically 80%.

The function of the sensitivity wizard is to record the amplitude of every A-scan or focal law on the calibration target and automatically adjust the focal law gain offsets to the desired amplitude, typically 80%.

3OmniScan MX2 Training ASME Reference for Calibration

4OmniScan MX2 Training Sensitivity Calibration Wizard Overview cont. Prior to sensitivity calibration lower angles will detect the target at a higher

amplitude than the higher angles due to a longer sound path and more attenuation.

Without sensitivity calibration defects can be missed and all focal laws cannot be used for code required amplitude based acceptance criteria such as ASME section V and similar.

25.7 Total dB (No sensitivity calibration)25.7 Total dB (No sensitivity calibration)

5OmniScan MX2 Training Sensitivity Calibration Wizard Overview cont. In the examples below, the MX2 general gain of 24.1dB is applied to all focal

laws in the group. After completion of the sensitivity calibration wizard each focal law applies a

calibrated gain offset that is added to the general gain to achieve the required sensitivity, typically 80% amplitude.

24.1 dB + 1.6 dB = 25.7 Total dB 24.1 dB + 9.2 dB = 33.3 Total dB

6OmniScan MX2 Training Sensitivity Calibration SDH Selection The target used for sensitivity calibration should be in the general range of

the area of interest for the inspection and specified in the work procedure. A general rule of thumb for weld inspection is to use the closest calibration

target available that is at least 1.5 times the skip thickness in true depth. SDH selection for sensitivity calibration that is too shallow or too deep

results in poor inspection results and may impede TCG construction.

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7OmniScan MX2 Training Use of Sensitivity Calibration Wizard After completing the group setup wizard process, position the probe so

that the calibration target can be seen in the S-scan. (15mm SDH from IIW as pictured below)

Ensure that the range is sufficient for the target on all focal laws. (45-70 degrees)

Enter the wizard to calibrate the S-scan for sensitivity (ACG) by selecting Wizard>Calibration>Type Ultrasound>Mode Sensitivity>All Angles.

Select start.

8OmniScan MX2 Training - Use of Sensitivity Calibration Wizard cont. Enter the reference amplitude. (default 80%) All focal laws will be

adjusted to this amplitude by addition of a focal law gain offset after sensitivity wizard completion.

Enter tolerance. The tolerance is a visual indicator for amplitude verification after the sensitivity calibration correction. In the example below a tolerance of 5% on an 80% calibration would place the window from 77.5% to 82.5%.

Select Next.

5% tolerance window

Amplitude envelope

9OmniScan MX2 Training - Use of Sensitivity Calibration Wizard cont. Select the last focal law to be calibrated for sensitivity. When there are no

obstructions from corners or adjacent calibration targets the entire sector scan can be calibrated at one time.

Excluding a portion of the S-scan as pictured to the right will allow the calibration to be completed in sections where the gate can be repositioned to avoid interference from corners of the block or adjacent calibration targets if necessary.

Select Next.

Focal law 61-70

Focal law 45-60

Focal law 45-70

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OmniScan MX2 Training - Use of Sensitivity Calibration Wizard cont. Set the start and width of gate A to ensure that the calibration target can be detected

by all focal laws in the S-scan. Set the gate A threshold as low as possible to ensure the last focal law can be

detected. Gate thresholds below approximately 10% may have an amplitude error beyond the tolerance when the focal law gain offset is calculated to correct to 80%.

Select Next.

Gate A

Gate A

G

a

t

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A

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OmniScan MX2 Training - Use of Sensitivity Calibration Wizard cont. Gain compensation is a tool that is used to ease calibration. Use of gain

compensation will allow a wider sector (50-65 degrees vs. 45-70 degrees) and will also allow calibration on a target with a longer sound path.

When gain compensation is selected in the example below, a 2dB per usec correction is added to each focal law in addition to the 14dB of general gain.

The longer the sound path to the calibration target, the more gain is added. (70 degrees receives more gain than 45 degrees)

The MX2 default is 2dB\usec for sector scans and .2dB\usec for linear angle and can be manually adjusted.

Select Apply and select Next.

2dB

2dB

2dB

2dB

2dB

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OmniScan MX2 Training - Use of Sensitivity Calibration Wizard cont. Move the probe across the calibration block with consistent pressure and coupling. As the calibration target travels through the gate of each focal law the green

envelope records the maximum amplitude detected. The MX2 will calculate the required gain offset in dB for each focal law to correct to

80%. Focal laws with amplitude over 80% but less than 100% will receive a negative gain offset.

Do not select Calibrate yet. Continue to next slide.

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OmniScan MX2 Training - Use of Sensitivity Calibration Wizard cont. The green envelope should be smooth and consistent without any radical changes

in amplitude between focal laws. No focal law can be higher than 100% amplitude and the lowest focal law must be

higher than approximately 10% amplitude prior to selecting calibrate. This ratio equates to approximately 20dB. The highest and lowest focal laws must

be within approx. 20dB of each other for the sensitivity wizard to function. If the amplitude envelope cannot be completed with a 10% ratio the

angular range of the S-scan must be reduced. (Reduce S-scan from 30-75 degrees to 45-70 degrees)

The longer the sound path and/or smaller the calibration target, the greater dB difference between the first and last focal laws of an S-scan calibration.

If the green envelope was not created properly select clear envelope and repeat the probe movement.

Select Calibrate. After sensitivity calibration a focal law offset is created in UT>Beam>GainOffset for every focal law.

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OmniScan MX2 Training - Use of Sensitivity Calibration Wizard cont. Successful sensitivity calibration of the S-scan is visualized by repeating the probe

movement over the calibration block with all focal laws corrected to 80% amplitude within the tolerance.

If any focal law is over 100% after calibration the complete process must be repeated by selecting Restart. Saturated focal laws cannot be corrected.

Calibrate may be selected repeatedly until all laws are within tolerance. Select Accept when satisfactory and a green S will appear in the MX2 indication

area indicating the sensitivity was completed.

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OmniScan MX2 Training Gain Offset Manual Edit The gain offset for individual focal laws can be manually edited in

UT>Beam>GainOffset.

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OmniScan MX2 Training Sensitivity Calibration Wizard Movie

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OmniScan MX2 Training Sensitivity Calibration Verification Movie

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