Sunday, December 1, 2013
Ultrasonic Testing procedure by Trinity NDT, Bangalore, India-Twin Crystal calibration
Calibration procedure for 25mm steel Using Dual Crystal Transducer
1. Connect probe leads to Ultrasonictesting equipment using two cables, select twin crystal Mode.
2. On the Ultrasonic testing equipment, select the test range to 10mm position and Ultrasonic test velocity inside the steel is 5920m/s to be adjusted on the equipment
3. Using Gain Control select the gain at approximately 40 dB
4. Switch Suppression (Reject) Control to off.
5. Position leading edge of Initial pulse at ‘0’ on the Ultrasonic testing machine screen grid line.
6. Apply couplant to the 'V1' block and place probe on the block. There should be no change in display since 25mm thickness of block will be outside range of the base at present.
7. Adjust the echoes such that a 2nd signal should appear to the right side of the ultrasonic equipment screen. This is 1st Back wall echo from IIW V1 block 25mm thickness
8. Using delay control adjust the initial pulse to ‘0’ on the Ultrasonic equipment screen
9. Adjust the Range and Delay controls to get the Initial pulse and BWE from 25mm thickness of the block on screen
10. Adjust delay control to move the 1st BWE to center of the screen. Second Back wall echo now will be appearing towards the right side of the Ultrasonic test equipment display.
11. Using delay control adjusts the 1st BWE to ‘0’ and using range control adjusts the 2nd BWE to the extreme right side of the screen (end of the screen). Repeat the adjustments if needed to adjust the 1st BWE to ‘0’ and 2nd BWE to the extreme right side of the screen.
12. Now using delay control bring the 1st BWE to the extreme right side of the screen. Now the distance between Initial Pulse and 1st BWE is 25mm and the total range calibrated using twin crystal is 0-25mm of steel. (Note: There may not be an Initial pulse after this calibration on the Ultrasonic equipment screen)