Determination Of The Basic Accuracy When Measuring Distance To The Defect (Thickness); By Straight Beam Probes - NOVOTEST UD3701 Operation Manual

Operation manual
Ultrasonic Flaw Detector NOVOTEST UD3701
4. Drive noise-signal to normal level (50 % of screen height) by gain control keys. Record
value of conventional response in dB (N
5. Calculate signal/noise ratio:
6. Put the probe, through couplant, on the standard calibration block SО-1 and receive echo-
signal from the most distance reflector with 2 mm diameter and 25 mm depth. Drive echo-
signal to normal level (50 % of screen height) by gain control button. Record value of
conventional response in dB (N
7. Repeat operations from p. 4. Signal/noise ratio in every point should be at least 16 dB.
Measured gain ratio and conventional response should not exceed values shown in Table
А.1 (see Appendix А).

3.2.8 Determination of the basic accuracy when measuring distance to the defect (thickness)

by straight beam probes

1. Connect single-element straight probe P111-2,5-К12 to generator output and make
verification (p. 2.5).
2. Set flaw detector parameters in the following way:
 velocity of UT propagation 6065 m/s («VEL – 6065 m/s»);
 measurement range 30 mm («RANGE – 30 mm»);
 probe frequency 2,5 MHz («FREQ – 2,5 MHz»);
 probe angle – 0 («ANGLE - 0»)
 level of excitation generator – U3 («Energy – U3»);
 level of the gate – 50 % (parameter group «Gates» parameter «Level – 50%»);
 method of echo-signal measurement – by peak («MEAS – PEAK»);
 probe type – single element («DUAL – OFF»);
 turn off TVG («TVG - OFF»;
 cutting off – 0% (REJ – 0)
3. Output on the screen depth value «Ya».
4. Put couplant and put the probe on calibration block MD4-0-12 (depth 10 mm). Drive echo-
signal of flat surface reflector-defect to 50 % of the screen by gain of flaw detector.
5. Overlay the gate on echo-signal. Measured value of reflector depth is displayed on the
screen.
6. Set the depth value equal to reference reflector depth (10 mm) by changing parameter
«DELAY» in parameter group «Probe».
7. Cover couplant and put the probe on calibration block MD4-0-14 (depth 180 mm).
Increase scanning time up to 210 mm («RANGE – 210 mm»). Drive echo-signal of flat
surface reflector-defect to 50 % of the screen by gain control.
8. Overlay the gate on echo-signal. Measured value of reflector depth is displayed on the
screen.
9. Set the depth value equal to reference reflector depth (180 mm) by changing parameter
«VEL» in parameter group «Basic».
10. Repeat p. 4 – 9 at least two times.
11. Determine the reflector depth for both calibration blocks MD4-0-12 (10 mm) and MD4-0-
14 (180 mm). On every block make at least 5 depth measurement.
12. Calculate the basic absolute accuracy when measuring reflector depth in every standard
block:
where Н – average depth readings of flaw detector;
av
Н – reference reflector depth in standard block.
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).
n
N = N - N
s/n s n
).
s
  
,
H H H
ср
(3.2)
(3.3)