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Introduction
This course to be familiar with the
different scanning techniques of UT
To be familiar with different UT systems
To analysis the different defects
To be ready for examination acc.
SNT –TC – 1A
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UT COURSE
1ST day
Applications, training, and principles
2nd day
Equipment control, wave propagation ,
transducers
3rd day
Beam spread , attenuation Scanning techniques,
4th day
Scanning techniques , contact & immersion
5th day
Interpretation of defects
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UT COURSE
6th day
Standard reference blocks, calibration
7th day
Practical Training on ut calibration
8th day
Classification of discontinuities ,
9th day
Aut and its applications
10th day
Examination
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Introduction to manual ultrasonic
Why use ultrasonic for nondestructive
material testing?
Ultrasonic frequency ( 0.5MHZ TO 25MHZ )
Both radiography and ultrasonic tests are
the most frequently for test internal flaws
Ultrasonic can discover volumetric defect
Planner defects can easily discover more
than radiography
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Detection of discontinuities
Angle reflection effect
Fig. 10b Tandem testing: center zone
Fig. 10c Tandem testing: lower zone F
Fig. 10a Tandem testing: upper zone F
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Amplifier
The gain difference ∆v = 20 log A2/A1
∆v = gain difference
A1 = echo amplitude 1
A2 = echo amplitude 2
a) Large voltage ratios can be given in small figures, e.g.
1000 : 1 = 60 dB
1000000 : 1 = 120 dB
b) A reversal of the voltage ratios only requires a change of the sign , e.g.
10000 : 1 = 80 dB
1 : 10000 = -80 dB
c) A multiplication of the voltage ratio corresponds to a simple addition of a dB
value ,
e.g.
Gain factor 2 + 6 dB
Gain factor 10 + 20 dB
Gain factor 100 + 40 dB
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4. Method of testing and instrument technology
Fig. 12 The principle of
time of flight measurement
Fig. 13 Block diagram:
Pulse Echo Method
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Fig. 17a Beam spot at the 4th scale
graduation
Fig. 17b Beam spot at the 8th scale
graduation
Fig. 18 Backwall echo at the 8th
scale graduation
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Fig. 20 Test object with
discontinuity, display with
flaw echo
Fig. 21a Discontinuity in
front of the backwall
Fig. 21b Discontinuity near
the surface
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Fig. 22 A non-detectable
near-to-surface discontinuity
Fig. 23 Shadowing of the
back-wall echo by a larger
near-to-surface reflector
Fig. 24 Echo sequence of a
near-to-surface discontinuity
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a = angle of incidence
b = angle of refraction
c 1 = sound velocity in medium 1
c 2 = sound velocity in medium 2
4.4 Refraction and mode conversion
Fig. 30a Refraction and reflection
without transverse waves
Fig. 30b Refraction and reflection
with transverse waves
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Fig. 32c Refraction:
2nd critical angle,
surface wave
Fig. 32d Total
reflection
Fig. 33 Usable range
for angle-beam
probes in steel
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Fig. 36 TR probe on the test object: CRT with
backwall echo
Fig. 37 TR probe on the test object:
discontinuity echo in the cross-talk echo
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Fig. 38 Wall thickness
measurement with a digital
thickness gauge in practice
s = sound path [mm]
c = sound velocity [km/s]
t = transit time [ms]
Fig. 39 USK 7: Backwall echo
sequence with a straight-beam probe
1st Echo = t,
2nd Echo = 2t,
3rd Echo = 3t, etc.
Thickness measurement
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Fig. 40 Calibration range: 0-10mm
Echo-No
i
Sound path si
[mm]
Scale factor k
[mm/scale grad.]
Skalen-position Ti
[scale grad.]
1 25 10 2.5
2 50 10 5.0
3 75 10 7.5
4 100 10 10.0
si = sound path of umpteenth echoes
Ti = scale position of the umpteenth echo
k= scale factor
Thickness measurements
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5.1.3 Calibration with an angle-beam probe
Fig. 48 Different probe angels at V1 block
Fig. 49a Sound path in the V1 block without angle reflection
Fig. 49b Sound path in the V1 block with
angle reflection.
Fig. 47b MWB 45-4E on Calibration Block 2
Fig. 47a WB 60-2E on Calibration Block 1
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Fig. 50 Range: 250 mm with a WB 60-2
on V1 block
Fig. 51a Path of a sound wave in a V2
block, radius 50 mm
Fig. 51b Path of a sound wave in a V2
block, radius 25 mm
Fig. 52 Range: 100 mm calibrated on V2,
radius 25 mm.
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Fig. 54a The flaw triangle
Fig. 54b Reduced surface distances and x-
value
Fig. 56a The apparent depth
Fig. 56b The real reflector depth after sound
reflection
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6. Evaluation of discontinuities
Fig. 57 A large reflector in the sound beam
Fig. 58b Top view with reflector for
extension.
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6.2 Evaluation of small discontinuities: The DGS method
Fig. 59 Reflectors with different areas and
their echoes
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The echo heights are proportional to
their area or The echo heights are
proportional to the square of their
diameter.
Fig. 60 Reflectors at different depths
and their echoes
The echo heights reduce to the
square of their distance
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Fig. 61 Distance amplitude curve of a
2 mm - disk reflector
Fig. 62 Evaluation of a discontinuity
(F) using evaluation curves.
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6.4.1 Comparison of echo amplitudes
Fig. 65 Test object with a
flaw: echo at 80%
(reference height)
Fig. 66 Reference block:
reference echo at 30%.
Fig. 67 References block:
reference echo to reference
height
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6.4.2 Distance amplitude curve
Fig. 68 Reference block wiht side drilled
holes and resulting echoes
Fig. 69 DAC of the reference echoes (top) and
with time corrected gain (bottom).
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Time of Flight Diffraction Technique (TOFD)
1 = transmitted wave
2 = reflected wave
3 = through transmitted wave
4 = diffracted wave at upper crack tip
5 = diffracted wave at lower crack tip
1- lateral wave
2 - diffraction signal at upper crack tip
3 - diffraction signal at lower crack tip
4- back wall reflection
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fig 37 Several techniques and applications for wheel-type search units, (a) Typical setup for a
wheel-type 9' - search unit. (b) Straight-beam inspection with beam entering the testpiece
perpendicular to the surface. (c) Angle-beam inspection with beam entering the testpiece at
45° to the surface. Beam can also be directed forward or to the side at 90° to the direction of
wheel rotation, (d) Use of two transducers to cross and angle the beams to the sides and
forward cross-eyed Lamb unit
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Setup for determining
the position of a
piston in a hydraulic
oil accumulator by use
of two contact search
units utilizing a
through transmission
arrangement
