Ultrasonic Testing
Ultrasonic Testing
Part 4
Part 4
DEFECT LOCATION
DEFECT LOCATION
DEFECT LOCATION IN ULTRASONIC
DEFECT LOCATION IN ULTRASONIC
TESTING IS BASED UPON THE PREMISE
TESTING IS BASED UPON THE PREMISE
THAT A  MAXIMISED ECHO RESPONSE CAN
THAT A  MAXIMISED ECHO RESPONSE CAN
ONLY COME FROM A REFLECTOR WHICH IS
ONLY COME FROM A REFLECTOR WHICH IS
LYING ON THE BEAM AXIS.
LYING ON THE BEAM AXIS.
THIS PREMISE CAN BE ASSUMED BECAUSE
THIS PREMISE CAN BE ASSUMED BECAUSE
THE GREATEST SOUND INTENSITY OR
THE GREATEST SOUND INTENSITY OR
PRESSURE IS CONCENTRATED IN A SMALL
PRESSURE IS CONCENTRATED IN A SMALL
VOLUME AROUND THE BEAM AXIS.
VOLUME AROUND THE BEAM AXIS.
DEFECT LOCATION IN FUSION WELDS
S
600
600
S = STAND OFF DISTANCE FROM ANY CONVENIENT DATUM
POINT (IN THIS CASE THE WELD CENTRELINE)
R = RANGE READ FROM THE FLAWDETECTOR SCREEN
R
DEFECT LOCATION IN FUSION WELDS
DEFECT LOCATION IN FUSION WELDS
TO ACCURATELY LOCATE DEFECTS IN A BUTT WELD
TO ACCURATELY LOCATE DEFECTS IN A BUTT WELD
THE FOLLOWING CRITERIA MUST BE MET:
THE FOLLOWING CRITERIA MUST BE MET:
1. THE PROBE EXIT POINT MUST BE ACCURATELY KNOWN.
1. THE PROBE EXIT POINT MUST BE ACCURATELY KNOWN.
2. THE BEAM ANGLE MUST BE ACCURATELY KNOWN.
2. THE BEAM ANGLE MUST BE ACCURATELY KNOWN.
3. THE WELD CENTRELINE MUST BE ACCURATELY KNOWN.
3. THE WELD CENTRELINE MUST BE ACCURATELY KNOWN.
4. THE MATERIAL THICKNESS MUST BE ACCURATELY
4. THE MATERIAL THICKNESS MUST BE ACCURATELY
KNOWN.
KNOWN.
5. THE FLAWDETECTOR MUST BE ACCURATELY
5. THE FLAWDETECTOR MUST BE ACCURATELY
CALIBRATED.
CALIBRATED.
DEFECT SIZING TECHNIQUES
DEFECT SIZING TECHNIQUES
1. 6 dB DROP TECHNIQUE (SOMETIMES
1. 6 dB DROP TECHNIQUE (SOMETIMES
CALLED HALF AMPLITUDE OR BEAM
CALLED HALF AMPLITUDE OR BEAM
SPLITTING TECHNIQUE).
SPLITTING TECHNIQUE).
2. 20 dB DROP TECHNIQUE (SOMETIMES
2. 20 dB DROP TECHNIQUE (SOMETIMES
CALLED BEAM BOUNDARY TECHNIQUE).
CALLED BEAM BOUNDARY TECHNIQUE).
3. MAXIMUM AMPLITUDE TECHNIQUE.
3. MAXIMUM AMPLITUDE TECHNIQUE.
6 dB DROP
6 dB DROP
1. THE DIMENSION OF THE REFLECTOR WHICH
1. THE DIMENSION OF THE REFLECTOR WHICH
IS BEING MEASURED MUST EXCEED THE
IS BEING MEASURED MUST EXCEED THE
BEAM WIDTH.
BEAM WIDTH.
2. THE ULTRASONIC BEAM MUST BE
2. THE ULTRASONIC BEAM MUST BE
SYMMETRICAL IN THE DIRECTION OF PROBE
SYMMETRICAL IN THE DIRECTION OF PROBE
MOVEMENT.
MOVEMENT.
3. WORKS BEST ON UNIFORM REFLECTORS
3. WORKS BEST ON UNIFORM REFLECTORS
WITH RELATIVELY STRAIGHT EDGES
WITH RELATIVELY STRAIGHT EDGES
Sizing Methods
6 dB Drop
" For sizing large planar reflectors only
" Signal / echo reduced to half the height
" Example:
100% to 50%
80% to 40%
70% to 35%
20% to 10%
Centre of probe marked representing the edge
of defect.
6 dB DROP
LENGTH
6 dB Drop
Defect BWE
The back wall echo reduced as some part
of the beam now striking the defect
The echo of the defect has NOT yet
maximise as the whole beam Not yet
Plan View
striking the defect
6 dB Drop
Defect
Now the whole beam is on the defect
Back wall echo is now may be
reduced or disappeared
Plan View
6 dB Drop
Defect BWE
The probe is moved back until the echo
is reduced by half of it s original height
At this point the probe centre beam is
directly on the edge of the defect
The probe is then removed and the
Plan View
centre is marked, and repeat to size the
whole defect
Equalization Technique
The equalization technique can ONLY be used
Defect BWE
if the defect is halfway the thickness
At this point the whole beam is on The BWE is at it maximum
the back wall
At this point the whole beam is
The Defect echo is at it
on the defect
maximum
At the edge of the defect, half of The defect echo is at equal
the beam is on the defect, and height as the back wall
another half is on the back wall
The point is marked as the edge of defect
20 dB DROP
20 dB DROP
1. THE DIMENSION OF THE REFLECTOR
1. THE DIMENSION OF THE REFLECTOR
WHICH IS BEING MEASURED MAY BE
WHICH IS BEING MEASURED MAY BE
EITHER LARGER OR SMALLER THAN THE
EITHER LARGER OR SMALLER THAN THE
BEAM WIDTH.
BEAM WIDTH.
2. THE ULTRASONIC BEAM NEED NOT BE
2. THE ULTRASONIC BEAM NEED NOT BE
SYMMETRICAL IN THE DIRECTION OF
SYMMETRICAL IN THE DIRECTION OF
PROBE MOVEMENT.
PROBE MOVEMENT.
3. THE BEAM SPREAD PARALLEL TO THE
3. THE BEAM SPREAD PARALLEL TO THE
DIRECTION OF PROBE MOVEMENT MUST BE
DIRECTION OF PROBE MOVEMENT MUST BE
KNOWN.
KNOWN.
4. WORKS BEST ON UNIFORM REFLECTORS
4. WORKS BEST ON UNIFORM REFLECTORS
WITH RELATIVELY STRAIGHT EDGES.
WITH RELATIVELY STRAIGHT EDGES.
20 dB DROP
LENGTH
20 dB Drop
Defect BWE
20 dB Beam profile
10%
When the main beam is on the defect the defect signal is at it maximum
If the probe is moved and the signal is observed until it is reduced to
10% (20dB Drop), the edge of the beam is on the edge of the defect
Repeat the above at the other side of the defect
Using the pre-constructed Beam profile and a plotting card, the
defect maybe sized
MAXIMUM AMPLITUDE
MAXIMUM AMPLITUDE
1. THE MAXIMUM AMPLITUDE TECHNIQUE IS AN
1. THE MAXIMUM AMPLITUDE TECHNIQUE IS AN
EXTENSION OF THE TECHNIQUE USED IN UT FOR
EXTENSION OF THE TECHNIQUE USED IN UT FOR
DEFECT LOCATION.
DEFECT LOCATION.
2. IT WORKS ON THE PREMISE THAT A MAXIMISED
2. IT WORKS ON THE PREMISE THAT A MAXIMISED
RESPONSE COULD ONLY COME FROM A POINT ON A
RESPONSE COULD ONLY COME FROM A POINT ON A
REFLECTOR WHICH IS ON THE SOUND BEAM AXIS.
REFLECTOR WHICH IS ON THE SOUND BEAM AXIS.
4. VOLUMETRIC REFLECTORS CAN BE SIZED VERY
4. VOLUMETRIC REFLECTORS CAN BE SIZED VERY
ACCURATELY IF THEY CAN BE APPROACHED FROM
ACCURATELY IF THEY CAN BE APPROACHED FROM
A VARIETY OF ANGLES.
A VARIETY OF ANGLES.
3. PLANAR REFLECTORS CAN OFTEN BE SIZED USING THIS
3. PLANAR REFLECTORS CAN OFTEN BE SIZED USING THIS
TECHNIQUE DUE TO THE PRESENCE OF TIP MAXIMA.
TECHNIQUE DUE TO THE PRESENCE OF TIP MAXIMA.
MAXIMUM AMPLITUDE
MAXIMUM AMPLITUDE
1. THE DIMENSION OF THE REFLECTOR
1. THE DIMENSION OF THE REFLECTOR
WHICH IS BEING MEASURED MAY BE
WHICH IS BEING MEASURED MAY BE
EITHER LARGER OR SMALLER THAN
EITHER LARGER OR SMALLER THAN
THE BEAM WIDTH.
THE BEAM WIDTH.
2. WILL WORK WITH ALMOST ANY
2. WILL WORK WITH ALMOST ANY
REFLECTOR.
REFLECTOR.
Sizing Method
" Maximum Amplitude Technique
For sizing multifaceted defect  eg. crack
Not very accurate
Small probe movement
Maximum Amplitude
Multifaceted defect : crack
The whole probe beam is on the on the
defect
At this point, multipoint of the defect
reflect the sound to the probe
The echo (signal) show as a few peaks
Maximum Amplitude
Multifaceted defect : crack
If the probe is moved into the defect,
the signals height increase
The probe is moved out of the
defect, the signal disappeared
One of the peak maximised
If the edge of the beam strike
At this point the MAIN BEAM is
the edge of the defect, a very
directly at the edge of the
small echo appears
defect
Maximum Amplitude
Remember: The peak which maximised does
not have to be the tallest or the first one
Length
The probe is to be moved to the other
Mark the point under
end of the defect
the centre of the probe
which indicates the
The signals will flactuate as the beam hits
edge of the defect
the different faces of the defects
The length of the defect is
The probe is moved back into the defect
measured
and to observe a peak of the signal
maximises
MAXIMUM AMPLITUDE
MAXIMUM AMPLITUDE
LACK OF
700 700
700 700
FUSION
TIP MAXIMA
ECHO DYNAMIC PATTERN
RANGE
AMPLITUDE
ULTRASONIC EXAMINATION OF WELDS
ULTRASONIC EXAMINATION OF WELDS
PRIMARY OBJECTIVES:
PRIMARY OBJECTIVES:
1. TO SCAN ALL FUSION FACES AT AN ANGLE
1. TO SCAN ALL FUSION FACES AT AN ANGLE
OF INCIDENCE = 00 +/- 200 (00 +/- 100 FOR
OF INCIDENCE = 00 +/- 200 (00 +/- 100 FOR
CRITICAL EXAMINATIONS).
CRITICAL EXAMINATIONS).
2. TO SCAN THE ENTIRE WELD VOLUME
2. TO SCAN THE ENTIRE WELD VOLUME
INCLUDING THE HEAT AFFECTED ZONE WITH
INCLUDING THE HEAT AFFECTED ZONE WITH
A MINIMUM OF TWO PROBE ANGLES.
A MINIMUM OF TWO PROBE ANGLES.
3. TO SCAN FOR POSSIBLE TRANSVERSE
3. TO SCAN FOR POSSIBLE TRANSVERSE
IMPERFECTIONS
IMPERFECTIONS
ULTRASONIC EXAMINATION OF WELDS
ULTRASONIC EXAMINATION OF WELDS
600
4
SINGLE SIDED BUTT WELD
2
20
ULTRASONIC EXAMINATION OF WELDS
450
450
THE 450 PROBE CAN NOT BE USED TO SCAN THE WELD ROOT
AT HALF SKIP, THEREFORE THE 700 PROBE MUST BE USED:
57 57
700 700
700 700
FIXED STAND-OFF SCAN OF WELD ROOT USING THE 700 PROBE
5
8
8
5
ULTRASONIC EXAMINATION OF WELDS
700 SCAN OF WELD VOLUME
120
120
23
23
700 700 700 700
700 700 700 700
COVERED AT
FULL SKIP
COVERED AT HALF
COVERED AT
& FULL SKIP
HALF SKIP
ULTRASONIC EXAMINATION OF WELDS
600 SCAN OF WELD VOLUME AND FUSION ZONES
80
80
23
23
600 600 600 600
600 600 600 600
COVERED AT
FULL SKIP
COVERED AT FULL
& HALF SKIP
COVERED AT
HALF SKIP
SCANNING FOR TRANSVERSE IMPERFECTIONS
SCANNING FOR TRANSVERSE IMPERFECTIONS
SCAN
P
R
O
E
B
B
E
O
R
P
P
E
R
B
O
O
B
R
E
P
RECOGNITION OF DEFECT TYPE
RECOGNITION OF DEFECT TYPE
DEFECT TYPES SUCH AS CRACK, LACK OF FUSION, SLAG
DEFECT TYPES SUCH AS CRACK, LACK OF FUSION, SLAG
INCLUSION etc WHICH ARE DETECTED BY UT CAN OFTEN BE
INCLUSION etc WHICH ARE DETECTED BY UT CAN OFTEN BE
RECOGNISED AS SUCH BY:
RECOGNISED AS SUCH BY:
1. OBSERVATION OF THE SHAPE OF THE ECHO RESPONSE
1. OBSERVATION OF THE SHAPE OF THE ECHO RESPONSE
AND IT S BEHAVIOUR WHEN THE PROBE IS MOVED IN
AND IT S BEHAVIOUR WHEN THE PROBE IS MOVED IN
VARIOUS DIRECTIONS.
VARIOUS DIRECTIONS.
2. OBSERVING THE SIZE OF THE ECHO RESPONSE.
2. OBSERVING THE SIZE OF THE ECHO RESPONSE.
3. OBSERVING THE POSITION OF THE REFLECTOR.
3. OBSERVING THE POSITION OF THE REFLECTOR.
4. MEASURING THE SIZE OF THE REFLECTOR.
4. MEASURING THE SIZE OF THE REFLECTOR.
5. TAKING INTO CONSIDERATION THE TYPES OF DEFECT
5. TAKING INTO CONSIDERATION THE TYPES OF DEFECT
WHICH ARE MOST LIKELY TO BE PRESENT.
WHICH ARE MOST LIKELY TO BE PRESENT.
THREADLIKE DEFECTS, POINT DEFECTS AND FLAT
PLANAR DEFECTS ORIENTATED NEAR-NORMAL TO
THE BEAM AXIS ALL PRODUCE AN ECHO RESPONSE
WHICH HAS A SINGLE PEAK:
THE ECHO RESPONSE FROM A LARGE SLAG
INCLUSION OR A ROUGH CRACK IS LIKELY TO HAVE
MULTIPLE PEAKS:
IN CASE  A IT WILL BE DIFFICULT TO DETERMINE
WHETHER THE DEFECT IS SLAG OR A CRACK.
 ROTATIONAL OR  ORBITAL PROBE MOVEMENTS
MAY HELP:
ORBITAL ROTATIONAL
TYPICAL ECHO DYNAMIC PATTERNS
CRACK
SLAG
ORBITAL
SCAN
ROTATIONAL
SCAN
Ultrasonic Testing
" Sensitivity
" Defect sizing
" Scanning procedures
Sensitivity
" The ability of an ultrasonic system to
find the smallest specified defect at the
maximum testing range
Depends upon
" Probe and flaw detector combination
" Material properties
" Probe frequency
" Signal to noise ratio
Methods of Setting Sensitivity
" Smallest defect at maximum test range
" Back wall echo
" Disc equivalent
" Grass levels
" Notches
" Side Drilled Holes, DAC Curves
Artificial / actual defect
Example: The defect echo is set
to FSH (Full Screen Height)
Ultrasonic Inspection
Part 3
Ultrasonic Inspection
" Sensitivity
" Scanning procedure
" Defect sizing
Sensitivity
" The ability of an ultrasonic system to
find the smallest specified defect at the
maximum testing range
Depends upon:
Depends upon:
Probe and flaw detector combination
Probe and flaw detector combination
Material properties
Material properties
Probe frequency
Probe frequency
Signal to noise ratio
Signal to noise ratio
Methods of Setting Sensitivity
" Smallest defect at maximum test range
" Back wall echo
" Disc (flat-bottom hole) equivalent
" Grass levels
" Side Drilled Holes, DAC Curves
Scanning procedure (welds)
Scanning procedure (welds)
1. Parent material
1. Parent material
2. Root inspection
2. Root inspection
3. Fusion face & HAZ inspection
3. Fusion face & HAZ inspection
4. Weld volume
4. Weld volume
5. Transverse scan
5. Transverse scan
ULTRASONIC SENSITIVITY
ULTRASONIC SENSITIVITY
THE SOUND PRESSURE AND INTENSITY ALONG THE
THE SOUND PRESSURE AND INTENSITY ALONG THE
AXIS OF AN ULTRASONIC BEAM VARY WITH RANGE:
AXIS OF AN ULTRASONIC BEAM VARY WITH RANGE:
THEREFORE THE ECHO HEIGHT FROM AN IDENTICAL
THEREFORE THE ECHO HEIGHT FROM AN IDENTICAL
REFLECTOR WILL VARY WITH RANGE.
REFLECTOR WILL VARY WITH RANGE.
VARIOUS METHODS ARE USED IN ULTRASONIC
VARIOUS METHODS ARE USED IN ULTRASONIC
TESTING IN ORDER TO COMPENSATE FOR THIS
TESTING IN ORDER TO COMPENSATE FOR THIS
VARIATION IN ECHO HEIGHT.
VARIATION IN ECHO HEIGHT.
THESE METHODS ARE REFERRED TO AS  SETTING
THESE METHODS ARE REFERRED TO AS  SETTING
SENSITIVITY OR  DISTANCE AMPLITUDE
SENSITIVITY OR  DISTANCE AMPLITUDE
CORRECTION.
CORRECTION.
DISTANCE AMPLITUDE CORRECTION
DISTANCE AMPLITUDE CORRECTION
VARIOUS STANDARD REFLECTORS ARE USED IN ULTRASONIC
VARIOUS STANDARD REFLECTORS ARE USED IN ULTRASONIC
TESTING IN ORDER TO ACHIEVE DISTANCE AMPLITUDE
TESTING IN ORDER TO ACHIEVE DISTANCE AMPLITUDE
CORRECTION. THESE COULD BE:
CORRECTION. THESE COULD BE:
1. BACKWALL REFLECTIONS
1. BACKWALL REFLECTIONS
2. GRAIN RESPONSE (GRASS)
2. GRAIN RESPONSE (GRASS)
3. SIDE DRILLED HOLES
3. SIDE DRILLED HOLES
4. FLAT BOTTOMED HOLES
4. FLAT BOTTOMED HOLES
5. SURFACE NOTCHES
5. SURFACE NOTCHES
6. DISTANCE GAIN SIZE (THEORETICAL METHOD)
6. DISTANCE GAIN SIZE (THEORETICAL METHOD)
DISTANCE AMPLITUDE CORRECTION
DISTANCE AMPLITUDE CORRECTION
NATIONAL CODES AND
NATIONAL CODES AND
STANDARDS SUCH AS BS EN 583-
STANDARDS SUCH AS BS EN 583-
2, ASME V OR AWS D1.1 SPECIFY
2, ASME V OR AWS D1.1 SPECIFY
STANDARD METHODS OF
STANDARD METHODS OF
ACHIEVING DISTANCE AMPLITUDE
ACHIEVING DISTANCE AMPLITUDE
CORRECTION.
CORRECTION.
FOR CONSTRUCTING DAC, A BLOCK CONTAINING 3
FOR CONSTRUCTING DAC, A BLOCK CONTAINING 3
mm DIAMETER SIDE DRILLED HOLES:
mm DIAMETER SIDE DRILLED HOLES:
3 mm Through drilled holes
3 mm Through drilled holes
D A C
D A C
BS EN 583-2
BS EN 583-2
The DAC reference block shall be either:
The DAC reference block shall be either:
1) a general purpose block of uniform low
1) a general purpose block of uniform low
attenuation and specified surface finish, and
attenuation and specified surface finish, and
having a thickness within 10% of the test object;
having a thickness within 10% of the test object;
Or
Or
2) a block of the same acoustic properties,
2) a block of the same acoustic properties,
surface finish, shape and curvature as the test
surface finish, shape and curvature as the test
object.
object.
TRANSFER LOSSES
TRANSFER LOSSES
AS ULTRASOUND PASSES FROM THE PROBE INTO THE
AS ULTRASOUND PASSES FROM THE PROBE INTO THE
MATERIAL THERE IS ALWAYS A LOSS OF ENERGY.
MATERIAL THERE IS ALWAYS A LOSS OF ENERGY.
THE AMOUNT OF ENERGY LOST FOR THE SAME
THE AMOUNT OF ENERGY LOST FOR THE SAME
MATERIAL WILL BE LESS IF THE SURFACE IS
MATERIAL WILL BE LESS IF THE SURFACE IS
PERFECTLY SMOOTH AND FLAT AND MORE IF IT IS
PERFECTLY SMOOTH AND FLAT AND MORE IF IT IS
NOT.
NOT.
UT OF WELDS IS OFTEN CARRIED OUT FROM AS
UT OF WELDS IS OFTEN CARRIED OUT FROM AS
ROLLED, CURVED OR CORRODED SURFACES.
ROLLED, CURVED OR CORRODED SURFACES.
IF THE SURFACE OF THE CALIBRATION BLOCK
IF THE SURFACE OF THE CALIBRATION BLOCK
DIFFERS FROM THAT OF THE COMPONENT THEN THE
DIFFERS FROM THAT OF THE COMPONENT THEN THE
DIFFERENCE IN TRANSFER EFFICIENCY HAS TO BE
DIFFERENCE IN TRANSFER EFFICIENCY HAS TO BE
COMPENSATED FOR.
COMPENSATED FOR.
ATTENUATION
ATTENUATION
AS ULTRASOUND PASSES THROUGH ANY MATERIAL
AS ULTRASOUND PASSES THROUGH ANY MATERIAL
ENERGY WILL BE LOST DUE TO SCATTERING AND
ENERGY WILL BE LOST DUE TO SCATTERING AND
ABSORPTION OF THE SOUND ENERGY. THIS LOSS OF
ABSORPTION OF THE SOUND ENERGY. THIS LOSS OF
ENERGY IS TERMED  ATTENUATION.
ENERGY IS TERMED  ATTENUATION.
IN THE ULTRASONIC TESTING OF TYPICAL
IN THE ULTRASONIC TESTING OF TYPICAL
ENGINEERING ALLOYS THE PRIMARY CAUSE OF
ENGINEERING ALLOYS THE PRIMARY CAUSE OF
ATTENUATION IS SCATTERING.
ATTENUATION IS SCATTERING.
WHEN THE GRAIN SIZE OF A MATERIAL EXCEEDS
WHEN THE GRAIN SIZE OF A MATERIAL EXCEEDS
HALF OF THE WAVELENGTH OF THE SOUND HIGH
HALF OF THE WAVELENGTH OF THE SOUND HIGH
ATTENUATION WILL ALWAYS BE EXPERIENCED.
ATTENUATION WILL ALWAYS BE EXPERIENCED.
ATTENUATION
ATTENUATION
THE GRAIN SIZE IN ANY GIVEN METAL
THE GRAIN SIZE IN ANY GIVEN METAL
COMPONENT DEPENDS ON:
COMPONENT DEPENDS ON:
1. THE METHOD OF PRODUCTION
1. THE METHOD OF PRODUCTION
(CAST/FORGED /ROLLED etc)
(CAST/FORGED /ROLLED etc)
2. THE CHEMICAL COMPOSITION
2. THE CHEMICAL COMPOSITION
3. HEAT TREATMENT
3. HEAT TREATMENT
Transfer &
Transfer &
Attenuation
Attenuation
loss
loss
METHODS OF COMPENSATING FOR TRANSFER AND
METHODS OF COMPENSATING FOR TRANSFER AND
ATTENUATION LOSS DIFFERENCES FOR 00
ATTENUATION LOSS DIFFERENCES FOR 00
COMPRESSION PROBES AND FOR SHEAR WAVE
COMPRESSION PROBES AND FOR SHEAR WAVE
PROBES. THESE ARE BASED ON OBTAINING SIMILAR
PROBES. THESE ARE BASED ON OBTAINING SIMILAR
ECHO RESPONSES ON BOTH THE CALIBRATION
ECHO RESPONSES ON BOTH THE CALIBRATION
BLOCK AND ON THE COMPONENT.
BLOCK AND ON THE COMPONENT.
FOR 00 PROBES BACKWALL ECHOES ARE USED TO
FOR 00 PROBES BACKWALL ECHOES ARE USED TO
ESTABLISH TRANSFER AND ATTENUATION
ESTABLISH TRANSFER AND ATTENUATION
CORRECTION.
CORRECTION.
FOR SHEAR WAVE PROBES TWO IDENTICAL PROBES
FOR SHEAR WAVE PROBES TWO IDENTICAL PROBES
ARE USED IN  PITCH - CATCH IN ORDER TO OBTAIN
ARE USED IN  PITCH - CATCH IN ORDER TO OBTAIN
WHAT ARE EFFECTIVELY BACKWALL ECHOES
WHAT ARE EFFECTIVELY BACKWALL ECHOES
EITHER METHOD CANNOT BE USED IF THE
EITHER METHOD CANNOT BE USED IF THE
COMPONENT DOES NOT HAVE A CONVENIENT
COMPONENT DOES NOT HAVE A CONVENIENT
PARALLEL SECTION.
PARALLEL SECTION.
TRANSFER & ATTENUATION
TRANSFER & ATTENUATION
CORRECTION: 00 PROBES
CORRECTION: 00 PROBES
24 dB 30 dB 36 dB
EXAMPLE:
EXAMPLE:
ECHOES
ECHOES
OBTAINED ON
OBTAINED ON
40 mm THICK
40 mm THICK
CALIBRATION
CALIBRATION
BLOCK
BLOCK
40 mm 80 mm 160 mm
TRANSFER & ATTENUATION
TRANSFER & ATTENUATION
CORRECTION: 00 PROBES
CORRECTION: 00 PROBES
26 dB 32 dB 38 dB
EXAMPLE:
EXAMPLE:
ECHOES
ECHOES
OBTAINED ON
OBTAINED ON
30 mm THICK
30 mm THICK
COMPONENT
COMPONENT
30 mm 60 mm 120 mm
TRANSFER & ATTENUATION
CORRECTION: 00 PROBES
BLOCK
TRANSFER CORRECTION
APPROXIMATELY 4 dB AT
COMPONENT
ALL RANGES
EXAMPLE:
IF THE RESULTS ARE
PLOTTED ON LOG -
LINEAR PAPER THEY
WILL FORM
STRAIGHT PARLLEL
LINES PROVIDED
THAT THERE IS NO
ATTENUATION
DIFFERENCE
IF AN ATTENUATION
DIFFERENCE
OCCURS THEN THE
RESULTANT LINES
WILL NO LONGER BE
10 100 1000
PARALLEL.
RANGE / mm
50
40
DECIBELS
30
20
TRANSFER & ATTENUATION CORRECTION:
TRANSFER & ATTENUATION CORRECTION:
SHEAR WAVE PROBES
SHEAR WAVE PROBES
THE PRINCIPLE FOR OBTAINING TRANSFER
THE PRINCIPLE FOR OBTAINING TRANSFER
CORRECTION FOR SHEAR WAVE PROBES IS THE SAME
CORRECTION FOR SHEAR WAVE PROBES IS THE SAME
AS IT WAS FOR COMPRESSION PROBES EXCEPT THAT
AS IT WAS FOR COMPRESSION PROBES EXCEPT THAT
BACKWALL ECHOES ARE REPLACED BY PITCH - CATCH
BACKWALL ECHOES ARE REPLACED BY PITCH - CATCH
RESPONSES.
RESPONSES.
TRANSMIT RECEIVE TRANSMIT RECEIVE
450 450 450 450
450 450 450 450
ONE SKIP TWO SKIPS
ASME V CALIBRATION BLOCK
ASME V CALIBRATION BLOCK
BLOCK MATERIAL: CHEMICAL BLOCK SURFACE FINISH AND
COMPOSITION, PRODUCT FORM CURVATURE TO REPLICATE
AND HEAT TREATMENT TO EXACTLY THAT OF THE COMPONENT
REPLICATE THAT OF THE
COMPONENT.
SIDE DRILLED HOLE
SURFACE NOTCHES
DIAMETER VARIES WITH
PROVIDED TO ASSIST
THE BLOCK THICKNESS
WITH THE
INTERPRETATION OF
SURFACE BREAKING
INDICATIONS
ASME V DOES NOT ALLOW
ASME V DOES NOT ALLOW
TRANSFER CORRECTION.
TRANSFER CORRECTION.
AVG (DGS) SYSTEM
AVG (DGS) SYSTEM
THE DISTANCE GAIN SIZE SYSTEM WAS
THE ISTANCE AIN IZE SYSTEM WAS
D G S
DEVELOPED IN GERMANY BY KRAUTKRAMER.
DEVELOPED IN GERMANY BY KRAUTKRAMER.
IT IS A THEORETICALLY BASED SYSTEM FOR
IT IS A THEORETICALLY BASED SYSTEM FOR
SETTING ULTRASONIC SENSITIVITY AND
SETTING ULTRASONIC SENSITIVITY AND
DISTANCE AMPLITUDE CORRECTION.
DISTANCE AMPLITUDE CORRECTION.
IT IS HIGHLY VERSATILE AND CAN BE VERY
IT IS HIGHLY VERSATILE AND CAN BE VERY
CONVENIENT TO USE, PROVIDED THAT THE
CONVENIENT TO USE, PROVIDED THAT THE
ULTRASONIC OPERATOR IS SUFFICIENTLY
ULTRASONIC OPERATOR IS SUFFICIENTLY
WELL TRAINED.
WELL TRAINED.
DGS CHART FOR A 10 mm DIA. 2 MHz 00
DGS CHART FOR A 10 mm DIA. 2 MHz 00
COMPRESSION PROBE
COMPRESSION PROBE
Range / mm
0 50 100 150 200
BWE
8 mm
6 mm
4 mm
3 mm
2 mm
1.5 mm
0 50 100 150 200
Range / mm
0
10
20
30
40
50
60
70
80
dB
dB
80
70
60
50
40
30
20
10
0
DGS
DGS
THE BASIC PRINCIPLE OF DGS IS THAT BY
THE BASIC PRINCIPLE OF DGS IS THAT BY
COMPARING THE ECHO HEIGHT FROM A FLAW WITH
COMPARING THE ECHO HEIGHT FROM A FLAW WITH
THE ECHO HEIGHT FROM A KNOWN REFLECTOR
THE ECHO HEIGHT FROM A KNOWN REFLECTOR
(USUALLY A BACKWALL ECHO) AT THE SAME RANGE
(USUALLY A BACKWALL ECHO) AT THE SAME RANGE
THE FLAW CAN BE CATEGORISED AS BEING
THE FLAW CAN BE CATEGORISED AS BEING
EQUIVALENT TO A FLAT BOTTOMED HOLE REFLECTOR
EQUIVALENT TO A FLAT BOTTOMED HOLE REFLECTOR
OF A GIVEN SIZE AT THE SAME RANGE.
OF A GIVEN SIZE AT THE SAME RANGE.
ALTHOUGH, WHEN USING DGS, IT IS USUAL TO TALK
ALTHOUGH, WHEN USING DGS, IT IS USUAL TO TALK
ABOUT A FLAW AS BEING AN  X mm FLAT
ABOUT A FLAW AS BEING AN  X mm FLAT
BOTTOMED HOLE EQUIVALENT THIS IS NOT A DIRECT
BOTTOMED HOLE EQUIVALENT THIS IS NOT A DIRECT
MEASURE OF THE SIZE OF THE FLAW.
MEASURE OF THE SIZE OF THE FLAW.
EQUIPMENT CHECKS
EQUIPMENT CHECKS
TIMEBASE LINEARITY
TIMEBASE LINEARITY
2.0 4.0 6.0 8.0 10.0
2.0 3.7 5.85 7.9 10.0
ACCEPTABLE
NOT ACCEPTABLE
EQUIPMENT CHECKS
EQUIPMENT CHECKS
AMPLIFIER LINEARITY
AMPLIFIER LINEARITY
ACCEPTABLE ACCEPTABLE
INDICATION SET dB CONTROL
LIMITS FOR LIMITS FOR
AT (%FSH) CHANGE (dB)
RESULTANT ECHO RESULTANT ECHO
HEIGHT HEIGHT
(BS 3923) (ASME V)
80% -6 dB 36-45% 32-48%
80% -12 dB 18-22% 16-24%
80% -24 dB visible N/A
40% +6 dB 71-90% 64-96%
20% +12 dB 71-90% 64-96%
(+/- 1 dB) (+/- 2 dB)
EQUIPMENT CHECKS
EQUIPMENT CHECKS
SIGNAL TO NOISE RATIO
SIGNAL TO NOISE RATIO
+14 dB
NOISE
SIGNAL
SIGNAL TO NOISE RATIO = 5:1 = 14 dB
RESOLUTION
BS 2704 A7 BLOCK:
1.5 mm
2, 3, 4 & (5) mm Steps
holes @
4 mm
centres
BS 2704 A5 BLOCK
BS 2704 A2 BLOCK
100, 85 & 91 mm Dimensions
1
h
.
5
o
2
.
l
m
c
5
e
e
s
m
m
n
@
t
m
r
e
s
EQUIPMENT CHECKS
EQUIPMENT CHECKS
RESOLUTION
RESOLUTION
RESOLUTION HOLES IN A5 BLOCK RESOLUTION HOLES IN A5 BLOCK
WITH 10 mm 450 4 MHz PROBE WITH 10 mm 450 2 MHz PROBE
EQUIPMENT CHECKS
EQUIPMENT CHECKS
DEAD ZONE
DEAD ZONE
1.5 mm Through drilled
holes at depths of 1, 2, 3, 5,
10, 15 & 20 mm below the
surface.
EQUIPMENT CHECKS
EQUIPMENT CHECKS
DEAD ZONE
DEAD ZONE
DETERMINE THE DEAD ZONE BY
FINDING THE HOLE ECHO WHICH
IS EASILY IDENTIFIABLE FROM
THE PROBE NOISE AT THE
SHORTEST RANGE
EQUIPMENT CHECKS
EQUIPMENT CHECKS
EXIT POINT
EXIT POINT
450
450
USING THE A2 BLOCK
EXIT POINT
S
450 450
450 450
S
USING THE A5 BLOCK
(MORE ACCURATE METHOD)
D
D
EQUIPMENT CHECKS
EQUIPMENT CHECKS
BEAM ANGLE
BEAM ANGLE
700 600
QUICK CHECK: USE THE SCALES
PROVIDED ON THE A2 BLOCK.
45
60
35
0
0
0
45
45
0
0
BEAM ANGLE
S
450 450
450 450
S
USING THE A5 BLOCK (MORE ACCURATE METHOD)
NOTE: The probe exit point can be marked either
before or during this operation.
D
D
20 dB BEAM PROFILE
(VERTICAL PLANE)
S
450450 450 450
450450 450 450
S
USING THE A5 BLOCK
NOTE: The probe exit point can be marked either
before or during this operation.
D
D
20 dB BEAM PROFILE
(HORIZONTAL PLANE)
Y
X
USE THE CORNER REFLECTION
FROM THE 1.5 mm HOLE.
LINES OF SYMMETRY IN VARIOUS ULTRASONIC
LINES OF SYMMETRY IN VARIOUS ULTRASONIC
BEAMS
BEAMS
0° Single Compression 0° Twin Compression
FULLY
SYMMETRICAL
TWO LINES OF
SYMMETRY
Single Shear Twin Shear
SINGLE LINE
OF SYMMETRY
0-6 dB 6-12 dB 12-20 dB
SOUND PRESSURE IN THE FAR ZONE
SOUND PRESSURE IN THE FAR ZONE
(IN A SECTION THROUGH THE BEAM)
(IN A SECTION THROUGH THE BEAM)
2 MHz
10 dia.
4 MHz
25 dia.
-2 -1 0 1 2 -2 -1 0 1 2
CRYSTAL DIAMETERS CRYSTAL DIAMETERS
0
0
dB
dB
-24
-20
-16
-12 -8
-4
-24
-20
-16
-12 -8
-4
DEFECT LOCATION
IN FUSION WELDS
S = STAND OFF DISTANCE FROM ANY CONVENIENT DATUM
POINT
R = RANGE READ FROM THE FLAWDETECTOR SCREEN
45
45
0
0
S
R
ULTRASONIC
EXAMINATION OF
WELDS
40
450
450
BACK
GOUGE
DOUBLE SIDED  T JOINT
40
ULTRASONIC
EXAMINATION OF
COVERAGE
OF FUSION
WELDS
FACES
COVERAGE
OF WELD
100
VOLUME
(approx.)
0
0
0
0
0
0
0
0
ULTRASONIC
EXAMINATION OF
COVERAGE
WELDS
OF FUSION
FACES
COVERAGE
OF WELD
VOLUME
45
45
0
0
45
45
0
0
0
0
45
45
0
0
45
45
SCANNING FOR TRANSVERSE IMPERFECTIONS
0
0
5
5
4
4
SCANNING FOR TRANSVERSE IMPERFECTIONS
THESE DEFECTS CAN BE DIFFERENTIATED BETWEEN
BY OBSERVING THE ECHO DYNAMIC BEHAVIOUR IN
LENGTH AND DEPTH SCANS:
PLANAR
POINT
THREADLIKE
(NEAR NORMAL INCIDENCE)
DEPTH
SCAN
LENGTH
SCAN
NOTE: THE RESPONSE FROM A PLANAR DEFECT WILL BE STRONGLY AFFECTED
BY PROBE ANGLE WHILE THAT FROM A THREADLIKE REFLECTOR WILL
REMAIN ALMOST UNCHANGED IF A DIFFERENT PROBE ANGLE IS USED.
SOMETIMES IT WILL BE POSSIBLE TO DIFFERENTIATE
BETWEEN THESE 2 DEFECTS SIMPLY BY PLOTTING
THEIR POSITION WITHIN THE WELD ZONE:
A. PROBABLE SLAG, POSSIBLE B. PROBABLE HAZ CRACK
CENTRELINE CRACK