UTpp4

Ultrasonic TestingUltrasonic TestingPart 4Part 4

DEFECT LOCATIONDEFECT LOCATION

DEFECT LOCATION IN ULTRASONIC DEFECT LOCATION IN ULTRASONIC TESTING IS BASED UPON THE PREMISE TESTING IS BASED UPON THE PREMISE

THAT A THAT A MAXIMISED ECHO RESPONSEMAXIMISED ECHO RESPONSE CAN 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

606000

S

R

S = STAND OFF DISTANCE FROM ANY CONVENIENT DATUM POINT (IN THIS CASE THE WELD CENTRELINE)

R = RANGE READ FROM THE FLAWDETECTOR SCREEN

DEFECT LOCATION IN FUSION WELDSDEFECT 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:1.1. THE PROBE EXIT POINT MUST BE ACCURATELY KNOWN.THE PROBE EXIT POINT MUST BE ACCURATELY KNOWN.

2.2. THE BEAM ANGLE MUST BE ACCURATELY KNOWN.THE BEAM ANGLE MUST BE ACCURATELY KNOWN.

3.3. THE WELD CENTRELINE MUST BE ACCURATELY KNOWN.THE WELD CENTRELINE MUST BE ACCURATELY KNOWN.

4.4. THE MATERIAL THICKNESS MUST BE ACCURATELY THE MATERIAL THICKNESS MUST BE ACCURATELY KNOWN.KNOWN.

5.5. THE FLAWDETECTOR MUST BE ACCURATELY THE FLAWDETECTOR MUST BE ACCURATELY CALIBRATED. CALIBRATED.

DEFECT SIZING TECHNIQUESDEFECT SIZING TECHNIQUES

1.1. 6 dB DROP TECHNIQUE (SOMETIMES 6 dB DROP TECHNIQUE (SOMETIMES CALLED HALF AMPLITUDE OR BEAM CALLED HALF AMPLITUDE OR BEAM SPLITTING TECHNIQUE).SPLITTING TECHNIQUE).

2.2. 20 dB DROP TECHNIQUE (SOMETIMES 20 dB DROP TECHNIQUE (SOMETIMES CALLED BEAM BOUNDARY TECHNIQUE).CALLED BEAM BOUNDARY TECHNIQUE).

3.3. MAXIMUM AMPLITUDE TECHNIQUE.MAXIMUM AMPLITUDE TECHNIQUE.

6 dB DROP6 dB DROP

1.1. THE DIMENSION OF THE REFLECTOR WHICH THE DIMENSION OF THE REFLECTOR WHICH IS BEING MEASURED MUST EXCEED THEIS BEING MEASURED MUST EXCEED THEBEAM WIDTH.BEAM WIDTH.

2.2. THE ULTRASONIC BEAM MUST BETHE ULTRASONIC BEAM MUST BESYMMETRICAL IN THE DIRECTION OF PROBE SYMMETRICAL IN THE DIRECTION OF PROBE MOVEMENT.MOVEMENT.

3.3. WORKS BEST ON UNIFORM REFLECTORSWORKS BEST ON UNIFORM REFLECTORSWITH RELATIVELY STRAIGHT EDGES WITH RELATIVELY STRAIGHT EDGES

Sizing Methods6 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 DropBWEDefect

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 striking the defectPlan View

6 dB Drop

Plan View

Now the whole beam is on the defect

Defect

Back wall echo is now may be reduced or disappeared

6 dB DropBWEDefect

Plan View

The probe is moved back until the echo is reduced by half of its original height

At this point the probe centre beam is directly on the edge of the defect

The probe is then removed and the centre is marked, and repeat to size the whole defect

Equalization Technique

At this point the whole beam is on the back wall

BWE

At this point the whole beam is on the defect

The BWE is at it maximum

The Defect echo is at it maximum

Defect

At the edge of the defect, half of the beam is on the defect, and another half is on the back wall

The defect echo is at equal height as the back wall

The point is marked as the edge of defect

The equalization technique can ONLY be used if the defect is halfway the thickness

20 dB DROP20 dB DROP1.1. THE DIMENSION OF THE REFLECTORTHE DIMENSION OF THE REFLECTOR

WHICH IS BEING MEASURED MAY BEWHICH IS BEING MEASURED MAY BEEITHER LARGER OR SMALLER THAN THEEITHER LARGER OR SMALLER THAN THEBEAM WIDTH.BEAM WIDTH.

2.2. THE ULTRASONIC BEAM NEED NOT BETHE ULTRASONIC BEAM NEED NOT BESYMMETRICAL IN THE DIRECTION OFSYMMETRICAL IN THE DIRECTION OFPROBE MOVEMENT.PROBE MOVEMENT.

3.3. THE BEAM SPREAD PARALLEL TO THE THE BEAM SPREAD PARALLEL TO THE DIRECTION OF PROBE MOVEMENT MUST BE DIRECTION OF PROBE MOVEMENT MUST BE KNOWN. KNOWN.

4.4. WORKS BEST ON UNIFORM REFLECTORS WORKS BEST ON UNIFORM REFLECTORS WITH RELATIVELY STRAIGHT EDGES. WITH RELATIVELY STRAIGHT EDGES.

20 dB DROP

LENGTH

20 dB DropDefect BWE

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

10%

Using the pre-constructed Beam profile and a plotting card, the defect maybe sized

Repeat the above at the other side of the defect

20 dB Beam profile

MAXIMUM AMPLITUDEMAXIMUM AMPLITUDE

1.1. THE MAXIMUM AMPLITUDE TECHNIQUE IS ANTHE MAXIMUM AMPLITUDE TECHNIQUE IS ANEXTENSION OF THE TECHNIQUE USED IN UT FOREXTENSION OF THE TECHNIQUE USED IN UT FOR

DEFECT LOCATION.DEFECT LOCATION.

2.2. IT WORKS ON THE PREMISE THAT A MAXIMISEDIT WORKS ON THE PREMISE THAT A MAXIMISEDRESPONSE COULD ONLY COME FROM A POINT ON ARESPONSE COULD ONLY COME FROM A POINT ON AREFLECTOR WHICH IS ON THE SOUND BEAM AXIS.REFLECTOR WHICH IS ON THE SOUND BEAM AXIS.

4.4. VOLUMETRIC REFLECTORS CAN BE SIZED VERYVOLUMETRIC REFLECTORS CAN BE SIZED VERYACCURATELY IF THEY CAN BE APPROACHED FROM ACCURATELY IF THEY CAN BE APPROACHED FROM A VARIETY OF ANGLES.A VARIETY OF ANGLES.

3.3. PLANAR REFLECTORS CAN OFTEN BE SIZED USING THISPLANAR REFLECTORS CAN OFTEN BE SIZED USING THISTECHNIQUE DUE TO THE PRESENCE OF TIP MAXIMA.TECHNIQUE DUE TO THE PRESENCE OF TIP MAXIMA.

1.1. THE DIMENSION OF THE REFLECTOR THE DIMENSION OF THE REFLECTOR WHICH WHICH IS BEING MEASURED MAY BE IS BEING MEASURED MAY BE EITHEREITHER LARGER OR SMALLER THAN LARGER OR SMALLER THAN THE BEAM WIDTH.THE BEAM WIDTH.

2.2. WILL WORK WITH ALMOST ANY WILL WORK WITH ALMOST ANY REFLECTOR. REFLECTOR.

MAXIMUM AMPLITUDEMAXIMUM AMPLITUDE

Sizing Method

Maximum Amplitude TechniqueFor sizing multifaceted defect eg. crackNot very accurate Small probe movement

Maximum Amplitude

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

Multifaceted defect : crack

Maximum Amplitude

Multifaceted defect : crack

The probe is moved out of the defect, the signal disappeared

If the edge of the beam strike the edge of the defect, a very small echo appears

If the probe is moved into the defect, the signals height increase

At this point the MAIN BEAM is directly at the edge of the defect

One of the peak maximised

Maximum Amplitude

The probe is to be moved to the other end of the defect

The signals will flactuate as the beam hits the different faces of the defects

The probe is moved back into the defect and to observe a peak of the signal maximises

Mark the point under the centre of the probe which indicates the edge of the defect

The length of the defect is measured

Length

Remember: The peak which maximised does not have to be the tallest or the first one

MAXIMUM AMPLITUDE

MAXIMUM AMPLITUDE

707000 707000LACK OF FUSION

RANGE

A

M

P

L

I

T

U

D

E

TIP MAXIMA

ECHO DYNAMIC PATTERN

ULTRASONIC EXAMINATION OF WELDSULTRASONIC EXAMINATION OF WELDS

PRIMARY OBJECTIVES:PRIMARY OBJECTIVES:

1.1. TO SCAN ALL FUSION FACES AT AN ANGLE TO SCAN ALL FUSION FACES AT AN ANGLE OF INCIDENCE = 0OF INCIDENCE = 00 +0 +//-- 20200 0 (0(00 +0 +//-- 10100 0 FOR FOR CRITICAL CRITICAL EXAMINATIONS).EXAMINATIONS).

2.2. TO SCAN THE ENTIRE WELD VOLUME 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 TRANSVERSE3. TO SCAN FOR POSSIBLE TRANSVERSEIMPERFECTIONSIMPERFECTIONS

20

2

4

600

SINGLE SIDED BUTT WELD

ULTRASONIC EXAMINATION OF WELDSULTRASONIC EXAMINATION OF WELDS

ULTRASONIC EXAMINATION OF WELDS

454500

THE 450 PROBE CAN NOT BE USED TO SCAN THE WELD ROOT AT HALF SKIP, THEREFORE THE 700 PROBE MUST BE USED:

707000 707000

57 57

58 58

FIXED STAND-OFF SCAN OF WELD ROOT USING THE 700 PROBE


707000707000 707000707000

23 23

120 120

COVERED AT FULL SKIP

COVERED AT HALF & FULL SKIPCOVERED AT

HALF SKIP

700 SCAN OF WELD VOLUME

COVERED AT FULL SKIP

COVERED AT HALF SKIP

COVERED AT FULL & HALF SKIP

600 SCAN OF WELD VOLUME AND FUSION ZONES


606000606000 60600060600023 23

80 80

SCANNING FOR TRANSVERSE IMPERFECTIONSSCANNING FOR TRANSVERSE IMPERFECTIONS

PROBE PROBE

PROBEPROBE

SCAN

RECOGNITION OF DEFECT TYPERECOGNITION 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 RESPONSE1. OBSERVATION OF THE SHAPE OF THE ECHO RESPONSEAND ITAND ITS BEHAVIOUR WHEN THE PROBE IS MOVED INS BEHAVIOUR WHEN THE PROBE IS MOVED INVARIOUS 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

CRACK SLAG

ORBITAL SCAN

ROTATIONAL SCAN

TYPICAL ECHO DYNAMIC PATTERNS

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 combinationProbe and flaw detector combinationMaterial propertiesMaterial propertiesProbe frequencyProbe frequencySignal to noise ratioSignal 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 material1. Parent material2. Root inspection2. Root inspection3. Fusion face & HAZ inspection3. Fusion face & HAZ inspection4. Weld volume4. Weld volume5. Transverse scan5. Transverse scan

ULTRASONIC SENSITIVITYULTRASONIC 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 THESE METHODS ARE REFERRED TO AS SETTING SETTING SENSITIVITYSENSITIVITY OR OR DISTANCE AMPLITUDE DISTANCE AMPLITUDE CORRECTION.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:

1.1. BACKWALL REFLECTIONSBACKWALL REFLECTIONS

2.2. GRAIN RESPONSE (GRASS)GRAIN RESPONSE (GRASS)

3.3. SIDE DRILLED HOLESSIDE DRILLED HOLES

4.4. FLAT BOTTOMED HOLESFLAT BOTTOMED HOLES

5.5. SURFACE NOTCHESSURFACE NOTCHES

6.6. DISTANCE GAIN SIZE (THEORETICAL METHOD) DISTANCE GAIN SIZE (THEORETICAL METHOD)

DISTANCE AMPLITUDE CORRECTIONDISTANCE AMPLITUDE CORRECTION

NATIONAL CODES AND NATIONAL CODES AND STANDARDS SUCH AS BS EN 583STANDARDS 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.

DISTANCE AMPLITUDE CORRECTIONDISTANCE AMPLITUDE 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 holes3 mm Through drilled holes

D A CD A C

BS EN 583BS EN 583--22

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;

OrOr

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 LOSSESTRANSFER 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.

ATTENUATIONATTENUATION

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 ENERGY IS TERMED ATTENUATION.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.

THE GRAIN SIZE IN ANY GIVEN METAL THE GRAIN SIZE IN ANY GIVEN METAL COMPONENT DEPENDS ON:COMPONENT DEPENDS ON:

1.1. THE METHOD OF PRODUCTION THE METHOD OF PRODUCTION (CAST/FORGED /ROLLED etc)(CAST/FORGED /ROLLED etc)

2.2. THE CHEMICAL COMPOSITIONTHE CHEMICAL COMPOSITION

3.3. HEAT TREATMENTHEAT TREATMENT

ATTENUATIONATTENUATION

METHODS OF COMPENSATING FOR TRANSFER AND METHODS OF COMPENSATING FOR TRANSFER AND ATTENUATION LOSS DIFFERENCES FOR 0ATTENUATION LOSS DIFFERENCES FOR 000COMPRESSION 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.

Transfer & Transfer & Attenuation Attenuation

lossloss

FOR 0FOR 000 PROBES BACKWALL ECHOES ARE USED TO 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 ARE USED IN PITCH PITCH -- CATCHCATCH IN ORDER TO OBTAIN IN ORDER TO OBTAIN WHAT ARE EFFECTIVELY BACKWALL ECHOESWHAT 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: 0CORRECTION: 000 PROBES PROBES

40 mm 80 mm 160 mm

24 dB 30 dB 36 dB

EXAMPLE:EXAMPLE:

ECHOES ECHOES OBTAINED ON OBTAINED ON 40 mm THICK 40 mm THICK CALIBRATION CALIBRATION

BLOCKBLOCK

TRANSFER & ATTENUATION TRANSFER & ATTENUATION CORRECTION: 0CORRECTION: 000 PROBES PROBES

26 dB 32 dB 38 dB

30 mm 60 mm 120 mm

EXAMPLE:EXAMPLE:

ECHOES ECHOES OBTAINED ON OBTAINED ON 30 mm THICK 30 mm THICK COMPONENTCOMPONENT

TRANSFER & ATTENUATION CORRECTION: 00 PROBES

2

0

3

0

4

0

5

0

D

E

C

I

B

E

L

S

10 100 1000RANGE / mm

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 PARALLEL.

COMPONENT

BLOCKTRANSFER CORRECTION APPROXIMATELY 4 dB AT

ALL RANGES

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 BACKWALL ECHOES ARE REPLACED BY PITCH -- CATCH CATCH RESPONSES.RESPONSES.

454500 454500 454500 454500

TRANSMIT TRANSMITRECEIVE RECEIVE

ONE SKIP TWO SKIPS

ASME V CALIBRATION BLOCKASME V CALIBRATION BLOCKBLOCK MATERIAL: CHEMICAL

COMPOSITION, PRODUCT FORM AND HEAT TREATMENT TO EXACTLY

REPLICATE THAT OF THE COMPONENT.

SIDE DRILLED HOLE DIAMETER VARIES WITH THE BLOCK THICKNESS

SURFACE NOTCHES PROVIDED TO ASSIST

WITH THE INTERPRETATION OF SURFACE BREAKING

INDICATIONS

BLOCK SURFACE FINISH AND CURVATURE TO REPLICATE THAT OF THE COMPONENT

ASME V DOES NOT ALLOW ASME V DOES NOT ALLOW TRANSFER CORRECTION.TRANSFER CORRECTION.

AVG (DGS) SYSTEMAVG (DGS) SYSTEM

THE THE DDISTANCE ISTANCE GGAIN AIN SSIZE SYSTEM WAS IZE SYSTEM WAS 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.

d

B

8

0

7

0

6

0

5

0

4

0

3

0

2

0

1

0

0

dB

0 10 20 30 40 50 60 70 80

0 50 100 150 200

Range / mm

Range / mm

0 50 100 150 200

BWE

8 mm

6 mm

4 mm

3 mm

2 mm

1.5 mm

DGS CHART FOR A 10 mm DIA. 2 MHz 0DGS CHART FOR A 10 mm DIA. 2 MHz 000COMPRESSION PROBECOMPRESSION PROBE

DGSDGSTHE 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 ABOUT A FLAW AS BEING AN XX mm FLAT 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.

2.0 4.0 6.0 8.0 10.0

ACCEPTABLE2.0 3.7 5.85 7.9 10.0

NOT ACCEPTABLE

TIMEBASE LINEARITYTIMEBASE LINEARITY

EQUIPMENT CHECKSEQUIPMENT CHECKS

AMPLIFIER LINEARITYAMPLIFIER LINEARITY

INDICATION SET AT (%FSH)

dB CONTROL CHANGE (dB)

ACCEPTABLE LIMITS FOR

RESULTANT ECHO HEIGHT

(BS 3923)

ACCEPTABLE LIMITS FOR

RESULTANT ECHO HEIGHT

(ASME V)

80%

80%

80%

40%

20%

-6 dB

-12 dB

-24 dB

+6 dB

+12 dB

36-45%

18-22%

visible

71-90%

71-90%

32-48%

16-24%

N/A

64-96%

64-96%

(+/- 1 dB) (+/- 2 dB)


SIGNALNOISE

+14 dB

SIGNAL TO NOISE RATIO = 5:1 = 14 dB

SIGNAL TO NOISE RATIOSIGNAL TO NOISE RATIO


RESOLUTIONBS 2704 A7 BLOCK:

2, 3, 4 & (5) mm Steps

BS 2704 A2 BLOCK100, 85 & 91 mm Dimensions

1.5 mm

holes @

2.5 mm

centres

1.5 mmholes @4 mm

centres

BS 2704 A5 BLOCK

RESOLUTIONRESOLUTION

RESOLUTION HOLES IN A5 BLOCK WITH 10 mm 450 4 MHz PROBE

RESOLUTION HOLES IN A5 BLOCK WITH 10 mm 450 2 MHz PROBE


1.5 mm Through drilled holes at depths of 1, 2, 3, 5, 10, 15 & 20 mm below the

surface.

DEAD ZONEDEAD ZONE


DEAD ZONEDEAD ZONE

DETERMINE THE DEAD ZONE BY FINDING THE HOLE ECHO WHICH

IS EASILY IDENTIFIABLE FROM THE PROBE NOISE AT THE

SHORTEST RANGE



454500

USING THE A2 BLOCK

EXIT POINTEXIT POINT

EXIT POINT

454500

D S

454500

USING THE A5 BLOCK(MORE ACCURATE METHOD)

S

D

700 600

600 450 350

454500

QUICK CHECK: USE THE SCALES PROVIDED ON THE A2 BLOCK.

BEAM ANGLEBEAM ANGLE


BEAM ANGLE

454500

D S

454500

USING THE A5 BLOCK (MORE ACCURATE METHOD)

NOTE: The probe exit point can be marked either before or during this operation.

S

D

454500454500

20 dB BEAM PROFILE(VERTICAL PLANE)

USING THE A5 BLOCK

NOTE: The probe exit point can be marked either before or during this operation.

454500

D S

454500 S

D

X Y

USE THE CORNER REFLECTION FROM THE 1.5 mm HOLE.

20 dB BEAM PROFILE(HORIZONTAL PLANE)

LINES OF SYMMETRY IN VARIOUS ULTRASONIC LINES OF SYMMETRY IN VARIOUS ULTRASONIC BEAMSBEAMS

6-12 dB0-6 dB 12-20 dB

0 Single Compression 0 Twin Compression

Twin ShearSingle Shear

FULLY SYMMETRICAL

TWO LINES OF SYMMETRY

SINGLE LINE OF SYMMETRY

SOUND PRESSURE IN THE FAR ZONESOUND PRESSURE IN THE FAR ZONE(IN A SECTION THROUGH THE BEAM)(IN A SECTION THROUGH THE BEAM)

-

2

4

-

2

0

-

1

6

-

1

2

-

8

-

4

0

d

B

-2 -1 0 1 2CRYSTAL DIAMETERS

-

2

4

-

2

0

-

1

6

-

1

2

-

8

-

4

0

d

B

-2 -1 0 1 2CRYSTAL DIAMETERS

4 MHz

2 MHz

25 dia.

10 dia.

454500

R

S

S = STAND OFF DISTANCE FROM ANY CONVENIENT DATUM POINT

R = RANGE READ FROM THE FLAWDETECTOR SCREEN

DEFECT LOCATION IN FUSION WELDS

450450

40

4

0

ULTRASONIC EXAMINATION OF

WELDS

DOUBLE SIDED T JOINT

BACK GOUGE


WELDS

00000000

100 (approx.)

COVERAGE OF FUSION

FACES

COVERAGE OF WELD VOLUME

454500

4

5

4

5

0

0

454500

4

5

4

5

0

0

COVERAGE OF FUSION

FACES

COVERAGE OF WELD VOLUME


WELDS

SCANNING FOR TRANSVERSE IMPERFECTIONS

454500

SCANNING FOR TRANSVERSE IMPERFECTIONS

THESE DEFECTS CAN BE DIFFERENTIATED BETWEEN BY OBSERVING THE ECHO DYNAMIC BEHAVIOUR IN

LENGTH AND DEPTH SCANS:

POINT THREADLIKE PLANAR(NEAR NORMAL INCIDENCE)

DEPTH SCAN

LENGTH SCAN

NOTE: THE RESPONSE FROM A PLANAR DEFECT WILL BE STRONGLY AFFECTEDBY PROBE ANGLE WHILE THAT FROM A THREADLIKE REFLECTOR WILLREMAIN 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 CENTRELINE CRACK

B. PROBABLE HAZ CRACK

Sizing Methods6 dB Drop6 dB Drop6 dB DropEqualization Technique20 dB DropSizing MethodMaximum AmplitudeMaximum AmplitudeMaximum AmplitudeUltrasonic TestingSensitivityMethods of Setting SensitivityArtificial / actual defectUltrasonic InspectionUltrasonic InspectionSensitivityMethods of Setting Sensitivity

UTpp4

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