day-3 session 1 ndt introduction + ut + rt to pmi final

7/31/2019 Day-3 Session 1 Ndt Introduction + Ut + Rt to Pmi Final

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NDT IS TESTING OF MATERIAL WITHOUT DISTROYING IT

IT ISUSED WORLD WIDE TO

DETECT THE PRESENCE OF CRACK OR OTHERDISCONTINUITY

DETECT MINUTE CHANGES IN SURFACE FINISH

MEASURE THE THICKNESS OF MATERIALS &COATING

DETERMINE OTHER CHARACTERISTICS OF

INDUSTRIAL PRODUCT

NON DESTRUCTIVE TESTING


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TYPICAL NONDESTRUCTIVE TEST METHODS WHICH CAN BE REQUIRED AT

FIELD ARE

1. ULTRASONIC TEST 6. VIBRATION ANALYSES

2. RADIOGRAPHY 7. COATING THICKNESS TEST

3. MAGNETIC PARTICLE TEST 8. HARDNESS TEST

4. LIQUID PENETRANT TEST 9. LEAK DETECTION

5. EDDY CURRENT TEST



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REASONS FOR USE OF NONDESTRUCTIVE TESTING

TO ENSURE PRODUCT RELIABILITY

TO PREVENT ACCIDENTS & SAVE HUMAN LIFE

TO ENSURE CUSTOMER SATISFACTION ANDTO MAINTAIN THE MANUFACTURERS GOODNAME

TO AID IN BETTER PRODUCT DESIGN



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REASONS FOR USE OF NONDESTRUCTIVE TESTING

TO CONTROL MANUFACTURING PROCESSES

TO LOWER MANUFACTURING COSTS

TO MAINTAIN A UNIFORM QUALITY LEVEL



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DEFINITIONS

TERMINOLOGY DEFINITION

DISCONTINUITY A BREAK OR INTERRUPTION IN THENORMAL PHYSICAL STRUCTURE OF

AN ARTICLE

DEFECT A CONDITION WHICH WILLINTERFERE WITH THE SAFE OR

SATISFACTORY SERVICE OF THEPARTICULAR PART IN QUESTION


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METHODS USED FOR DETECTION OF DISCONTINUITIES

DISCONTINUITY DETECTED BY

INTERNALDISCONTINUIIES

ULTRASONIC TEST

RADIOGRAPHIC TEST

SURFACE ORSUBSURFACEDISCONTINUITIES

MPI

LPI

UT WITH SURFACE PROBES EDDY CURRENT


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DISCONTINUITIES IN FERROMAGNETIC MATERIALS

DISCONTINUITIES OCCURS DURING

INHERENTDISCONTINUITIES

INITIAL MELTING & REFININGPROCESSES

SOLIDIFICATION FROM MOLTENSTATE A BREAK OR INTERRUPTIONIN THE NORMAL PHYSICAL

STRUCTURE OF AN ARTICLE

PRIMARY PROCESSINGDISCONTINUITIES

STEEL INGOT WORKED DOWN TOSHAPE SUCH AS BILLETS & SLABS

HOT AND COLD WORKING TOPRODUCE SHAPES SUCH AS

PLATES,BARS,ROD,WIRE,TUBINGAND PIPE


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DISCONTINUITIES IN FERROMAGNETIC MATERIALS

DISCONTINUITIES OCCURS DURING

SECONDARY PROCESSINGDISCONTINUITIES

FORMING,

MACHINING,

WELDING &

HEAT TREATMENT

SERVICE DISCONTINUITIES SERVICE / OPERATION


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INHERENT DISCONTINUITIES

DISCONTINUITY LOCATION CAUSE

COLD SHUT SURFACE OR

SUBSURFACE

THE MEETING OF TWO STREAMS

OF LIQUID METAL THAT DO NOTFUSE TOGETHER

PIPE SUBSURFACE AN ABSENCE OF MOLTEN METALDURING FINAL SOLIDIFICATIONPROCESS

HOT TEARS SURFACE RESTRAIN FROM CORE OR MOLDDURING SOLIDIFICATIONPROCESS


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COLD SHUT IN THE CASTING

INDICATION OF COLD SHUT IN THE CASTINGDURING MAGNETIC PARTICLE INSPECTION


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POROSITY SURFACE OR

SUB - SURFACE

ENTRAPPED GASES DURING

SOLIDIFICATION

INCLUSION SURFACE ORSUB SURFACE CONTAMINANTS INTRODUCEDDURING THE CASTING PROCESS

SEGREGATION SURFACE ORSUB SURFACE

LOCALIZED DIFFERENCE INMATERIAL COMPOSITION


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POROSITY IN THE CASTING


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PRIMARY PROCESSING DISCONTINUITIES


SEAM SURFACE ELONGATION OF UNFUSED

SURFACE DISCONTINUITIES INROLLED PRODUCTS

LAMINATION SUB - SURFACE ELONGATION OF INHERENT

DISCONTINUITIES DURING THEROLLING PROCESS

STRINGERS SUB - SURFACE -DO-

CUPPING SUB - SURFACE INTERNAL STRESSES DURINGCOLD DRAWING


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FORMATION OF A SEAM


UNDERFILL RESULTS WHEN THERE IS NOT

ENOUGH METAL TO FILL THE ROLL

A SEAM IN THE FINISHED BAR OCCUR WHEN UNDERFILL

IS SQUEEZED TIGHT IN THE SUBSEQUENT ROLLING PASS

UNDERFILL SEAM


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CUPPING


CROSS SECTION SHOWING SEVERE CUPPING IN A 35 MM BAR


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COOLING CRACKS SURFACE UNEVEN COOLING OF COLDDRAWN PRODUCTS

LAPS SURFACE MATERIAL FOLD OVER ANDCOMPRESSED

BURSTS SURFACE ORSUBSURFACE

FORMING PROCESSES ATEXCESSIVE TEMPERATURES

HYDROGEN FLAKES SUB - SURFACE AN ABUNDANCE OF HYDROGENDURING FORMING PROCESS


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FORMATION OF A LAP


AN OVERFILL PRODUCES EXCESS METAL

SQUEEZED OUT OF ROLLS CAUSING A FIN

A LAP RESULTS WHEN THE PROJECTION IS

FOLDED OVER AND FORCED BACK INTO THE

BARS SURFACE DURING SUBSEQUENT ROLLING PASS

FIN LAP

SECONDARY PROCESSING DISCONTINUITIES


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GRINDING CRACKS SURFACE LOCALIZED OVERHEATING OF

THE MATERIAL DUE TOIMPROPER GRINDINGPROCEDURE

HEAT TREATINGCRACKS

SURFACE UNEVEN HEATING OR COOLING

QUENCH CRACKS SURFACE SUDDEN COOLING FROMELEVATED TEMERATURES



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GRINDING CRACKS

GRINDING CRACKS AS REVEALED BY

MAGNETIC PARTICLE INSPECTION

GRINDING CRACKS AS REVEALED BY

FLUOROSCENT MAGNETIC PARTICLE INSPECTION



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QUENCH CRACKS



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PICKLING CRACKS SURFACE RESIDUAL STRESSES BEINGRELIEVED.

MACHINING TEARS SURFACE IMPROPER MACHINING

PRACTICES

PLATING CRACKS SURFACE RESIDUAL STRESSES BEINGRELIEVED.

SERVICE INDUCED DISCONTINUITIES


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FATIGUE CRACKS SURFACE CYCLICALLY APPLIED STRESSES

CREEP CRACKS SURFACE ORSUB SURFACE

MATERIAL SUBJECTED TOELEVATED TEMERATURE &STRESS BELOW YIELD POINT.

STRESS CORROSIONCRACKING

SURFACE COMBINED EFFECTED OF STATICTENSILE LOAD & CORROSIVEENVIRONMENT.

HYDROGENCRACKING

SURFACE ORSUB SURFACE

COMBINED EFFECTED OF STATICTENSILE LOAD OR RESIDUALSTRESS & HYDROGENENCIRCLED ENVIRONMENT.



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FATIGUE CRACKS IN MANUFACTURED COMPONENTS


GEAR TOOTH ROOT

AUTOMOBILE CRANKSHAFTAIRCRAFT COMPONENT

ULTRASONIC TESTING


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PRINCIPLES OF ULTRASONIC TESTING

TECHNIQUES

EQUIPMENT AND PROBES

INTERPRETATION

LIMITATIONS

ULTRASONIC TESTING

ULTRASONIC WAVES


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MECHANICAL VIBRATIONS

FREQUENCY OF VIBRATION IS BEYOND THEAUDIBILITY RANGE OF HUMAN EAR (20 Hz -20KHz)

FREQUENCY RANGE (20 KHz - 50 MHz)

ULTRASONICWAVES

ULTRASONIC WAVES ARE

ULTRASONIC WAVES


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TRAVELS IN MOST OF METAL WITHOUT SERIOUS

LOSS OF ENERGY

EXCEPTIONS

BRASS,

COPPER,

URANIUM,

CAST IRON,

AUSTENITIC STEEL

ULTRASONICWAVES

ULTRASONIC WAVES


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CAN TRAVEL LONG DISTANCE IN SOLIDMATERIALS

TRAVEL IN WELL DEFINED BEAM

VELOCITY IS CONSTANT IN HOMOGENOUS

MATERIALS

WAVES ARE REFLECTED/REFRACTED WHERE

ELASTIC & PHYSICAL PROPERTIES CHANGE

ULTRASONIC WAVES

PROPERTIES OF ULTRASONIC WAVES

ULTRASONIC WAVES


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CAPABLE OF VERY HIGH SENSITIVITY

POROSITY, BLOW HOLES, CRACK, INCLUSIONS

LIE IN THE PATH OF AN ULTRASONIC BEAM

PRODUCE STRONG REFLECTION

ULTRASONICWAVES

EXAMINATION BY ULTRASONIC WAVES

ULTRASONIC WAVES


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SHEAR WAVES OR TRANSVERSE WAVES

DIRECTION OF PROPAGATION

PARTICLE MOTION

MEDIUM

ULTRASONICWAVES

WAVE PROPAGATION CHARACTERISTICS

ON THE BASIS OF PARTICLE DISPLACEMENT IN THE MEDIUM,

ULTRASONIC WAVES ARE CLASSIFIED AS


PARTICLE MOTION

MEDIUM

LONGITUDINAL WAVES

ULTRASONIC WAVES


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WAVE PROPAGATION CHARACTERISTICS

SURFACE WAVES OR RAYLEIGH WAVES


PARTICLE MOTION

MEDIUM SURFACE

ULTRASONICWAVES

TRANSMISSION REFLECTION & MODE CONVERSION OF


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VL = VS = CL = CS

Sin1 Sin3 Sin4 Sin2

TRANSMISSION, REFLECTION & MODE CONVERSION OF

LONGITUDINAL WAVES AT AN INTERFACE

INCIDENT LONGITUDINAL WAVEVELOCITY = VL

REFLECTED LONGITUDINAL WAVEVELOCITY = VL

REFLECTED SHEAR WAVEVELOCITY = VS

TRANSMITTED SHEAR WAVE

VELOCITY = CS

4

2

11

3

TRANSMITTED LONGITUDINAL WAVEVELOCITY = CL

MEDIUM - 1

MEDIUM - 2

INTERFACE

SNELLS LAW

PRINCIPLE OF ULTRASONIC TESTING


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TRANSDUCER

MATERIALDISCONTINIUITY

BACK WALL REFLECTIONREFLECTION FROM

DICONTINUITY

AMPLITUDE

INITIAL PULSE

DISCONTINUITYINDICATION

BACK WALL ECHO

HORIZONTALSWEEP

PRINCIPLE OF ULTRASONIC TESTING

ULTRASONIC DISPLAYS


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A - SCAN DISPLAY

A - SCAN IS A TIME VERSUS AMPLITUDE DISPLAY WHICH REVEALS A DISCONTINUITYUSING A PIP ON A CRT

ULTRASONIC DISPLAYS

RELATIVE FLAW SIZE CAN BE OBTAINED BY COMPARING THE HEIGHT OFECHO FROM AN ACTUAL FLAW AND ONE ARTIFICIALLYPRODUCED OF KNOWN PARAMETER

DISTANCE OF DISCONTINUITYFROM TEST SURFACE

CAN BE READ ON HORIZONTAL TRACE OF CRT

TRANSDUCER

MATERIAL DISCONTINIUITY BACK WALLREFLECTION

REFLECTIONFROM

DICONTINUITY

AMPLITUDE INITIAL PULSE DISCONTINUITYINDICATION

BACK WALL ECHO

HORIZONTALSWEEP

ULTRASONIC DISPLAYS


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FRONT SURFACE

BACK SURFACE

PROBE TRAVEL

ULTRASONIC DISPLAYS

B - SCAN DISPLAY CROSS SECTIONAL VIEW OF THE MATERIAL SHOWINGDEPTH AND WIDTH OF THE DISCONTINUITY

DISCONTINUITIESPROBE POSITIONS

FRONT SURFACE

BACK SURFACE

THICKNESS OFTEST MATERIAL

B SCAN PRESENTATION

ULTRASONIC DISPLAYS


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FRONT SURFACE

BACK SURFACE

PROBE TRAVEL

ULTRASONIC DISPLAYS

C - SCAN DISPLAY

DISCONTINUITIES

C SCAN PRESENTATION

GIVES PLAN VIEW OF THE TEST SPECIMEN

SHOWS THE SHAPE AND LOCATION OF THE DEFECT

IT WILL NOT GIVE DEPTH OF THE DEFECT

ULTRASONIC TRANSDUCER


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ULTRASONIC TRANSDUCER

TYPE OF ULTRASONICTRANSDUCER

PROPERTIES

PIEZOELECTRIC REVERSIBLE

MOST WIDELY USED

ELECTROMAGNETIC REVERSIBLE CAN BE USED FOR METAL

TESTING WITHOUT CONTACT

ELECTROSTATIC REVERSIBLE LOW FREQUENCY APPLICATION

MAGNETORESTRICTIVE

REVERSIBLE LOW FREQUENCY APPLICATION

CONTACT NECESSARY

LASER NOT REVERSIBLE NO MATERIAL CONTACT


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PIEZOELECTRIC MATERIAL


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PIEZOELECTRICMATERIAL

PIEZOELECTRICMATERIAL

PROPERTIES

QUARTZ EXCELLENT STABILITY

WEAR RESISTANT

LEAST EFFICIENT GENERATOR

OF ACOUSTIC

CERAMIC MOST EFFICIENT GENERATOR OF

ACOUSTIC

LOW MECHANICAL STRENGTH

USABLE UP TO 300

O

CLITHIUM SULPHATE INTERMEDIATE GENERATOR

FRAGILE

SOLUBLE IN WATER

APPLICATION LIMITED TO 74O C

METHODS OF ULTRASONIC TESTING OF MATERIALS


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LAMINATIONS CAN BE DETECTED BY THIS METHOD

THICKNESS = 0.5 WAVELENGTH


1. RESONANCE METHOD

MAINLY USED FOR THICKNESS MEASUREMENT

CONTINUOUS LONG WAVES ARE USED

STATIONARY WAVES ARE SET UP IN THE MATERIAL

THICKNESS d = 0.5*V/fe

fe = f n+1 - fn

THICKNESS = 1 WAVELENGTH



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100% INTENSITY

HIGH FREQUENCYGENERATOR AMPLIFIER

AMPLIFIER

0

INTENSITY METER

TRANSMITTING PROBE RECEIVING PROBE

DISCONTINUITY

25% INTENSITY DUE TO PARTIAL ENERGY BEINGRECEIVED BECAUSE OF THE DISCONTINUITY


2. THROUGH TRANSMISSION METHOD

INTENSITY OF ULTRASOUND IS MEASURED AFTER IT HAS PASSED THROUGH

THE TEST PIECE



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2. THROUGH TRANSMISSION METHOD

CAPABILITY OF TESTING THICKER TEST SPECIMENS

DEFECTS VERY NEAR TO THE SURFACE CAN BEDETECTED

ADVANTAGES

LIMITATIONS

DEFECT LOCATION IS NOT POSSIBLE.

BOTH SIDES SHOULD BE ACCESSIBLE.



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AMPLIFIER

TRANSMITTER

RECEIVER

HIGH FREQUENCYGENERATOR


3. PULSE ECHO METHOD



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0.5 TO 6 MHz COMMONLY USED FREQUENCY FORCONTACT TESTING

10 TO 25 MHz IMMERSION TESTING

PULSE ECHO METHOD

NORMALPROBE

ANGLEPROBE

T.R.PROBE

CONTACT TESTING

NORMALPROBE

ANGLEPROBE

IMMERSION TESTING

O S O U SO C S G O S

3. PULSE ECHO METHOD

CONTACT TESTING


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CONTACT TESTING

SIDE - 1 SIDE - 2

SIDE - 3 SIDE - 4

DOUBLE V BUTT JOINT

SCANNING FROM ALL FOUR SIDES

ADVANTAGES

IT IS PORTABLE.

SYSTEM DOES NOT REQUIRE LARGE AMOUNT OF

ACCESSORIES

IMMERSION TESTING


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IMMERSION TESTING

WATER

TRANSDUCER FRONT SURFACE

BACK SURFACE DISCONTINUITY

x

y

INITIAL PULSE REFLECTION FROMFRONT SURFACE

DISCONTINUITY

BACKREFLECTION

WATER PATHx

TEST PIECE PATHy

MOST COMMONLY USED COUPLANT IS WATER

MORE SENSITIVE, AS HIGHER FREQUENCY PROBES CAN BE USED

HOWEVER REQUIRES LARGE NUMBER OF ACCESSORIES

ULTRASONIC FLAW DETECTOR


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ULTRASONIC FLAW DETECTOR

1

0

2040

0 2 4 6 8 10

0

20

40

60

80

100

23

1a

1b

2

3

3a4

4a 5

6

7

14

8

8a

13 13a 13b

17

CONNECTOR SOCKETS (1a & 1b) SUPPRESSION CONTROL(5)

ON/OFF SWITCH (2) DELAY CONTROL(6)

TEST RANGE CONTROL (3 & 3A) FOCUS(7)

GAIN CONTROL (4 & 4a)

MONITOR GATE START & WIDTH CONTROL (8 & 8A)

FRONT VIEW

CALIBERATION BLOCKS


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100

91

6

2002

100

55

30

15

400 600500

600

700

750

35

25

FOCAL POINT10

5

1.5 HOLE

50 HOLE

300

25

2

1.5

PERSPEX

INSERT

THICKNESS OF THE PERSPEX INSERT

EQUIVALENT TO 50 MM STEEL

CALIBERATION BLOCKS

1. IIW V1 BLOCK

CALIBERATION BLOCKS


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75

25 50

12.5

450 60020

C O OC S

1. IIW V2 BLOCK

MINIATURE ANGLE BEAM BLOCK

FOCAL POINT

1.5 HOLE

ANGLE BEAM PROBE

CONSTRUCTION OF PROBES


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CHARACTERISTIC OF ULTRASONIC PROBES


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SENSITIVITY

ABILITY OF THE PROBE TO DETECT SMALLEST DISCONTINUITY

MEASURED BY THE AMPLITUDE OF ITS RESPONSE TO ENERGYREFLECTED FROM A STANDARD DISCONTINUITY

SAME REFLECTOR, SAME DISTANCE & GAIN SETTING PROBE N0 - 2 IS MORE SENSITIVE

0 2 4 6 8 10

0

20

40

60

80

100

0 2 4 6 8 10

0

20

40

60

80

100

FLAT BOTTOM HOLE

PROBE NO. - 1

FLAT BOTTOM HOLE

PROBE NO. - 2

HIGHER THE FREQUENCY, MORE THE SENSITIVITY



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RESOLUTION

ABILITY TO SEPARATE ECHOES FROM TWO OR MORE DISCONTINUITIES

LOCATED CLOSE TOGETHER IN DEPTH

HIGHER THE FREQUENCY, BETTER WILL BE RESOLUTION

0 2 4 6 8 10

0

20

40

60

80

100

0 2 4 6 8 10

0

20

40

60

80

100

GOOD RESOLUTION POOR RESOLUTION



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DEAD ZONE ZONE IN WHICH NO DEFECTS CAN BE DETECTEDWIDTH OF INITIALPULSE COVERED IS CALLED DEAD ZONE DISTANCE

T TIME FOR WHICH PULSE IS APPLIED BY INSTRUMENT

x TIME TAKEN BY CRYSTAL TIME TO STOP VIBRATION (BECAUSE OF INERTIA)

D DISTANCE TRAVELLED BY SOUND WAVE DURING (T + x) SEC.ORDER OF FEW mm

USE SHORT PULSE, HIGH DAMPING TO REDUCE D

D

DISTANCE TRAVELLEDBY PULSE IN T SEC.

DISTANCE TRAVELLEDBY PULSE IN x SEC.

0 2 4 6 8 100

20

40

60

80

100

INITIAL ECHO DEFECTECHO

DEFECTINDICATION

DEFECTECHO

CALIBERATION OF ULTRASONIC EQUIPEMENT


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MINIMUM TWO REFERENCE POINTS ARE NECESSARY

FIRST REFERENCE ALWAYS CONTROLLED WITH THE HELP OF

DELAY CONTROL KNOB

SECOND REFERENCE POINT ALWAYS CONTROLLED WITH THE HELPOF RANGE CONTROL KNOB

IIW V1 BLOCK

GENERAL RULES

0 2 4 6 8 10

0

20

40

60

80

100

INITIAL ECHO 1ST BACK WALL ECHO(BWE)

CALIBERATION OF ULTRASONIC EQUIPEMENT


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IIW V1 BLOCK

RANGE CALIBERATION BY NORMAL PROBE

0 2 4 6 8 10

0

20

40

60

80

100

INITIAL ECHO 1ST BACK WALL ECHO(BWE)

0 2 4 6 8 10

0

20

40

60

80

100

INITIAL ECHO

1ST BWE2NDBWE

0 2 4 6 8 10

0

20

40

60

80

100

INITIAL ECHO 1ST BWE

2ND

BWE

APPLICATIONS OF ULTRASONIC TESTING


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0 2 4 6 8 10

0

20

40

60

80

100

INITIAL ECHO 1ST BWE 2ND BWE

1. TESTING OF LAMINATION IN PLATES

LAMINATION IN THE PLATEPLATE

NO DEFECT

0 2 4 6 8 10

0

20

40

60

80

100

INITIAL ECHO 1ST BWEFROM DEFECT

2ND BWEFROM DEFECT

3RD BWE

FROM DEFECT

4TH BWEFROM DEFECT

DEFECT INDICATION

APPLICATIONS OF ULTRASONIC TESTING


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2. BOND TESTING

0 2 4 6 8 10

0

20

40

60

80

100

INITIAL ECHO 1ST BWEFROM DEFECT

2ND BWEFROM DEFECT

DEFECT INDICATION

0 2 4 6 8 10

0

20

40

60

80

100

INITIAL ECHOFIRST ECHO

FROM INTERFACE 1ST BWE

NO DEFECT

DEFECT IN BONDINGAT INTERFACE CALLED DISBONDING

BEARINGCASTING PORTION

BABBIT METAL

INTERFACE

INTERPRETATION OF FLAW ECHO INDICATIONS


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1

2

PLANAR FLAW

0 2 4 6 8 10

0

20

40

60

80

100

INITIAL ECHO

INDICATION FROM

PLANAR FLAWBWE

SCREEN PRESENTATIONWHEN PROBE IS AT 1

0 2 4 6 8 10

0

20

40

60

80

100

INITIAL ECHO BWE

SCREEN PRESENTATIONWHEN PROBE IS AT 2

1. PLANAR FLAW (CRACK, LACK OF FUSION)

SHARP INDICATION WHEN BEAM IS STRIKING r TO IT.

CONSIDERABLE DIFFERENCE WHEN ANGLE OF APPROACH CHANGED

IN ECHO HEIGHT

INTERPRETATION OF FLAW ECHO INDICATIONS


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2. SPHERICAL FLAW (POROSITY)

REFLECT ONLY A SMALL AMOUNT OF SOUND

ECHO HEIGHT SMALL

ECHO HEIGHT REMAINS UNCHANGED WHEN ANGLE OF

APPROACH IS CHANGED

0 2 4 6 8 10

0

20

40

60

80

100

INITIAL ECHO

INDICATION FROMSPHERICAL FLAW

BWE

SCREEN PRESENTATIONWHEN PROBE IS AT 1 OR 2 OR 3 OR 4

1

2

SPHERICALFLAW

3

4

WELD TESTING


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0 2 4 6 8 10

0

20

40

60

80

100

INITIAL ECHO

INDICATION FROM CORNER

SCREEN PRESENTATION

WHEN PROBE IS AT 1 OR 2

1 2

LACK OF PENETRATION

ANGLE PROBEWELD

INTERPRETATION OF ULTRASONIC INDICATIONS

1. LACK OF PENETRATION

SHARP ECHO FROM BOTH SIDES OF WELD

INDICATION REMAINS AT THE SAME POSITION WHEN PROBE ISMOVED ALONG THE LENGTH

WELD TESTING


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2. EXCESS PENETRATION

SHARP ECHO DEPENDS ON SHAPE OF ROOT SURFACE

INITIAL ECHO

INDICATION FROMEXCESS PENETRATION

0 2 4 6 8 10

0

20

40

60

80

100

SCREEN PRESENTATION WHEN PROBEIS AT 1

ECHO MAY BE ABSENT WHEN PROBEAT 2 DEPENDING ON SURFACECONTOUR

1 2

EXCESS PENETRATION

ANGLE PROBEWELD

WELD TESTING


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3. MISMATCH

STRONG ECHO INDICATION WHEN SCANNED FROM LOWER SIDE OFTHE WELD

NO INDICATION FROM OTHER SIDE

0 2 4 6 8 10

0

20

4

0

60

80

100

INITIAL ECHO

INDICATION FROMMISMATCH

SCREEN PRESENTATION WHEN PROBEIS AT 2

ECHO MAY BE ABSENT WHEN PROBEAT 1 DEPENDING ON SURFACECONTOUR

1 2

MISMATCH

ANGLE PROBEWELD

WELD TESTING


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4. ROOT CONCAVITY

0 2 4 6 8 10

0

20

40

60

80

1

00

INITIAL ECHO

INDICATION FROMROOT CONCAVITY

SCREEN PRESENTATION WHEN PROBEIS AT 1 OR 2

1 2

ROOT CONCAVITY

ANGLE PROBE WELD

ULTRASONIC TESTING


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UT OF TURBINE ROTOR

UT OF TURBINE & PUMPS JOURNAL & THRUST

BEARING

UT OF FANS SHAFT

UT OF PUMPS SHAFT

DURING OVERHAUL OF POWER PLANT UNITS

ULTRASONIC TESTING


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UT OF REPAIR WELDS IN HIGH PRESSURELINES

UT OF VALVE SPINDLES

BOILER TUBE THICKNESS SURVEY USINGULTRASONIC THICKNESS MEASURINGINSTRUMENT

DURING OVERHAUL OF POWER PLANT UNITS

SELECTION OF TEST FREQUENCIES


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TEST PARPMETERS RECOMMENDEDFREQUENCY RANGE

CAST IRON

COARSE GRAIN MATERIALS

0.5 MHz

REFINED GRAIN STEELS

SMALL DISCONTINUITIES

(BURST,FLAKING,PIPE)

LARGE FORGINGS

2.25 TO 5.0 MHz

SMALL FORGINGS 5.0 - 10.0 MHz

MICROSCOPIC DEFECTS,

FATIGUE CRACKS ETC.

10.0 MHz

SELECTION OF PROBES


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TYPE OF PROBE SIZE APPLICATION / ADVANTAGE

NORMAL BEAMPROBELARGEDIAMETER USED FOR THICKER SECTION

MAXIMUM BEAM COVERAGE

MINIMUM NUMBER OF

SCANNING PASSES

LOW BEAM SPREAD

SMALLDIAMETER

LESS THICK SECTION

BEAM SPREAD IS MORE

DESIRABLE FOR RANDOMLY

ORIENTED FLAW

D

D

SELECTION OF PROBES


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TYPE OFPROBE

SIZE APPLICATION / ADVANTAGE

ANGLE BEAMPROBE

MINIATURE (8*9) FOR DEFECTS AT ANGLE TO

TEST SURFACE

FLAW DETECTABILITY IS

BETTER, AS SHEAR WAVES ARE

USED

T. R. PROBE 10 MM DIAMETER MUST BE USED FOR LOW

THICKNESS PLATES (5 - 20 mm)

TO DETECT NEAR SURFACE

DEFECT

ULTRASONIC TESTING


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ADVANTAGES

ABILITY TO TEST MATERIAL WITH ACCESS ONLYON ONE SIDE

GREATER PENETRATION POWER

RESULTS ARE KNOWN IMMEDIATELY

NO HEALTH HAZARD LIKE RADIOGRAPHY

ULTRASONIC TESTING


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LIMITATIONS

REQUIRES LOT OF SKILL

PROPERLY TRAINED, QUALIFIED & EXPERIENCEDOPERATOR IS NEEDED

CAN BE USED ONLY FOR THOSE MATERIAL IN WHICHULTRASOUND CAN BE TRANSMITTED

VERY THIN SHEETS, COARSE GRAIN MATERIAL AREDIFFICULT TO TEST

GEOMETRY OF THE OBJECT & GRAIN STRUCTURE CANMAKE TESTING DIFFICULT

ORIENTATION OF THE DEFECT, SIZE, NATURE &DISTRIBUTION CAN AFFECT THE DETECTABILITY

RADIOGRAPHIC TESTING


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PRINCIPLES OF RADIOGRAPHY

EQUIPMENT FOR RADIOGRAPHY

PHOTOGRAPHIC ASPECTS OF RADIOGRAPHY

TECHNIQUES OF RADIOGRAPHY

INTERPRETATION OF RADIOGRAPHS

APPLICATIONS OF RADIOGRAPHY

LIMITATIONS OF RADIOGRAPHY



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BASIC SETUP FOR MAKING A RADIOGRAPH

ANODE FOCAL SPOT

DIAPHRAGM

SPECIMEN

FLAW

X - RAY FILM



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RADIOGRAPH IS A SHADOW PICTURE REVEALING THE INTERNALSTRUCTURE OF AN OBJECT

IT IS 2-D PROJECTION OF THE 3-D SPECIMEN

PHOTOGRAPHIC RECORD PRODUCED BY THE PASSAGE OF X - RAYSOR GAMMA RAYS THROUGH AN OBJECT ONTO A FILM

A RADIOGRAPH

ANODE FOCAL SPOT

DIAPHRAGM

SPECIMEN

FLAW

X - RAY FILM

A RADIOGRAPH



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AMOUNT OF RADIATION TRANSMITTED DEPENDS UPON

NATURE OF MATERIAL THICKNESS

QUALITY OF RADIATION

RADIATION PROCEEDS IN STRAIGHT LINES FROM SOURCE TO OBJECT

SOME RAYS PASS THROUGH SOME ARE ABSORBED

A RADIOGRAPH

ANODE FOCAL SPOT

DIAPHRAGM

SPECIMEN

FLAW

X - RAY FILM



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MORE RADIATIONREACHING TO THAT AREA

A RADIOGRAPH

A RADIOGRAPH

RELATIVELY DARKER REGIONOF RADIOGRAPH

ANODE FOCAL SPOT

DIAPHRAGM

SPECIMEN

FLAW

X - RAY FILM



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THEY PENETRATE MATTER

PENETRATION IS LESS IN HIGHER DENSITY ANDGREATER THICKNESS MATERIAL

THEY TRAVEL IN STRAIGHT LINES

THEY AFFECT PHOTOGRAPHIC EMULSIONS

THEY MAKE CERTAIN CHEMICALS FLUORESCE

PROPERTIES OF X - RAYS AND GAMMA RAYS



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THEY MAY BE SCATTERED

THEY MAY BE REFLECTED,REFRRACTED ANDDIFFRACTED

THEY CANNOT BE FELT,SEEN,HEARD, OR BEDETECTED IN ANY OTHER WAY BY THE HUMANBODY

THEY DAMAGE LIVING TISSUE.

THEY IONIZE GASES

PROPERTIES OF X - RAYS AND GAMMA RAYS

GEOMETRIC PRINCIPAL OF SHADOW FORMATION


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POINT SOURCE

OBJECT

SHADOWOF THE OBJECT

RAYS

SCREEN



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FLAT SOURCE

EFFECT OF INCREASINGTHE SOURCE DISTANCE

OBJECT

SCREEN

GEOMETRIC PRINCIPAL OF SHADOW FORMATIONPOINT SOURCE


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POINT SOURCE

SCREEN

OBJECT



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A. TWO CIRCULAR OBJECTS CAN BE RENDERED AS TWO SEPEARATE CIRCLE

B. TWO OVERLAPPING CIRLCLES

DEPENDING UPON THE DIRECTION OF THE RADIATION

A

B

ELECTROMAGNETIC RADIATION


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X - RAYS AND

GAMMA RAYSFORM OF ELECTROMAGNETIC

RADIATION

X RAYS = 10-13 TO 10-9 m

USUALLY PRODUCED BY ALLOWING

A STREAM OF HIGH ENERGYELECTRONS TO IMPINGE ON AMETALLIC TARGET.

PHOTONS PRODUCED BYDECELERATION OF ELECTRONSGAMMA RAYS ELECTROMAGNETIC RADIATION OF

NUCLEAR ORIGIN

ELECTROMAGNETIC RADIATION


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107 106 105 104 103 102 101 100 10-1 10-2 10-3 10-4 10-5

INFRARED

VISIBLE

LIGHT

ULTRAVIOLET

X RAYS

- RAYS COSMICRAYS

RADIO

RADIATION WAVELENGTH IN ANGSTROMS

ELECTROMAGNETIC SPECTRUM

GENERATION OF X - RAYS


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X - RAYS ARE GENERATED WHENEVER MATTER IS BOMBARDEDBY A STREAM OF ELECTRONS

K.E. OF ELECTRON AT ARRIVAL TO THE TARGET (W)

W = mev2 = eV

v TARGET

ELECTRON



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TRANSFORMATION OF ELECTRON ENERGY INTO X RAYS

TRANSFORMATION CAN BE INTO SEVERAL WAYS

1. ELECTRON INTERACT DIRECTLY WITH THE NUCLEUS

ELECTRON IS STOPPED BY THE NUCLEUS

ALL K.E. TRANSFORMED INTO QUANTUM OF RADIATION

where,

h = PLANCKS CONSTANT

C = VELOCITY OF LIGHT

min = hC/eV = 12395/V (in Ao)



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TRANSFORMATION OF ELECTRON ENERGY INTO X RAYS

2. IMPINGING ELECTRONS INTERACT WITH ELECTRONS ASSOCIATEDWITH THE TARGET ATOMS

PART OF K.E. IS REQUIRED TO REMOVE AN ELECTRON FROM TARGETATOM

ENERGY OF MOVING ELECTRON REACHING NUCLEUS < eV

> min

X - RAYS OF MANY WAVELENGTHS GENERATED

X - RAY SOURCE


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THREE IMPORTANT ELECTRICAL CHARACTERISTICS OF X - RAY TUBES

1. FILAMENT CURRENT CONTROLS THE FILAMENT TEMPERATURE

IN TURN QUANTITY OF ELECTRONS THAT ARE

EMITTED

2. TUBE VOLTAGE CONTROLS THE ENERGY, OR PENETRATINGPOWER OF X - RAY BEAM

3. TUBE CURRENT DIRECTLY RELATED TO FILAMENT TEMP.

REFERRED TO AS MILLIAMPERAGE

X - RAY SOURCE


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INTENSITY OF X RAY BEAM APPROX. PROPORTIONAL TO MILLIAMPERAGEMEASURED IN ROENTGEN

ONE ROENTGEN AMOUNT OF RADIATION THAT PRODUCESIONS CARRYING ONE ELECTROSTATIC UNITOF ELECTRICITY IN 1.293 mg OF AIR

GAMMA RAYS


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HIGH ENERGY ELECTROMAGNETIC WAVES OFRELATIVELY SHORTER WAVELENGTH

EMITTED DURING THE RADIACTIVE DECAY OF BOTHNATURALLY OCCURING AND ARTIFICIALLY PRODUCED

UNSTABLE ISOTOPES

UNLIKE BROAD SPECTRUM RADIATION PRODUCED BY X

RAY TUBE, GAMMA RAY SOURCE EMIT ONE OR MOREDESCRETE WAVELENGTHS OF RADIATION

GAMMA RAY SOURCES


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THULIUM -170

IRIDIUM - 192

CESIUM - 137

COBALT - 60

GAMMA RAYS SOURCES ARE

GAMMA RAY SOURCE

DEFINITIONS


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IT IS MEASURE OF THE DISINTEGRATION OF ASOURCE

IT IS DEFINED AS 3.7*1010 DISINTEGRATIONSPER SECOND

IT IS INDEPENDENT OF MODE OF DECAY

IT IS USEFUL IN COMPARING THE STRENGTH OF

VARIOUS SOURCES OF THE SAME ISOTOPES

DEFINITIONS

THE CURIE

GAMMA RAY SOURCE


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BECQUEREL

IT IS SI UNIT OF SOURCE STRENGTH

IT IS ONE DISINTEGRATION PER SECOND

HALF LIFE PERIOD

IT IS THE TIME (T) IN WHICH THE NUMBER OFATOMS PRESENT AT ANY INSTANT IS REDUCEDTO HALF

N0/2 = N0eT

T = 0.6931/

GAMMA RAY SOURCE

ADVANTAGES


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NEED NO POWER SUPPLY, NO COOLINGSYSTEM

AVAILABLE IN RANGE OF DIAMETERS

SMALL DIAMETER SOURCE CAN BE USED FORVERY SHORT SFD (PIPES)

SOME RADIO - ISOTOPES HAVE HIGHPENETRATING POWER. THEY CAN BE USEDFOR VERY THICK METAL SPECIMEN

ADVANTAGES

GAMMA RAY SOURCE


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RADIOGRAPHS HAVING LESS CONTRASTCOMPARE TO X - RAY

IT IS NOT USEFUL FOR THIN STEEL SPECIMEN

IT IS IMPOSSIBLE TO SWITCH OFF RADIATION,SOURCE HAVE TO BE EFFECTIVELY SHIELDED

RADIATION CANNOT BE ADJUSTED IN ENERGY

DISADVANTAGES

RADIOGRAPHIC SOURCES


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DEFINITIONS

TERM DEFINITIONSPECIFIC ACTIVITY IT IS DEGREE OF CONCENTRATION OF

RADIOACTIVE MATERIAL WITH IN AGAMMA RAY SOURCE.

IT IS EXPRESSED IN CURIE PER GRAMOR BECQURELS PER GRAM

HIGH SPECIFICACTIVITY SOURCE

IT WILL BE OF SMALLER SIZE FOR GIVESTRENGTH

IT YIELDS SHARPER RADIOGRAPHS

RADIOGRAPHIC SOURCES

O


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DEFINITIONS

TERM DEFINITIONEXPOSURE MILLIAMPERE * EXPOSURE TIME

(FOR X RAY SOURCE)

INTENSITY * EXPOSURE TIME

(FOR - SOURCE)

EXPOSUREFACTOR

MILLIAMPERE * EXPOSURE TIME / (DISTANCE)2

(FOR X RAY SOURCE)

CURIE * EXPOSURE TIME / (DISTANCE)2

(FOR - SOURCE)

RADIOGRAPHIC IMAGING


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SOURCE OF RADIATION SHOULD BE SMALL - AS NEARLY ASPOINT

SOURCE OF RADIATION SHOULD BE AS FAR FROM THE OBJECTAS PRACTICAL

THE RECORDING SURFACE SHOULD BE CLOSE TO THE OBJECTAS POSSIBLE

THE RAYS OF RADIATION SHOULD BE DIRECTED r TORECORDING SURFACE

PLANE OF THE OBJECT AND PLANE OF THE RECORDINGSURFACE SHOULD BE PARALLEL

CONDITIONS FOR SHARPEST, TRUEST SHADOW OF THE OBJECT

RADIOGRAPHIC IMAGING

DEFECT ORIENTATION AND BEAM DIRECTION


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SHAPE OF PROJECTED IMAGE OF DEFECT DEPENDSUPON

ORIENTATION OF THE DEFECTWITH RESPECT TO BEAM

FORM OF THE DEFECT

DEFECT ORIENTATION AND BEAM DIRECTION

RADIOGRAPHIC IMAGINGEXAMPLES


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SL.NO.

SHAPE OFDEFECT

BEAM DIRECTION IMAGE SHAPE

1. EGGED SHAPE PARALLEL TO LONG AXIS CIRCULAR

r TO LONG AXIS OVAL

2. SPHERICAL ANY DIRECTION CIRCULAR

EXAMPLES

RADIOGRAPHIC IMAGINGEXAMPLES


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SL.NO.

SHAPE OFDEFECT

BEAM DIRECTION IMAGE SHAPE

3. FLAT & CIRCULAR PLANE r TO BEAMDIRECTION

CIRCULAR

PLANE TILTED TO BEAMDIRECTION

IMAGEDISTORTED TOOVAL SHAPE

EXAMPLES

DEFECT ORIENTATION & BEAM DIRECTION


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IMAGE OF A CRACK CHANGES MARKEDLY WITH BEAM DIRECTION

IMAGE OF A LINEAR DEFECT RELATIVELY UNCHANGED

PLANAR DEFECTS (LACK OF FUSION IN SIDE WALLS)

BEST REVEALED WHEN CENTRAL RAY DIRECTION ISALONG THE PLANE OF SUSPECTED DEFECT

1 3

2LACK OF

SIDE WALL FUSION

BEST REVEALED WHEN DIRECTION OF RAY IS 1

TERMS USED IN RADIOGRAPHY


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DEFINITION

ABILITY TO DETECT IMAGE EDGES ON A RADIOGRAPH

IT IS RELATED TO UNSHARPNESS

IT IS IMPORTANT FOR A RADIOGRAPH TO EXHIBIT

BEST POSSIBLE DEFINITION

HIGHEST POSSIBLE CONTRAST

LEAST AMOUNT OF UNSHARPNESS

UNSHARPNESS

GEOMETRIC UNSHARPNESS

FILM UNSHARPNESS

SCATTER UNSHARPNESS

TERMS USED IN RADIOGRAPHYF


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GEOMETRIC UNSHARPNESS

Ug

D/t

F=

D

tIMAGE

OBJECT

Ug

FILM OR INHERENT UNSHARPNESS



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RADIATION ENERGY FILM GRAIN SIZE

SCREEN MATERIAL FILM DEVELOPING TEMPERATURE PROCESSING TECHNIQUE

FILM OR INHERENTUNSHARPNESS

DEPENDS UPON

TOTAL UNSHARPNESS AS A FUNCTION OF FOCAL SPOT SIZE

UTOTAL = [UG3 + UF

3 + US3]1/3

0

1

2

3

4

5

6

0.1 0.2 0.5 2.0 5.0 10.01.0

TOTALUNSHARPNESSIN

MM

FOCAL SPOT DIAMETER IN MM

D/t = 1

D/t = 2

D/t = 3

D/t = 6



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QUALITY OF A RADIOGRAPH DECIDES THE EFFICIENCY OFFLAW DETECTION

QUALITY OF A RADIOGRAPH IS DETERMINED BY

- DENSITY

- SENSITIVITY

RADIOGRAPHIC IMAGE QUALITY



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IT REFERS TO QUANTITATIVE MEASURE OF FILM BLACKENING

DENSITY = log10 (IO / It)

WHERE,

I0 = INTENSITY OF LIGHT INCIDENT ON FILM

It = INTENSITY OF LIGHT TRANSMITTED

PHOTOGRAPHIC DENSITY

PHOTOGRAPHIC DENSITY


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TO OBTAIN SAME DENSITY FILM J MUST BE GIVEN BIGGER EXPOSURE THAN FILM H

FILM H IS FASTER THAN FILM J

FILM N SLOWEST FILM, HIGHEST SLOPE

THE HIGHER THE SLOPE, THE GREATER THE IMAGE CONTRAST

FINER THE GRAINS IN THE FILM HIGHER THE CONTRAST , LOWER ITS SPEED

HN

J

Log E

DENSITY

1.0

2.0

3.0

DO

CHARACTERISTIC CURVES OF FILM H,J AND N



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IT IS THE DIFFERENCE IN FILM DENSITY BETWEEN THEIMAGE OF A DEFECT AND THE BACKGROUND FILMDENSITY.

RADIOGRAPHIC CONTRAST

IT IS DECIDED BY FILM CONTRAST &

SUBJECT CONTRAST

TERMS USED IN RADIOGRAPHYFILM CONTRAST


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IT IS THE ABILITY OF THE FILM TO DETECT ANDRECORD DIFFERENT RADIATION EXPOSURES ASDIFFERENCE IN DENSITY

IT INCREASES WITH FILM DENSITY

AT SAME DENSITY, FINE GRAIN FILMS HAVE HIGHER

CONTRAST THAN COARSE GRAIN FILM

IT DEPENDS ON PROCESSING TECHNIQUES

FILM CONTRAST

SUBJECT CONTRAST



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IT IS AFFECTED BY

THICKNESS DIFFERENCE IN THE SPECIMEN

RADIATION QUALITY

SCATTERED RADIATION

SUBJECT CONTRAST

IT IS RATIO OF THE HIGHEST TO THE LOWEST RADIATIONINTENSITIES FALLING ON TO THE FILM

TERMS USED IN RADIOGRAPHYRADIOGRAPHIC SENSITIVITY


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IT IS DEFINED AS ABILITY TO VIEW THE DISCONTINUITY OR

FLAW IN THE RADIOGRAPH EXACTLY AS PRESENT IN THESPECIMEN

THE MORE THE EXACTNESS BETTER IS SENSITIVITY

RADIOGRAPHIC SENSITIVITY

RADIOGRAPHIC SENSITIVITY IS AFFECTED BY

CONTRAST

DEFINITION

TERMS USED IN RADIOGRAPHYRADIOGRAPHIC SENSITIVITY


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FACTORS AFFECTING THE VALUES ARE

FLAW LOCATION

ITS NATURE

ITS ORIENTATION


% FLAW SENSITIVITY =

DIMENSION OF THE SMALLEST FLAW THAT CAN BE SEEN ON RADIOGRAPH

THICKNESS OF THE SPECIMEN

IN PRACTICE IT IS NOT POSSIBLE TO OBTAIN A UNIFORM VALUE




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WIRE TYPE

STEP WEDGE TYPE

STRIP HOLE TYPE


TO CHECK RADIOGRAPHIC SENSITIVITY IMAGE QUALITYINDICATOR (IQI) IS USED

THERE ARE THREE TYPES OF IQI

TERMS USED IN RADIOGRAPHYCALCULATION OF RADIOGRAPHIC SENSITIVITY


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C CU O O OG C S S

WIRE TYPE IQI

DIAMETER OF THINNEST WIRE VISIBLE

THICKNESS OF THE OBJECT


STEP HOLE TYPE IQI

DIAMETER OF SMALLEST VISIBLE HOLE

THICKNESS OF THE OBJECT


SENSITIVITY CRITERIA

LOWER THE % FLAW SENSITIVITY BETTER THE QUALITY


VISIBILITY INDEX N


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VISIBILITY INDEX N

N = a - b

a = NO. OF HOLES OR WIRES VISIBLE ON RADIOGRAPH

b = NO. OF HOLES WHOSE DIAMETERS ARE EQUAL TO

OR LARGER THAN 5% THICKNESS OF OBJECT

IN CASE OF STEP WEDGE TYPE IQI

b = NO. OF WIRES WHOSE DIAMETERS ARE EQUAL TOOR LARGER THAN 2% THICKNESS OF OBJECT

IN CASE OF WIRE TYPE IQI

IMAGE QUALITY IS BETTER WITH HIGHER VALUES OF N

1 WELD INSPECTION

APPLICATION OF RADIOGRAPHY


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1. WELD INSPECTION

FINE CRACK IN BUTT WELDS MOST DANGEROUS

RADIOGRAPHIC TECHNIQUE MUST BE DESIGNED TO GIVE THEBEST CHANCE TO DETECT IT.

RADIOGRAPHIC EXAMINATION OF BUTT WELD BETWEEN TWO FLATE PLATES

APPLICATION OF RADIOGRAPHYCIRCUMFERENTIAL WELD


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SOURCE

FILM

FILM

SOURCE

A. FILM INSIDE; SOURCE OF RADIATION OUTSIDE

IT IS POSSIBLE ONLY WHEN ACCESS INSIDE FOR FILM

APPLICATION OF RADIOGRAPHYB. FILM OUTSIDE; SOURCE OF RADIATION INSIDE


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BEST & MOST EFFICIENT TECHNIQUE.

IF SOURCE IS AT CENTRE, POSSIBLE TO COVER WHOLE WELD IN ONEEXPOSURE

USE OF SMALL SOURCE BECAUSE OF SMALL SFD

IT IS POSSIBLE TO OFFSET THE SOURCE, MORE THAN ONE EXPOSURE

NEEDED

;

SOURCE

FILM

FILM

SOURCE

FILM

SOURCE

FILM

SOURCE

C SOURCE OF RADIATION OUTSIDE; FILM OUTSIDE

APPLICATION OF RADIOGRAPHY


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C. SOURCE OF RADIATION OUTSIDE; FILM OUTSIDE

USED WHEN THERE IS NO ACCESS TO INSIDE OF THE PIPE OR VESSEL

2. CASTING INSPECTION

PROBABILITY OF FINE CRACKS ARE LESS

CASTING DEFECTS MOST LIKELY TO OCCUR, WHERE SECTION CHANGES

APPLICATIONS OF RADIOGRAPHY


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GENERALIZATION

1. FOR LIGHT ALLOYS & LOW DENSITY MATERIALS NO SUITABLE GAMMA RAYSOURCE

2. FERROUS & COPPER ALLOYS < 12 mm THK X - RAY PREFERRED

3. FERROUS MATERIAL > 150 mm THK EXPOSURE TIME EVEN WITHHIGH INTENSITY GAMMA RAYSOURCE ARE LONG

IF LARGE QTY OF RADIOGRAPH,MEGA VOLTAGE X - RAY SET IS

DESIRABLE.

4. FERROUS MATERIAL 70mm


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RADIOGRAPHY OF STEEL SPECIMENS

X - RAYS (KV) MAXIMUM THICKNESS(mm)

HIGH SENSITIVITY LOW SENSITIVITYTECHNIQUE TECHNIQUE

100 10 25200 25 75400 75 110

2000 200 25031000 325 450

GAMMA RAYS THICKNESS RANGE (mm)

Ir - 192 18 - 60 6 - 100Cs - 137 30 -100 20 - 110Co - 60 50 - 125 30 - 185

CONTRAST OF THE RADIOGRAPH WILL DEPEND UPON


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- KV OF X - RAY OR THE QUALITY OF GAMMA RAY

- CONTRAST CHARACTERISTICS OF THE FILM

- TYPE OF THE SCREEN

- DENSITY TO WHICH RADIOGRAPH IS EXPOSED

- PROCESSING

day-3 session 1 ndt introduction + ut + rt to pmi final

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