66122729 non destructive examination 2

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IGCAR/QAD/QA&NDTS/NDEIGCAR/QAD/QA&NDTS/NDE 11

NONNON--DESTRUCTIVEDESTRUCTIVE

EXAMINATION /EXAMINATION /

EVALUATIONEVALUATION

R.SUBBARATNAMR.SUBBARATNAM

RETD., HEAD, QA&NDT SECTIONRETD., HEAD, QA&NDT SECTIONQUALITY ASSURANCE DIVISIONQUALITY ASSURANCE DIVISION

ENGINEERING SERVICES GROUPENGINEERING SERVICES GROUP

INDIRA GANDHI CENTRE FOR ATOMIC RESEARCHINDIRA GANDHI CENTRE FOR ATOMIC RESEARCH

KALPPAKAMKALPPAKAM

[email protected][email protected]


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--

EVALUATIONEVALUATION

Examination with out destructionExamination with out destruction

Used for assessment and evaluation ofUsed for assessment and evaluation of

Raw materialsRaw materials Rolled (Plate, Pipe); cast; forgedRolled (Plate, Pipe); cast; forged

Component & SystemComponent & System FabricationFabrication WeldWeld

PrePre--Service & InService & In--Service InspectionService Inspection

UnconventionalUnconventional Assembly, Level measurement, GapAssembly, Level measurement, Gap

measurementmeasurement

Visual ImagingVisual Imaging 3 Dimensional information3 Dimensional information

Position, size, orientationPosition, size, orientation

Macro, Micro, Nano LevelsMacro, Micro, Nano Levels


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NDE METHODSNDE METHODS

LEAKTESTING

UE

RE EC

MPE

LPE

VISUAL

BASICNDE SURFACE

NDE

VOLUMETRIC

NDE


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ADVANCED NDE METHODSADVANCED NDE METHODS

NRT

UETOFD, SAFT

AE

VA

IR

ADVNDE


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VISUAL EXAMINATIONVISUAL EXAMINATION


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Visual ExaminationVisual Examination

Most common and First method of NDEMost common and First method of NDE

EasyEasy

QuickQuick

Low CostLow Cost

Guide for other NDE methodsGuide for other NDE methods

Reflection of light from the specimenReflection of light from the specimen

EyeEye tool for the examinationtool for the examination

Adequate and proper cleaning and lighting of surfaceAdequate and proper cleaning and lighting of surface

Surface preparation in certain cases requiredSurface preparation in certain cases required


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EYEEYE

The registering deviceThe registering device

VariableVariable individual point of viewindividual point of view

Variation in eyeVariation in eye

Unreliable with different light intensitiesUnreliable with different light intensities optical illusionoptical illusion

Relative brightness of different light sources can be judgedRelative brightness of different light sources can be judged

approximatelyapproximately with same order of brightnesswith same order of brightness

Large image if the retinal image is largeLarge image if the retinal image is large

Angle subtended at the eye by the object called theAngle subtended at the eye by the object called the VisualVisual

AngleAngle


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VIEWINGVIEWING

Converging lens increases visual angle and increases the sizeConverging lens increases visual angle and increases the sizeof imageof image

Diameter of the pupil is ~2.5 mm for 5500 A wavelengthDiameter of the pupil is ~2.5 mm for 5500 A wavelength

Minimum angular separation of two points resolvable by theMinimum angular separation of two points resolvable by theeye is about one minute of arceye is about one minute of arc

Minimum size of the defect detected depends onMinimum size of the defect detected depends on

Surface being examinedSurface being examined

Brightness levelBrightness level Contrast between the area and the backgroundContrast between the area and the background

Brightness falling on the retina is most important than theBrightness falling on the retina is most important than thebrightness on the specimenbrightness on the specimen

Brightness on the retina is determined by area of pupilBrightness on the retina is determined by area of pupil Pupil size variable from 1 to 6 mm and hence the area variesPupil size variable from 1 to 6 mm and hence the area varies

by a factor of 36by a factor of 36


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SENSITIVITY OF EYESENSITIVITY OF EYE

Sensitivity of human eye varies for different wave lengthsSensitivity of human eye varies for different wave lengths

With ordinary conditions it is most sensitive to yellow green liWith ordinary conditions it is most sensitive to yellow green light withght with

wave length of 5500 Awave length of 5500 A

Human eye will provide satisfactory vision over wide range of coHuman eye will provide satisfactory vision over wide range of conditionsnditions

Eye has excellent visual perception, however adequate lighting iEye has excellent visual perception, however adequate lighting is primes prime

importanceimportance

Time of inspection permitted to work shall be limited to avoid eTime of inspection permitted to work shall be limited to avoid errors due torrors due to

decrease in visual reliability and discriminationdecrease in visual reliability and discrimination


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LIGHTINGLIGHTING

The amount of light reaching shall be sufficient for bestThe amount of light reaching shall be sufficient for bestdefinition obtainable with aided or unaided eyedefinition obtainable with aided or unaided eye

Relation between the visual acuity and brightness shall beRelation between the visual acuity and brightness shall be

consideredconsidered The ratio of least perceptible brightness difference to theThe ratio of least perceptible brightness difference to the

brightness at which it is measured is nearly constant over largebrightness at which it is measured is nearly constant over largerange of 1 to 100000 candles / mrange of 1 to 100000 candles / m22 [ordinary interior[ordinary interior

illumination to bright day light]illumination to bright day light]

But the visual acuity varies quit sharply over the lower andBut the visual acuity varies quit sharply over the lower andmiddle portion of the rangemiddle portion of the range

visual acuity is considered to be dependant on the thresholdvisual acuity is considered to be dependant on the thresholdresponse of the cones in the retina. But no data available toresponse of the cones in the retina. But no data available togive explanation.give explanation.


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OPTICAL AIDSOPTICAL AIDS

Optical aidsOptical aids

MirrorMirror

LensLens

MicroscopeMicroscope PeriscopePeriscope

TelescopeTelescope

FiberscopeFiberscope

BoroscopeBoroscope

Provide a means of compensating for the limits of visual acuityProvide a means of compensating for the limits of visual acuity

by enlarging small image in to largeby enlarging small image in to large

Improving viewing conditions for rapid inspection of smallImproving viewing conditions for rapid inspection of smallprecision parts, inaccessible areas and reducing operator fatiguprecision parts, inaccessible areas and reducing operator fatiguee


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MIRRORMIRROR

Simplest way of looking inaccessible areaSimplest way of looking inaccessible area

Advantage of a portion of mirror is used and cone ofAdvantage of a portion of mirror is used and cone ofrays is limited by the pupil of eyerays is limited by the pupil of eye

Other instrument / equipment can also be added withOther instrument / equipment can also be added withmirrormirror

Mirror surface shall be extremely flatMirror surface shall be extremely flat

Mirror must be kept free from dustMirror must be kept free from dust Reflecting power of mirror reduces after some periodReflecting power of mirror reduces after some period

of useof use

Reflecting power of two three mirrors are much lessReflecting power of two three mirrors are much less

However the reflecting power can be increased byHowever the reflecting power can be increased byspecial coatingspecial coating


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BOROSCOPEBOROSCOPE

Boroscope is the instrument to inspect the inside surface ofBoroscope is the instrument to inspect the inside surface oftube, bore or chambertube, bore or chamber

Precision built optical system with prism and lenses throughPrecision built optical system with prism and lenses through

which light also passeswhich light also passes Light source is located in font of object lens provides light inLight source is located in font of object lens provides light in

the required areathe required area

The design of the objective determines the angle of view, sizeThe design of the objective determines the angle of view, size

of visual field and amount of light gatheredof visual field and amount of light gathered

Design of the middle lenses has an important influence on theDesign of the middle lenses has an important influence on theimage obtained. Most middle lenses are achromatic for theimage obtained. Most middle lenses are achromatic for thepurpose of preserving the sharpness of the image and colorpurpose of preserving the sharpness of the image and colorvaluesvalues

Different angle of vision [0, 45, 60, 90]Different angle of vision [0, 45, 60, 90]


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FIBERSCOPEFIBERSCOPE

Fiberscope is the instrument used to inspect surface ofFiberscope is the instrument used to inspect surface ofpipeline. Compared to the Boroscope this is flexible and thepipeline. Compared to the Boroscope this is flexible and theimage transmission is by optical fibers.image transmission is by optical fibers.

Possibility of lighting of the surface of the objectPossibility of lighting of the surface of the object Various diameters, operating length and angle of viewing [0,Various diameters, operating length and angle of viewing [0,

45, 60, 90], backward and forward throw45, 60, 90], backward and forward throw

LimitationLimitation guiding to proper location is requiredguiding to proper location is required

Image acquisition in the digital form possible in bothImage acquisition in the digital form possible in both

Boroscope and FiberscopeBoroscope and Fiberscope


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LIQUID PENETRANT EXAMINATIONLIQUID PENETRANT EXAMINATION


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SURFACE NDESURFACE NDE

OPEN TO SURFACE DISCONTINUITIES ONLYOPEN TO SURFACE DISCONTINUITIES ONLY

PRINCIPLEPRINCIPLE CAPILARY ACTIONCAPILARY ACTION

SIX METHODSSIX METHODS

Two types & Three TechniquesTwo types & Three Techniques

FIVE STAGESFIVE STAGES

HIGH SENSITIVITY WITH POST EMULSIFICATION ANDHIGH SENSITIVITY WITH POST EMULSIFICATION AND

FLUREOSCENTFLUREOSCENT

1010 SENSITIVITY WITH FLOURESCENT AND 25SENSITIVITY WITH FLOURESCENT AND 25 WITH VISIBLEWITH VISIBLE -- SOLVENT REMOVALSOLVENT REMOVAL

Temp.Temp. 15 to 5015 to 50 CC


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BASIC PRINCIPLEBASIC PRINCIPLE CAPILARY ACTIONCAPILARY ACTION


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Factors influencing Penetrant infiltration intoFactors influencing Penetrant infiltration into

discontinuitiesdiscontinuities

surface tension of the liquid Penetrantsurface tension of the liquid Penetrant

discontinuity configuration constantdiscontinuity configuration constant surface coatings and contaminantssurface coatings and contaminants

additives and contaminants in the liquid Penetrantadditives and contaminants in the liquid Penetrant

mechanical obstructionsmechanical obstructions temperature of the test objecttemperature of the test object

roughness of the interior walls of the discontinuityroughness of the interior walls of the discontinuity


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VISIBLEOR

FLOURSCENT

WATERWASHABLE

POSTEMULSIFICATION

SOLVENTREMOVABLE

LPE METHODSLPE METHODS


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LPELPE -- STEPSSTEPS

PrePre--CleaningCleaning

PenetrantPenetrant ApplnAppln..

Dwell Time (10 min to >1 Hr.)Dwell Time (10 min to >1 Hr.) Penetrant CleaningPenetrant Cleaning

Water WashableWater Washable

Post EmulsificationPost Emulsification Solvent RemovableSolvent Removable

DeveloperDeveloper ApplnAppln. (Dry or Wet). (Dry or Wet)

Developing time (~5 min)Developing time (~5 min) InterpretationInterpretation

Post CleaningPost Cleaning


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LPE STEPSLPE STEPS


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LPE INDICATIONSLPE INDICATIONS


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LPE INDICATIONSLPE INDICATIONS


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MAGNETIC PARTICLE EXAMINATIONMAGNETIC PARTICLE EXAMINATION


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SURFACE AND SUBSURFACE AND SUB--SURFACE (Up To 6mm)SURFACE (Up To 6mm) FERRO MAGNETIC MATERIALSFERRO MAGNETIC MATERIALS -- LIMITATIONLIMITATION

PRINCIPLEPRINCIPLE MAGNETIC FLUX LEAKAGE DUE TOMAGNETIC FLUX LEAKAGE DUE TODISCONTINUITYDISCONTINUITY

SPECIMEN MAGNETISATIONSPECIMEN MAGNETISATION Permanent Magnet; Magnetic Yoke; Prod; Head Shot (FixingPermanent Magnet; Magnetic Yoke; Prod; Head Shot (Fixing

component in head and tail stocks and passing current); Coilcomponent in head and tail stocks and passing current); Coil

AC or DCAC or DC

DETECTIONDETECTION APPLN. OF IRON POWDER (Wet or Dry)APPLN. OF IRON POWDER (Wet or Dry)

Visible and FluorescentVisible and Fluorescent

DISCONTINUITIES NORMAL TO THE MAGNETICDISCONTINUITIES NORMAL TO THE MAGNETICLINES WILL BE DETECTEDLINES WILL BE DETECTED

Temp.Temp. Max 300Max 300 CC


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Methods & Means ofMethods & Means of

Generation of Magnetic FieldGeneration of Magnetic Field

Magnetisation with permanent Magnet and by Electric CurrentMagnetisation with permanent Magnet and by Electric Current(Induced)(Induced)

Characteristics of magnetic FieldCharacteristics of magnetic Field Field around permanent magnetField around permanent magnet

In & around a conductorIn & around a conductor

Types of MagnetisationTypes of Magnetisation

ContinuousContinuous ResidualResidual

CircularCircular

LongitudinalLongitudinal

Magnetic Fields in and around the jobMagnetic Fields in and around the job Longitudinal magnetizationLongitudinal magnetization

Circular MagnetisationCircular Magnetisation

Magnetic Field Strength & Field distributionMagnetic Field Strength & Field distribution

DemagnetizationDemagnetization


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Magnetic Particle Testing TechniquesMagnetic Particle Testing Techniques

Type of CurrentType of Current

AC, DC, HWDC, FWDC (Single & three phase)AC, DC, HWDC, FWDC (Single & three phase)

MethodMethod

Dry or Wet MethodDry or Wet Method

Types of particleTypes of particle

Dry ParticlesDry Particles

Wet Particles and Carrier (Water, Kerosene etc)Wet Particles and Carrier (Water, Kerosene etc)

Fluorescent and Non FluorescentFluorescent and Non Fluorescent

Type of MagnetisationType of Magnetisation

Circular, Longitudinal, ResidualCircular, Longitudinal, Residual

Type of EquipmentType of Equipment

Portable, Stationary or special purpose equipmentPortable, Stationary or special purpose equipment


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Magnetic Particle Test Equipments & AccessoriesMagnetic Particle Test Equipments & Accessories

EquipmentsEquipments PermanentPermanent

Electro MagnetElectro Magnet -- YokesYokes

Small , medium, Stationary and Portable EquipmentsSmall , medium, Stationary and Portable Equipments TypeType

Prods (Circular Mag.)Prods (Circular Mag.)

Coils (Longitudinal Mag.)Coils (Longitudinal Mag.) Head Shot (Circular Mag.)Head Shot (Circular Mag.)

Black Light (Fluorescent) EquipmentsBlack Light (Fluorescent) Equipments

PIE Gauge,PIE Gauge, KETOKETOss Ring, Shims with Notches forRing, Shims with Notches forfield measurement & Gauge for residual mag. Fieldfield measurement & Gauge for residual mag. Fieldmeasurementmeasurement


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MPE PrincipleMPE Principle


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MAGNETISATION METHODSMAGNETISATION METHODS


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MAGNETISATION METHODSMAGNETISATION METHODS


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MPE INDICATIONSMPE INDICATIONS

M i P i l I di i


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Magnetic Particle Indication


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EDDY CURRENT EXAMINATIONEDDY CURRENT EXAMINATION


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SURFACE AND SUBSURFACE AND SUB--SURFACE (Up To 6 mm)SURFACE (Up To 6 mm) CONDUCTIVE MATERIALCONDUCTIVE MATERIAL LIMITATIONLIMITATION

PRINCIPLEPRINCIPLE INDUCTION OF CURRENT (CIRCULARINDUCTION OF CURRENT (CIRCULAR EDDY) IN THE SPECIMEN AND ANALYSINGEDDY) IN THE SPECIMEN AND ANALYSINGINTERACTION (Induction, Permeability)INTERACTION (Induction, Permeability)

PROBE CONFIGURATIONPROBE CONFIGURATION

Encircling or Bobbin; Surface; Multiple Frequency ProbesEncircling or Bobbin; Surface; Multiple Frequency Probes

DISCONTINUITIES NORMAL TO EDDY CURRENTDISCONTINUITIES NORMAL TO EDDY CURRENTDETECTABLEDETECTABLE

EXAMINATION FAST (Less Time)EXAMINATION FAST (Less Time)

USED FORUSED FOR

Material Sorting (Permeability; Electrical Conductivity); DefectMaterial Sorting (Permeability; Electrical Conductivity); DefectDetection; Coating Thk.Detection; Coating Thk.


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ECTECT PRINCIPLE & COIL ARRANGEMENTPRINCIPLE & COIL ARRANGEMENT


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ECTECT -- EQUIPMETEQUIPMET


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ECTECT -- INSTRUMENTATIONINSTRUMENTATION

COIL APPLICATIONCOIL APPLICATION


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COIL APPLICATIONCOIL APPLICATION


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Eddy Current InspectionEddy Current Inspection

Probe

Signals producedby variousamounts ofcorrosionthinning.

Periodically, power plants areshutdown for inspection.Inspectors feed eddy current

probes into heat exchangertubes to check for corrosiondamage.

Pipe with damage


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RADIOGRAPHIC EXAMINATIONRADIOGRAPHIC EXAMINATION

PRINCIPLES OF RADIOGRAPHYPRINCIPLES OF RADIOGRAPHY


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PRINCIPLES OF RADIOGRAPHYPRINCIPLES OF RADIOGRAPHY Differential absorption of short wavelength radiationsDifferential absorption of short wavelength radiations

Difference in density is the effect ofDifference in density is the effect of

variations in thickness of the part,variations in thickness of the part,

differences in absorption characteristics caused by variations idifferences in absorption characteristics caused by variations inncompositions.compositions.

Shadow projection, an image, on a detectorShadow projection, an image, on a detector -- varying grey levelsvarying grey levels

SourcesSources -- XX--rays, gamma rays, neutrons, protons, electrons.rays, gamma rays, neutrons, protons, electrons.

X and gamma rays are common sources for industrial radiographyX and gamma rays are common sources for industrial radiography

DetectorDetector radiographic films, image intensifiers or scintillatorradiographic films, image intensifiers or scintillatorscreens / counters.screens / counters.

Double coated, fine grain, high contrast XDouble coated, fine grain, high contrast X--ray films usedray films used

Radiography is the best method for the detection of volumetricRadiography is the best method for the detection of volumetricdefects.defects.

It can be applied on a variety of component ranging from miniatuIt can be applied on a variety of component ranging from miniaturereintegrated circuits to mammoth missile parts and complexintegrated circuits to mammoth missile parts and complexassemblies.assemblies.


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RADIOGRAPHY SET UPRADIOGRAPHY SET UP

Source

Specimen

Variation inRadiographicDensity


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SOURCES OF RADIATIONSSOURCES OF RADIATIONS X RAYX RAY

XX--ray and gamma raysray and gamma rays

XX--ray machine consistsray machine consists

XX--ray tube head, highray tube head, high--voltage generators, control unit, cooling circuit.voltage generators, control unit, cooling circuit.

Glass tube headsGlass tube heads -- earlier, modern Xearlier, modern X--ray headsray heads -- metal ceramicmetal ceramic When fast moving electrons impinging on a metal target XWhen fast moving electrons impinging on a metal target X--rayray

is produced .is produced .

Most of the energy (98%)Most of the energy (98%) -- as heat, only a fraction isas heat, only a fraction is

converted into Xconverted into X--rays.rays.

Depends on the atomic number of the target material, level ofDepends on the atomic number of the target material, level ofvacuum.vacuum.

XX--ray tube targetray tube target -- high atomic number and high melting pointhigh atomic number and high melting point-- TungstenTungsten


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XX RAY EQUIPMENTRAY EQUIPMENT

GAMMA RAY


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GAMMA RAYGAMMA RAY

Isotopic sources emitting gamma raysIsotopic sources emitting gamma rays -- extensive applications.extensive applications.

Main advantage of gamma ray sourcesMain advantage of gamma ray sources

simplicity of apparatus, compactness and portability.simplicity of apparatus, compactness and portability.

does not require cooling and power supplydoes not require cooling and power supply -- field applications.field applications. Main disadvantage of these sourcesMain disadvantage of these sources

decay with time and hence required replacementdecay with time and hence required replacement

energy of the gamma rays is fixed and cannot be varied to matchenergy of the gamma rays is fixed and cannot be varied to match thethe

thickness of objects for better sensitivity.thickness of objects for better sensitivity. The commonly used gamma sources are CobaltThe commonly used gamma sources are Cobalt--60, Iridium60, Iridium--

192, Cesium 137 and Thulium 170.192, Cesium 137 and Thulium 170.


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GAMMA RAY SOURCESGAMMA RAY SOURCES

0.250.250.380.380.550.551.31.3OUTPUTOUTPUT

RHM/CiRHM/Ci

127 Days127 Days33.1 Yrs33.1 Yrs74 Days74 Days5.3 Yrs5.3 YrsHALFHALF

LIFELIFE

0.052,0.052,

0.0840.084

0.660.660.45 (0.45 (AvgAvg))1.1.7 &1.1.7 &

1.331.33

ENERGYENERGY

(MeV)(MeV)

THULIUMTHULIUM

170170

CESIUMCESIUM

137137

IRIDIUMIRIDIUM

192192

COBALTCOBALT

6060

GAMMA CAMERA / EXPOSUREGAMMA CAMERA / EXPOSURE


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GAMMA CAMERA / EXPOSUREGAMMA CAMERA / EXPOSURE

DEVICEDEVICE

RADIOGRAPHIC FILMRADIOGRAPHIC FILM


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Radiographic film most widely used as detectorsRadiographic film most widely used as detectors ConsistsConsists -- base, emulsion, binding layer protective layerbase, emulsion, binding layer protective layer

Polyester is mostPolyester is most--commonly used material for film basecommonly used material for film base

Emulsion ofEmulsion of silver bromidesilver bromide

is coated over the baseis coated over the base Gelatin acts a binding layer between film base andGelatin acts a binding layer between film base and

emulsion.emulsion.

protective layerprotective layer -- hardened gelatin, serves to protect thehardened gelatin, serves to protect the

emulsion from physical damage, abrasion and stressemulsion from physical damage, abrasion and stressmarks.marks.

Industrial radiographic films are double coatedIndustrial radiographic films are double coated

the emulsion is coated on both sides of the base.the emulsion is coated on both sides of the base.

increases the film speed.increases the film speed.



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When X or gamma rays strike the grains of the sensitive silverWhen X or gamma rays strike the grains of the sensitive silvercompound in the emulsion, change takes place in the physicalcompound in the emulsion, change takes place in the physicalstructure of the grains. This change is of such a nature that itstructure of the grains. This change is of such a nature that it

cannot be detected by ordinary physical methods. When thecannot be detected by ordinary physical methods. When theexposed film is treated with a chemical solution (calledexposed film is treated with a chemical solution (calleddeveloper) a reaction takes place, causing the formation ofdeveloper) a reaction takes place, causing the formation ofblack metallic silver. This blackening of the film is called asblack metallic silver. This blackening of the film is called as

optical density (D) and is given by the relation.optical density (D) and is given by the relation.

D = Log10 (ID = Log10 (I00/I/Itt))

Base 50

Protective Layer5

Emulsion 10


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Characteristic CurveCharacteristic Curve


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Characteristic CurveCharacteristic Curve

Intensifying ScreensIntensifying Screens

d d h i d i h i li


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Screens used to reduce the exposure times and improve the imageScreens used to reduce the exposure times and improve the image qualityquality

of the radiographs.of the radiographs. Two types of radiography screensTwo types of radiography screens -- metallic and fluorescent screensmetallic and fluorescent screens

Both of these differ in Speed, contrast and elimination of scattBoth of these differ in Speed, contrast and elimination of scatterederedradiation.radiation.

Metal screensMetal screens

--

Lead is most widely usedLead is most widely used

Being a metal with high Z, Lead acts to absorb the scattered radBeing a metal with high Z, Lead acts to absorb the scattered rad iationiationof lower wavelength. This improves the radiographic contrast. Duof lower wavelength. This improves the radiographic contrast. Due toe tophotoelectric interactions of Xphotoelectric interactions of X--rays with lead, photoelectrons arerays with lead, photoelectrons areemitted which serve to reduce the exposure time by more than 50%emitted which serve to reduce the exposure time by more than 50%..

This is called as intensification action.This is called as intensification action. Intensification action expressed in terms of intensifying FactIntensification action expressed in terms of intensifying Factors (IF)ors (IF)

Intensification factor depends on element, thickness, energy ofIntensification factor depends on element, thickness, energy of radiation.radiation.Apart from lead, copper screens have also used.Apart from lead, copper screens have also used.

Exposure time required producing a film with particular density without screen

IF= -------------------------------------------------------------------------------------------------------Exposure time required producing the same density with screen

Fluorescent Screens and FiltersFluorescent Screens and Filters


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Fluorescent Screens and Filters

Fluorescent or salt screens of calcium tungstate or zinc sulphidFluorescent or salt screens of calcium tungstate or zinc sulphideeprovide greater intensification factor compared to metallic screprovide greater intensification factor compared to metallic screens.ens.However, they are used in medical radiography due to the highHowever, they are used in medical radiography due to the highscreen unsharpness and poor image quality and not in industrialscreen unsharpness and poor image quality and not in industrialradiography.radiography.

Filters are metallic sheets of high atomic number used to absorbFilters are metallic sheets of high atomic number used to absorb thethesoft component of the radiation emanating from the tube port. Fisoft component of the radiation emanating from the tube port. Filtersltersthus harden the radiation beam.thus harden the radiation beam.

The purpose of using filterThe purpose of using filter increase the contrast around the specimen edgeincrease the contrast around the specimen edge

reduce the undercut due to scatter at the edge of thinner sectioreduce the undercut due to scatter at the edge of thinner sectionsnsandand

record a wide range of thickness in a given film.record a wide range of thickness in a given film. Increasing the voltage or time of exposure compensates the lossIncreasing the voltage or time of exposure compensates the loss ofof

intensity caused by filter.intensity caused by filter.

Generally filters are made of copper, steel or aluminum.Generally filters are made of copper, steel or aluminum.

RADIOGRAPHIC TECHNIQUESRADIOGRAPHIC TECHNIQUES


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RADIOGRAPHIC TECHNIQUESRADIOGRAPHIC TECHNIQUES

Quality of radiographs or detection of discontinuity dependsQuality of radiographs or detection of discontinuity depends

on extent of the optical density of the image.on extent of the optical density of the image.

Selection of exposure parameters required to produce theSelection of exposure parameters required to produce the

required radiographic density to reveal the discontinuityrequired radiographic density to reveal the discontinuity Exposure TimeExposure Time

Exposure TechniqueExposure Technique Component / Specimen ShapeComponent / Specimen Shape

Coded Requirements on ImageCoded Requirements on Image Radiographic DensityRadiographic Density

Image QualityImage Quality

RADIOGRAPHIC EXPOSURE TIMERADIOGRAPHIC EXPOSURE TIME


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XX RayRay Exposure ChartsExposure Charts

Constant Parameters Like Matl., Film, SFDConstant Parameters Like Matl., Film, SFD

Gamma RayGamma Ray CalculationCalculation

Exposure Time (Min) = (FF x (SFD)Exposure Time (Min) = (FF x (SFD) 22 x 2x 2 (thickness/HVL)(thickness/HVL) x 60)x 60)

/ (S x RHM x (100)/ (S x RHM x (100)22

))

Where FF is the film factor in roentgens, S is the source strengWhere FF is the film factor in roentgens, S is the source strength inth in

curies and SFD the source to film distance in cm.curies and SFD the source to film distance in cm.

Any VariationAny Variation

MaterialMaterial

FilmFilm

Source to Film Distance (SFD)Source to Film Distance (SFD)

ScreenScreen

E Ch tE Ch t XX RR


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Exposure ChartExposure Chart XX -- RayRay

Const.:Material SteelFilm Agfa D7

SFD 700 mmScreen LeadIntensifying

Developing Std.

mA min

120 kV100 kV

200 kV

Matl Thk.

Variation or Change in Exposure ParametersVariation or Change in Exposure Parameters


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g pg p

MaterialMaterial Steel (High energy) or Al (Low energy) Taken as Standard MateriaSteel (High energy) or Al (Low energy) Taken as Standard Materiall

Any change in the material shall be referred to RadiographicAny change in the material shall be referred to RadiographicEquivalent Factors for that energy and sourceEquivalent Factors for that energy and source

SFDSFD Variation in SFD Varies the beam intensityVariation in SFD Varies the beam intensity -- I1 / I2= D2I1 / I2= D222/ D1/ D122 [Inverse[Inverse

Square Law]Square Law]

TIME & DISTANCE RELATIONSHIP: T2 / T1 = D1TIME & DISTANCE RELATIONSHIP: T2 / T1 = D122

/ D2/ D222

MILLIAMPERAGE & TIME RELATIONSHIP:M1 / M2 = T2 / T1MILLIAMPERAGE & TIME RELATIONSHIP:M1 / M2 = T2 / T1

FilmFilm

Medium film to slow film increases exposure time or vice versaMedium film to slow film increases exposure time or vice versa

Film manufacturer provides the film speed factorsFilm manufacturer provides the film speed factors

Ex: D7 to D4 increases the Exp. Time by 3 timesEx: D7 to D4 increases the Exp. Time by 3 times

Selection of Radiographic TechniquesSelection of Radiographic Techniques

Selection of particular radiographic technique is based upon theSelection of particular radiographic technique is based upon the sensitivitysensitivity


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Selection of particular radiographic technique is based upon theSelection of particular radiographic technique is based upon the sensitivitysensitivityrequirements.requirements.

Getting information on small discontinuity image is possible onlGetting information on small discontinuity image is possible only with ay with aproper techniqueproper technique

Radiographic technique is affected by radiation source, film usRadiographic technique is affected by radiation source, film used, sources toed, sources tofilm distance andfilm distance and radiation beam alignmentradiation beam alignment

A technique is selected on the basic of the knowledge about theA technique is selected on the basic of the knowledge about the followingfollowingfactors.factors.

Test objectTest object materialmaterial -- thickness and configurationthickness and configuration

Fabrication processes (Welds, Casting, Assembly)Fabrication processes (Welds, Casting, Assembly)

Anticipated discontinuities and its locations & orientation,Anticipated discontinuities and its locations & orientation,

Areas of interestAreas of interest Sensitivity level requiredSensitivity level required

Radiographic techniques can be broadly classified asRadiographic techniques can be broadly classified as

High sensitivity technique & Low Sensitivity TechniqueHigh sensitivity technique & Low Sensitivity Technique

Also Classified according to the configuration asAlso Classified according to the configuration as single wall single image (SWSI) techniquesingle wall single image (SWSI) technique

double wall single image (DWSI) techniquedouble wall single image (DWSI) technique

double wall double image (DWDI) techniquedouble wall double image (DWDI) technique

Radiographic TechniquesRadiographic Techniques -- ConfigurationConfiguration


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Three TechniquesThree Techniques

SWSISWSI Both side accessBoth side access

DWDIDWDI -- Single side AccessSingle side Access -- For Pipes Dia < 89 mmFor Pipes Dia < 89 mm

DWSIDWSI Single side AccessSingle side Access -- For pipes Dia > 89 mmFor pipes Dia > 89 mm

SWSI D W D I D W S I

Depth of DiscontinuityDepth of Discontinuity


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Stereo RadiographyStereo Radiography Only illusionOnly illusion Double Exposure MethodDouble Exposure Method Generally FollowedGenerally Followed

Two exposures by shifting the source with half exp. timeTwo exposures by shifting the source with half exp. time

d = b x SFD/a+bd = b x SFD/a+b

a

b

SFD - d

d

Film ProcessingFilm Processing

Fil iFil i i fi @ 18i fi t @ 18 2424 CC


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Film processingFilm processing -- in five stages @ 18in five stages @ 18 2424 CC DevelopingDeveloping

Stop bathStop bath

FixingFixing

Clearing in running waterClearing in running water

DryingDrying The developing converts the exposed silver bromide grains /The developing converts the exposed silver bromide grains /

crystals to metallic silver i.e. creation of the visible imagecrystals to metallic silver i.e. creation of the visible image 55MinMin

The second stage stop bath, stops the developing action andThe second stage stop bath, stops the developing action andremoves all the developerremoves all the developer 2 Min2 Min

The fixing process fixes this metallic silver and removes allThe fixing process fixes this metallic silver and removes allunexposed silver bromide grains / crystalsunexposed silver bromide grains / crystals 10 Min10 Min

Washing in running waterWashing in running water 20 Min20 Min The drying dries all the wetness on the film.The drying dries all the wetness on the film.

After drying the film is ready for interpretation.After drying the film is ready for interpretation.

Processing consumes minimum of 30 minutes.Processing consumes minimum of 30 minutes.

Image Quality Indicators (IQI) / PenetrameterImage Quality Indicators (IQI) / Penetrameter

Radiographic sensitivity is judged by the use of Image QualityRadiographic sensitivity is judged by the use of Image Quality


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Radiographic sensitivity is judged by the use of Image QualityRadiographic sensitivity is judged by the use of Image Quality

Indicators (IQI)Indicators (IQI) Many type of IQIMany type of IQI -- Plate and Hole, Wire, Step, Step and holePlate and Hole, Wire, Step, Step and hole

Sensitivity assessed by the image of IQI on the radiographSensitivity assessed by the image of IQI on the radiograph

Normally the sensitivity is represented in percentage.Normally the sensitivity is represented in percentage.

Lower the percentage the higher the sensitivityLower the percentage the higher the sensitivity

IQI is selected based on the thickness of specimen to beIQI is selected based on the thickness of specimen to beradiographed and general codes specify IQI thickness equal toradiographed and general codes specify IQI thickness equal to2% of specimen thickness.2% of specimen thickness.

Codes of construction provide the IQI requirementsCodes of construction provide the IQI requirements Sensitivity (plate and hole IQI) = 100/TSensitivity (plate and hole IQI) = 100/T [[t x h / 2]t x h / 2] Sensitivity (wire IQI) = [Dia of minimum wire seenSensitivity (wire IQI) = [Dia of minimum wire seen

in radiograph /Specimen Thk. ] x 100in radiograph /Specimen Thk. ] x 100

Generally radiographic sensitivity shall be specified to a levelGenerally radiographic sensitivity shall be specified to a levelof 2%of 2%

IQIIQI


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IGCAR/QAD/QA&NDTS/NDEIGCAR/QAD/QA&NDTS/NDE

6868

10 Fe 16

10

Wire Step and Hole Plate and Hole

Radiographic Quality / SensitivityRadiographic Quality / Sensitivity

Quality of the radiograph is assessed by radiographic sensitivitQuality of the radiograph is assessed by radiographic sensitivityy


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IGCAR/QAD/QA&NDTS/NDEIGCAR/QAD/QA&NDTS/NDE

6969

Quality of the radiograph is assessed by radiographic sensitivitQuality of the radiograph is assessed by radiographic sensitivityy

Type of filmType of film

Chemical processingChemical processing

Scattering ofScattering of

radiation by filmradiation by filmgrains due to type ofgrains due to type of

screenscreen

Screen film ContactScreen film Contact

Source sizeSource size

Source to specimenSource to specimen

distancedistanceObject to filmObject to film

distancedistance

Source off setSource off set

Abruptness ofAbruptness of

thicknessthickness

Shape and surfaceShape and surface

condition of the objectcondition of the object

Type of filmType of film

Film processingFilm processing

Variation in filmVariation in film

densitydensityIntensifying screensIntensifying screens

Thickness differenceThickness difference

in the specimenin the specimen

Density difference inDensity difference in

the specimenthe specimenInIn--homogeneity ofhomogeneity of

the object materialthe object material

Incident radiationIncident radiation

energyenergy

FiltersFilters

Radiation associatedRadiation associated

scattered energyscattered energy

Film graininessFilm graininessGeometryGeometryFilm contrastFilm contrastSubject contrastSubject contrast

DefinitionDefinitionContrastContrast

RADIOGRAPHIC SENSITIVITYRADIOGRAPHIC SENSITIVITY

Evaluation of Radiographs / InterpretationEvaluation of Radiographs / Interpretation

Radiographs inform the presence of discontinuity by theRadiographs inform the presence of discontinuity by the


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Radiographs inform the presence of discontinuity by theRadiographs inform the presence of discontinuity by the

radiographic density differenceradiographic density difference Discontinuities are evaluated for its type, location and sizeDiscontinuities are evaluated for its type, location and size

Radiographs provide length and width of the discontinuityRadiographs provide length and width of the discontinuity

Conventional radiography is widely used for the inspection ofConventional radiography is widely used for the inspection of

weldments, casting and complete assembliesweldments, casting and complete assemblies Types of discontinuities vary from process to process likeTypes of discontinuities vary from process to process like

Lack of penetration in the weld, shrinkage in the casting etc.Lack of penetration in the weld, shrinkage in the casting etc.

Type of the discontinuity is arrived from the shape andType of the discontinuity is arrived from the shape and

location of the indicationlocation of the indication Radiographic image are interpreted for acceptance orRadiographic image are interpreted for acceptance or

otherwise of the discontinuity indications depends on the codeotherwise of the discontinuity indications depends on the codeof manufacturing like ASME, BS etc, which is based on theof manufacturing like ASME, BS etc, which is based on the

service requirementsservice requirements

High Energy RadiographyHigh Energy Radiography


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Radiographic Examination using sources having energy level ofRadiographic Examination using sources having energy level of1MeV or more is called high energy radiography.1MeV or more is called high energy radiography.

Basic technique is same as conventional radiography.Basic technique is same as conventional radiography.

Major advantages are:Major advantages are:

Examination of higher thicknesses of 100 to 1000 mm of steelExamination of higher thicknesses of 100 to 1000 mm of steelaccording to the energy levelaccording to the energy level

Higher distance to thickness ratio (D/T) possible with lowHigher distance to thickness ratio (D/T) possible with lowgeometrical distortiongeometrical distortion

Short exposure time and higher productivityShort exposure time and higher productivity

Three types of highThree types of high--energy sources are usedenergy sources are used VanVan--dede--Graf GeneratorGraf Generator

BetetronBetetron

Linear AcceleratorLinear Accelerator

Linear Accelerator (LINAC) are more common in industriesLinear Accelerator (LINAC) are more common in industries LINACS are available with energy levels up to 15 MeV and 10000LINACS are available with energy levels up to 15 MeV and 10000

rads / min out put.rads / min out put.

Advanced radiographic TechniquesAdvanced radiographic Techniques

High Resolution TechniqueHigh Resolution Technique


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g qg q

Advancement in areas of electronics and sciences made to obtainAdvancement in areas of electronics and sciences made to obtainvery fine focal in the order of 10very fine focal in the order of 10 XX Ray units.Ray units.

Called as MicroCalled as Micro--Focal Units (having Focal size < 100Focal Units (having Focal size < 100 ))

Control and very fineControl and very fine--tuning of Xtuning of X--Ray parameters are possibleRay parameters are possible

Allows radiography of components with magnification andAllows radiography of components with magnification andachievement of very high definition and sensitivity (in the ordeachievement of very high definition and sensitivity (in the order ofr of2525 ).).

This technique enables the examination of very small and intricaThis technique enables the examination of very small and intricatete

components like PCBcomponents like PCBs, thin walled (400s, thin walled (400 ) welds etc.) welds etc. Also these are having Rod Anode type XAlso these are having Rod Anode type X--Ray heads that enables theRay heads that enables the

radiography of tube to tuberadiography of tube to tube--sheet welds of steam generator in thesheet welds of steam generator in thepower industries, which is not possible by conventional radiograpower industries, which is not possible by conventional radiography.phy.

Added advantage of this technique is the adoptability with realAdded advantage of this technique is the adoptability with real timetime

systems.systems. Major limitation is the examination limited to the thicknessMajor limitation is the examination limited to the thickness

according to the kV rating of the unit.according to the kV rating of the unit.

Real Time Radiography (RTR)Real Time Radiography (RTR)Fl / RTR / C t d di h diff f ti l


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Fluoroscopy / RTR / Computed radiography differs from conventionFluoroscopy / RTR / Computed radiography differs from convention

alal

radiographyradiography

image is observed on a fluorescent screen rather than on the filimage is observed on a fluorescent screen rather than on the filmm

Present day systems use image intensifiers or Flat Panel detectoPresent day systems use image intensifiers or Flat Panel detectors, videors, videocamera and monitor or PCcamera and monitor or PC

Image intensifier converts the photon to electron and are multipImage intensifier converts the photon to electron and are multiplied andlied andaccelerated and then converted to light and imageaccelerated and then converted to light and image

Cesium Iodide (Cs I) used to convert the Photon to electronCesium Iodide (Cs I) used to convert the Photon to electron

with image enhancement system provide a higher sensitivitywith image enhancement system provide a higher sensitivity

Flat panel detector replaces image intensifierFlat panel detector replaces image intensifier

use Selenium (Se) for conversionuse Selenium (Se) for conversion can provide a very good sensitivity even to micron levelcan provide a very good sensitivity even to micron level

RTR system is finding increasing applications in industryRTR system is finding increasing applications in industry

advantages of high speed and comparatively low costadvantages of high speed and comparatively low cost

added advantages of images in the digital form, can be processedadded advantages of images in the digital form, can be processed andandanalysed furtheranalysed further

digital images can be stored and be verified at later point of tdigital images can be stored and be verified at later point of t ime toime tocompare the latest resultscompare the latest results

systems are used for auto analysis for acceptance or rejection.systems are used for auto analysis for acceptance or rejection.

ENERGY LEVELENERGY LEVEL

APPROXIMATE RADIOGRAPH EQUIVALENT FATORSAPPROXIMATE RADIOGRAPH EQUIVALENT FATORSMETALMETAL


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3.43.412.612.63.93.94.04.012.012.016.016.020.020.0UraniumUranium

3.03.09.09.012.012.014.014.0HafniumHafnium

2.32.34.04.02.72.72.52.55.05.012.012.014.014.014.014.0LeadLead

1.01.01.21.21.01.014.014.01.01.01.51.51.71.72.02.02.32.32.42.4ZirconiumZirconium

1.21.21.71.7MonelMonel

1.31.31.31.31.31.31.31.31.31.31.31.31.31.31.41.4Inconel XInconel X

1.01.01.11.11.01.01.11.11.21.21.31.31.31.31.41.4BrassBrass

1.01.01.11.11.21.21.31.31.31.31.41.4ZincZinc

1.11.11.11.11.21.21.11.11.11.11.41.41.41.41.41.41.61.61.51.5CopperCopper

1.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.0Iron/all SteelsIron/all Steels

0.90.90.90.90.90.90.90.90.90.90.710.710.540.540.540.54TitaniumTitanium

0.350.350.350.350.180.180.140.140.100.10AluminumAluminum

AlloyAlloy

0.350.350.350.350.180.180.120.120.080.08AluminumAluminum

0.080.080.050.050.050.05MagnesiumMagnesium

COCO6060IRIR19219244--2525

MeVMeV

2MeV2MeV1MeV1MeV400kV400kV250kV250kV220kV220kV150kV150kV100kV100kV

Effects of RadiationEffects of Radiation


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Exposure to radiations (x,Exposure to radiations (x, ,, ,, )) are hazardousare hazardous Radiations produce ions and modify the cellRadiations produce ions and modify the cell

Natural mechanism of the body rectifies the damagesNatural mechanism of the body rectifies the damages

When this is not successful, irradiation causes the following:When this is not successful, irradiation causes the following:

Chromosome aberrationsChromosome aberrations Gene mutationGene mutation

Cell deathCell death

Radiation effects are depends onRadiation effects are depends on

type of radiationtype of radiation

energy of radiationenergy of radiation

dose & duration of exposuredose & duration of exposure

mode (internal or external)mode (internal or external) region of the body exposed.region of the body exposed.

Radiation monitoring and ControlRadiation monitoring and Control


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Data are available on this from experimental studies, medicalData are available on this from experimental studies, medicalexposures, uranium miners, survivors of Hiroshima and Nagasakiexposures, uranium miners, survivors of Hiroshima and Nagasakietcetc

International Committee on Radiological Protection (ICRP) arriveInternational Committee on Radiological Protection (ICRP) arrive atata safe limits of exposure based on these dataa safe limits of exposure based on these data

Whole body radiation limited to 2.0 rem / year is permitted forWhole body radiation limited to 2.0 rem / year is permitted forradiation workers and for general public limited to 0.2 rem/yearradiation workers and for general public limited to 0.2 rem/year

Radiation is invisible, can be detected and monitored using radiRadiation is invisible, can be detected and monitored using radiationationgauges, monitors and survey metersgauges, monitors and survey meters

Instruments are working by the principle of ionizationInstruments are working by the principle of ionizationcharacteristics of radiationcharacteristics of radiation

Radiation workers are monitored by the use of film / TLD badgesRadiation workers are monitored by the use of film / TLD badgesand pocket dosimeters.and pocket dosimeters.

Permanent records are made for the individual radiation workerPermanent records are made for the individual radiation worker

Level of radiation in particular areas ( Area Monitoring)Level of radiation in particular areas ( Area Monitoring) Cordoning of areasCordoning of areas

Evaluation of RadiographsEvaluation of Radiographs

Some typical Weld DiscontinuitiesSome typical Weld Discontinuities


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Lack of Penetration

Slag inclusion

Porosity

Micro Focal RadiographyMicro Focal Radiography


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Radiographic Image ProcessingRadiographic Image Processing


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ULTRASONIC EXAMINATIONULTRASONIC EXAMINATION

Fundamentals of UltrasonicFundamentals of Ultrasonic

CHARACTERISTICS:CHARACTERISTICS:


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ULTRASONIC WAVEULTRASONIC WAVESound waves are vibration of particles of solid,Sound waves are vibration of particles of solid,liquid or gas, of Greater Than Audible Freq.liquid or gas, of Greater Than Audible Freq. -- 20 KHz FREQ.20 KHz FREQ.

Audible Freq.Audible Freq.20 Hz20 Hz20 KHz20 KHz

Particle DisplacementParticle Displacement

Three FactorsThree FactorsVelocityVelocity -- V, FrequencyV, Frequency -- f , Wave Lengthf , Wave Length --

V = fV = f ; f = V/; f = V/ ;; = V/f= V/fVelocityVelocity The speed at which the energy is transported between twoThe speed at which the energy is transported between twopoints.points.

Frequency (f)Frequency (f) Oscillation of the atom in the medium when the wave isOscillation of the atom in the medium when the wave istraveling. Unittraveling. UnitHz, KHz, MHz. Time period (T) = 1/fHz, KHz, MHz. Time period (T) = 1/f

Wave Length (Wave Length ()) The distance traveled by the wave during the timeThe distance traveled by the wave during the timeperiod (T) in the medium.period (T) in the medium.

Fundamentals of UltrasonicFundamentals of Ultrasonic


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Time

period - T

One cycle

Time /Distance

Amplitude

Displacement

Acoustic Impedance (Z) : The resistance offered to the propagation of

ultrasonic wave by the material Z = V Acoustic Pressure (P) : Denotes the amplitude of alternating stresses

on material by propagating ultrasonic wave P = Z a

Acoustic intensity (I) : Acoustic Energy passing through unit area

TYPES OF ULTRASONIC WAVESTYPES OF ULTRASONIC WAVES


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Longitudinal / Compression WaveLongitudinal / Compression Wave Alternative compression and rarefactionAlternative compression and rarefaction

Particles Vibration parallel to the wave propagationParticles Vibration parallel to the wave propagation

Propagate in all mediaPropagate in all media Solid, Liquid and GasSolid, Liquid and Gas

Transverse / Shear WaveTransverse / Shear Wave

Particles Vibration perpendicular to wave propagationParticles Vibration perpendicular to wave propagation

Propagation only in solidsPropagation only in solids

Surface / Raleigh WaveSurface / Raleigh Wave

Particle vibration generally ellipticalParticle vibration generally elliptical

Travel along the surfaceTravel along the surface -- up to one wave length depthup to one wave length depth

Lamb / Plate WaveLamb / Plate Wave

Velocity depends on type of material, material thk., freq.Velocity depends on type of material, material thk., freq.

Complex modesComplex modes

V l = E/

V t = G/

V s = 0.9 V t

ACOUSTIC PROPERTIESACOUSTIC PROPERTIES


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3131----3303300.0930.093AirAir

1 4801 480----1480148010001000WaterWater

1 5141 514----17401740870870OilOil

3 2213 221143014302730273011801180PerspexPerspex

28 28428 284318031806230623045404540TitaniumTitanium

46 62946 629325032505950595078507850SteelSteel

41 83041 830226022604700470089008900CopperCopper

17 06417 064313031306300630027002700AluminumAluminum

ZZ

101033 PaPa s/ms/m

VelVel ShearShear

m/sm/s

VelVel LongLong

m/sm/s

DensityDensity

Kg/mKg/m33MaterialMaterial

WAVE PROPAGATIONWAVE PROPAGATION

Transmission, Reflection & RefractionTransmission, Reflection & Refraction


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Wave undergoes Transmission Reflection and RefractionWave undergoes Transmission Reflection and Refraction

Normal incidence at interfaceNormal incidence at interface Transmission and reflectionTransmission and reflection

(Acoustic impedance mismatch)(Acoustic impedance mismatch)Refraction at the reflective interfaceRefraction at the reflective interface

Oblique Incidence at interfaceOblique Incidence at interface Transmission, reflection andTransmission, reflection and

Refraction (Mode conversion)Refraction (Mode conversion)

Reflection R = (ZReflection R = (Z11--ZZ22))22/ (Z/ (Z11+Z+Z22))

22

Transmission T = ZTransmission T = Z11ZZ22 / (Z/ (Z11+Z+Z22))22

Angle of Refraction = sin a / sin b = VAngle of Refraction = sin a / sin b = V11/ V/ V22(Snell(Snells Law)s Law)

S

S

L

L

T R

Refra

Reflec

Mode conversion and critical anglesMode conversion and critical anglesWhen the longitudinal wave incident obliquely at interface, insiWhen the longitudinal wave incident obliquely at interface, inside thede the


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specimen the beam refracts in to longitudinal and transverse modspecimen the beam refracts in to longitudinal and transverse modes. This ises. This is

calledcalled Mode ConversionMode Conversion..

When the incident angle increased, at one angle the refracted loWhen the incident angle increased, at one angle the refracted longitudinalngitudinal

beam will be gliding on the scanning surface. This is called thebeam will be gliding on the scanning surface. This is called the First CriticalFirst Critical

AngleAngle..

If the incident angle increased further, then at one angle the rIf the incident angle increased further, then at one angle the refracted shear /efracted shear /

transverse beam becomes gliding and is called astransverse beam becomes gliding and is called as Surface WaveSurface Wave and theand the

angle is called asangle is called as Second Critical AngleSecond Critical Angle..

The angle beam transducers are designed between these critical aThe angle beam transducers are designed between these critical angles tongles to

produce the desired angle.produce the desired angle.

Wave PropagationWave Propagation

Beam Divergence, Near Field, Far FieldBeam Divergence, Near Field, Far Field

Th di bTh di b


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The wave propagate as a divergent beamThe wave propagate as a divergent beam

Near FieldNear Field Sound Pr. is not uniformSound Pr. is not uniform DD22/ 4/ 4 Far FieldFar Field -- FraunhauferFraunhaufer ZoneZone After Near zoneAfter Near zone

Beam Divergence / SpreadBeam Divergence / Spread SinSin = K= K / D/ DValue KValue K -- 1.22 (100%1.22 (100%-- 40dB); 1.08 (10%40dB); 1.08 (10% -- 20dB); 0.55 (50%20dB); 0.55 (50%--6dB)6dB)

DD Dia of probeDia of probe

NearField Far Field

Attenuation of Ultrasonic BeamAttenuation of Ultrasonic Beam

Ultrasonic beam undergoes losses during propagationUltrasonic beam undergoes losses during propagation

C liC li


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CouplingCoupling Surface roughnessSurface roughness

AbsorptionAbsorption

ScatteringScattering

Coupling and Surface roughnessCoupling and Surface roughness External condition of theExternal condition of thespecimenspecimen

Absorption and ScatteringAbsorption and Scattering Internal condition of the specimenInternal condition of the specimen Grain structure and Grain sizeGrain structure and Grain size

Fine grainFine grain AbsorptionAbsorption

Coarse grainCoarse grain -- ScatteringScattering

P=PP=P00ee--dd Since the sound Pr. Is proportional to echo ht.Since the sound Pr. Is proportional to echo ht.

Attn. Coeff.Attn. Coeff. = 20/d log (H= 20/d log (H00/H) dB/m; dB = 20 log (H/H) dB/m; dB = 20 log (H11/ H/ H22))

Effect Of FrequencyEffect Of Frequency


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IncreasesIncreasesAttenuationAttenuation

(Absorption / Noise)(Absorption / Noise)

IncreasesIncreases

(NZ = D(NZ = D22/ 4/ 4 = D= D22 f / 4 V )f / 4 V )

Near ZoneNear Zone

IncreasesIncreases

( s =( s = / 2 = V/ 2 f)/ 2 = V/ 2 f)

SensitivitySensitivity

DecreasesDecreases

(1.2(1.2 / D =/ D = 1.2 V / f D)1.2 V / f D)

Beam Spread / DivergenceBeam Spread / Divergence

Effect of Frequency( )Effect of Frequency( )Beam CharacteristicsBeam Characteristics

Generation of UltrasoundGeneration of Ultrasound MagnetostrictionMagnetostriction Ferromagnetic materials like Fe, Ni, CoFerromagnetic materials like Fe, Ni, Co

h th t th l th ( i ) b i d b li ti fh th t th l th ( i ) b i d b li ti f


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shows that the length (size) can be varied by application ofshows that the length (size) can be varied by application ofmagnetic field. If alternating mag. field applied this willmagnetic field. If alternating mag. field applied this willvibrate. Hence, the production of ultrasound in the contactvibrate. Hence, the production of ultrasound in the contactspecimenspecimen

Piezoelectric EffectPiezoelectric Effect A piezoelectric material will develop anA piezoelectric material will develop anelectrical potential when subjected to mech. Pr..electrical potential when subjected to mech. Pr..

Two types of piezoelectric transducersTwo types of piezoelectric transducers

Single crystalSingle crystal Natural / ArtificialNatural / Artificial Quartz, Lithium SulphateQuartz, Lithium Sulphate Polycrystalline materialsPolycrystalline materials PolarisedPolarised Ceramic MaterialsCeramic Materials -- BariumBarium

Titanate, Lead Zirconate Titanate (PZT), Lead Metabionate.Titanate, Lead Zirconate Titanate (PZT), Lead Metabionate.

These are made by heating them to their curie point and coolingThese are made by heating them to their curie point and cooling themthemunder the influence of voltage.under the influence of voltage.

Characteristic of Transducer CrystalsCharacteristic of Transducer Crystals

LimitationLimitationAdvantageAdvantageMaterialMaterial


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Piezoelectric property reduces withPiezoelectric property reduces with

aging, Low resistance to wear, sufferaging, Low resistance to wear, sufferfrom mode conversion.from mode conversion.

Efficient Generators, Operate inEfficient Generators, Operate in

low voltage, Some can be usedlow voltage, Some can be usedfor high tem. Appln. (leadfor high tem. Appln. (lead

metabionate)metabionate)

PolarisedPolarised

CeramicsCeramics

Very Fragile, Soluble in water, LimitedVery Fragile, Soluble in water, Limited

to use with temp.to use with temp. can be used belowcan be used below

7575 CC

Most efficient receiver, Does notMost efficient receiver, Does not

age, Very little modeage, Very little mode

conversion, Low acousticconversion, Low acousticimpedanceimpedance

LithiumLithium

SulphateSulphate

Expensive, Least efficient generator,Expensive, Least efficient generator,

Suffers from mode conversion, HighSuffers from mode conversion, High

voltage for operationvoltage for operation

Hard & High resistance to wear,Hard & High resistance to wear,

Aging. Mech, & ElectricalAging. Mech, & Electrical

stability. Used up to ~500stability. Used up to ~500 CC

QuartzQuartz

LimitationLimitationAdvantageAdvantageMaterialMaterial

Construction of TransducersConstruction of Transducers

The Transducers are of two typesThe Transducers are of two types


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Longitudinal / Compression modeLongitudinal / Compression mode

Shear / Transverse modeShear / Transverse mode

Generally the compression mode is used for the construction of sGenerally the compression mode is used for the construction of shearhear

transducers.transducers.

WearPlate

CrystalBacking

L

S

Acoustic

Barrier

DelayBlock

Long. Probe Shear Probe Long. TR Probe Focused Probe

CouplantCouplant

Air is having low acoustic impedance compared to the probe and tAir is having low acoustic impedance compared to the probe and thehe


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Air is having low acoustic impedance compared to the probe and tAir is having low acoustic impedance compared to the probe and thehespecimen. Hence the beam is reflected at the probe specimenspecimen. Hence the beam is reflected at the probe specimeninterface.interface.

A medium with the acoustic impedance between the specimen andA medium with the acoustic impedance between the specimen and

probe has to be usedprobe has to be used Commonly used CouplantCommonly used Couplant

Water, Oils, Glycerin, Petroleum Grease, Silicon GreaseWater, Oils, Glycerin, Petroleum Grease, Silicon Grease

Selection of Couplant based onSelection of Couplant based on

Surface finish, Specimen Temperature, Chemical reaction with theSurface finish, Specimen Temperature, Chemical reaction with thespecimen, Post Cleaningspecimen, Post Cleaning

Transfer correction (ExternalTransfer correction (External condncondn. Of. Of specnspecn.).)

Loss due to surface roughness, Couplant thicknessLoss due to surface roughness, Couplant thickness

Amt. of gain difference between the specimen and reference, in dAmt. of gain difference between the specimen and reference, in dB to beB to beadded during scanningadded during scanning

EQUIPMENTEQUIPMENT

Ultrasonic Flaw DetectorUltrasonic Flaw Detector

Pulse GeneratorPulse Generator


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Pulse GeneratorPulse Generator Pulse ReceiverPulse Receiver

Signal Processing & Control CircuitrySignal Processing & Control Circuitry

Display System (CRT)Display System (CRT)

a

bc

a

b c

Specimen

Time BaseGenerator

CRT

Clock orTimer

PulseGenerator

Amplifier

PresentationPresentation

Three Presentation AvailableThree Presentation Available

D

B B


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Three Presentation AvailableThree Presentation Available A ScanA Scan Amplitude vs. Time/DistanceAmplitude vs. Time/Distance

B / D ScanB / D Scan Side ViewSide View

C ScanC Scan Plan ViewPlan View

Width

Specimen & Transducer

CRT Presentation

A SCAN B SCANC SCAN

Thk.

Length

D

B B

C C

TESTING TECHNIQUESTESTING TECHNIQUES

ResonanceResonance Exist when the thickness of a material equals to half theExist when the thickness of a material equals to half thel th lti l f dl th lti l f d f V / 2 tf V / 2 t


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ResonanceResonance Exist when the thickness of a material equals to half theExist when the thickness of a material equals to half thewavelength or multiples of soundwavelength or multiples of sound f = V / 2 tf = V / 2 t

Through transmissionThrough transmission Two probes transmitter and receiver on either sideTwo probes transmitter and receiver on either side

of the specimenof the specimen Defect position will not be given.Defect position will not be given.

Pulse EchoPulse Echo Sound in pulsesSound in pulses transmitted and receivedtransmitted and received

Contact & ImmersionContact & Immersion -- Longitudinal & Angle beamLongitudinal & Angle beam

Pulse Echo TechniquePulse Echo Technique

Widely UsedWidely Used

Two typesTwo types Contact & ImmersionContact & Immersion


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Two typesTwo types Contact & ImmersionContact & Immersion

Normal BeamNormal Beam Used to detect discontinuities parallel toUsed to detect discontinuities parallel to

scanning surfacescanning surface

Angle BeamAngle Beam Used to detect discontinuities at angle toUsed to detect discontinuities at angle toscanning surfacescanning surface

Surface Wave TechniqueSurface Wave Technique

1.1. Use of high freq. IncreasesUse of high freq. Increases

sensitivity.sensitivity.

2.2. Easy manipulation of requiredEasy manipulation of required

angle & odd shape jobs.angle & odd shape jobs.

3.3. Automation possible.Automation possible.

1.1. Easy ScanningEasy Scanning

2.2. Suitable for site conditionSuitable for site condition

3.3. Defect position identification easyDefect position identification easy

ImmersionImmersionContactContact

CALIBRATION OF TESTING SYSTEMCALIBRATION OF TESTING SYSTEM

Using reference blocksUsing reference blocks IIW, V2IIW, V2

Calibration of Eqpt & ProbeCalibration of Eqpt & Probe


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Calibration of Eqpt. & ProbeCalibration of Eqpt. & Probe Time BaseTime Base

Probe IndexProbe Index

Probe AngleProbe Angle

Time base LinearityTime base Linearity Vertical LinearityVertical Linearity

Amplitude LinearityAmplitude Linearity

ResolutionResolution Ability of the system to detect close defectsAbility of the system to detect close defects Lat. & Depth.Lat. & Depth.

SensitivitySensitivity Ability of the system to detect the smaller defectsAbility of the system to detect the smaller defects depends ondepends on

probe frequencyprobe frequency Dead ZoneDead Zone The zone occupied by the initial pipThe zone occupied by the initial pip -- depends on probedepends on probe

frequency, equipmentfrequency, equipment

Maximum Penetrating powerMaximum Penetrating power PerspexPerspex

ASTM Reference BlocksASTM Reference Blocks

DistanceDistance AmplitudeAmplitude AreaArea -- AmplitudeAmplitude

Types of Discontinuities & their DetectionTypes of Discontinuities & their Detection

PlanarPlanar


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PlanarPlanar Cracks, Lamination, Lack of penetration and FusionCracks, Lamination, Lack of penetration and Fusion

VolumetricVolumetric

InclusionInclusion Gas, SlagGas, Slag

Ultrasonic Examination is ideal for detection of PlanarUltrasonic Examination is ideal for detection of Planar

discontinuitiesdiscontinuities

Discontinuities parallel to scanning surfaceDiscontinuities parallel to scanning surface LongitudinalLongitudinal

BeamBeam

Discontinuities in oblique / angleDiscontinuities in oblique / angle Angle BeamAngle Beam

Reference BlocksReference Blocks

Three types of references usedThree types of references usedFlat Bottom Hole (Normal beam / Long )Flat Bottom Hole (Normal beam / Long )


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ypyp Flat Bottom Hole (Normal beam / Long.)Flat Bottom Hole (Normal beam / Long.)

Side Drilled Hole (Angle Beam / Shear)Side Drilled Hole (Angle Beam / Shear)

Notches (Shear / Angle beam)Notches (Shear / Angle beam)

Reference blocks shall be acoustically similar and should have sReference blocks shall be acoustically similar and should have sameame

shape, thickness.shape, thickness.

BA C

B

C

B

CAA

Distance AmplitudeCorrection Curve (DAC)

Flaw Sizing and CharacterisationFlaw Sizing and Characterisation

Scanning techniqueScanning technique Probe movement to determine theProbe movement to determine thedi ti itdi ti it L ti L th d O i t tiL ti L th d O i t ti


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g qg qdiscontinuitydiscontinuitys Location, Length and Orientations Location, Length and Orientation

Ultrasonic Signal gives the information about theUltrasonic Signal gives the information about the

discontinuitydiscontinuitys Characterisation / Types Characterisation / Type

Sharp High Ampl. SignalSharp High Ampl. Signal Planar type of discontinuityPlanar type of discontinuity

Wide Low Ampl. SignalWide Low Ampl. Signal Volumetric Type of discontinuityVolumetric Type of discontinuity

Flaw SizingFlaw Sizing

Flaw LocationFlaw Location


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Flaw LengthFlaw Length

P

S

Stand Off (S) = P sin Depth (d) = P cos

dt

Length

Probe Travel

Amplitude

t

d

ULTRASONIC EXAMINATION OFULTRASONIC EXAMINATION OF

PRODUCTSPRODUCTS

PlatesPlates


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Tubular ProductsTubular Products Pipes & Tubes, FittingsPipes & Tubes, Fittings

Forgings & BarsForgings & Bars

CastingCasting

Fabricated componentsFabricated components -- WELDSWELDS

Ultrasonic ExaminationUltrasonic Examination

CastingCasting Restricted / Difficult due to Coarse grainRestricted / Difficult due to Coarse grain


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ForgingForging Widely used as the fine grain existsWidely used as the fine grain exists Long. &Long. &

Angle beam usedAngle beam used

Semi finished productsSemi finished products Billets, RodsBillets, Rods

Rolled ProductsRolled Products

PlatesPlates both contact & immersionboth contact & immersion -- Long. & Angle ,Long. & Angle ,

Pipes & TubesPipes & Tubes ImmersionImmersion -- Long. & AngleLong. & Angle

WeldingWelding Usually AngleUsually Angle

PLATEPLATE

Scanning on any major surface of plateScanning on any major surface of plate


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After heat treatmentAfter heat treatment

Longitudinal / Straight & / or Shear / Transverse BeamLongitudinal / Straight & / or Shear / Transverse Beam

According to the stage & defects expectedAccording to the stage & defects expected Scanning 100% or on GridsScanning 100% or on Grids 100 to 225 mm grids100 to 225 mm grids

Calibration ReferenceCalibration Reference

Long.Long. Back wallBack wall

ShearShear -- 33 10% Notch10% Notch

AcceptanceAcceptance

Long.Long. Total loss of back reflectionTotal loss of back reflection --


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gg Shear / Transverse beamShear / Transverse beam

Scanning in axial and circumferential directionsScanning in axial and circumferential directions

Calibration ReferenceCalibration Reference 3%3% 10% Notch on ID & OD10% Notch on ID & OD

Both in Axial and CircumferentialBoth in Axial and Circumferential

AcceptanceAcceptance Indication less than reference (DAC)Indication less than reference (DAC)

Generally automatic scanningGenerally automatic scanning using immersionusing immersion

Thk.

OD Notches

ID Notches

FORGINGFORGING

DISC ForgingDISC Forging Straight beamStraight beam AxialAxial -- Flat face & RadialFlat face & Radial Thk.Thk.


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S a g ag a a a a a

CLYLINDRICAL ForgingCLYLINDRICAL Forging

Straight beamStraight beam Axial & RadialAxial & Radial

HOLLOW ForgingHOLLOW Forging Straight beam and Angle BeamStraight beam and Angle Beam

Axial and Radial from ODAxial and Radial from OD

OD / ID Ratio < 2OD / ID Ratio < 2

Calibration ReferenceCalibration Reference St. BeamSt. Beam FBH / Back ReflectionFBH / Back Reflection

Angle BeamAngle Beam 3 / 5 / 10% Notches3 / 5 / 10% Notches

on OD and IDon OD and ID

Angle Beam Scanning in two perpendicular & oppositeAngle Beam Scanning in two perpendicular & oppositedirectionsdirections

T

CASTINGCASTING

Low FrequencyLow Frequency 0.50.5 2 MHz2 MHz Reference blocks with FBHReference blocks with FBH


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Reference blocks with FBHReference blocks with FBH

Surface conditionSurface condition -- RoughRough

To be machined to accommodate scanningTo be machined to accommodate scanning

Amplitude correctionAmplitude correction

Difficulty exist in ultrasonic examinationDifficulty exist in ultrasonic examination

Coarse grain structureCoarse grain structure

Lower S/N RatioLower S/N Ratio

Different configuration and shapeDifferent configuration and shape

DAC

WELDSWELDS

Parent metalParent metal Weld Joint configurationWeld Joint configuration


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Weld Joint configurationWeld Joint configuration

Welding ProcessWelding Process

Weld DiscontinuitiesWeld Discontinuities Code, Specification & ProcedureCode, Specification & Procedure

Equipment, Transducer & CalibrationEquipment, Transducer & Calibration

Examination method / TechniqueExamination method / Technique

ReferenceReference

Scanning sequenceScanning sequence

SignalSignal

Evaluation & ReportingEvaluation & Reporting

UE OF WELDUE OF WELD -- BASE METALBASE METAL

Carbon SteelCarbon Steel

Alloy steelAlloy steel


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yy

Stainless SteelStai

66122729 non destructive examination 2

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