Introduction to Ndt for Pt 1

INTRODUCTION TO NON-DESTRUCTIVE TESTING TECHNIQUE

INTRODUCTION TO NON-DESTRUCTIVE TESTING TECHNIQUEK. SURESH SENANAYAKE ,B.Sc. (Hons) Phy. (Sp.), Grad. IP (SL), NDT Qualification as per ISO 9712TestingDestructive testing (DT)Semi-destructive testingNon-destructive testing (NDT)Tensile testBend testCharpy testHardness testFatigue testCreep testMetallographyChemical analysis, etc.Coring testTension testCarbonation testMortar test

Ultrasonic testEddy current testRadiography testVisual testMagnetic particle testPenetrant testIR thermographyLeak testAcoustic emissionLaser shearographySURESH SENANAYAKE | NCNDT2NDTDefinitionNon-destructive testing (NDT) is the testing of material to detect internal and surface defects or discontinuities using methods that do not damage or destroy the material under test.

SURESH SENANAYAKE | NCNDT33Engineering Materials MaterialsAluminumCopperZincTitaniumTungsten NickelSteelStainless steelCast ironFerrousNon-FerrousMetalsCeramicsPolymersCompositesSURESH SENANAYAKE | NCNDT4Material DiscontinuitiesShould identify the types of metal manufacturing and service discontinuities (i.e. to know what causes the defects)DefectsInherent Processing DefectsPrimary Processing DefectsSecondary Processing DefectsService DefectsThe refining stage where metals are extracted from oresInclusions (Slag)Porosity (Blown hole)PipeSegregation Metal ingots are worked into usable forms such as billets or blooms by wrought processing or castingSeamsLapsLaminationForging burstsInclusionsporosityFinal stages of parts manufacturingGrinding cracks (thermal cracks)Machining cracksWelding defectsHeat treat cracks (quenching cracks)Occurs during the use of the partFatigue cracksStress cracksCorrosion SURESH SENANAYAKE | NCNDT5Where is NDT used?where we need to ensure the serviceability of a specimenwhere we cannot afford the cost of a failure of the specimen because failure would be financially unacceptable or cause harm to usexist to prevent injury or death to the human user of the tested item

SURESH SENANAYAKE | NCNDT6Why we need NDT?Generally, NDT is employed in various industries for the following reasons;To prevent accidents and save human livesTo improve product reliabilityTo give profit to the user by;Ensuring customer satisfactionHelping in better product designControlling manufacturing processesLowering manufacturing processesMaintaining a uniform quality levelSURESH SENANAYAKE | NCNDT7When is NDT used?NDT is used both before, during and after constructionUsing NDT "before or during construction" prevents a substandard material or part from wasting time and increasing scrap productionUsing NDT after to monitor performance after being service.

SURESH SENANAYAKE | NCNDT8NDT METHODSThere are six major NDT methods ;Visual testing (VT)Radiography testing (RT)Ultrasonic testing (UT)Magnetic particles testing (MT)Liquid penetrant testing (PT)Eddy current testing (ET)

NDTEddy CurrentTestingVisualTesting

SURESH SENANAYAKE | NCNDT9Other NDT methods;Leak testingStrain gaugingAcoustic emissionIR ThermographyLaser shearography

SURESH SENANAYAKE | NCNDT10NDT.The choice of test method to be carried out on a certain piece depends on several factors, the most important ones being;

Types of discontinuity expectedInherent limitations of each methodWorking conditionsMaterial to be testedSURESH SENANAYAKE | NCNDT11IndicationEach non-destructive test is designed to provide visual evidence of discontinuities in parts, which are not normally visible to the unaided eye.The visual evidence left by each method is called an indication.NOTE: There is no single NDT method capable of detecting all type of discontinuitiesSURESH SENANAYAKE | NCNDT12VISUAL TESTINGEye of a qualified technician can be supplemented with various optical aids and mechanical gauges for visual inspection.

It is a most commonly used NDT method for detecting and evaluating defects.Inspect using human eye. Optical equipment use to enhance sensitivity. But decreases the area of coverage.SURESH SENANAYAKE | NCNDT13Visual Testing.Employs the eyes to look directly at the component Mostly used on detection of corrosion Needs lot of skill and trainingQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQOQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQTraining- 01SURESH SENANAYAKE | NCNDT14

Visual Testing..OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOQOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOTraining- 0210SURESH SENANAYAKE | NCNDT15

Visual TestingEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEFEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEFEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEFEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEETraining- 03SURESH SENANAYAKE | NCNDT16

Most basic and common inspection method.

Tools include Lights, Mirrors, fiberscopes, borescopes, magnifying glasses and CCTV.Robotic crawlers permit observation in hazardous or tight areas, such as air ducts, reactors, pipelines.

Portable video inspection unit with zoom allows inspection of large tanks and vessels, railroad tank cars, sewer lines.Visual InspectionSURESH SENANAYAKE | NCNDT17

RADIOGRAPHY TESTING (RT)Principle of OperationUsing electromagnetic radiation (X-, Gamma-, Neutron-, etc.) to penetrate through materials.Discontinuities is recorded on film

SURESH SENANAYAKE | NCNDT18Radiography..Testing by means of radiation is based on the following factors:The capacity that radiation has to pas through matterDifferent radiation absorption depending on the piece being testedThe possibility of measuring this absorption differencesThe testing involves the use of,

A radiation sourceA radiation detector (film)

SURESH SENANAYAKE | NCNDT19

Radiographic ImageA radiographic image is a document composed of a photographic film on to which the image of an object which the radiation has passed through is recorded.


Radiography..The radiographic technique gives a true image of the piece section (a photographic image) allowing many different types of material to be examined, even very thick materials.Main disadvantages


RADIOGRAPHY

Limitations High capital and running costRequire source of electricity (in the case of X-ray)Trained and skill operators are necessaryPose potential radiation hazardNot sensitive to planar defect

ApplicationsApplicable to almost all metals and non-metalsCapable of detecting (and subsequently recording on the film) surface and internal discontinuities


ULTRASONIC TESTING (UT)Principle of OperationUltrasonic testing is based on the reflection that on acoustic wave is subjected to when, while moving through a certain material, it finds its propagation impared.Signal due to discontinuities is presented on cathode ray tube screen (CRT)


UltrasonicThe test requires a system comprising the following elements:A probe (which emits the acoustic beam)A detection unit (which records the reflected beam on a screen)


Ultrasonic..The ultrasonic beam emitted by the probe passes through the test piece and, after reaching the bottom wall, is reflected back to the probe which signals it on the screen.

If the beam finds a discontinuity along its path, it returns to the probe more quickly, in this way signaling the presence of a defect.


Ultrasonic..The ultrasonic technique allows for immediate examination of the piece with extremely low working times.It is easy to carry out and proves particularly suitable for creating automatic or semi-automatic systems as the discontinuity is detected by the presence or lack of signal from the reflected waves.


ULTRASONIC..ApplicationsApplicable to almost all metals and non-metalsCapable of detecting surface and internal discontinuitiesAutomatic inspection and new computerized image processing allows signal to be permanently recorded on paperMeasure thicknessMaterial characterization (e.g. measure elastic modulus, etc.)

Crankshaft - Northern Power Plant Ultrasonic Testing SURESH SENANAYAKE | NCNDT27

ULTRASONIC..LimitationsRelatively high capital costRequires highly trained and experienced operatorInterpretation of results can be extremely difficultNot sensitive to defects parallel to the beam direction


MAGNETIC PARTICLE TESTING (MT)Principle of OperationUsing magnetic or current flow to produce magnetic field in the materialsThe pattern of field distribution provides indication of the existence discontinuities

SURESH SENANAYAKE | NCNDT29Magnetic Particle..Magnetic testing is based on the following factors:The possibility of magnetizing the piece to be tested;Magnetic field variations generated by the piece discontinuities;The possibility of detecting surface and sub-surface variations piece in the pieces magnetic field.


MAGNETIC PARTICLEApplicationsApplicable to ferromagnetic materialsCapable of detecting surface and sub-surface discontinuitiesEasily operated portable equipment makes it suitable for field inspection


Magnetic ParticleThe test requires a system comprising the following elements:Equipment for piece magnetization;Magnetic powders (or particles) to be spread over the piece to reveal the magnetic field variations.Limitations Not applicable to non-ferromagnetic materialsRequires a sources of electricityMagnetization in two perpendicular directions is necessaryInspected objects have to be demagnetized

Magnetization Equipment (Yoke)Magnetic powdersSURESH SENANAYAKE | NCNDT32

Magnetic Particle crack indications


PENETRANT TESTING (PT)Principle of OperationUsing liquid to penetrate materialsImage of discontinuities become visible after development


Penetrant Testing..Penetrant testing requires a use of:Penetrant liquidsDeveloper


Penetrant TestingAdvantagesIt can be applied to any material (ferromagnetic and non-ferromagnetic);It can also be carried out on parts that are not easily accessible;It is relatively simple in terms of procedure and interpretation;Compared to other examinations, the equipment is much more economical.LimitationsIt can detect only discontinuities opened to the surface;Discontinuities filled with extraneous matter (dirt, oxides, etc.) cannot be detected;Surface conditioning must be more accurate than in other types of examination.ApplicationsInspect non porous materials (metals, glass, ceramic, etc.)Detect surface defectsSimple equipment


EDDY CURRENT TESTING (ET)Principal of OperationUse electrical current in coils to induce eddy current within specimenIndicator will be deflected when discontinuities disturb the path of eddy current

The test probe in eddy current inspection is basically a coil of wire through which AC is passed. When AC is passed through the coil, a magnetic field is generated in and around the coil.When the probe is brought in close proximity to a conductive material, the magnetic field generates current flow in the material.The induced current flows in closed loops in planes perpendicular to the magnetic flux and are named eddy currents.SURESH SENANAYAKE | NCNDT37Eddy Current.Conductive material CoilCoilsmagnetic fieldEddy CurrentsEddy Currentsmagnetic fieldSURESH SENANAYAKE | NCNDT38

Eddy Current.6/12/2015MATERIALFLAWPROBEPROBEPROBEPROBECRACK DETECTIONSURESH SENANAYAKE | NCNDT39

Eddy CurrentApplicationsInspect conducting materialsDetect surface and sub-surface discMeasure hardness and thickness of layer and thin sheet Sub surface flaw detectionMulti-layered aircraft structures.- Fuselage- Wings- Around FastenersPhase indicates flaw depthMagnitude indicates flaw severity at depth


Eddy Current..Limitations Defect detection is limited to only few mm below surfaceDoes not indicate the shape of discontinuitiesConductivity measurementRaw materials sortingManufacturing process verificationHeat damageReference measurement


Eddy Current..A typical NDT jobAC failure or fault foundDefine DEFECT Choose NDT methodSpecify technique and equipmentRisk analysis of fleet(s)Inspection plan Review design of faulty part


Who is involved in Aerospace in service NDT?Airline operators Airworthiness authoritiesComponent part manufacturerNDT equipment supplierAircraft manufacturerQualified NDT inspector

SURESH SENANAYAKE | NCNDT43What needs to be avoided?


A defect that went undetected in an engine disk was responsible for the crash of United Flight 232.


SURESH SENANAYAKE | NCNDT46Reliability of NDTMethodDiscontinuitySuperficialInternalDetectionLength evaluationHeight evaluationDetectionLength evaluationHeight evaluationDepth evaluationVTAdequateAdequate Inapplicable InapplicableInapplicableInapplicableInapplicablePTAdequateAdequateInapplicableInapplicableInapplicableInapplicableInapplicableMTAdequateAdequateApplicable with limitations Low efficiencyLow efficiencyInapplicableInapplicableUTApplicable with limitationsLow efficiencyLow efficiencyAdequateGoodLow efficiencyAdequateRTAdequateAdequateInapplicableAdequateGoodLow efficiencyApplicable with double exposure and calculusETGood Good Adequate Low efficiencyLow efficiencyLow efficiencyLow efficiencySURESH SENANAYAKE | NCNDT47Advantages of NDTTested objects or parts can be re-used (unless proven defective)Tests can be conducted to all samples (100% inspection) or representative samplesMore than one inspection techniques can be applied to a similar objectInspection on a certain product may be repeatedRequires minimum (or no) specimen preparationEquipment are normally portable and suitable for field inspectionInspection may be performed while the objects or parts are in serviceLimitations of NDTResults are normally qualitativeRequires highly trained and experienced personnelSURESH SENANAYAKE | NCNDT48Advantages of DTResults are normally quantitativeDoes not require highly trained and experienced personnelLimitations of DTTested objects or parts become scrap and considered lossTests can only be conducted to representative samples (100% inspection is not possible)Each object or part can only be tested onceRepetitive inspection cannot be performed on a similar object Objects or parts to be inspected have to be taken away from the system and replacedRequire systematic specimen preparationEquipment are normally stationarySURESH SENANAYAKE | NCNDT49Thank you!SURESH SENANAYAKE | NCNDT50

Introduction to Ndt for Pt 1

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