ImportanceImportance

If NDT were used here?If NDT were used here?

United Flight 232

R il id t

Mumbai pipeline tragedy

G j t b id t dRailway accident Gujrat bridge tragedy

Bhopal Gas Tragedy

IndexIndex

1.Definition

2.Features of NDT

3 Methods of NDT3.Methods of NDT

Visual inspection

Liquid Penetrant testing

Magnetic Particle Testing

Radiographic Testing

Ultrasonic Testing

4.Applications

5 Conclusion5.Conclusion

6.References

DefinitionDefinition

The use of noninvasive 

techniques to determine 

the integrity of a material, 

component or structurecomponent or structure 

or 

quantitatively measure

some characteristic of

an object.

i I t ith t d i hi.e. Inspect or measure without doing harm.

FeaturesFeatures

Any complicated objects can be tested without disturbing its configuration.

No effect on future use of test object.

Higher accuracy of fault finding than any other methods.

NDT can test faults deep inside the object .

Potential low cost.

On line testingOn line testing.

Methods of NDTMethods of NDT

Visual inspectionX-rayUlt i T tiUltrasonic TestingAcoustic EmissionFlux LeakageLaser InterferometryAcoustic MicroscopyLiquid PenetrantqMagnetic Particle testingThermographyEddy currentEddy currentMagnetic Testing

Six most common NDT M th dMethods

• Visual• Liquid Penetrant • Magnetic

Ult i• Ultrasonic• Eddy Current• X-rayX ray

Liquid PenetrantLiquid Penetrant

Eddy current

X-ray

Visual Inspectionp

Most basic and commonMost basic and common inspection method.

T l i l dTools include fiberscopes, bore scopes, magnifying

Portable video inspection unit

glasses and mirrors.

with zoom allows inspection of large tanks and vessels,

railroad tank cars, sewer lines.

Robotic crawlers permit observation in hazardous or tight areas, such as air ducts, reactors, pipelines.

Liquid penetrant method

A li id ith hi h f tti h t i ti i

q p

• A liquid with high surface wetting characteristics is applied to the surface of the part and allowed time to seep into surface breaking defects.

• A developer (powder) is applied to pull the trapped penetrant out the defect and spread it on the surface where it can be seen.the surface where it can be seen.

• Visual inspection is the final step in the process. The penetrant used is often loaded with a fluorescent dye and the inspection is done underfluorescent dye and the inspection is done under UV light to increase test sensitivity.

Magnetic Particle T tiTesting 

The part is magnetized.  Finely milled iron particles coated with a dye pigment are then applied to the specimen. These particles are attracted to magnetic flux leakage fields and will cluster to form an indication directly over the discontinuity.  This indication can be visually detected under proper lighting conditions. 

Magnetic Particle crack i di tiindication 

Radiographyg p y

The radiation used in radiography testing is a higher energy (shorter wavelength) version of the electromagnetic waves that

High Electrical Potential

Electronswe see as visible light. The radiation can come from an X-ray generator or a radioactive source.

Electrons-+

Radioactive Source Creates Radiation

Radiation RadiationPenetratesampleple

Exposure Recording Device

p p

Film Radiography

The part is placed between the

g p y

The part is placed between the radiation source and a piece of film. The part will stop some of theThe part will stop some of the radiation. Thicker and more dense area will stop more of the radiation.

The film darkness (density) will vary with

X-ray filmthe amount of radiation reaching the film through the test objectthe test object.

= less exposure

= more exposure

Eddy current testing

C il'

y g

CoilCoil's magnetic field

Eddy current's magnetic field

Eddy currents

g

Conductive

currents

material

Eddy current testingy g

Eddy current testing is well suited for detecting surface crack but can also be used to make electrical conductivity & coating thickness measurementsmeasurements.

Ultrasonic testing

High frequency sound waves are introduced into a material and

g

High frequency sound waves are introduced into a material and they are reflected back from surfaces or flaws.

Reflected so nd energ is displa ed ers s time and inspectorReflected sound energy is displayed versus time, and inspector can visualize a cross section of the specimen showing the depth of features that reflect sound.

initial pulse

back surface

crackecho

back surfaceecho

plate

crack

0 2 4 6 8 10

Oscilloscope, or flaw detector screen

Applicationspp

i)C li tii)Common applications:-Inspection of raw products. Inspection following secondaryInspection following secondary processing. In-service Damage inspection. g p

ii)Special applications:-P l t i tiPower plant inspection Wire rope inspection Storage tank inspectionStorage tank inspection Aircraft inspection Jet engine inspection g pRail inspection etc.

Common Applicationspp

1.Inspection of raw productsForgings,C iCastings,Extrusions, etc.

2 Inspection Following Secondary Processing2. Inspection Following Secondary ProcessingMachiningWeldingGrindingGrindingHeat treatingPlating , etc.

3. Inspection of In service productCrackingCorrosionErosion/WearHeat Damage, etc.

Special Applicationsp pp

Power Plant inspection

Wire rope inspection

Aircraft inspection

Wire rope inspection

Special Applicationsp pp

Jet engine inspection Rail inspectiong

Conclusion

Looking towards the large importance and application of NDT is the great type of technology, which is going to increase worldwide and we are sure that there will not be a single manufacturing industry which will not use this technology. And also there are special education is present for NDT and its part of engineering curriculumpresent for NDT and its part of engineering curriculum now.

Referencesf

Referred websites:-www.ndt-ed.org www.ndt.org

Thanks to ,

Amit GolaitPoonam KanojiaProf : Mrs. Kirti Agashe