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Non destructive testing

ROHIT S TEMGIRE ANIKET BIRAJDAR

(PATIL)

TY MECHANIC

K E S POLYTECHNIC

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Introduction to

Nondestructive Testing

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The use of noninvasivetechniques to determine

the integrity of a material,

component or structure

or

quantitatively measure

some characteristic of

an object.

i.e. Inspect or measure without doing harm.

Definition of NDT

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Type of Nondestructive

Testing

• 1 Visual testing

•

2 Dye-penetrent testing• 3 Magnetic Partical testing

• 4 Ultrasonic testing

• 5 Radiographic (X-rays) testing• 6 Eddy current testing

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What are Some Uses

of NDE Methods?

• Flaw Detection and Evaluation

• Leak Detection

• Location Determination

• Dimensional Measurements• Structure and Microstructure Characterization

• Estimation of Mechanical and Physical Properties

•Stress (Strain) and Dynamic ResponseMeasurements

• Material Sorting and Chemical Composition

Determination

Fluorescent penetrant indication 

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Common pplication

of NDT

• Inspection of Raw Products

• Inspection Following SecondaryProcessing

• In-Services Damage Inspection

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Most basic and common

inspection method.

Tools include fiberscopes,

borescopes, magnifying

glasses and mirrors.

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 Inspection

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2

1. Section of material with asurface-breaking crack that

is not visible to the naked

eye.

2. Penetrant is applied to

the surface.

3. Excess penetrant is

removed.

4. Developer is applied,

rendering the crack visible

Liquid penetrant testing

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Liquid Penetrant

Inspection

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RadiographyThe radiation used in radiography testingis a higher energy (shorter wavelength)version of the electromagnetic waves thatwesee as visible light. The radiation cancome from an X-ray generator or aradioactive source.

High Electrical Potential

Electrons

-+

X-ray Generatoror Radioactive

Source Creates

Radiation

Exposure Recording Device

RadiationPenetrate

the Sample

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Film Radiography

Top view of developed film 

X-ray film

The part is placed between the radiation

source and a piece of film. The part will

stop some of the radiation. Thicker and

more dense area will stop more of the

radiation.

= more exposure

= less exposure

The film darkness

(density) will vary with

the amount of radiation

reaching the film throughthe test object.

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Radiographic Images

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

Reflected sound energy is displayed versus time, andinspector can visualize a cross section of the specimenshowing the depth of features that reflect sound. f

plate

crack

0 2 4 6 8 10

initial

pulse

crack

echo

back surface

echo

Oscilloscope, or

flaw detector

Ultrasonic Inspection (Pulse-Echo)

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Conductivematerial 

Coil Coil'smagnetic field 

Eddycurrents 

Eddy current'smagnetic field 

Eddy Current Testing 

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15 

Magnetic Partical testing

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16 

→Introduction of the Magnetic

Field

1.Using a permanent magnet or anelectromagnet that contacts the test piece

2.Flowing an electrical current through thespecimen

3.Flowing an electrical current through a coil

of wire around the part or through a centralconductor running near the part.

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Power Plant Inspection

Prob

eSignals produced

by variousamounts of

corrosion thinning.

Periodically, power plants are

shutdown for inspection.

Inspectors feed eddy current

probes into heat exchanger tubes

to check for corrosion damage.

Pipe with damage

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18 

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