This document discusses non-destructive testing (NDT) methods. It introduces destructive and non-destructive testing, with NDT allowing detection of internal flaws without impairing the component. Various NDT methods are described including visual inspection, liquid penetrant, magnetic particle, ultrasonic, radiography, acoustic emission and thermography testing. Specific NDT techniques like hammer testing and oil whitening are also outlined along with their applications in industries like steel plants and railroads.

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*INTRODUCTION TO NDT
*By:
Zoha Nasir
Assistant professor
JIT, Barabanki

2. *
In order to confirm that our product is free from any
harmful defects or flaws and to determine there
mechanical properties certain test are conducted,
mainly divided into two groups:
Destructive testing
Non destructive testing.
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3. Destructive testing: In this test specimens of materials are
fractured and the tests are performed on them.
Non-destructive testing: In this method, detection of internal
flaws in materials ,components is done without impairing its
future usefulness, means test are performed on components
without breaking them.
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NDT methods are very useful in several fields:
In automotive-engine parts, frame and other accessories.
Aviation field space and air frame.
In power plant- propeller, engines, gas turbines, heat exchangers etc.
In surface flaws, cracks, gagging, dimensions etc..
In construction of bridges, structures.
Manufacturing of machine parts, casting, forging
Submarines, naval ships
Medical applications( X-rays and gamma rays)
In railways.
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Visual inspection: 1- with naked eye.
2-with optical aids.
Liquid penetrant: 1-zyglo testing.
2-dye and wet powder.
3-oil whitening.
Magnetic particle testing: DC and AC magnetization.
Eddy current inspection.
Ultrasonic testing.
Radiography: 1-Xray radiography.
2-gamma rays radiography.
Accoustic emission testing.
Thermography.
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One of the oldest technique of testing.
It is used for knowing hot cracks in the weld metal
or partially melted zone because it imposes a
relatively high restrained in the weld zone transverse
to the weld.
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In this object is hammered or ringed, if the metal
produces a good ringing sound then it indicates that
it contain no defect other wise flat sound indicate the
presence of some defect.
We can use stethoscope to magnify the sound.
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Blacksmiths for checking the utensil of iron.
Sword smith.
Bell makers.
To test the structural welds.
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It is also known as oil whitening test.
The basic procedure of this test is:
i. Dip the part into thinned oil.
ii. Paint with white coating.
iii. Powder is dried/oil comes through capillary action.
iv. Powder becomes brown.
v. Inspection.
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In heavy steel plants.
Rail road industry.
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