NDT is a group of analysis techniques used to evaluate materials, components, or systems without damaging them. Some common NDT methods include dye penetrant testing, magnetic particle testing, ultrasonic testing, eddy current testing, and radiography testing. NDT is useful for detecting internal and surface flaws in materials and components, evaluating assemblies and systems, validating integrity and reliability, and maintaining safety. It allows for inspection and evaluation to take place without destroying the sample being analyzed.

1. What is NDT?
• Nondestructive testing or non-
destructive testing (NDT) is a wide
group of analysis techniques used in
science and technology
industry to
evaluate
material,
component
the properties of
a or system
without
causing damage.
• The terms nondestructive examination
(NDE), nondestructive inspection (NDI),
and nondestructive evaluation (NDE)
are also commonly used to describe this
technology.

2. • Because NDT does not permanently alter
the article being inspected, it is a highly
valuable technique that can save both
money and time in product evaluation,
troubleshooting, and research.

3. NDT does not directly measure mechanical
properties but they are used to locate defects
or flaws in the component.
Flaws reduce useful life of component
resulting in premature failure even with a
sound design and proper selection of
materials.
To obtain high level of reliability , defect
should be absent or at minimum level.
 NDT is carried out periodically.
Replacement of component before its
premature failure to avoid dangerous results.

4. ADVANTAGES OF NDT
• The equipments are easy to handle
• Defects can be detected without damaging the
components
• Methods are quick and accurate
• Components can be sorted out on the basis of
electrical, magnetic or chemical properties
• Test results and other information can be
conveniently recorded on paper films, cassettes
and floppies

5. DIFFERENCE BETWEEN DESTRUCTIVE
AND NON DESTRUCTIVE TEST
NON DESTRUCTIVE TEST DESTRUCTIVE
TEST
Used for finding out defects of
materials
Used for finding out the properties
of the material
Load is not applied on the material Load is applied on the material
No load applications, so no chance
for material damage
Due to load application, material
gets damaged
No requirement of special
equipments
Special equipments are required
Non expensive Expensive
Less skill Skill is required
e.g: dye penetrate test, ultrasonic,
radiography, etc
e.g: tensile test, compression test,
hardness test, etc

6. METHODS OF NDT
• Dye Penetrant Testing (DPT)
• Magnetic Particle Testing (MPT)
• Ultrasonic Testing (UT)
• Eddy Current Testing (ECT)
• Radiography Testing (RT)

7. 1.Dye Penetrant Inspection
Invisible cracks, porosity and other defects on
the surface of components easily detected by
this technique.
Components may be ferrous, nonferrous,
plastic, glass or ceramic.
 Procedure:-
1. Cleaning of surface.(Grease, oil, any
other material).
2. Drying of surface.

8. 3. Applying dye-penetrant on clean and dry
surface. It is allowed to penetrate in surface
flaws.
i) Liquid Soluble Penetrant
ii) Fluroscent
4. Removing excess penetrant by soft or clean
cotton.
5. Applying developer on surface. This pulls out
dye from flaws and flaws are revealed by
colour of dye. Instead of developer, fine
developing powder or talc powder can be
sprinkled on the surface.

10. PROCESS FOR DPT
https://www.youtube.com/watch?v=bHTRmTQDZzg

13. Advantages of Dye Penetrant Inspecti
• This test can be applied to almost any type
of metals, nonmetals, magnetic or non
magnetic type.
• Simple to utilize and control.
• Results of test can be interpreted fastly.
• Cost of test is very less as it does not
require any instrument or electronic
display units.
• Sensitivity is greater than that of magnetic
particle testing.

14. Disadvantages of Dye Penetrant
Inspection
• Cleaningof componentsis must before
and after testing to avoid rusting
• Misleading results may be obtained in case
of components with surface films and
coatings
• Only surface defects can be detected
• Test is not applicable for powder
metallurgical components

15. MAGNETIC PARTICLE TESTING
• This method is suitable for the detection of
surface and near surface discontinuities in
magnetic material , mainly ferrite steel and
iron
• METHODS OF MPT
• Dry method
• Wet method

16. PRINCIPLE OF MPT
• In the first figure the magnetized metal has no crack and there
only two poles that is north pole and south pole.
• And in second figure the magnetized metal has a crack and at
the crack point there creates another north and south pole for
the magnetic flux leakage.

17. MPT Procedure
1. Cleaning Surface
2. Magnetization
3. Application of ferromagnetic
Powder
4. Observation and Inspection
5. Demagnetization
https://www.youtube.com/watch?v=sfjK1GZ2W9A

18. MPT IN GAS PIPE WELDING
Particles make a cluster at the welding joint for magnetic flux
leakage because of welding defects.

19. ADVANTAGES OF MPT
• Principally and relatively simple method
• Economical and easy to perform
• Portable for field testing
• Fast for production testing
• Reveal or disclose small surface flaws or
cracks which may be tight

20. LIMITATIONS OF MPT
• Material must be ferromagnetic
• Orientation and strength of magnetic field is
critical
• Detects surface and near-to-surface
discontinuities only
• Large currents are required

21. Principle-
1.Measure of time required by ultrasonic
vibrations to penetrate material of interest ,
reflect from opposite side or from internal
discontinuity and return to point from where
first introduced.
2.Behaviour of waves through cycle with
regard to time is recorded on CRO screen.
3.By observing this presence of defect and
their location can be detected.
Two types of Ultrasonic testing
method- i)Pulse –echo method
3.Ultrasonic Test/inspection

22. PULSE-ECHO METHOD
https://www.youtube.com/watch?v=DwYQilMGPFk

23. TRANSMISSION METHOD

24. ADVANTAGES OF ULTRASONIC TESTING
• Thickness and lengths up to 30 ft can be
tested
• Position, size and type of defect can be
determined
• Instant test results
• Portable
• Capable of being fully automated
• Access to only one side necessary

25. LIMITATIONS OF ULTRASONIC TESTING
• The operator can decide whether the test
piece is defective or not while the test is in
progress.
• Considerable degree of skill necessary to
obtain the fullest information from the test.
• Very thin sections can prove difficult.

26. ULTRASONIC MEASUREMENT

27. EDDY CURRENT TESTING(ECT)
• Used to detect surface flaws, to
measure thin walls from one surface
only
• To measure thin coating sand in some
applications to measure depth. This
method is applicable to electrically
conductive materials only
• In this method eddy currents are
produced in the product by bringing
it close to an alternating current
carrying coil.
• The main applications of the eddy
current technique are for the
detection of surface or subsurface
flaws, conductivity measurement and
coating thickness measurement.
https://www.youtube.com/watch?v=NILzyvEaiPE

28. APPLICATION OF ECT
• Crack Detection
• Corrosion Monitoring
• Material Thickness Measurements
• Coating Thickness Measurements
• Conductivity Measurements

29. ADVANTAGES OF ECT
• Sensitive to small cracks and other defects
• Detect surface and near surface defects
• Inspection gives immediate results
• Equipment is very portable
• Method can be used for much more than flaw
detection
• Inspects complex shapes and sizes of
conductive materials

30. LIMITATIONS OF ECT
• Only conductive materials can be inspected
• Skill and training required is more extensive
than other techniques
• Surface finish and roughness may interfere
• Depth of penetration is limited.

31. RADIOGRAPHY
• Radiography Testing (RT), or
industrial radiography is NDT
method of inspecting materials for
hidden flaws by using the ability of
short wavelength electromagnetic
radiation (high energy photons)to
penetrate various materials
• Radiographic Testing Method is
nothing but to take the shadow
picture of an object onto a film by
the passage of X-ray or Gamma ray
through it
• It is the same as the medical
radiography (X-ray). Only
difference in their wave length.

32. RADIOGRAPHY TESTING PROCESS
https://www.youtube.com/watch?v=7oR_l8nXdmo

33. DIFFERENCE BETWEEN X RAY AND GAMMA
RAY RADIOGRAPHY
X RAYS GAMMARAYS
Larger wavelength Shorter wavelength
Less penetration power High penetration power
Used for components having thickness
up to 62mm
Used for more thickness components
Only one component can be examined
at a time
Many components can be examined at
a time
Equipment is larger in size Equipment is smaller in size
More intensity and faster Less intensity and slower

34. RADIOGRAPHY

35. LIMITATIONS OF RADIOGRAPHY
• Possible health hazard
• Need to direct the beam accurately for two-
dimensional defects
• Film processing and viewing facilities are
necessary
• Not suitable for automation
• Not suitable for surface defects.

36. APPLICATION OF RADIOGRAPHY
• For detection of internal defects
• For detection of porosity, casting, lack of
fusion in welding, cracks
• For measurement of geometry variation
and thickness of components

37. RADIOGRAPHY

38. ULTRASONIC TESTING RADIOGRAPHY TESTING
Less flaw detection capabilities More flaw detection capabilities
Compared to radiography less
operational
safety is required
More operational safety is required as
the
radiations are harmful
Probe is used Probe is not used
Better accuracy and reliability Very fast method of testing
Operated manually Less or no manual work
Used for detection of internal defect,
measurement of conductivity and
crack depth
For detection of internal defects,
porosity, casting, lack of fusion in
welding, cracks, measurement of
geometry variation and thickness of
components

39. Ultrason
ic
testing
Radiograp
hy testing

40. Common Application of NDT
• Inspection of Raw Products
• Inspection Following Secondary
Processing
• In-Services Damage Inspection

41. Inspection of Raw Products
• Forgings,
• Castings,
• Extrusions,
• etc.

42. • Machining
• Welding
• Grinding
• Heat treating
• Plating
• etc.
Inspection Following
Secondary Processing

43. • Cracking
• Corrosion
• Erosion/Wear
• Heat Damage
• etc.
Inspection For
In-Service Damage

44. Power Plant Inspection
Probe
Signals produced by
various amounts 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

45. Wire Rope Inspection
Electromagnetic devices and
visual inspections are used to
find broken wires and other
damage to the wire rope that is
used in chairlifts, cranes and
other lifting devices.

46. Storage Tank Inspection
Robotic crawlers use
ultrasound to inspect
the walls of large above
ground tanks for signs
of thinning due to
corrosion.
Cameras on long
articulating arms
are used to
inspect
underground
storage tanks for
damage.

47. Aircraft Inspection
• Nondestructive testing is used
extensively during the
manufacturing of aircraft.
• NDT is also used to find cracks
and corrosion damage during
operation of the aircraft.
• A fatigue crack that started at the
site of a lightning strike is shown
below.

48. Jet Engine Inspection
• Aircraft engines are overhauled after
being in service for a period of time.
• They are completely disassembled,
cleaned, inspected and then
reassembled.
• Fluorescent penetrant inspection is
used to check many of the parts for
cracking.

49. Sioux City, Iowa, July 19, 1989
A defect that went
undetected in an
engine disk was
responsible for the
crash of United Flight
232.
Crash of United Flight 232

50. Pressure Vessel Inspection
The failure of a pressure vessel can
result in the rapid release of a large
amount of energy. To protect against
this dangerous event, the tanks are
inspected using radiography and
ultrasonic testing.

51. Rail Inspection
Special cars are used to inspect
thousands of miles of rail to
find cracks that could lead to a
derailment.

52. Bridge Inspection
• The US has 578,000
highway bridges.
• Corrosion, cracking and
other damage can all affect
a bridge’s performance.
• The collapse of the Silver
Bridge in 1967 resulted in
loss of 47 lives.
• Bridges get a visual
inspection about every 2
years.
• Some bridges are fitted with
acoustic emission sensors
that “listen” for sounds of
cracks growing.

53. NDT is used to inspect pipelines to
prevent leaks that could damage the
environment. Visual inspection,
radiography and electromagnetic testing
are some of the NDT methods used.
Remote visual inspection using a
robotic crawler.
Radiography of weld joints.
Magnetic flux leakage inspection. This
device, known as a pig, is placed in the
pipeline and collects data on the
condition of the pipe as it is pushed
along by whatever is being
transported.
Pipeline Inspection

54. Special Measurements
Boeing employees in Philadelphia were given the privilege of evaluating
the Liberty Bell for damage using NDT techniques. Eddy current methods
were used to measure the electrical conductivity of the Bell's bronze
casing at a various points to evaluate its uniformity.

55. CONCLUSION
• NDT is a new technology and system for
industrial inspection and testing
• Many developed countries uses this
technology because of its huge benefits
• Modern NDT methods will become just as an
important tool for risk based inspection
approaches and maintenance planning
• For this purpose every industry should have a
NDT division with NDT personnel

56. REFERENCES
• Material Science and Metallurgy for
Engineers by V D Kodgire and S V
Kodgire