This document provides information on non-destructive testing (NDT) methods. It discusses several NDT techniques including dye penetrant testing, magnetic particle testing, ultrasonic testing, eddy current testing, and radiography testing. For each method, it describes the basic principles, applications, advantages, and limitations. The key NDT methods covered allow for detection of surface and internal defects without damaging the test components. The document aims to educate about non-destructive evaluation and quality control techniques for metal parts.

1. MATERIAL SCIENCE AND METALLURGY
ALA ON
“NON DESTRUCTIVE TESTING”
Branch : Mechanical
Prepared by: Chandresh Suthar

2. NDT

3. NON-DESTRUCTIVE TESTING
•Non destructive testing(NDT) is one of
the important methods used for
evolution and quality control of metal
components
•During testing, the metal component
does not get damaged
•These tests are used to locate or find out
the defects or flaws in the component

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. BASIC ELEMENTS OF NDT METHOD
•SOURCE
•MODIFICATION
•DETECTION
•INDICATION
•INTERPRETATION

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

8. DYE PENETRANT TEST
•Used for detect the surface cracks or defects
•One of the most widely used NDT methods
•Used to inspect almost any material provided
that its surface is not extremely rough
•It is used for surface detection of forging,
casting, weld elements

9. PROCESS FOR DPT
• CLEANING
• DRYING OF
SURFACE
• APPLICATION OF
PENETRATE
• REMOVAL OF
EXCESS OF
PENETRATE
• APPLICATION OF
DEVELOPER

11. ADVANTAGES OF DPT
• All types of solids and non ferrous materials can be tested
• Economical and easy to use
• Indications are produced directly on the surface of the part and constitute
a visual representation of the flaw
• Does not require any machine or instrument
• Does not require electronic display or calculations

12. LIMITATIONS OF DPT
• Only surface defects can be detected
• The inspector must have direct access to the surface being inspected
• Surface films like paints or coating may interfere with the results
• Cleaning is must before and after the test to avoid rusting
• Cannot be applied to porous materials

13. 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

14. 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.

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

16. 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

17. 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

18. ULTRASONIC TESTING
• A typical UT system consists of several functional units, such as
the pulser/receiver, piezoelectric transducer, and display devices.
• A pulser/receiver is an electronic device that can produce high
voltage electrical pulses.
• Driven by the pulser, the transducer generates high frequency
ultrasonic energy.
• The sound energy is introduced and propagates through the
materials in the form of waves.
• When there is a discontinuity (such as a crack) in the wave path,
part of the energy will be reflected back from the flaw surface.
• The reflected wave signal is transformed into an electrical signal
by the piezo electrical transducer and is displayed on a screen.

19. PULSE-ECHO METHOD

20. TRANSMISSION METHOD

21. 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

22. 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.

23. ULTRASONIC MEASUREMENT

24. 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.

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

26. 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

27. 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.

28. 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.

29. RADIOGRAPHY TESTING
PROCESS

30. DIFFERENCE BETWEEN X RAY AND
GAMMA RAY RADIOGRAPHY
X RAYS GAMMA RAYS
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

31. RADIOGRAPHY

32. 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.

33. 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

34. RADIOGRAPHY

35. 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

36. Ultrasonic
testing
Radiography
testing

37. 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