PRESENTATION ON NON-DESTRUCTIVE TEST (NDT)

1. DITYA INSTITUTE OF TECHNOLOGY
AND MANAGEMENT
DEPARTMENT OF MECHANICAL
ENGINEERING
Presentation on
Non-Destructive Testing (NDT)
Presented By
Niroj Kumar Yadav
13a51a0378

2. Contents
 Introduction
 Uses of Non-Destructive Testing (NDT)
 Six most common NDT methods
 Process of each NDT Method
 Advantages and limitations of NDT methods
 Conclusion

3. Introduction
What is NDT?
• Non-Destructive testing is the use of
noninvasive techniques to determine
the integrity of a material, component
or structure or quantitatively measure
some characteristics of an object. It is
the testing of materials, for surface or
internal flaws or metallurgical
condition, without interfering in any
way with the integrity of the material
or its suit
• i.e. Inspect or measure without doing
harm

4. Uses of NDT
• Flaw Detection and Evaluation
• Leak Detection
• Location Determination
• Dimensional Measurements
• Structure and Microstructure Characterization
• Estimation of Mechanical and Physical Properties
• Stress (Strain) and Dynamic Response Measurements
• Material Sorting and Chemical Composition Determination

5. Six Most Common NDT Methods
• Radiography Testing (RT)
• Ultrasonic Testing (UT)
• Magnetic Particle Testing (MPT)
• Liquid Penetrant Testing (DPT)
• Visual Testing (VT)
• Eddy Current Testing (ECT)

6. Radiography Testing (RT)
• Principle of RT is Differential Absorption.
• Radiography is an NDT method, which uses penetrating
radiation.
• In this inspection the source of radiation can be from
radioactive sources, typically Irridium-192, Cobalt-60,
Caesium-137, which emit gamma rays or from a specially built
machine that can emit X rays.

7. 7
X-ray film
Top view of developed film
Electrons
-+
Radiation
Penetrate
the Sample
Radiography Testing Process
X-ray Generator or
Radioactive
Source Creates
Radiation
Radioactive Source

8. Radiography Testing Process
The principles are the same for both X and Gamma radiography.
In X-radiography the penetrating power is determined by the
number of volts applied to the X-Ray tube - in steel
approximately 1000 volts per inch thickness is necessary. To
produce an X or Gamma radiograph, the film package is placed
close to the surface of the subject. The source of radiation is
positioned on the other side of the subject some distance away,
so that the radiation passes through the subject and on to the
film.

9. Radiography Testing Process
• After the exposure period the film is removed, processed,
dried, and then viewed by transmitted light on a special
viewer. Various radiographic and photographic accessories are
necessary, including such items as radiation monitors, film
markers, image quality indicators, darkroom equipment, etc.
Where the last is concerned there are many degrees of
sophistication, including fully automatic processing units.
These accessories are the same for both X and Gamma
radiography systems. Also required are such consumable items
as radiographic film and processing chemicals

10. Advantages :-
• Applicable to almost all
materials
• Produce permanent
images that are readily
retrievable for future
reference
• Capable of detecting
surface, subsurface and
internal discontinuities
Limitations :-
• Radiation used is
hazardous to workers
and members of public
• Expensive method
• Incapable of detecting
laminar discontinuities
• Require highly trained

11. Ultrasonic Testing
UT principle:- Acoustic Impedance
mismatch
This technique is used for the detection of
internal surface (particularly distant
surface) defects in sound conducting
materials. In this method high frequency
sound waves are introduced into a material
and they are reflected back from surface
and flaws. Reflected sound energy is
displayed versus time, and inspector can
visualize a cross section of the specimen
showing the depth of features.
11

12. High frequency sound waves are introduced into a material and they
are reflected back from surfaces or flaws.
Reflected sound energy is displayed versus time, and inspector can
visualize a cross section of the specimen showing 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 screen
Ultrasonic Testing

13. • Requires only one side
accessibility
• Capable of detecting
internal defect
• Not hazardous
• Very sensitive to planar
type discontinuity
• Suitable for automation
• Not capable of
detecting defect whose
plane is parallel to the
direction of sound beam
• Require the use of
couplant to enhance
sound transmission
• Require highly skillful
and experience operator
Limitations :-Advantages :-

14. Magnetic Particle Testing
This method is suitable for the detection
of surface and near surface
discontinuities in magnetic material,
mainly ferrite steel and iron. Magnetic
particle Testing (MPT) is a
nondestructive testing method used for
defect detection. MPT is fast and
relatively easy to apply, and material
surface preparation is not as critical as it
is for some other NDT methods.
14

15. 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.
SN
S N
N S
Magnetic Flux Line
Fig.1: Magnetized Metal with no crack Fig.2: Magnetized Metal with crack
CrackMagnetic Flux Leakage
Basic Principle of MPT

16. 16
Magnetic Particle Testing
Process
16
The first step in a magnetic
particle testing is to magnetize the
test component by a MPT
equipment. If there any defects on
the surface or near to the surface
are present, the defects will create
a leakage field.
Then finely milled iron particles coated with a dye pigment are
applied to the specimen. These particles are attracted to magnetic
flux leakage fields and will cluster to form an indication directly
over the defects. This indication can be visually detected under
proper lighting conditions.

17. Magnetic Particle Testing in
Super heater Pipe Welding
17
First the welding joint
is magnetized by MPT
equipment. Then finely
milled iron particles are
applied to the
magnetized weld joint.
Iron particles make a cluster at
the welding joint for magnetic
flux leakage because of welding
defects.
Cluster

18. Advantages :-
• Inexpensive
• Equipment are portable
• Equipment easy to operate
• Provide instantaneous
results
• Sensitive to surface and
subsurface discontinuities
Limitations :-
• Applicable only to
ferromagnetic materials
• Insensitive to internal
defects
• Require magnetization and
demagnetization of
materials to be inspected
• Require power supply for
magnetization
• Material may be burned
during magnetization

19. Liquid Penetrate Inspection
• Liquid penetrate is an NDT method that utilizes the principle
of capillary action in which liquid of suitable physical
properties can penetrate deep into extremely fine cracks or
pitting that are opened to the surface without being affected by
the gravitational force.

20. Advantages :-
• Simple to perform
• Inexpensive
• Applicable to materials with
complex geometry
Limitation :-
• Limited to detection of surface
breaking discontinuity
• Not applicable to porous
material
• Require access for pre- and
post-cleaning
• Irregular surface may cause the
presence of non-relevant
indication

21. Inspection of Raw Products
• Forgings,
• Castings,
• Extrusions,

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

23. conclusion
oIn India NDT is a new technology and system for inspection
and testing. But many developed countries use it because of its
huge benefits.
oModern NDT methods are becoming ever more quantitative
and non-intrusive. This is valid for NDT of new construction and
for maintenance inspections.