2. 1.1 Introduction
1. This module presents information on the NDT method of radiographic inspection
or radiography.
2. Radiography uses penetrating radiation that is directed towards a component.
3. The component stops some of the radiation. The amount that is stopped or
absorbed is affected by material density and thickness differences.
4. These differences in “absorption” can be recorded on film, or electronically.
5. Detection of internal defects such as porosity, voids and inclusions
Fig (1)
2
3. 1.2 Electromagnetic Radiation
The radiation used in Radiography testing is a higher energy (shorter
wavelength) version of the electromagnetic waves that we see every day.
Visible light is in the same family as x-rays and gamma rays.
Fig (2)
3
4. 1.3 Technology development
The essential difference between X-Rays and Gamma Rays and other
electromagnetic radiations such as light, Ultra-violet rays and infrared rays
from the testing and evaluation point of view is that X-Ray and Gamma Rays
are able to penetrate matter which is opaque to light but have a
photographic action similar to light.
Fig (3)
4
5. 1.4 Characteristics of Gamma Radiation and X-Rays :-
1. Gamma radiation and X-rays are electromagnetic radiation like visible
light, radio waves, and ultraviolet light. These electromagnetic radiations
differ only in the amount of energy they have.
2. Gamma radiation is able to travel many meters in air and many
centimeters in human tissue. It readily penetrates most materials and is
sometimes called "penetrating radiation”
3. Radioactive materials that emit gamma radiation and X-rays constitute
both an external and internal hazard to humans.
4. Gamma radiation or X-rays frequently accompany the emission of alpha
and beta radiation.
Fig (4)
5
6. 1.5 Advantages of Radiography
1. -Technique is not limited by material type or density.
2. -Can inspect assembled components.
3. -Minimum surface preparation required.
4. -Sensitive to changes in thickness, corrosion, voids, cracks, and material
density changes.
5. -Detects both surface and subsurface defects.
6. -Provides a permanent record of the inspection.
1.6 Disadvantages of Radiography
1. -Many safety precautions for the use of high intensity radiation.
2. -Many hours of technician training prior to use.
3. -Determining flaw depth is impossible without additional angled exposures.
4. -Expensive initial equipment cost.
5. Access to both sides of sample required.
6. Orientation of equipment and flaw can be critical.
6
7. 1.7 General Principles of 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
through the test object.
Fig (5)
7
8. 2.1 X-ray
1. Electromagnetic radiations.
2. Wavelength of x rays 0.01 to 10 nanometers longer than gamma rays.
3. Can penetrate some solids and liquids, and all uncompressed gases.
4. Used for diagnostic radiology.
2.2 Radiation Sources
Industrial radiography is often subdivided into “X-ray Radiography” or
“Gamma Radiography”, depending on the source of radiation used.
Fig (6)
8
9. 9
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10. 2.3 Computed Radiography
Computed Radiography (CR) is a digital imaging process that uses a
special imaging plate which employs storage phosphors.
Fig (7)
10
12. 2.4 Parts of X-ray machine
x-rays are produced by an X-ray generator
system,These systems typically include an:-
1) X-ray tube head
2) high voltage generator
3) control console
• X-rays are produced by establishing a very
high voltage between two electrodes, called
the anode and cathode.
• To prevent arcing, the anode and cathode are
located inside a vacuum tube, which is
protected by a metal housing.
Fig (8)
Parts of X-ray machine
control
12
13. Fig (10) X-ray Radiography
High Electrical Potential
Electrons
-+
X-ray Generator or
Radioactive Source
Creates Radiation
Exposure Recording Device
Radiation
Penetrate
the Sample
• The cathode contains a small
filament much the same as in a
light bulb.
• Current is passed through the
filament which heats it. The heat
causes electrons to be stripped
off.
• The high voltage causes these
“free” electrons to be pulled
toward a target material (usually
made of tungsten) located in the
anode.
• The electrons impact against the
target. This impact causes an
energy exchange which causes
x-rays to be created.
13
14. Medicine: for medical analysis.
Industry: to inspect products made by various kinds of materials.
Science: to analyze the arrangement of atoms in many kinds of
substances, particularly crystals.
Consumer Goods: X-rays are also used in consumer goods the
manufactures treat certain kinds of plastic to check the quality of many
mass produced products.
Also suitable for detecting changes in
1. Material composition
2. Thickness measurement
3. Locating defective parts or components from
assembled part
14
15. 3.1 Gamma Radiography
1. Gamma-ray is often denoted by the Greek letter gamma,
2. Gamma-ray is a form of radiant energy from the atom nuclei emission of
radioactive substances or electromagnetic radiation produced by
radioactivity or nuclear
3. Gamma rays are produced by a radioisotope.
4. Gamma-ray wave length ranging is between 10–5 nm to 0.1 nm
5. Gamma-ray has frequencies between 1020 - 1025 Hz
3.2 The type that this inspection can detect:
1. cracks
2. non-uniformity of material
3. density change
4. weld defects
3.3 Equipment :
1. portable or fixed setups on industry / company requirement
2. traditional radiography requires film development facilities and equipment
15
16. 3.4 The occurrence of Gamma-ray
Gamma-ray () is resulted from the destruction of the merger process of two
high-energy atomic nuclei in atomic nuclei (gamma decay) and high-energy
particle interactions of sub-atomic in natural processes and man made
mechanisms.
Fig (11)
16
17. 3.5 Gamma ray use :-
1. medicine :- Gamma rays used in medicine for kill carcinogens cells and
prevent them from growing.
2. industry :- Gamma rays are used in industry to check the oil pipeline and
discover the weak points.
3. the field of science :- Gamma rays used in the development of nuclear
reactors and bombs.
3.6 Flaw Orientation :
Radiography has sensitivity limitations when detecting cracks.
Gamma-rays “see” a crack as a thickness variation and the larger the variation, the
easier the crack is to detect.
When the path of the Gamma-rays is not parallel to a crack, the thickness variation
is less and the crack may not be visible.
Fig (12)
17
18. 3.7 Question
λ = 1.10-4 nm
Velocity of the wave in vacuum is 3.108 m/s. Determine the frequency of
gamma-ray (λ = 1.10-4 nm)!
Known:
v = 3.108 m/s
λ = 1.10-4 nm
Asked:
f = ?
Answered:
f =
v
λ
f =
3 x108
1 x10− 4
x10−9
f = 3 x1021
Hz
18
19. 1919
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My first step in Islam :-
( http://www.1ststepsinislam.com/en/introduction.aspx )
Women in Islam :-
( http://womeninislam.ws/en/introduction.aspx )
The key to understanding Islam :-
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This is true :-
http://www.thisistruth.org/
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20. 20
Contans:-
1.1 Introduction
1.2 Electromagnetic Radiation
1.3 Technology development
1.4 Characteristics of Gamma Radiation and X-Rays
1.5 Advantages of Radiography
1.6 Disadvantages of Radiography
1.7 General Principles of Radiography
2.1 X-ray
2.2 Radiation Sources
2.3 Computed Radiography
2.4 Parts of X-ray machine
2.5 Uses
3.1 Gamma Radiography
3.2 The type that this inspection can detect
3.3 Equipment
3.4 The occurrence of Gamma-ray
3.5 Gamma ray use
3.6 Flaw Orientation
3.7 Question
