8/6/2019 Introduction to NDT Methods
1/23
Nondestructive Tests
Prepared by:
Mostafa Mohammed Ahmed Aref
TWI
8/6/2019 Introduction to NDT Methods
2/23
We use Non Destructive Testing (NDT) when we wish to
assess the integrity of a structure without destroying it
Types of NDT used are:
Dye penetrant inspection (PT)
Magnetic particle inspection (MT)
Radiographic inspection (RT)
Ultrasonic inspection (UT)
Introduction
8/6/2019 Introduction to NDT Methods
3/23
Dye penetrant inspection(PT)
8/6/2019 Introduction to NDT Methods
4/23
Surface breaking defects only detected
Penetrant applied to the component and drawn
into the defects by capillary action
Applicable to all non- porous materials.
Introduction
8/6/2019 Introduction to NDT Methods
5/23
Procedure
8/6/2019 Introduction to NDT Methods
6/23
Two types of penetrants are:
1) ColourColour contrastcontrast 2) Fluorescent PenetrantFluorescent Penetrant
Any penetrant that has been drawn into a crack by capillary
action will be drawn out into the developer
Once the contact time has elapsed, the penetrant isremoved and a developer is then applied
First the work must be cleaned thoroughly, then a
penetrant is applied for a specified time
Procedure
8/6/2019 Introduction to NDT Methods
7/23
Apply Penetrant Clean then apply Developer Result
Method
8/6/2019 Introduction to NDT Methods
8/23
Magnetic particle inspection(MT)
8/6/2019 Introduction to NDT Methods
9/23
Surface and slight sub-surface detection
Relies on magnetization of component being tested
Ferro-magnetic materials only can be tested
Methods of applying a magnetic field, yoke, permanent magnetand prods.
Any defect which interrupts the magnetic field, will create aleakage field, which attracts the particles
Introduction
8/6/2019 Introduction to NDT Methods
10/23
Collection of ink
particles due to
leakage field
Prods
DC or AC
Electro-magnet
(yoke) DC or AC
Crack like
indication
Crack likeindication
Method
8/6/2019 Introduction to NDT Methods
11/23
The types of magnetic media used are:
1) Wet ink1) Wet ink 2)2) Dry powderDry powder 3)3) Fluorescent inkFluorescent ink
The weld length must be crossed at 90by the magnetic field
A magnetic ink is applied which will concentrate in areas of
flux leakage, as those caused by flaws
First the work must be cleaned and a whitener applied for
contrast. A magnetic flux is then applied by permanent magnet,
electro magnet, or straight current
Procedure
8/6/2019 Introduction to NDT Methods
12/23
Contrast paint Magnet & Ink Result
Method
8/6/2019 Introduction to NDT Methods
13/23
Radiographic inspection(RT)
8/6/2019 Introduction to NDT Methods
14/23
Radiation is transmitted to varying degrees dependant upon
the density of the material through which it is travelling
Thinner areas and materials of a less density show as darkerareas on the radiograph
Thicker areas and materials of a greater density show as
lighter areas on a radiograph
Applicable to metals, non-metals and composites
Introduction
8/6/2019 Introduction to NDT Methods
15/23
The 2 types of radiation used in industrial radiography:
1) X rays (from Cathode Ray Tube)
2) Gamma rays (from a Radioactive Isotope)
Any imperfections in line with the beam of radiation will be
shown on the film after exposure and development
A film is placed inside a cassette between lead screens.
It is then placed to the rear of the object to be radiographed
A radiographic source, is exposed to the work and film for a
pre-calculated time
Procedure
8/6/2019 Introduction to NDT Methods
16/23
Source
Radiation beamImage quality indicator
Test specimenRadiographic film
Method
8/6/2019 Introduction to NDT Methods
17/23
Source
Radiation beamImage quality indicator
Radiographic film with latent image after exposure
Test specimen
Method
8/6/2019 Introduction to NDT Methods
18/23
Ultrasonic inspection(UT)
8/6/2019 Introduction to NDT Methods
19/23
This detection method uses high frequency sound waves,
typically above 2MHz to pass through a material
A probe is used which contains a piezo electric crystal totransmit and receive ultrasonic pulses and display the signals on
a cathode ray tube or digital display
The actual display relates to the time taken for the ultrasonic
pulses to travel the distance to the interface and back
An interface could be the back of a plate material or a defect
Introduction
8/6/2019 Introduction to NDT Methods
20/23
Any imperfections will rebound the sound waves causing a
signal to occur on the cathode ray tube
A probe is then applied with the correct angle for the weld
preparation and sound waves are transmitted
First the work must be cleaned thoroughly, then a couplant is
applied to increase sound transmission
Procedure
8/6/2019 Introduction to NDT Methods
21/23
Apply Couplant Sound wave
Signal reboundedSignal rebounded
from Lack of fusionfrom Lack of fusion
CRT display
Result
Method
8/6/2019 Introduction to NDT Methods
22/23
defect
0 10 20 30 40 50
defect
echoBack wall
echo
CRT DisplayCompression Probe
Material Thk
initial pulse
Method
8/6/2019 Introduction to NDT Methods
23/23
Top Related