Transcript NON-DESTRUCTIVE TESTING

NON-DESTRUCTIVE
TESTING
by
GROUP-E
MEMBERS
1 JUDE RINALDO
2 JUDE PRADEEP
3 AARYL D’SA
4 SWAROOP SUNDER
Describe the five types of
non-destructive test used in
ship construction
NON-DESTRUCTIVE TESTING
 In this process the material is tested for any flaws
without applying any kind of stress
 The test piece is not destroyed or deformed
 Non-destructive tests are desirable for materials that are
costly or difficult to fabricate or that have been formed
into finished or semi finished products.
 At the end of these tests there are no damage to the
components
 Non-destructive testing is required to enable the
soundness of ship welds to be assessed
NON-DESTRUCTIVE TESTING
There are five of non destructive tests:
 Visual examination
 Dye penetrant test
 Magnetic particle inspection
 Radiographic inspection
 Ultra sonic inspection
VISUAL EXAMINATION
Any surface defects are noticed by the
experienced and responsible personnel
Some of the defects are:
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Incorrect bead shape
High spatters
Under cutting
Bad stop and start points
Incorrect alignment
Surface cracks
VISUAL EXAMINATION
 Visual inspection can be simply visual i.e. with the naked
eye or at magnifications up to 40 times.
 This test can be done in conjunction with NDT or as
stand alone.
 When this test is done as stand alone then it is used for
identifying macro manufacturing defects.
VISUAL EXAMINATION
 When used in conjunction
with NDT it is essentially
applied at every stage
involving human eye e.g.
reading measuring
instrument screens.
 This forms the simplest
form of investigation used
as there are no
sophisticated and costly
instruments used.
VISUAL EXAMINATION
Advantages
 It is a routine procedure
 The cost of visual inspection is low
 It can be very effective where examination is
made before,during, and after welding
DYE PENETRANT TEST
Process
 Liquid ( containing either dye or ultra violet-sensitive
substances) is sprayed onto specimen
 The liquid is drawn into the crack by capillary action, then
by highlighting its presence after application of a
developing agent
 It will show up a surface flaw
 To aid the detection of a surface crack, the dye is often
luminous and is revealed under an ultra violet light
DYE PENETRANT TEST
The dye penetrant test consists of the following steps:
 The surface of the metal to be inspected is cleaned first and a
low viscosity penetrant is sprayed on.
 After a set time the surface is cleaned again.
 Then a developer is coated on the surface the dye seeps out if
there is any crack and stains the developer red
DYE PENETRANT TEST
Advantages
 A simple way to detect surface opening cracks and
porosities in non porous and clean specimen
 Low-cost
 It can detect small defect on smooth and clean
surfaces
Disadvantages
 Cannot be used for rough and dirty surfaces
MAGNETIC PARTICLE INSPECTION
Process
 It is carried out by locally magnetizing the specimen by
a yoke or a coil
 Then by spreading a fluid of magnetic particles e.g. iron
fillings suspended in paraffin on its surface
 Any discontinuity such as a surface crack will show up
as the particles will concentrate at the point where there
is an alteration in the magnetic field
MAGNETIC PARTICLE INSPECTION
 A component is place between two poles of a
magnet The lines of magnetism concentrate around
flaws.
 Magnetic particles are then applied, in a light oil or
dry sprayed, onto the surface where they indicate the
lines of magnetism and any anomalies
MAGNETIC PARTICLE INSPECTION
MAGNETIC PARTICLE INSPECTION
Advantages
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Portable
Fast and rapid
Low cost
Defects like cracks, slag inclusions and gas porosities
can be detected
Disadvantages
 Can be used only in Ferro-magnetic material
only
RADIOGRAPHIC INSPECTION
Process
 A material is subjected to
radiation from one side, and
record the radiation emitted
from the opposite side
 Either x ray or gamma ray
devices may be used to provide
the source of radiation
 Ant obstacle in the path of the
radiation will affect the radiation
density emitted and may be
recorded
 As radiation will expose photo
graphic plates, they are used to
record the emitted rays
 The photographic plates
records changes in radiation
density emitted
 Thus any defects in welding can
be found out by this method
RADIOGRAPHIC INSPECTION
Equipment used
RADIOGRAPHIC INSPECTION
Advantages
 It can give a permanent record of the test for future
evidence
 It is a quick process
 Accurate results
Disadvantages
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Cannot use for thick sections
Cannot use in places of difficult access
The process fails without electricity
To interpret the weld radiograph a large amount of
experience is required
gamma rays is an alternative to x rays
because of this disadvantages
ULTRASONIC INSPECTION
Process
 The principle of
ultrasonic inspection
depends on the fact that
pulses of ultrasonic
energy are reflected
from any surface which
they encounter
 Virtually total reflection
occurs at an air-metal
interface, and therefore
to get the ultrasonic
wave into the metal a
liquid (usually grease) is
placed between the
source and metal
 Pulsed beams of
ultrasonic waves pass
through the object
ULTRASONIC INSPECTION
 Waves traveling through a plate may be reflected from
the surface of the metal and also from the surfaces of any
flaws in the metal
 A receiver detects the reflected waves signal, which is
displayed after signal amplification and analysis by the
instrument
 The pattern of reflection is revealed on either Cathode
ray tube or liquid crystal display
 From that we will be able to recognize type and location
of flaws
ULTRASONIC INSPECTION
Advantages
 Low cost
 Equipments used are easy to handle
 No health hazards
 The technique is used for locating fine cracks, which
are missed by radiography
 They can also be used for assessing the thickness of
structural members