non-destructive testing by group-e members 1 jude rinaldo 2 jude pradeep 3 aaryl dsa 4 swaroop...
TRANSCRIPT
NON-DESTRUCTIVE TESTING
by GROUP-E
MEMBERS 1 JUDE RINALDO2 JUDE PRADEEP3 AARYL D’SA4 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
There are five of non destructive tests:
Visual examinationDye penetrant testMagnetic particle inspectionRadiographic inspectionUltra sonic inspection
NON-DESTRUCTIVE TESTING
VISUAL EXAMINATIONAny surface defects are noticed by the
experienced and responsible personnel
Some of the defects are: Incorrect bead shape High spatters Under cutting Bad stop and start points Incorrect alignment Surface cracks
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
VISUAL EXAMINATION
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
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
DYE PENETRANT TEST
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
Advantages Portable Fast and rapid Low cost Defects like cracks, slag inclusions and gas porosities
can be detected
DisadvantagesCan be used only in Ferro-magnetic
material only
MAGNETIC PARTICLE INSPECTION
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
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 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
RADIOGRAPHIC INSPECTION
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
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
ULTRASONIC INSPECTION