NON-DESTRUCTIVE TESTING

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NON-DESTRUCTIVE TESTING

• by
• GROUP-E
• MEMBERS
• 1 JUDE RINALDO
• 2 JUDE PRADEEP
• 3 AARYL DSA
• 4 SWAROOP SUNDER

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• Describe the five types of non-destructive test
  used in ship construction

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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

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NON-DESTRUCTIVE TESTING

• There are five of non destructive tests
• Visual examination
• Dye penetrant test
• Magnetic particle inspection
• Radiographic inspection
• Ultra sonic inspection

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VISUAL EXAMINATION

• Any 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

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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.

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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.

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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

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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

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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

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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

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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

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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

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MAGNETIC PARTICLE INSPECTION
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MAGNETIC PARTICLE INSPECTION

• Advantages
• 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

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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

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RADIOGRAPHIC INSPECTION

• Equipment used

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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

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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

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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

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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