Non Destructive Examination

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Non Destructive Examination

• (NDE)

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Non Destructive Examination (NDE)

• Non Destructive Examination is the act of
  evaluating a welded component (or material to be
  welded) without affecting the serviceability of
  the part or material.

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NDE

• All Welds have flaws.
• Another name for a flaw is a discontinuity
• Discontinuities are interruptions in the normal
  crystalline structure (or grain) of the metal.
• Discontinuities are NOT always defects

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NDE

• The purpose of welding inspections is to locate
  and determine the size of any discontinuities
• Discontinuities that are to large or repeat too
  often within the weld become defects
• Defects will compromise the welds overall
  strength

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What are some common defects?

• Porosity
• Undercutting
• Rollover or Cold Lap
• Slag inclusion
• Poor penetration
• Voids
• Hydrogen Embrittlement

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Typical faults in a finished weld.
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How would you find these faults ?

• Non Destructive Examination
  NDE

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Common methods used in NDE

• Visual Inspection (VT)
• Magnetic Particle Inspection (MT)
• Liquid (Dye) Penetrant Inspection (PT)
• X-Ray inspection (RT)
• Ultrasonic testing (UT)
• Air or water pressure testing (LT)

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Visual Inspection (VT)

• Visual is the most common inspection method
• VT reveals spatter, excessive buildup,
  incomplete slag removal, cracks, heat distortion,
  undercutting, poor penetration
• Typical tools for VT consist of Fillet gauges
  Magnifying glasses, Flashlights, Tape measures
  or calipers.

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Visual Inspection (VT)

• Fillet gauges measure
• The Legsof the weld
• Convexity
• (weld rounded outward)
• Concavity
• (weld rounded inward)
• Flatness

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Magnetic Particle Inspection (MT)

• Magnetic Particle Inspection (commonly referred
  to as Magnaflux testing) is only effective at
  checking for flaws located at or near the
  surface.
• MT uses a metallic power or liquid along with
  strong magnetic field probes to locate flaws.
  (Particles will align along voids)
• MT can only be used on materials that can be
  magnetized

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Liquid (Dye) Penetrant Inspection (PT)

• Liquid penetrant inspection uses colored or
  fluorescent dye to check for surface flaws.
• PT will not show sub-surface flaws.
• PT can be used on both metallic and non metallic
  surfaces such as ceramic, glass, plastic, and
  metal.
• PT dose not require the part to be Magnetized.

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X-Ray inspection (RT)

• Welds may be checked for internal discontinuities
  my means of X- Rays
• An X-Ray is a wave of energy that will pass
  through most materials and develop the negative
  image of what it passes through on film.
• A Radiograph ( X-Ray picture) is a permanent
  record of a weld used for quality inspection
  purposes
• RT inspections can reveal flaws deep within a
  component

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Ultrasonic testing (UT)

• Ultrasonic testing (UT) is a method of
  determining the size and location of
  discontinuities within a component using high
  frequency sound waves.
• Sound waves are sent through a transducer into
  the material and the shift in time require for
  their return or echo is plotted.
• Ultrasonic waves will not travel through air
  therefore flaws will alter the echo pattern.

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Air or water pressure testing (LT)

• Pressure testing or leak testing can be
  performed with either gasses or liquids.
• Voids that allow gasses or liquids to escape from
  the component can be classified as gross (large)
  or fine leaks.
• Extremely small gas leaks measured in PPM (parts
  per million) require a Mass Spectrometer to
  Sniff for tracer gases

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Quiz time

• True or False ?
• Dye penetrate inspections can only be used on non
  magnetic material.
• Answer False

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Quiz time

• True or False ?
• X-Rays can only be used to locate flaws at or
  near the surface of a weld.
• Answer False

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Quiz time

• True or False ?
• Virtually all welds have flaws.
• Answer True

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Quiz time

• True or False ?
• Magnetic particle testing can only detect flaws
  at or near the surface.
• Answer True

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Quiz time

• True or False ?
• Magnet particle testing can only be done on
  materials that can be magnetized.
• Answer True

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Quiz time

• The letters NDE Mean ___________ ?
• A nondestructive inspection
• B nondestructive evaluation
• C nondisruptive evaluation
• D nondestructive examination

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Quiz time

• The method most often used to check for leaks as
  small as one part per million (PPM) from a gas
  line or cylinder is the _________ Method ?
• A hydrostatic
• B mass spectrometer
• C soap suds bubble
• D scleroscope

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Modern WeldingYork County School of Technology