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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 thesurface.

MT uses a metallic power or liquid along

with strong magnetic field probes to locateflaws. (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 ofX- Rays

AnX-Ray is a wave of energy that will passthrough 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 inspectionpurposes

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 usinghigh frequency sound waves.

Sound waves are sent through a transducer

intothe material and the shift in timerequire 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 bubbleD: scleroscope

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Modern WeldingYork County School of Technology