2 ndt tests steel
TRANSCRIPT
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The Big Five NDE Methods for
Steel structures Visual Examination (VT) Penetrant Examination (PT) Magnetic Particle Examination (MT) Ultrasonic Examination (UT)
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Radiographic Examination (RT)
Visual Examination (VT)
inspection
Effective form of quality assurance Most extensively used NDE method
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Visual ExaminationAdvantages Disadvantages
Quick Inexpensive Comprehensive
experience
Need clean, lightedarea
Surface onl
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mp e oo s Measuring tools lighting cleaning
Penetrant Examination
into cracks by capillary action
Surface is cleaned, but penetrant is trappedin cracks
cracks are revealed where the enetrant
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remains
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PT Procedure
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Penetrant ExaminationAdvantages Disadvantages
quick Inexpensive Simple equipment
afterSurface onlyRequires smooth
surface
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asy n erpre a on
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Magnetic Particle Examination
(MT)
electro-magnetization Permanent magnets
At cracks, magnetic field leaks
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on surface are attracted to leaks providing
indication
MT Concept
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MT Concept
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Magnetic Particle ExaminationAdvantages Disadvantages
Economical Quick Can go over thin coating Near surface flaws
detectable
only
Electricity usuallyrequired
Arc strikes No substantial sub-surface
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etect on Detection can be difficult
on rough surfaces
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Ultrasonic Examination (UT)
A sound wave is directed through tested material Sound waves reflect at interface of different medium - -
waves Application:
Detect and evaluate flaws inside components (i.e. cracks, voids) Weld examination
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UT ConceptDistance = Velocity Time
Back surfaceBack surface
echoecho
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Example of longitudinal testingExample of longitudinal testing
Void echoVoid echo
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Example of longitudinal testingExample of longitudinal testing
UT Concept Signal path analogous to light
reflection Use angle beam (shear
waves) Vary transducer orientation
14Similarities between reflectionsSimilarities between reflectionsof light and sound boundariesof light and sound boundaries
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UT flaw detectorUT flaw detector
UT Field Inspection
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Ultrasonic ExaminationAdvantages Disadvantages
Immediate result Versatile Accurate
Skilled operator
required Fillet welds
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anardiscontinuities
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2121
2222
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Radiographic Examination
(RT) -.
Radiation is absorbed by the test piece Thick or dense areas absorb more Thin or open areas absorb less
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Film measures passed radiation providing indication Light areas represent areas hard to penetrate Dark areas represent areas easy to penetrate
(discontinuity)
RT Concept: Detection
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Application: Good tool in measuring general/uniform wall thickness
loss.
Good tool for locating localized corrosion. Provide actual icture (film ne ative of item/area
inspected. Qualitative results for assessment of corrosion severity
generally require supporting methods (manual UT) .
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Radiographic ExaminationAdvantages Disadvantages
Detects surface andinternal
Planar discontinuityorientation
Provides permanent record(to scale!)
accurate
Radiation hazard (largearea must be evacuateddue to radiation concern)
Initial cost/size limitation Requires skilled operators/
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nterpreters Must access both sides Relatively slow due to
radiation control and filmprocessing
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Ima e can be viewed in real time.
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Excellent tool for location welds under insulation. Little to no ability to locate general/uniform wall loss. Good tool for detecting localized corrosion-external only. Assessment in strictly qualitative.