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Non-destructive testing — method picker

Pick the right NDT for the damage mechanism

Capability matrix across 11 methods (VT / PT / MT / UT / PAUT / TOFD / RT / ECT / IRIS / IRT / AE). Rank by what you're hunting (cracks / thinning / corrosion), filter by base material or geometry.

PTPenetrant Testing

ASME V Article 6 · ASTM E165 / E1417 · ASNT TC-1A
cracks
best
thinning
no
corrosion
limited
cost
low
speed
med
pros
  • Detects very fine surface cracks
  • Inexpensive
  • Portable
cons
  • Surface only
  • Surface-prep critical
  • Solvent disposal hazard
access: clean surface · 5-min dwell
applicable: non-magnetic metals (austenitic SS, Al, Cu, Ti), ceramics, glass

MTMagnetic Particle Testing

ASME V Article 7 · ASTM E709 / E1444 · ASNT TC-1A
cracks
best
thinning
no
corrosion
limited
cost
low
speed
fast
pros
  • Very sensitive to surface cracks
  • Faster than PT
  • Detects shallow sub-surface
cons
  • Ferromagnetic only (304/316 won't work)
  • Demagnetization may be needed
access: access for yoke or coil · ferromagnetic only
applicable: ferromagnetic CS / low-alloy / 12Cr martensitic

PAUTPhased-Array UT

ASME V Article 4 (mandatory annex) · ASTM E2700
cracks
best
thinning
best
corrosion
best
cost
high
speed
fast
pros
  • Best modern technique for weld inspection
  • B/C/D/S-scans for archive
  • Replaces RT for fitness-for-service
cons
  • Capital cost (~$50-100k system)
  • Calibration block per geometry
  • Skilled operator
access: one-side access · couplant
applicable: girth + longitudinal welds, thick CS/SS, Code Case 2235

TOFDTime-of-Flight Diffraction

ASME V Article 4 Appendix N · ASTM E2373
cracks
best
thinning
limited
corrosion
limited
cost
high
speed
fast
pros
  • Sub-millimetre crack-tip sizing
  • Best for in-service crack monitoring
  • Code-acceptable for FFS
cons
  • Two-sided access mandatory
  • Capital + skill needed
  • Geometry sensitivity
access: two-side access (across weld)
applicable: heavy-wall pressure-vessel welds, HIC / fatigue cracks

UTUltrasonic Testing — manual + AUT

ASME V Article 4 · ASTM E114 / E797 / E2375 · ASNT TC-1A
cracks
good
thinning
best
corrosion
best
cost
med
speed
med
pros
  • Quantitative thickness
  • Detects internal cracks
  • Single-sided access
cons
  • Needs couplant
  • Coarse-grain SS / Inconel can scatter
  • Operator skill matters
access: one-side access · couplant
applicable: most metals, thick wall (UT covers up to ~250 mm)

RTRadiographic Testing

ASME V Article 2 · ASTM E94 / E747 / E1742 · ASNT TC-1A
cracks
good
thinning
limited
corrosion
limited
cost
med
speed
slow
pros
  • Permanent record (film / DR)
  • Volumetric coverage
  • Good for casting porosity
cons
  • Radiation exposure / shielding
  • Slow (1-4 h per shot)
  • Misses tight cracks parallel to beam
  • Replaced by PAUT in modern fabrication
access: two-side access for film placement · radiation safety zone
applicable: all metals, butt welds, castings

ECTEddy Current Testing

ASME V Article 8 · ASTM E309 / E2096
cracks
good
thinning
good
corrosion
good
cost
med
speed
fast
pros
  • No couplant
  • Fast tube inspection
  • Pit detection in HEX tubes
cons
  • Conductivity-dependent
  • Limited depth (~5 mm)
  • Liftoff-sensitive
access: probe access · liftoff < 1 mm
applicable: conductive non-magnetic preferred (Al, Ti, SS), HEX tube ID via IRIS / ECT array

AEAcoustic Emission

ASME V Article 12 · ASTM E569 / E976 · ASNT TC-1A
cracks
good
thinning
limited
corrosion
limited
cost
med
speed
fast
pros
  • Detects active cracking in real time
  • Localises source from time-of-arrival
  • Monitors during hydrotest
cons
  • Detects only growing flaws (not dormant)
  • Background noise filtering needed
  • Calibration intensive
access: permanent transducer array
applicable: storage tanks during hydrotest, pressure-vessel stress-test, continuous monitoring

VTVisual Testing

ASME V Article 9 · ASNT TC-1A
cracks
limited
thinning
limited
corrosion
good
cost
low
speed
fast
pros
  • Cheapest
  • Universal first step
  • No special equipment beyond borescope
cons
  • Surface only
  • Misses tight cracks
  • Operator-dependent
access: direct line of sight (with mirror / borescope optional)
applicable: all materials, all geometries

IRISIRIS — Internal Rotary UT

ASTM E2118
cracks
limited
thinning
best
corrosion
best
cost
high
speed
med
pros
  • Quantitative wall thickness all 360°
  • Finds OD pitting + ID erosion
  • Best HEX tube tech
cons
  • Tube must be water-filled
  • Slow per tube
  • Capital cost
access: tube ID · water fill
applicable: HEX tubes, small-bore tubing

IRTInfra-Red Thermography

ASTM E1316 / E2582 · ISO 18434-1
cracks
no
thinning
limited
corrosion
limited
cost
med
speed
fast
pros
  • No contact
  • Wide-area screening
  • CUI under insulation jacket
cons
  • Indirect — confirms with UT
  • Surface emissivity matters
  • Wind / sun affect
access: line of sight + thermal contrast
applicable: CUI screening, refractory loss, electrical hot-spots, composite delamination
Sources: ASME V (NDE) · ASTM E-series (per method) · ASNT SNT-TC-1A (qualification) · API 510 / 570 / 653 (in-service inspection codes). For damage-mechanism-specific NDT recommendations see /console/failure-atlas.