Inspection, Testing, and Non-Destructive Examination
What this domain tests
Inspection and NDE questions test method selection, coverage, calibration and acceptance. You must know when RT, UT, PAUT, TOFD, MT, PT, ET or ACFM is appropriate, and how thickness surveys support API 510/570 intervals.
Core rules and concepts
- Surface methods (MT, PT) find surface and near-surface discontinuities; volumetric methods (RT, UT) find internal ones. UT is strong for thick welds and corrosion mapping; RT is strong for porosity and fusion defects but has orientation limits.
- Procedure qualification, calibration and surface preparation are mandatory. UT thickness gauging needs couplant, known velocity and a verified probe.
- Inspect at the worst-case location: low points, welds, nozzles, supports and dead zones. A grid of readings is better than a few spot readings.
- Acceptance criteria come from the construction code, not from the inspector's preference.
Worked example
A vessel has t_actual = 13.6 mm at the critical grid point, t_min = 10.0 mm, and a verified corrosion rate of 0.35 mm/y. Remaining life = (13.6 - 10.0)/0.35 = 10.3 years. If the next planned inspection is in 5 years, the predicted thickness is 13.6 - 0.35(5) = 11.85 mm, still above t_min; if inspection is in 12 years, it is not.
Traps that cost marks
Reporting an average thickness that hides a pit; using the wrong couplant or velocity; missing weld orientation with RT; accepting a discontinuity without the correct code criterion; skipping calibration checks.