Non-Destructive Examination Methods Flashcards

When performing wet fluorescent magnetic particle testing (WFMT) on a pressure vessel weld, what is the primary advantage over dry magnetic particle testing?

Answer: Higher particle mobility allowing detection of fine, tight discontinuities

Wet fluorescent magnetic particle testing provides higher sensitivity for fine and tight discontinuities because liquid suspension allows particles to migrate more freely to weak leakage fields.

In ultrasonic testing using the pulse-echo technique, what does a high-amplitude back-wall echo that suddenly disappears during scanning indicate?

Answer: A large planar discontinuity is reflecting the sound beam away

Loss of back-wall echo during UT scanning typically indicates a large planar discontinuity (such as a lamination or large crack) oriented perpendicular to the sound beam, redirecting energy away from the transducer.

Per API 510, which NDE method is most appropriate for detecting subsurface hydrogen-induced cracking (HIC) in pressure vessel shells?

Answer: Ultrasonic testing

Ultrasonic testing is most appropriate for detecting subsurface HIC because it can locate internal discontinuities, whereas PT and MT are limited to surface and near-surface indications.

What is the purpose of the reference block (IIW block or equivalent) used during ultrasonic testing calibration?

Answer: To establish distance amplitude correction (DAC) curves and verify equipment sensitivity

Reference calibration blocks are used to establish DAC curves and verify that the UT instrument is set to the correct sensitivity level for the specific examination.

During radiographic testing of a pressure vessel butt weld, the density of the radiograph is too low. What is the most likely corrective action?

Answer: Increase the exposure time or increase the kV/Ci

Low radiographic density means insufficient radiation reached the film; increasing exposure time or source strength (kV or Ci) will increase the density to the acceptable range.

In eddy current testing of heat exchanger tubes, what condition is indicated by a phase angle reading that falls in the mix channel and shows a figure-eight pattern on the impedance plane?

Answer: Denting or tube support plate interference

A figure-eight or suppressed signal in the mix channel during eddy current inspection of tubes is characteristic of tube support plate signals or denting, which must be mixed out to detect underlying corrosion.

Which of the following statements about acoustic emission (AE) testing is correct as applied to pressure vessel inspection per API 510?

Answer: AE monitors for active defects that emit stress waves during pressurization

Acoustic emission testing monitors for active, growing discontinuities that release stress waves during pressurization or load application, making it useful for in-service screening.