API 510 Non-Destructive Examination Methods 2 — Questions and Answers
Question 1: When performing wet fluorescent magnetic particle testing (WFMT) on a pressure vessel weld, what is the primary advantage over dry magnetic particle testing?
- Higher particle mobility allowing detection of fine, tight discontinuities (Correct answer)
- Ability to inspect non-ferromagnetic materials
- No requirement for demagnetization after testing
- Faster inspection speed for large surface areas
Correct 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.
Question 2: In ultrasonic testing using the pulse-echo technique, what does a high-amplitude back-wall echo that suddenly disappears during scanning indicate?
- The transducer has lost contact with the surface
- A large planar discontinuity is reflecting the sound beam away (Correct answer)
- The material thickness has increased
- The couplant has been fully absorbed
Correct 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.
Question 3: Per API 510, which NDE method is most appropriate for detecting subsurface hydrogen-induced cracking (HIC) in pressure vessel shells?
- Liquid penetrant testing
- Magnetic particle testing
- Ultrasonic testing (Correct answer)
- Visual inspection
Correct 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.
Question 4: What is the purpose of the reference block (IIW block or equivalent) used during ultrasonic testing calibration?
- To verify the chemical composition of the base metal
- To establish distance amplitude correction (DAC) curves and verify equipment sensitivity (Correct answer)
- To determine the couplant viscosity required for the examination
- To measure the surface roughness prior to scanning
Correct 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.
Question 5: During radiographic testing of a pressure vessel butt weld, the density of the radiograph is too low. What is the most likely corrective action?
- Decrease the source-to-film distance
- Increase the exposure time or increase the kV/Ci (Correct answer)
- Use a faster film speed
- Reduce the amount of lead screen backing
Correct 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.
Question 6: 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?
- Through-wall pitting on the tube OD
- Denting or tube support plate interference (Correct answer)
- A crack oriented axially along the tube
- Ferromagnetic deposits on the tube ID
Correct 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.
Question 7: Which of the following statements about acoustic emission (AE) testing is correct as applied to pressure vessel inspection per API 510?
- AE can only be performed on vessels that are out of service and depressurized
- AE monitors for active defects that emit stress waves during pressurization (Correct answer)
- AE provides exact defect sizing in millimeters
- AE replaces the requirement for periodic thickness measurements
Correct 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.
API 510 Non-Destructive Examination Methods 2
When performing wet fluorescent magnetic particle testing (WFMT) on a pressure vessel weld, what is the primary advantage over dry magnetic particle testing?