API 510 Non-Destructive Examination Methods 5 — Questions and Answers
Question 1: Which NDE method is used in API 510 fitness-for-service evaluations to characterize the dimensions of an embedded crack-like flaw in a pressure vessel wall for fracture mechanics calculations?
- Magnetic particle testing for length measurement only
- Radiographic testing for through-wall depth determination
- Phased array ultrasonic testing (PAUT) for both length and through-wall height measurement (Correct answer)
- Eddy current testing for surface-breaking crack sizing
Correct answer: Phased array ultrasonic testing (PAUT) for both length and through-wall height measurement
Phased array UT (PAUT) combined with TOFD or conventional UT techniques is used to accurately characterize flaw height and length needed for fracture mechanics-based fitness-for-service assessment per API 579.
Question 2: What condition must be met before applying liquid penetrant testing to a pressure vessel that was in high-temperature service (above 500°F)?
- The surface must be at or below 125°F before applying penetrant (Correct answer)
- The surface must be cooled to ambient temperature and all scale removed by abrasive blasting
- Penetrant can be applied immediately if fluorescent materials are used
- The surface must be preheated to 200°F to improve penetrant flow
Correct answer: The surface must be at or below 125°F before applying penetrant
ASME Section V limits penetrant application to surfaces between 40°F and 125°F (unless procedure qualification covers other ranges), so hot surfaces must cool adequately before PT can be applied.
Question 3: During time-of-flight diffraction (TOFD) ultrasonic examination, what is the 'lateral wave' and why is it significant?
- A wave traveling along the outer surface used as a timing reference for shallow defect sizing (Correct answer)
- A wave that reflects off the inside surface used to measure wall thickness
- A creeping wave that travels along the inner bore and detects ID corrosion
- A mode-converted wave used to increase sensitivity to transverse cracks
Correct answer: A wave traveling along the outer surface used as a timing reference for shallow defect sizing
In TOFD, the lateral wave travels along the outer (entry) surface and arrives first at the receiver; it serves as a timing reference and defines the near-surface dead zone above which shallow defects cannot be resolved.
Question 4: Per API 510 and ASME V, when is a written NDE procedure required to be qualified and demonstrated?
- Only when the Authorized Inspector specifically requests a procedure demonstration
- For all NDE methods whenever ASME Code or API 510 requires written procedures (Correct answer)
- Only for radiography; all other NDE methods may use verbal instructions
- Only for new NDE technologies not listed in ASME Section V
Correct answer: For all NDE methods whenever ASME Code or API 510 requires written procedures
ASME Section V and API 510 require written, qualified procedures for all specified NDE methods to ensure repeatability, consistency, and documented technical basis for the examination.
Question 5: What is 'pulsed eddy current' (PEC) testing particularly advantageous for in pressure vessel inspection applications?
- Detecting surface cracks in welds without removing paint or coatings
- Measuring wall thickness through insulation, fireproofing, and coatings without removal (Correct answer)
- Measuring the tensile strength of pressure vessel base metal
- Detecting hydrogen embrittlement in high-strength steel components
Correct answer: Measuring wall thickness through insulation, fireproofing, and coatings without removal
Pulsed eddy current is specifically designed for screening wall thickness through insulation, fireproofing, and protective coatings, making it the primary tool for CUI detection surveys without insulation removal.
Question 6: Which of the following is a limitation of radiographic testing that makes it less suitable than UT for detecting planar flaws such as lack-of-fusion in heavy wall pressure vessel welds?
- RT cannot detect flaws deeper than 2 inches from the surface
- RT is most sensitive to volumetric flaws and may miss planar flaws not aligned with the radiation beam (Correct answer)
- RT requires the vessel to be in service during examination
- RT cannot be used on alloy steel materials above 2.5% chromium content
Correct answer: RT is most sensitive to volumetric flaws and may miss planar flaws not aligned with the radiation beam
Radiographic testing has poor sensitivity to planar discontinuities (cracks, lack-of-fusion) unless the flaw plane is closely aligned with the radiation beam, making UT preferred for detecting these crack-like flaws in heavy welds.
Question 7: During a magnetic particle test using the yoke technique, how is the adequacy of the magnetic field verified at the examination surface?
- By measuring the yoke's AC amperage draw with a clamp meter
- By using a calibrated Hall-effect gauss meter or a pie-shaped (Berthold) field indicator at the surface (Correct answer)
- By visually confirming the yoke poles are in contact with the test surface
- By checking that the yoke produces an audible hum during energization
Correct answer: By using a calibrated Hall-effect gauss meter or a pie-shaped (Berthold) field indicator at the surface
The adequacy of the magnetic field at the examination surface is verified using a calibrated Hall-effect gauss meter or a pie-shaped field indicator (also called a Berthold gauge) to confirm sufficient tangential field strength.
API 510 Non-Destructive Examination Methods 5
Which NDE method is used in API 510 fitness-for-service evaluations to characterize the dimensions of an embedded crack-like flaw in a pressure vessel wall for fracture mechanics calculations?