NDT Material Properties & Inspection Standards 5 — Questions and Answers
Question 1: What is the primary purpose of radiographic testing (RT) in boiler weld inspection?
- Measure the hardness of the heat-affected zone
- Detect volumetric discontinuities such as porosity and inclusions within the weld (Correct answer)
- Determine residual stress distribution across the weld
- Measure the depth of surface cracks
Correct answer: Detect volumetric discontinuities such as porosity and inclusions within the weld
RT uses X-ray or gamma radiation to reveal internal volumetric discontinuities (porosity, slag inclusions, lack of fusion) as density variations on film or digital detector.
Question 2: In boiler inspection, 'pitting corrosion' is characterized by:
- Uniform thinning across a large surface area
- Localized attack forming small cavities or pits on the metal surface (Correct answer)
- Rapid oxidation of the entire outer surface
- Delamination of protective oxide layers
Correct answer: Localized attack forming small cavities or pits on the metal surface
Pitting corrosion creates localized cavities that penetrate deep into the metal while the surrounding surface remains relatively unaffected, making it particularly dangerous in pressure equipment.
Question 3: What does the Brinell Hardness Number (BHN) test measure?
- The energy absorbed during a high-speed impact
- The depth of penetration by a diamond pyramid under a specific load
- The diameter of indentation made by a hardened steel ball under a fixed load (Correct answer)
- The rebound height of a dropped ball bearing
Correct answer: The diameter of indentation made by a hardened steel ball under a fixed load
The Brinell test applies a fixed load to press a hardened steel ball into the material surface, then calculates hardness from the ratio of load to the curved area of the indentation.
Question 4: Which document type in an ASME pressure vessel file contains the complete material certifications, NDE reports, and final inspection records?
- Material test report (MTR)
- Design specification sheet
- Manufacturer's data report (Form U-1) (Correct answer)
- Non-conformance report (NCR)
Correct answer: Manufacturer's data report (Form U-1)
The ASME Manufacturer's Data Report (Form U-1) is the official document certifying that the vessel was manufactured and inspected in accordance with ASME Section VIII requirements.
Question 5: The term 'heat-affected zone' (HAZ) in a weld refers to:
- The zone where base metal was melted and solidified during welding
- The region of base metal adjacent to the weld that was not melted but experienced microstructural changes due to heat (Correct answer)
- The discolored area on the surface caused by welding fumes
- The zone in the weld metal where porosity is most likely to occur
Correct answer: The region of base metal adjacent to the weld that was not melted but experienced microstructural changes due to heat
The HAZ is the portion of base metal that was not melted but whose microstructure and properties were altered by the heat of welding.
Question 6: According to ASME Section V, who is responsible for establishing written NDE procedures?
- The authorized inspector (AI) employed by the jurisdiction
- The owner-user of the pressure vessel
- The manufacturer or contractor performing the examination (Correct answer)
- The NDE equipment manufacturer
Correct answer: The manufacturer or contractor performing the examination
ASME Section V requires the manufacturer or contractor performing NDE to establish, document, and qualify written procedures that meet the applicable code requirements.
Question 7: What property distinguishes a ferritic steel from an austenitic steel in terms of magnetic behavior?
- Ferritic steels are non-magnetic; austenitic steels are magnetic
- Both ferritic and austenitic steels are equally magnetic
- Ferritic steels are magnetic; austenitic steels are generally non-magnetic (Correct answer)
- Magnetism is unrelated to the crystal structure of these steels
Correct answer: Ferritic steels are magnetic; austenitic steels are generally non-magnetic
Ferritic steels have a body-centered cubic (BCC) crystal structure and are ferromagnetic, while austenitic steels have a face-centered cubic (FCC) structure and are generally non-magnetic.
NDT Material Properties & Inspection Standards 5
What is the primary purpose of radiographic testing (RT) in boiler weld inspection?