NDT Material Properties & Inspection Standards 2 — Questions and Answers
Question 1: What does the term 'anisotropy' mean in the context of boilermaker materials?
- Uniform properties in all directions
- Properties that vary depending on direction of measurement (Correct answer)
- Resistance to high-temperature oxidation
- Tendency to crack under cyclic loading
Correct answer: Properties that vary depending on direction of measurement
Anisotropy describes materials whose mechanical or physical properties differ based on the direction in which they are measured.
Question 2: Which ASME standard governs the inspection and testing of pressure vessels?
- ASME B31.3
- ASME Section VIII (Correct answer)
- ASME Section IX
- ASME B16.5
Correct answer: ASME Section VIII
ASME Section VIII, Division 1 and 2 cover the design, fabrication, and inspection requirements for pressure vessels.
Question 3: The hardness of a material is best defined as its resistance to:
- Fracture under impact loading
- Permanent surface indentation or scratching (Correct answer)
- Elastic deformation under tensile stress
- Fatigue under cyclic stress
Correct answer: Permanent surface indentation or scratching
Hardness is the material's resistance to localized plastic deformation, typically measured by indentation tests like Rockwell or Brinell.
Question 4: In NDT of boiler materials, what condition does 'hydrogen embrittlement' describe?
- Loss of ductility due to hydrogen absorption into the metal lattice (Correct answer)
- Formation of hydrogen gas bubbles during welding
- Corrosion of steel caused by hydrogen sulfide gas
- Reduction in tensile strength due to elevated temperatures
Correct answer: Loss of ductility due to hydrogen absorption into the metal lattice
Hydrogen embrittlement occurs when atomic hydrogen diffuses into metal, reducing ductility and increasing susceptibility to cracking.
Question 5: What is the purpose of a Charpy impact test on boiler plate material?
- Determine the tensile strength at elevated temperatures
- Measure resistance to fatigue cracking
- Evaluate notch toughness and ductile-to-brittle transition temperature (Correct answer)
- Assess the material's resistance to surface corrosion
Correct answer: Evaluate notch toughness and ductile-to-brittle transition temperature
The Charpy V-notch test measures how much energy a material absorbs during fracture, indicating toughness and the temperature at which it transitions from ductile to brittle behavior.
Question 6: Under ASME Section V, which article specifically covers radiographic examination?
- Article 1
- Article 2 (Correct answer)
- Article 5
- Article 7
Correct answer: Article 2
ASME Section V, Article 2 provides the requirements and procedures for radiographic examination of welds and materials.
Question 7: Which type of steel is most commonly used in high-pressure boiler drum construction due to its combination of strength and weldability?
- Austenitic stainless steel (304)
- Low-alloy chromium-molybdenum steel (Correct answer)
- Cast iron
- High-carbon tool steel
Correct answer: Low-alloy chromium-molybdenum steel
Chromium-molybdenum low-alloy steels offer excellent high-temperature strength, creep resistance, and good weldability, making them ideal for pressure vessel and boiler construction.
NDT Material Properties & Inspection Standards 2
What does the term 'anisotropy' mean in the context of boilermaker materials?