API 510 Welding Inspection 3 — Questions and Answers
Question 1: Per API 510, who has the authority to approve a welding repair procedure for a pressure vessel?
- The welding foreman
- The plant manager
- The Authorized Pressure Vessel Inspector (Correct answer)
- The vessel owner only
Correct answer: The Authorized Pressure Vessel Inspector
The Authorized Pressure Vessel Inspector (API 510 Inspector) has the authority to approve repair procedures for pressure vessels.
Question 2: What NDE method is most appropriate for volumetric examination of a completed groove weld in a pressure vessel shell plate?
- Visual Testing (VT)
- Magnetic Particle Testing (MT)
- Radiographic Testing (RT) or Ultrasonic Testing (UT) (Correct answer)
- Liquid Penetrant Testing (PT)
Correct answer: Radiographic Testing (RT) or Ultrasonic Testing (UT)
RT and UT are volumetric methods capable of detecting internal discontinuities such as porosity, slag, and lack of fusion within the weld volume.
Question 3: When a welder is qualified for a particular base metal P-Number group under ASME IX, that qualification generally covers welding of:
- Only that specific material grade
- All P-Numbers within the same group and certain other P-Numbers per ASME IX rules (Correct answer)
- Any material in the entire ASME IX P-Number system
- Only materials with the same nominal composition
Correct answer: All P-Numbers within the same group and certain other P-Numbers per ASME IX rules
ASME Section IX qualification for a P-Number group covers all materials within that group and extends to other groups as specifically permitted by the code.
Question 4: An API 510 inspector finds porosity clustered at the weld stop/start location. The most likely root cause is:
- Excessive preheat temperature
- Contamination or improper arc restart technique (Correct answer)
- Incorrect filler metal diameter
- Over-tight weld joint fitup
Correct answer: Contamination or improper arc restart technique
Clustered porosity at weld start/stop locations is typically caused by contamination, moisture, or improper arc restart technique that traps gas in the solidifying weld pool.
Question 5: For a pressure vessel weld repair involving a P-No. 1 carbon steel material with a wall thickness of 1.5 inches, what preheat temperature is typically required per ASME Section I/VIII and referenced by API 510?
- No preheat required
- 150°F (65°C) minimum (Correct answer)
- 200°F (93°C) minimum
- 300°F (149°C) minimum
Correct answer: 150°F (65°C) minimum
For P-No. 1 carbon steel above 1 inch thickness, ASME typically requires a minimum preheat of 150°F (65°C) to prevent hydrogen cracking.
Question 6: The essential variables in a Welding Procedure Specification (WPS) are important because a change in an essential variable requires:
- Only a revision to the WPS document
- Requalification of the welding procedure with a new PQR (Correct answer)
- Notification to the jurisdiction only
- Re-testing of the welders only
Correct answer: Requalification of the welding procedure with a new PQR
A change in an essential variable alters the mechanical properties of the weld and therefore requires requalification of the procedure with a new Procedure Qualification Record (PQR).
Question 7: When performing a visual inspection of a fillet weld, the inspector measures the weld leg size and finds it is undersized. Which geometric property of the fillet weld determines its structural load-carrying capacity?
- The weld length
- The throat dimension (Correct answer)
- The reinforcement height
- The bead width
Correct answer: The throat dimension
The effective throat of a fillet weld, measured from the root perpendicular to the hypotenuse, determines the cross-sectional area and load-carrying capacity of the weld.
API 510 Welding Inspection 3
Per API 510, who has the authority to approve a welding repair procedure for a pressure vessel?