API 510 Repair and Alteration Standards 3 — Questions and Answers
Question 1: According to API 510, a weld overlay repair used to restore wall thickness must have a minimum deposited thickness that meets:
- The minimum required wall thickness per the applicable code (Correct answer)
- Any thickness as long as NDT shows no flaws
- Twice the original corroded thickness
- 0.125 inches regardless of design pressure
Correct answer: The minimum required wall thickness per the applicable code
Weld overlay (cladding) must restore the wall to at least the minimum required thickness calculated per the applicable construction code.
Question 2: When an existing pressure vessel nozzle is being replaced, the replacement nozzle must conform to:
- The original construction code or a later edition approved by the jurisdiction (Correct answer)
- Only the current ASME Section VIII requirements
- API 510 inspection requirements only
- The manufacturer's original design drawings with no deviation allowed
Correct answer: The original construction code or a later edition approved by the jurisdiction
Replacement nozzles must conform to the original construction code or a later code edition acceptable to the jurisdiction.
Question 3: Which preheat practice is used to prevent hydrogen cracking in high-strength low-alloy (HSLA) steel repair welds?
- Maintaining elevated preheat and interpass temperatures throughout welding (Correct answer)
- Quenching immediately after each weld pass
- Welding at ambient temperature with no preheat
- Using only the highest heat input to dilute hydrogen
Correct answer: Maintaining elevated preheat and interpass temperatures throughout welding
Maintaining proper preheat and interpass temperatures slows the cooling rate and allows hydrogen to diffuse out before cracking can occur.
Question 4: In API 510, the term 'fitness-for-service' (FFS) evaluation is used to:
- Assess whether a degraded vessel can continue to operate safely under defined conditions (Correct answer)
- Determine the frequency of future inspections only
- Replace hydrostatic testing requirements for new vessels
- Certify a vessel for a higher MAWP
Correct answer: Assess whether a degraded vessel can continue to operate safely under defined conditions
A fitness-for-service evaluation assesses the structural integrity and remaining life of a vessel with degradation to determine if continued operation is safe.
Question 5: When a pressure vessel shell is repaired by inserting a full-circumference insert plate, the longitudinal weld seams of the insert must be:
- Offset from the original shell seams by a minimum distance specified in the code (Correct answer)
- Aligned exactly with the original shell seams
- Eliminated by using a seamless insert plate only
- Welded from one side only without back-gouging
Correct answer: Offset from the original shell seams by a minimum distance specified in the code
Insert plate longitudinal seams must be offset from the original seams to avoid weld intersections that concentrate stress.
Question 6: After completing welded repairs, what is the preferred method to verify the repair weld's integrity in a vessel that had active corrosion?
- Hydrostatic test or pneumatic test per the applicable code (Correct answer)
- Visual inspection only
- Radiographic testing of every inch of weld
- Hardness testing across the weld
Correct answer: Hydrostatic test or pneumatic test per the applicable code
A pressure test (hydrostatic or pneumatic) is the preferred verification after welded repairs, confirming the repaired area can sustain the design conditions.
Question 7: Which of the following welding processes is classified as a 'low-hydrogen' process and is preferred for repairing pressure vessel steels?
- Submerged arc welding (SAW) and gas metal arc welding (GMAW) (Correct answer)
- Shielded metal arc welding (SMAW) with E6010 electrodes
- Oxyacetylene welding
- Carbon arc welding
Correct answer: Submerged arc welding (SAW) and gas metal arc welding (GMAW)
SAW and GMAW are inherently low-hydrogen processes; when SMAW is used, low-hydrogen (EXX18) electrodes are required for pressure vessel repairs.
API 510 Repair and Alteration Standards 3
According to API 510, a weld overlay repair used to restore wall thickness must have a minimum deposited thickness that meets: