API 510 Repair and Alteration 5 — Questions and Answers
Question 1: Under API 510, an authorized inspector must be present to witness which activity during a vessel repair?
- All grinding operations
- Final closure welds on the pressure boundary (Correct answer)
- All surface preparation activities
- Painting and coating application
Correct answer: Final closure welds on the pressure boundary
The authorized inspector must witness critical repair steps including final closure welds to verify compliance with the approved repair procedure.
Question 2: A vessel that requires repair due to fire damage must first be evaluated for:
- Cost of repair vs. replacement only
- Metallurgical changes caused by the elevated temperatures before repair welding begins (Correct answer)
- Surface rust and scale removal only
- Whether the nameplate is still readable
Correct answer: Metallurgical changes caused by the elevated temperatures before repair welding begins
Fire damage can cause metallurgical degradation, sensitization, or loss of heat treatment in the vessel material, which must be evaluated before any repair welding.
Question 3: Which of the following best describes an acceptable alternative to a hydrostatic test after a pressure vessel repair?
- Visual inspection by two independent inspectors
- A pneumatic test at a reduced pressure with appropriate safety precautions (Correct answer)
- A vacuum box test on all weld seams
- A magnetic particle test of the repair welds only
Correct answer: A pneumatic test at a reduced pressure with appropriate safety precautions
A pneumatic test can substitute for a hydrostatic test when it is impractical to fill the vessel with water, provided appropriate safety precautions are taken per the applicable code.
Question 4: When a repair involves replacing a section of vessel shell with new material, the replacement material must be:
- The same heat and lot as the original material
- Of equal or superior specification to the original material per the applicable code (Correct answer)
- The cheapest material meeting minimum strength requirements
- Approved only by the repair organization's metallurgist
Correct answer: Of equal or superior specification to the original material per the applicable code
Replacement materials must meet or exceed the specification of the original material to ensure equivalent pressure-containing capability.
Question 5: Under API 510, which of the following conditions would NOT typically classify as an alteration?
- Installing a new manway in a vessel shell
- Replacing a corroded nozzle with an identical nozzle of the same size and material (Correct answer)
- Increasing the vessel's MAWP by modifying the shell thickness
- Changing the vessel's service to a more corrosive fluid
Correct answer: Replacing a corroded nozzle with an identical nozzle of the same size and material
Replacing a nozzle with an identical replacement (same size, material, and rating) is classified as a repair, not an alteration, since no design change is made.
Question 6: After completing a repair weld on an in-service pressure vessel, which NDE method is most commonly specified to verify full fusion and detect internal defects?
- Visual testing (VT) alone
- Radiographic testing (RT) or ultrasonic testing (UT) (Correct answer)
- Magnetic particle testing (MT) alone
- Liquid penetrant testing (PT) alone
Correct answer: Radiographic testing (RT) or ultrasonic testing (UT)
RT or UT are volumetric NDE methods capable of detecting internal weld defects such as lack of fusion, porosity, and cracks within the repair weld.
Question 7: A pressure vessel repair that uses a different material than the original construction requires which additional step beyond standard repair procedures?
- Approval from the original vessel manufacturer
- Engineering review to confirm compatibility including weldability and corrosion resistance (Correct answer)
- Filing a variance with the state pressure vessel authority only
- A nameplate change without further documentation
Correct answer: Engineering review to confirm compatibility including weldability and corrosion resistance
Material substitutions require engineering review to confirm that the alternative material is compatible with the original design, service environment, and welding requirements.
API 510 Repair and Alteration 5
Under API 510, an authorized inspector must be present to witness which activity during a vessel repair?