API 510 Pressure Vessel Design & Inspection Codes 3 — Questions and Answers
Question 1: According to API 510, which organization must approve a repair organization performing welded repairs on pressure vessels?
- The American Petroleum Institute directly
- The National Board of Boiler and Pressure Vessel Inspectors or equivalent jurisdiction (Correct answer)
- The vessel's original manufacturer only
- OSHA's process safety management office
Correct answer: The National Board of Boiler and Pressure Vessel Inspectors or equivalent jurisdiction
Repair organizations must hold a valid National Board 'R' stamp or equivalent jurisdiction authorization to perform welded repairs on pressure vessels.
Question 2: Under API 510, when is a pressure vessel alteration different from a repair?
- An alteration changes the design temperature, pressure, capacity, or configuration beyond original design (Correct answer)
- An alteration involves only cosmetic changes to the vessel exterior
- A repair involves adding material while an alteration only removes material
- There is no distinction; both terms are used interchangeably in API 510
Correct answer: An alteration changes the design temperature, pressure, capacity, or configuration beyond original design
An alteration changes the vessel's design temperature, pressure, capacity, or configuration from the original design, which is more significant than a repair that restores original condition.
Question 3: What is the purpose of a hydrostatic leak test performed after a pressure vessel repair?
- To verify the corrosion rate has been reduced
- To confirm the integrity and tightness of the repair before returning to service (Correct answer)
- To establish a new MAWP for the vessel
- To replace the need for nondestructive examination of the repair
Correct answer: To confirm the integrity and tightness of the repair before returning to service
A hydrostatic test after repair verifies the structural integrity and tightness of the repair welds before the vessel returns to service.
Question 4: According to ASME Section VIII, the standard hydrostatic test pressure for a vessel is:
- Equal to the MAWP
- 1.3 times the MAWP adjusted for allowable stress at test temperature (Correct answer)
- 1.5 times the operating pressure
- 2 times the design pressure regardless of material
Correct answer: 1.3 times the MAWP adjusted for allowable stress at test temperature
ASME VIII requires hydrostatic test pressure of 1.3 times the MAWP multiplied by the ratio of allowable stress at test temperature to allowable stress at design temperature.
Question 5: In API 510, who has the authority to approve an alteration to a pressure vessel?
- The plant maintenance supervisor
- An API 510 Authorized Pressure Vessel Inspector (Correct answer)
- The original equipment manufacturer only
- The local fire marshal
Correct answer: An API 510 Authorized Pressure Vessel Inspector
An API 510 Authorized Pressure Vessel Inspector must review and approve all alterations to pressure vessels covered by the code.
Question 6: Which type of weld joint requires the highest joint efficiency value under ASME VIII Division 1 when full radiographic examination is performed?
- Category D fillet welds
- Category A butt welds with full RT (Type 1) (Correct answer)
- Category B single-welded butt joints without backing
- Category C nozzle attachment welds
Correct answer: Category A butt welds with full RT (Type 1)
Category A double-welded butt joints (Type 1) with full radiographic examination achieve the highest joint efficiency of 1.0 under ASME VIII Div. 1.
Question 7: When does API 510 allow an external inspection to be substituted for an internal inspection of a pressure vessel?
- Whenever the inspector prefers external inspection for safety reasons
- When the vessel cannot be entered safely and on-stream inspection techniques can assess internal condition (Correct answer)
- Only when the vessel contains non-corrosive service fluids
- External inspection can never substitute for internal inspection under any circumstances
Correct answer: When the vessel cannot be entered safely and on-stream inspection techniques can assess internal condition
API 510 permits external on-stream inspection techniques to substitute for internal inspection when entry is not practical and the methods can adequately assess the internal condition.
API 510 Pressure Vessel Design & Inspection Codes 3
According to API 510, which organization must approve a repair organization performing welded repairs on pressure vessels?