API 510 Pressure Testing 2 — Questions and Answers
Question 1: According to API 510, what is the minimum hold time for a pneumatic pressure test on a pressure vessel?
- 10 minutes (Correct answer)
- 30 minutes
- 1 hour
- 2 hours
Correct answer: 10 minutes
API 510 requires a minimum hold time of 10 minutes for pneumatic pressure tests before conducting the inspection.
Question 2: When performing a hydrostatic test, the test pressure at the top of the vessel must account for which of the following?
- Insulation weight
- Liquid head pressure (Correct answer)
- Wind loading
- Seismic loading
Correct answer: Liquid head pressure
The liquid head pressure must be considered when setting test pressure, as the pressure at the top differs from the pressure at the bottom due to fluid column height.
Question 3: Which condition would require the owner/user to obtain approval before performing a pressure test after a repair?
- Minor weld repairs on non-pressure parts
- Major repairs involving welding on pressure boundary (Correct answer)
- Replacement of gaskets
- Tightening of bolts
Correct answer: Major repairs involving welding on pressure boundary
Major repairs involving welding on the pressure boundary require an authorized inspection agency to approve the pressure test per API 510.
Question 4: A vessel has an MAWP of 500 psi. The standard hydrostatic test pressure per ASME Code is approximately:
- 500 psi
- 600 psi
- 650 psi (Correct answer)
- 750 psi
Correct answer: 650 psi
ASME requires hydrostatic test pressure to be 1.3 times the MAWP, so 500 × 1.3 = 650 psi.
Question 5: What is the primary reason pneumatic testing is considered more hazardous than hydrostatic testing?
- Gas is harder to contain than liquid
- Compressed gas stores significantly more energy than liquid at the same pressure (Correct answer)
- Gas causes more corrosion
- Pneumatic tests require higher pressures
Correct answer: Compressed gas stores significantly more energy than liquid at the same pressure
Compressed gases store far more energy than incompressible liquids at the same pressure, resulting in a much more violent potential failure.
Question 6: During a pressure test, a small leak is detected at a flange. What is the appropriate action per API 510?
- Continue the test and document the leak
- Depressurize the vessel before attempting repairs (Correct answer)
- Tighten the flange bolts while under pressure
- Increase pressure to see if the leak seals itself
Correct answer: Depressurize the vessel before attempting repairs
The vessel must be fully depressurized before any repairs are attempted to ensure personnel safety.
Question 7: Which of the following exemptions allows a pressure test to be omitted after a repair per API 510?
- When the repair is performed by a certified welder
- When the inspector determines testing is impractical and alternative NDE methods are used (Correct answer)
- When the vessel is over 20 years old
- When the repair cost is less than 10% of vessel replacement cost
Correct answer: When the inspector determines testing is impractical and alternative NDE methods are used
API 510 allows the inspector to waive a pressure test when it is impractical, provided suitable NDE and examination methods are substituted.
API 510 Pressure Testing 2
According to API 510, what is the minimum hold time for a pneumatic pressure test on a pressure vessel?