API 510 Pressure Testing Procedures 3 — Questions and Answers
Question 1: What is the standard hydrostatic test pressure for a repaired pressure vessel per API 510, expressed as a multiple of the maximum allowable working pressure (MAWP)?
- 1.3 times MAWP (Correct answer)
- 1.5 times MAWP
- 2.0 times MAWP
- 1.1 times MAWP
Correct answer: 1.3 times MAWP
API 510 specifies that the hydrostatic test pressure for repairs is typically 1.3 times the MAWP, consistent with the current ASME Code.
Question 2: When test fluid temperature is a concern during pneumatic testing, API 510 recommends keeping the test fluid temperature above what value to prevent brittle fracture?
- 30°F above the minimum design metal temperature (MDMT) (Correct answer)
- The ambient temperature at time of test
- 100°F regardless of MDMT
- 0°F
Correct answer: 30°F above the minimum design metal temperature (MDMT)
To avoid brittle fracture, the test temperature should be at least 30°F above the MDMT of the vessel being tested.
Question 3: Which document must be prepared and approved before conducting a pneumatic pressure test on a pressure vessel?
- A written test procedure reviewed by an inspector or engineer (Correct answer)
- A manufacturer data report
- A radiography report
- An ASME Code stamp application
Correct answer: A written test procedure reviewed by an inspector or engineer
Due to the hazards of pneumatic testing, a documented test procedure must be prepared and approved before the test begins.
Question 4: After completing a hydrostatic test, what action must be taken before returning the vessel to service?
- Vent the vessel to remove all test fluid and ensure it is dry if required by service (Correct answer)
- Re-stamp the vessel nameplate
- Apply a new coating to the interior
- Submit a new National Board inspection report
Correct answer: Vent the vessel to remove all test fluid and ensure it is dry if required by service
Residual test fluid must be drained and the vessel vented; for certain services such as hydrogen or oxygen, complete dryness is essential.
Question 5: In API 510, a 'sensitive leak test' using pressure is typically performed at what pressure level?
- A fraction of MAWP, typically around 10% or less (Correct answer)
- Exactly at MAWP
- 1.3 times MAWP
- 2.0 times MAWP
Correct answer: A fraction of MAWP, typically around 10% or less
Sensitive leak tests such as the bubble test method are performed at very low pressures, typically around 10% of MAWP or less.
Question 6: When pressure testing a vessel with multiple chambers, how should the test pressure be applied?
- Each chamber should be tested independently at its respective design pressure (Correct answer)
- All chambers simultaneously at the highest design pressure
- Only the chamber with the highest MAWP needs to be tested
- Chambers should be tested together at the lowest MAWP
Correct answer: Each chamber should be tested independently at its respective design pressure
Each pressure chamber must be tested independently at its own design test pressure to avoid over-pressuring adjacent chambers.
Question 7: Which of the following scenarios would make it impractical to perform a hydrostatic test, potentially justifying a pneumatic test?
- The vessel structure cannot support the weight of the test fluid (Correct answer)
- The vessel is made of carbon steel
- The MAWP exceeds 100 psi
- The vessel has been in service for more than 10 years
Correct answer: The vessel structure cannot support the weight of the test fluid
If the vessel or its supporting structure cannot sustain the added weight of water required for a hydrostatic test, a pneumatic test may be justified.
API 510 Pressure Testing Procedures 3
What is the standard hydrostatic test pressure for a repaired pressure vessel per API 510, expressed as a multiple of the maximum allowable working pressure (MAWP)?