GPT GPT Pressure Testing & System Commissioning 1 — Questions and Answers
Question 1: What is the standard test pressure for a gas piping system before commissioning per NFPA 54?
- 1.5 times the maximum allowable operating pressure (Correct answer)
- Operating pressure only
- 10 psi flat
- 50 psi flat
Correct answer: 1.5 times the maximum allowable operating pressure
NFPA 54 requires pressure tests at 1.5 times the maximum allowable operating pressure to verify system integrity.
Question 2: Which test medium is preferred for leak testing gas piping systems?
- Natural gas
- Air or inert gas (Correct answer)
- Water
- Steam
Correct answer: Air or inert gas
Air or inert gas is preferred for pressure testing to eliminate explosion risk if a leak is discovered during the test.
Question 3: How long must a gas piping system hold test pressure to pass a standard pressure test per NFPA 54?
- 5 minutes
- 15 minutes (Correct answer)
- 30 minutes
- 60 minutes
Correct answer: 15 minutes
NFPA 54 requires piping to maintain test pressure for a minimum of 15 minutes without any measurable pressure drop.
Question 4: What procedure must be performed after pressure testing before gas is introduced into a new system?
- Flushing with water
- Purging with inert gas (Correct answer)
- Chemical cleaning
- Hydraulic pressure test
Correct answer: Purging with inert gas
Purging with inert gas displaces air and moisture from the piping to prevent combustible air-gas mixtures when gas is introduced.
Question 5: Before performing a pressure test, appliance connections must be:
- Left connected and operational
- Disconnected or capped (Correct answer)
- Turned off only
- Removed from the premises
Correct answer: Disconnected or capped
Appliance connections must be disconnected or capped to isolate the piping system so only the pipe is being tested.
Question 6: A drop in pressure during a static pressure test indicates:
- The system passed inspection
- The pressure gauge is faulty
- A leak exists in the system (Correct answer)
- Normal thermal expansion
Correct answer: A leak exists in the system
Any measurable pressure drop during a static test confirms a leak that must be located and repaired before commissioning.
GPT GPT Pressure Testing & System Commissioning 1
What is the standard test pressure for a gas piping system before commissioning per NFPA 54?