GPT GPT Pressure Testing & System Commissioning 2 — Questions and Answers
Question 1: What is the maximum allowable test pressure for plastic gas piping?
- 100 psi
- 50 psi
- 10 psi above operating pressure
- Manufacturer's rated pressure (Correct answer)
Correct answer: Manufacturer's rated pressure
Plastic gas piping must never be tested above the manufacturer's rated pressure to avoid material damage or failure.
Question 2: A manometer is used during pressure testing primarily to:
- Measure gas flow rate
- Detect pressure changes indicating a leak (Correct answer)
- Regulate gas pressure
- Calibrate the gas meter
Correct answer: Detect pressure changes indicating a leak
A manometer measures pressure precisely, allowing technicians to detect even small pressure drops that signal a leak.
Question 3: Which type of pressure test is typically used for high-pressure gas transmission lines?
- Air pressure test
- Hydrostatic test (Correct answer)
- Vacuum test
- Soap bubble test
Correct answer: Hydrostatic test
Hydrostatic testing uses water to safely test high-pressure transmission lines at elevated pressures without explosion risk.
Question 4: When should a pressure test be performed on a gas piping system?
- After all connections are insulated
- Before covering, concealing, or placing in service (Correct answer)
- Only when the customer requests it
- After the system is placed in service
Correct answer: Before covering, concealing, or placing in service
Code requires pressure testing before covering or concealing piping so all connections remain accessible for visual inspection.
Question 5: What is the purpose of a regulator lock-up test during commissioning?
- Verify the regulator shuts off gas at maximum flow
- Verify the regulator maintains outlet pressure when there is no flow (Correct answer)
- Verify the regulator vents excess pressure safely
- Verify the regulator resists physical damage
Correct answer: Verify the regulator maintains outlet pressure when there is no flow
A lock-up test confirms the regulator holds a stable outlet pressure when downstream flow stops, preventing over-pressurization.
Question 6: Which standard governs the installation and commissioning of gas piping systems in the US?
- NFPA 70
- NFPA 54 / ANSI Z223.1 (Correct answer)
- NFPA 101
- OSHA 1910.119
Correct answer: NFPA 54 / ANSI Z223.1
NFPA 54, also known as the National Fuel Gas Code (ANSI Z223.1), is the primary US standard governing gas piping installation and commissioning.
GPT GPT Pressure Testing & System Commissioning 2
What is the maximum allowable test pressure for plastic gas piping?