G33 MASTER GAS PIPE FITTER EXAM – COMPLETE
QUESTIONS WITH 100% VERIFIED ANSWERS AND
EXPLANATIONS
1. What is the primary component of natural gas as delivered to most
homes and businesses?
A. Propane
B. Butane
C. Methane
D. Ethane
Correct Answer: C – Natural gas is composed primarily of methane
(CH₄), typically 90% or more.
2. Which code is the primary standard for fuel gas piping systems in
the United States?
A. OSHA 1926
B. NFPA 54 / ANSI Z223.1
C. ASTM A53
D. Uniform Mechanical Code (UMC)
Correct Answer: B – NFPA 54, also known as the National Fuel Gas
Code, is the primary code governing the design, installation, and
inspection of fuel gas piping systems.
3. A sediment trap must be installed on which type of gas appliance?
A. Any appliance over 150,000 BTU
,B. Appliances with regulators
C. Appliances susceptible to debris intrusion
D. Appliances with electronic ignition
Correct Answer: C – Sediment traps protect sensitive appliances from
debris; code requires them where debris could cause malfunction.
4. Black steel pipe used for gas piping must comply with which
standard?
A. ASTM A53
B. ASTM A36
C. ASTM A500
D. ASTM B88
Correct Answer: A – Gas piping uses ASTM A53 steel pipe; A36 is
structural steel, A500 is tubing, and B88 is copper plumbing.
5. The minimum test pressure for a new low-pressure gas system
(under 2 psi) is:
A. 1 psi
B. 3 psi
C. 10 psi
D. 20 psi
Correct Answer: C – Code requires not less than 10 psi for a minimum
15-minute test for low-pressure systems.
6. Threaded steel gas pipe must have threads conforming to:
A. NPT
B. BSP
C. NPS
D. TPI
,Correct Answer: A – NPT (National Pipe Taper) is the required tapered
standard for gas-tight threaded joints.
7. A gas pipe passing through a masonry wall must be:
A. Unprotected
B. Wrapped or sleeved
C. Threaded at both ends
D. Filled with mortar
Correct Answer: B – Piping must be protected from corrosion and
abrasion when penetrating masonry.
8. The allowable pressure drop for a natural gas piping system is
normally:
A. 0.1 in. w.c.
B. 0.3 in. w.c.
C. 0.5 in. w.c.
D. 1.0 in. w.c.
Correct Answer: C – Standard sizing assumes 0.5" w.c. drop unless
otherwise engineered.
9. When sizing gas piping, the length used is:
A. Exact length to the appliance
B. Longest run in the system
C. Sum of all branches
D. Distance to the meter only
Correct Answer: B – Sizing is based on the longest run for safety and
simplicity.
10. Which pipe is prohibited for interior natural gas distribution?
A. Black steel
, B. Corrugated stainless steel tubing
C. Copper tubing (in some jurisdictions)
D. PVC
Correct Answer: D – PVC is never permitted for gas piping due to
temperature and permeability issues.
11. A manual shutoff valve must be located:
A. At the meter only
B. At the appliance only
C. At both meter and appliance
D. Only where the inspector can see it
Correct Answer: C – Code requires accessible shutoffs at meter and
appliance.
12. Excess flow valves are used to:
A. Regulate pressure
B. Automatically shut off flow if a line breaks
C. Filter debris from the gas stream
D. Measure gas consumption
Correct Answer: B – Excess flow valves are designed to automatically
shut off gas flow in the event of a line rupture or significant leak.
13. What is the specific gravity of natural gas?
A. 0.60
B. 1.00
C. 1.52
D. 2.00
Correct Answer: A – Natural gas has a specific gravity of approximately
0.60, meaning it is lighter than air.
QUESTIONS WITH 100% VERIFIED ANSWERS AND
EXPLANATIONS
1. What is the primary component of natural gas as delivered to most
homes and businesses?
A. Propane
B. Butane
C. Methane
D. Ethane
Correct Answer: C – Natural gas is composed primarily of methane
(CH₄), typically 90% or more.
2. Which code is the primary standard for fuel gas piping systems in
the United States?
A. OSHA 1926
B. NFPA 54 / ANSI Z223.1
C. ASTM A53
D. Uniform Mechanical Code (UMC)
Correct Answer: B – NFPA 54, also known as the National Fuel Gas
Code, is the primary code governing the design, installation, and
inspection of fuel gas piping systems.
3. A sediment trap must be installed on which type of gas appliance?
A. Any appliance over 150,000 BTU
,B. Appliances with regulators
C. Appliances susceptible to debris intrusion
D. Appliances with electronic ignition
Correct Answer: C – Sediment traps protect sensitive appliances from
debris; code requires them where debris could cause malfunction.
4. Black steel pipe used for gas piping must comply with which
standard?
A. ASTM A53
B. ASTM A36
C. ASTM A500
D. ASTM B88
Correct Answer: A – Gas piping uses ASTM A53 steel pipe; A36 is
structural steel, A500 is tubing, and B88 is copper plumbing.
5. The minimum test pressure for a new low-pressure gas system
(under 2 psi) is:
A. 1 psi
B. 3 psi
C. 10 psi
D. 20 psi
Correct Answer: C – Code requires not less than 10 psi for a minimum
15-minute test for low-pressure systems.
6. Threaded steel gas pipe must have threads conforming to:
A. NPT
B. BSP
C. NPS
D. TPI
,Correct Answer: A – NPT (National Pipe Taper) is the required tapered
standard for gas-tight threaded joints.
7. A gas pipe passing through a masonry wall must be:
A. Unprotected
B. Wrapped or sleeved
C. Threaded at both ends
D. Filled with mortar
Correct Answer: B – Piping must be protected from corrosion and
abrasion when penetrating masonry.
8. The allowable pressure drop for a natural gas piping system is
normally:
A. 0.1 in. w.c.
B. 0.3 in. w.c.
C. 0.5 in. w.c.
D. 1.0 in. w.c.
Correct Answer: C – Standard sizing assumes 0.5" w.c. drop unless
otherwise engineered.
9. When sizing gas piping, the length used is:
A. Exact length to the appliance
B. Longest run in the system
C. Sum of all branches
D. Distance to the meter only
Correct Answer: B – Sizing is based on the longest run for safety and
simplicity.
10. Which pipe is prohibited for interior natural gas distribution?
A. Black steel
, B. Corrugated stainless steel tubing
C. Copper tubing (in some jurisdictions)
D. PVC
Correct Answer: D – PVC is never permitted for gas piping due to
temperature and permeability issues.
11. A manual shutoff valve must be located:
A. At the meter only
B. At the appliance only
C. At both meter and appliance
D. Only where the inspector can see it
Correct Answer: C – Code requires accessible shutoffs at meter and
appliance.
12. Excess flow valves are used to:
A. Regulate pressure
B. Automatically shut off flow if a line breaks
C. Filter debris from the gas stream
D. Measure gas consumption
Correct Answer: B – Excess flow valves are designed to automatically
shut off gas flow in the event of a line rupture or significant leak.
13. What is the specific gravity of natural gas?
A. 0.60
B. 1.00
C. 1.52
D. 2.00
Correct Answer: A – Natural gas has a specific gravity of approximately
0.60, meaning it is lighter than air.
