Gas Fitter Licensing Exam Questions With
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. Which of the following is the primary purpose of a gas pressure
regulator?
a) To increase the gas pressure for appliance operation
b) To measure gas flow
c) To reduce and control gas pressure to a safe level
d) To prevent backflow of gas
Rationale: A gas pressure regulator reduces the incoming high-
pressure gas from the utility to a level safe for appliances and
ensures consistent flow.
2. What is the correct thread sealant for natural gas piping?
a) Silicone caulk
b) Pipe dope for water only
c) Approved gas-rated pipe thread compound
d) Epoxy resin
Rationale: Only gas-rated compounds are suitable for threaded
joints on gas piping to prevent leaks and ensure safety.
,3. Before performing any gas fitting work, the first safety step is:
a) Installing new piping immediately
b) Lighting a test appliance
c) Starting welding procedures
d) Shutting off the gas supply
Rationale: Always turn off the gas supply before beginning work
to prevent accidental leaks or explosions.
4. Which type of gas meter is commonly installed for residential
natural gas service?
a) Turbine meter
b) Diaphragm meter
c) Ultrasonic meter
d) Diaphragm-type meter
Rationale: Residential installations typically use diaphragm
meters due to their accuracy at low flow rates.
5. What is the maximum allowable distance between supports for 1-
inch steel gas pipe?
a) 2 feet
b) 6 feet
c) 12 feet
d) 8 feet
, Rationale: According to code, 1-inch steel gas pipe must be
supported at intervals no greater than 6 feet to prevent sagging
and stress.
6. For a gas appliance vent, what is the minimum clearance to
combustibles?
a) 0 inches
b) 1 inch
c) 6 inches
d) 2 inches for listed venting or per manufacturer specifications
Rationale: Clearance depends on manufacturer specifications
and local codes; typically, 2 inches is a safe minimum for listed
vents.
7. What is the purpose of a sediment trap in a gas line?
a) To increase gas pressure
b) To collect debris and prevent it from entering the appliance
c) To measure gas volume
d) To reduce gas temperature
Rationale: Sediment traps protect appliances from debris and
moisture, preventing ignition problems and damage.
8. Which gas is considered lighter than air?
a) Propane
, b) Natural gas
c) Butane
d) Carbon dioxide
Rationale: Natural gas is lighter than air, so leaks tend to rise,
whereas propane is heavier and settles near the floor.
9. How should a gas pipe be tested after installation?
a) By lighting a match at the outlet
b) Using an approved pressure gauge and test pressure
c) By visual inspection only
d) By smelling for leaks alone
Rationale: Pressure testing with a gauge ensures the line is leak-
free; open flame testing is dangerous and prohibited.
10. Which material is NOT approved for underground gas
piping?
a) Black steel
b) Polyethylene (PE)
c) Copper
d) PVC
Rationale: PVC is not rated for gas due to permeation and
strength issues; approved materials are black steel or
polyethylene.
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. Which of the following is the primary purpose of a gas pressure
regulator?
a) To increase the gas pressure for appliance operation
b) To measure gas flow
c) To reduce and control gas pressure to a safe level
d) To prevent backflow of gas
Rationale: A gas pressure regulator reduces the incoming high-
pressure gas from the utility to a level safe for appliances and
ensures consistent flow.
2. What is the correct thread sealant for natural gas piping?
a) Silicone caulk
b) Pipe dope for water only
c) Approved gas-rated pipe thread compound
d) Epoxy resin
Rationale: Only gas-rated compounds are suitable for threaded
joints on gas piping to prevent leaks and ensure safety.
,3. Before performing any gas fitting work, the first safety step is:
a) Installing new piping immediately
b) Lighting a test appliance
c) Starting welding procedures
d) Shutting off the gas supply
Rationale: Always turn off the gas supply before beginning work
to prevent accidental leaks or explosions.
4. Which type of gas meter is commonly installed for residential
natural gas service?
a) Turbine meter
b) Diaphragm meter
c) Ultrasonic meter
d) Diaphragm-type meter
Rationale: Residential installations typically use diaphragm
meters due to their accuracy at low flow rates.
5. What is the maximum allowable distance between supports for 1-
inch steel gas pipe?
a) 2 feet
b) 6 feet
c) 12 feet
d) 8 feet
, Rationale: According to code, 1-inch steel gas pipe must be
supported at intervals no greater than 6 feet to prevent sagging
and stress.
6. For a gas appliance vent, what is the minimum clearance to
combustibles?
a) 0 inches
b) 1 inch
c) 6 inches
d) 2 inches for listed venting or per manufacturer specifications
Rationale: Clearance depends on manufacturer specifications
and local codes; typically, 2 inches is a safe minimum for listed
vents.
7. What is the purpose of a sediment trap in a gas line?
a) To increase gas pressure
b) To collect debris and prevent it from entering the appliance
c) To measure gas volume
d) To reduce gas temperature
Rationale: Sediment traps protect appliances from debris and
moisture, preventing ignition problems and damage.
8. Which gas is considered lighter than air?
a) Propane
, b) Natural gas
c) Butane
d) Carbon dioxide
Rationale: Natural gas is lighter than air, so leaks tend to rise,
whereas propane is heavier and settles near the floor.
9. How should a gas pipe be tested after installation?
a) By lighting a match at the outlet
b) Using an approved pressure gauge and test pressure
c) By visual inspection only
d) By smelling for leaks alone
Rationale: Pressure testing with a gauge ensures the line is leak-
free; open flame testing is dangerous and prohibited.
10. Which material is NOT approved for underground gas
piping?
a) Black steel
b) Polyethylene (PE)
c) Copper
d) PVC
Rationale: PVC is not rated for gas due to permeation and
strength issues; approved materials are black steel or
polyethylene.
