GPT Installation Techniques 3 — Questions and Answers
Question 1: When sizing a gas pipe using the longest-length method, which value is used as the pipe length for ALL branches in the system?
- The length of each individual branch
- The total length of the longest run from meter to farthest appliance (Correct answer)
- The average length of all branches combined
- The shortest branch length in the system
Correct answer: The total length of the longest run from meter to farthest appliance
The longest-length method uses the single longest run distance for all pipe segments, which is a conservative approach that ensures adequate pressure throughout the system.
Question 2: A gas valve is required to be installed upstream of every appliance. What is the maximum allowable distance of this shutoff from the appliance it serves?
- 3 feet
- 5 feet
- 6 feet (Correct answer)
- 10 feet
Correct answer: 6 feet
Per IFGC, an accessible manual shutoff valve must be installed within 6 feet of each appliance to allow quick isolation in an emergency.
Question 3: Which of the following pipe materials is approved for use inside a building above grade for natural gas distribution?
- Polyethylene (PE)
- Copper tubing Type L with no lead solder
- Black steel pipe with threaded fittings (Correct answer)
- PVC pressure pipe
Correct answer: Black steel pipe with threaded fittings
Black steel pipe with threaded or welded fittings is a standard approved material for interior above-grade gas distribution; PE and PVC are not approved for indoor use.
Question 4: When installing CSST (corrugated stainless steel tubing), which installation requirement is unique to CSST versus rigid pipe?
- It must be installed with a drip leg at every bend
- It requires equipotential bonding to mitigate lightning strike damage (Correct answer)
- It must be pressure tested at twice the operating pressure
- It must be sleeved inside rigid conduit throughout its length
Correct answer: It requires equipotential bonding to mitigate lightning strike damage
CSST requires equipotential bonding because its thin corrugated wall is susceptible to perforation from electrical arcing caused by nearby lightning strikes.
Question 5: What type of joint is required when connecting gas piping inside a concealed plenum or air-handling space?
- Threaded joints with yellow PTFE tape only
- Welded or brazed joints only
- Mechanically formed or welded leak-free joints (Correct answer)
- Compression fittings approved for gas
Correct answer: Mechanically formed or welded leak-free joints
Joints in plenum or air-handling spaces must be leak-free mechanically formed or welded connections because any gas leak could be distributed throughout the ventilation system.
Question 6: A technician is installing gas pipe through a floor joist bay. The pipe must be protected from physical damage when closer than _____ to the edge of the joist.
- 1 inch
- 1.25 inches (Correct answer)
- 2 inches
- 1.5 inches
Correct answer: 1.25 inches
Gas pipe within 1.25 inches of the edge of a wood framing member must be protected by a steel nail plate to prevent accidental puncture from fasteners.
Question 7: When installing a gas appliance in a confined space, which ventilation method provides combustion air from inside the building?
- Direct vent (sealed combustion)
- Indoor air (conventional) ventilation (Correct answer)
- Powered combustion air intake
- Balanced flue system
Correct answer: Indoor air (conventional) ventilation
Indoor air (conventional) ventilation uses openings or louvers to draw combustion air from inside the building into the confined equipment space.
GPT Installation Techniques 3
When sizing a gas pipe using the longest-length method, which value is used as the pipe length for ALL branches in the system?