Journeyman Plumbers Exam Gas Piping Systems 2 — Questions and Answers
Question 1: What is the maximum allowable pressure drop for a gas piping system serving appliances on a low-pressure system (under 2 psi)?
- 0.3 inches water column
- 0.5 inches water column (Correct answer)
- 1.0 inches water column
- 2.0 inches water column
Correct answer: 0.5 inches water column
Low-pressure gas systems (under 2 psi) are typically designed for a maximum allowable pressure drop of 0.5 inches water column from the meter to the appliance.
Question 2: Which type of gas piping material is NOT permitted for use inside a building above grade?
- CSST (corrugated stainless steel tubing)
- Black steel pipe
- Copper tubing (for natural gas)
- Cast iron pipe (Correct answer)
Correct answer: Cast iron pipe
Cast iron pipe is not approved for interior gas piping above grade due to its brittleness and susceptibility to cracking under stress.
Question 3: When a gas meter is located inside a building, it must be installed in a location that is:
- Adjacent to the main electrical panel
- Ventilated and accessible (Correct answer)
- In a locked utility closet
- Below the gas appliance served
Correct answer: Ventilated and accessible
Gas meters installed indoors must be in a ventilated, accessible location to allow for meter reading, maintenance, and safe dispersal of any gas leaks.
Question 4: A sediment trap (drip leg) in a gas piping system must be installed:
- At the gas meter outlet
- Immediately upstream of each appliance (Correct answer)
- At the highest point in the system
- Only on systems using propane
Correct answer: Immediately upstream of each appliance
Sediment traps must be installed immediately upstream of each appliance connection to collect moisture and debris before they enter the appliance's gas valve.
Question 5: What is the minimum burial depth for a gas service line made of steel pipe installed under a public sidewalk?
- 12 inches
- 18 inches
- 24 inches (Correct answer)
- 36 inches
Correct answer: 24 inches
Steel gas service lines installed beneath public sidewalks must be buried a minimum of 24 inches deep to protect them from surface loads and damage.
Question 6: When sizing a gas piping system using the longest length method, what determines the pipe size for each section?
- The actual length of that section only
- The longest supply length from meter to the farthest appliance (Correct answer)
- The total connected load of all appliances
- The operating pressure at the meter
Correct answer: The longest supply length from meter to the farthest appliance
The longest length method sizes all pipe using the longest run from the meter to the farthest appliance, ensuring adequate pressure throughout the entire system.
Question 7: Which fitting is required when connecting CSST (corrugated stainless steel tubing) to a rigid gas appliance connector?
- A flare fitting
- A manufacturer-approved mechanical fitting (Correct answer)
- A compression fitting
- A sweated solder fitting
Correct answer: A manufacturer-approved mechanical fitting
CSST must be connected using manufacturer-approved mechanical fittings specifically designed for the product, as improper fittings can cause leaks or damage.
Journeyman Plumbers Exam Gas Piping Systems 2
What is the maximum allowable pressure drop for a gas piping system serving appliances on a low-pressure system (under 2 psi)?