Plumbing Gas Piping Systems

Question 1

What type of pipe is most commonly used for natural gas distribution inside residential buildings?

Accepted Answer

Black steel pipe

Answer

PVC plastic pipe

Answer

Copper tubing

Answer

CPVC pipe

Question 2

Which gas has a specific gravity GREATER than air, causing it to sink and accumulate in low areas?

Accepted Answer

Propane (LP gas)

Answer

Natural gas (methane)

Answer

Hydrogen

Answer

Carbon monoxide

Question 3

What is the purpose of a drip leg (sediment trap) installed on a gas supply line near an appliance?

Accepted Answer

To collect moisture and debris before they enter the appliance valve

Answer

To reduce gas pressure before the appliance

Answer

To regulate gas flow rate

Answer

To prevent gas from flowing backward

Question 4

What test method is required to verify gas piping integrity before placing the system in service?

Accepted Answer

Pressure test with air or an inert gas

Answer

Smoke test using theatrical fog

Answer

Hydrostatic (water) pressure test

Answer

Vacuum test at negative pressure

Question 5

What fitting is typically installed at each gas appliance to allow individual shutoff without interrupting the entire system?

Accepted Answer

Appliance shutoff valve (gas cock)

Answer

Union fitting

Answer

Tee fitting

Answer

Ball check valve

Question 6

What color jacket is standard on corrugated stainless steel tubing (CSST) used for gas piping?

Accepted Answer

Yellow

Answer

Black

Answer

Red

Answer

Orange

Question 7

What is the minimum burial depth required for a natural gas service line running underground to a residential building?

Accepted Answer

12 inches

Answer

6 inches

Answer

18 inches

Answer

36 inches