Gas Piping Systems Flashcards

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

Answer: Black steel pipe

Black steel pipe is the most widely approved material for interior natural gas distribution due to its strength, durability, and resistance to permeation.

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

Answer: Propane (LP gas)

Propane has a specific gravity of about 1.52 relative to air, so it sinks and can pool in basements, crawl spaces, and pits where it poses an explosion risk.

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

Answer: To collect moisture and debris before they enter the appliance valve

A drip leg collects condensate and pipe debris that would otherwise clog or damage the appliance gas valve and controls.

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

Answer: Pressure test with air or an inert gas

Gas piping must be pressure tested with air or an inert gas (not the actual gas) to safely detect leaks before the system is charged.

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

Answer: Appliance shutoff valve (gas cock)

An appliance shutoff valve (gas cock or stop valve) is required at each appliance connection to allow safe individual isolation for service or emergencies.

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

Answer: Yellow

CSST gas piping is covered with a yellow plastic jacket, universally recognized as a gas-service identifier and providing physical protection.

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

Answer: 12 inches

Natural gas service lines must be buried at least 12 inches deep under normal conditions to protect them from surface disturbance and damage.