Gas Line
A gas line is the system of pipes and fittings that delivers natural gas or liquid propane (LP) from the utility meter or propane tank to individual appliances in a home — water heaters, furnaces, boilers, gas ranges, dryers, fireplaces, and outdoor grills. Because gas is flammable and can displace oxygen in an enclosed space, gas line work is among the most regulated and potentially hazardous tasks in residential plumbing.
Materials
- Black steel pipe with threaded fittings: the traditional standard inside walls and for buried mains. Durable, code-approved everywhere, but requires threading tools and joint compound (pipe dope rated for gas).
- CSST (corrugated stainless steel tubing): flexible stainless tubing used for runs inside finished walls and attics. Faster to install than black pipe but must be properly bonded to the electrical ground to prevent lightning-induced arc damage.
- Copper: accepted in some jurisdictions for LP (propane) but prohibited in many areas for natural gas (sulfur compounds in natural gas corrode copper).
- Black polyethylene: underground distribution only.
Code requirements
Gas line work requires a permit in virtually every jurisdiction. The rough-in is inspected by the building department before walls close, and the final connection is inspected after appliances are installed. Many localities require a licensed plumber or gas fitter — homeowners are generally prohibited from making gas connections themselves beyond attaching appliance connectors.
Detecting a gas leak
Natural gas is odorless; utilities add mercaptan (a sulfur compound) that smells like rotten eggs. If you smell gas: don't operate any switches or flames, leave the building immediately, and call 911 or your gas utility from outside. Minor leaks at fittings can be detected with soapy water (bubbles at the joint) or a gas leak detector spray.
Adding a gas appliance
Adding a gas dryer, generator hookup, or outdoor grill line typically costs $300–$800 for a plumber to run a new branch, depending on distance from the main and complexity. A whole-house gas line replacement runs $1,500–$5,000+ depending on home size and material choice.