Homes that use natural gas for heating and cooking must be connected to the gas mains that run down the street, which are owned or operated by the gas company. While the gas company is responsible for running a gas line called the gas lateral from the main to the curb in front of the house, a plumber connects it to the house where it will supply gas to the furnace and appliances.
Purpose of Gas Lines
Gas lines are run through the house much like other plumbing lines such as water supply. The lateral gas line feeds into a distribution system that feeds into a manifold, which is similar to an electrical panel containing breakers. The distributor is typically located outside the gas meter and its function is to lower the pressure of the gas in the gas line lateral to one that is compatible with the appliances in your home.
Elements of a Gas Line
Newer gas lines that run from the gas main to the house are often made from plastic tubing. In the past, they were made from steel, but were subject to rusting after a period of time and would need to be replaced.
Adjacent to this gas line is what is called a tracer wire, which is used by the gas company in case of a leak. The tracer line emits an electrical charge that the gas company can use to locate the leak in the gas line. Gas lines inside the house are made usually made from steel and are joined together by a material called pipe dope.
Another gas line feeds into the manifold and distribution lines of each gas appliance in the home. Manifolds are often located in the attic and offer a straight shot to the furnace in the basement.
Gas Lines in the Past
Originally, gas lines were made of black cast iron pipes that had to be fitted together to create a continuous line without any leaks. Pipes had to be cut on site and joined securely whenever there was a change of direction or level. Once the gas line was finished, changes were close to impossible to make without a major undertaking.
Gas Lines Today
Today many plumbers use flexible steel pipe for the gas lines. Flexible steel pipe is corrugated and comes in 250-foot long rolls. Because it is flexible, there is very little need to cut and join pieces of pipe together, eliminating the potential for gas leaks.