There are currently two varieties of gas piping on the market: high-pressure gas piping and low-pressure gas piping. High-pressure pipes are smaller than low-pressure pipes, but they require employing pressure reduction regulators where the pipe meets an appliance. Low-pressure pipes do not necessarily require regulators.
Only a few materials are approved for use in the fabrication of gas pipes. Currently, the types of pipes approved for use in the construction of gas furnace systems include steel pipes, copper pipes, aluminum pipes, ductile iron pipes, yellow brass pipes, PE (polyethylene) pipes and PVC (polyvinyl chloride) pipes, according to The Engineering Tool Box.
Local codes regulate the types of pipes that are to be used in gas furnace installation projects. Codes usually vary by state. Building codes should be referenced before committing to a gas furnace installation project involving a specific type of pipe, according to the sources at Propane-Generators.com. Aluminum gas piping is not approved for use in every state.
Steel pipes can be used above ground as long as corrosion will not be an issue. Yellow brass gas piping is almost exclusively used for indoor gas piping applications. According to The Engineering Tool Box, aluminum gas pipes are not approved for use underground. Ductile iron pipes, PE pipes and PVC pipes are often used outside and underground.
Copper piping and steel piping are the most common types of piping used in buildings to distribute gas to and from a gas furnace. Only type “L” or type “K” copper pipes should be used in a gas furnace installation project. Flexible connectors are available to connect pipes to a furnace, but approval of these connectors varies state by state.