What is a common material used for gas lines in residential plumbing?

The use of black iron or flexible corrugated stainless steel tubing (CSST) is standard for gas lines in residential plumbing due to their excellent resistance to high pressure and the ability to safely transport natural gas and propane. Black iron pipes are traditionally used because they can withstand the risks associated with combustible gases, are durable, and have a strong structure that can handle the pressures involved in gas distribution. CSST offers added flexibility, which can be advantageous for installation, as it can be bent around obstacles without the need for additional fittings, making it easier to work with in confined spaces.

In contrast, CPVC and PVC are primarily used for water supply lines and drainage systems and are not suitable for gas lines because they can fail under the pressure and temperature conditions of gas applications. Galvanized steel was once used for gas lines but is less common now as it can corrode over time when exposed to gas, which compromises its integrity and safety. Therefore, black iron and CSST are the preferred choices for safely transporting gas in residential settings.