CSST, or corrugated stainless steel tubing, is a flexible gas pipe used to carry natural gas or propane to appliances. Its bendable stainless steel wall installs faster than rigid black iron pipe. Traditional yellow CSST must be bonded to the home's grounding system to lower the risk of lightning damage.
For decades, gas lines meant heavy black iron pipe, cut and threaded one rigid piece at a time. CSST changed that. Short for corrugated stainless steel tubing, it is a flexible gas pipe that bends around corners and through framing like a stiff hose. It was approved for wide use in the United States around 2003 and now runs in more than half of new homes.
Why Installers Use It
CSST is a thin, ridged stainless steel tube inside a colored plastic jacket, usually yellow or black. The ridges let it flex without kinking. Because it bends by hand and uses far fewer joints, a plumber can run a line in a fraction of the time black iron takes. Fewer fittings also means fewer spots that can leak. It carries both natural gas and propane and is built to the CSA/ANSI LC-1 product standard, one of the approved gas piping materials. Gas still passes through a gas pressure regulator before it reaches each appliance. To weigh the two pipe types, see CSST vs black iron gas pipe.
Bonding Is Not Optional
Traditional yellow CSST comes with one strict rule. Its thin wall can be punctured by the surge from a nearby lightning strike, which can burn a pinhole and leak gas. To lower that risk, code and the maker require the system to be bonded. A dedicated wire ties the gas piping to the home's grounding electrode system and drains that voltage away. The bonding wire must be at least 6 AWG copper and no longer than 75 feet. Newer arc-resistant CSST, often black and sold as products like Gastite's FlashShield, uses a tougher jacket and does not need the extra bonding wire.
Leave It to a Pro
Because bonding is a safety step and gas is involved, CSST work calls for a licensed gas plumber and a permit. Running new tubing is common when you add a gas line for a range, dryer, or pool heater.