Corrugated stainless steel tubing (CSST) is a flexible, stainless steel piping system used to supply natural gas and propane in residential, commercial, and industrial structures. Standard CSST is coated with a yellow exterior plastic coating. It has been safely used in homes and businesses since 1990 and is an effective means of delivering natural gas and propane gas to homes and businesses. CSST has typically 75% fewer fittings than traditional pipe which means a safer system, less leak potential and reduced callbacks.

Like all gas piping systems, CSST must be properly installed by a qualified professional and in accordance with the Manufacturer’s Design and Installation (D&I) Guide, which now expressly includes bonding and grounding of the system in new installations. A bonding connection installed on a gas piping system, as with any metallic system within a house, will reduce the likelihood of electrical arcing to or from other bonded metallic systems in the structure.

However, some previously installed CSST systems prior to 2006 may not have the proper bonding for optimal safety: If lightning strikes on or near a structure, there is risk it can travel through the structure’s gas piping system and cause a leak, and in some cases a fire. If you have yellow CSST that was installed prior to 2006, it’s possible that it does not meet current installation requirements, and it is strongly recommended that you contact a licensed electrician to make sure that your system is properly bonded.

Note: CSST should not be confused with flexible gas appliance connectors – the product that joins a movable appliance to your home or building’s gas supply line. The difference is flexible connectors attach directly to the movable appliance from the wall or floor. CSST is usually routed beneath, through and alongside floor joists in your basement, inside interior wall cavities and on top of ceiling joists in attic spaces.