The following is taken from CSST Safety website. Corrugated Stainless Steel Tubing (CSST) is a flexible, stainless steel pipe used to supply natural gas and propane in residential, commercial and industrial structures. CSST is often coated with a yellow, or in some cases, a black exterior plastic coating. CSST should NOT be confused with flexible gas appliance connectors – the product that joins a moveable appliance to your home or building’s gas supply line.
Bonding is provided primarily to prevent a possible electric shock to people who come in contact with the gas piping and other metal objects connected to the grounding system. Nearby lightning strikes can result in an electrical surge that can potentially puncture a hole in CSST and cause a fire. Proper bonding and grounding will reduce the risk of damage and fire from a lightning strike.
The importance of proper venting of gas appliances cannot be understated. With the increased efficiency of today’s furnaces and water heaters, venting into older masonry chimneys designed for low efficiency furnaces and water heaters, can create unsafe conditions. In many older homes, new high efficiency furnaces are being installed which no longer use the old masonry chimney, leaving the orphaned water heater to vent into a flue that is over sized. This condition can result in exhaust fumes entering teh home each time the water heater is used. For more on this we have attached a report from WSSC.