Both CSST and FAC are corrugated stainless steel pipes used to transport natural gas or propane. Because each has different limitations, it important to be able to determine which one you are looking at. Corrugated Stainless Steel Tubing (shown above) has a sheathing over the pipe, which is usually yellow or black, and the corrugation is only visible at any gaps in the sheathing at pipe connections. A Flexible Appliance Connector does not have sheathing. It is painted and the corrugation is visible.

    Here’s a few other differences between them:

CSST - is designed to be installed permanently and secured in place at regular intervals. It is not rated for connection to moveable appliances, such as a range or clothes dryer. Corrugated Stainless Steel Tubing may be installed directly to a gas meter and run through walls or into an appliance cabinet, but must be bonded.

FAC - is used only as the last section of pipe that connects to an appliance after the shut-off valve. It must be replaced when a new gas appliance is installed and is limited to 6 feet length. Only one Flexible Appliance Connector, like the one shown below, is allowed per appliance. The entire length must be visible, so it cannot enter the cabinet of an appliance or run through a wall. FAC will tolerate occasional movement after installation.

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Here’s links to a collection of our other blog posts about PLUMBING PIPES:

• How can I protect my pipes to keep them from bursting during a hard winter freeze in North Florida?

• Can galvanized steel pipe still be used for new water lines in a house? 

• How can I tell if I have cast iron pipes in my house? 

• Why can't a sanitary tee be used for a horizontal-to-horizontal drain pipe connection? 

• What is the difference between green and white sewer drain pipes?

• Is a washing machine drain hose required to be secured at the standpipe?

• What causes a gurgling sound when a bathtub or sink drains? 

• What is a "combination waste and vent" in a plumbing system? 

• What is a building trap?  

• What is a galvanized nipple?

• What are the pipes sticking out near my water valves?

• How do you accurately find a broken water pipe leak under the floor slab?

• What is the difference between water pipe and sewage (waste) pipe? 

• Why is there a flexible accordion pipe under the sink? 

• What is the difference between PVC and ABS plumbing pipe?

• What is the difference between water service pipe and water supply pipe? 

• What are the pipes on my roof? 

• How can I find out what type of water pipe runs underground from the water meter to the house (service pipe)?

• What is a P-trap?

• Why is old galvanized steel water pipe a problem for homebuyers?

• What does polybutylene pipe look like? Why is it a problem? 

• Which water pipes are an insurance problem and possibly uninsurable?

• Can you connect CPVC pipe directly to a gas water heater?  

     Visit our PLUMBING page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.