CSST FAQs

GENERAL QUESTIONS
What is CSST gas piping?
What is the history of CSST?
Can CSST be damaged by lightning?
Has anyone ever been injured in a fire caused by lightning damage to CSST?
How many homes use CSST?

CONSUMER QUESTIONS
What are the chances of my house being struck by lightning?
Is CSST piping safe to use in my home?
Where is CSST piping located in my home?
If I have CSST piping in my home, what should I do?

CONTRACTOR QUESTIONS
What are the benefits of using CSST flexible gas piping?
Why is it important to bond CSST piping?
Who is recommended to perform this work?
What information will the electrician need?

CODE QUESTIONS
What is the current code status of CSST piping?
What is the approval status of black iron pipe?
Are codes the same for gas piping nationwide?
Is direct bonding required in the gas and electrical codes?



GENERAL QUESTIONS

What is CSST gas piping?
Historically, rigid piping was used to pipe buildings for gas to supply furnaces, hot water heaters and other gas appliances. In some cases, rigid black iron pipe is used to make this connection. But due to earthquakes and other natural disasters that fracture rigid pipe, in the 1980s the Japanese developed a more robust flexible piping system. Subsequently, a flexible pipe design was developed for the United States by the American Gas Association and its research arm, the Gas Research Institute. In 1991, the American National Standards Institute (ANSI) published the ANSI LC 1 standard, and products based on this standard are called Corrugated Stainless Steel Tubing (CSST).

CSST is a flexible, corrugated stainless steel tubing used to supply natural gas and propane in residential, commercial, and industrial buildings. It should not be confused with appliance connectors, the similar flexible piping that connects directly to moveable appliances—like ranges or dryers—from the wall or floor. CSST piping is a high-strength piping system that can be routed beneath, through and alongside the basement joists, inside the interior wall cavity or through attic spaces. It also has fittings that are easy to assemble with standard hand tools and make a leak tight seal.

What is the history of CSST?
CSST was developed—first in Japan and then in the United States—by the gas industry to provide a better and safer gas distribution system. There have been over 750 million feet of CSST made and installed in the United States over the last 20 years, and during that time CSST has built an outstanding safety record.

Can CSST be damaged by lightning?
All building systems can be damaged by lightning including the structure, electrical system, electronics and communications and all gas piping components. Direct strikes are highly destructive, and there is little that can be done to protect a building from these events unless a lightning protection system is installed. Indirect lightning strikes are less severe, and tend to energize the electrical and mechanical systems and can damage the building’s systems and contents, including electronics.  Differences in electrical potential between the metal systems may allow a charge to arc between the two materials. Such arcing can damage piping and cause leaks in various ways.  CSST manufacturers provide specific installation instructions to protect the pipe from damage due to the electrical arcing, and it is safe when installed in accordance with these instructions and code requirements. 

Has anyone ever been injured in a fire caused by lightning damage to CSST?
No. There have been no deaths or injuries caused by CSST piping.

How many homes use CSST?
In the United States over the last two decades, CSST has been installed in nearly five million homes. Over 750 million feet—enough to circle the earth five times—has been installed in residential, commercial, and industrial buildings in the United States.

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CONSUMER QUESTIONS

What are the chances of my house being struck by lightning?
Lightning’s behavior is 100% random and unpredictable. Any locale can experience lightning anytime if certain weather conditions prevail. However, states along the Gulf of Mexico and the Mississippi River have a higher lightning risk than the rest of the country. (See map). In general, there are on average about 4,400 lightning fires to residential homes in the United States each year, so there would be a very small chance of a lightning fire. However, the lightning density varies across the United States, and other factors can affect your chances. For example, a house on a tall hill without any nearby trees would be more likely to be struck by lightning and have a fire.

The best defense is to recognize (be aware of) the unsafe situation and take appropriate safety measures. According to the National Lightning Safety Institute, each part of the country experiences a different rate of lightning strike occurrences, known as the “flash density rate.”

Is CSST piping safe to use in my home?
CSST is safe. CSST must be installed by a qualified professional and in accordance with the manufacturer's design and installation guide and local codes, using proper procedures to bond the piping directly to the electrical service. After nearly 20 years and five million installations, there have been no deaths or injuries caused by CSST.

Where is CSST located in my home?
CSST runs from the gas meter or propane source to gas appliances through the basement, walls and attic, depending on the type of construction. It can also be installed with portions of black iron pipe or copper. It is typically visible in the basement, attic and at fixed appliances such as hot water heaters or furnaces. CSST piping is coated with a yellow or black exterior jacket. CSST piping should NOT be confused with flexible appliance connectors attached to moveable appliances like ranges and dryers.

If I have CSST piping in my home, what should I do?
CSST is safe when installed and bonded in accordance with manufacturer’s requirements. This bonding is the same as bonding for copper water pipe. In general, bonding involves the attachment of a 6-gauge copper wire at the gas service entrance to the electrical service bonding point or grounding electrode. If you are concerned that the system may not be properly bonded, the assistance of a qualified electrician may be required to perform the inspection, as well as any upgrade per the manufacturer’s bonding instructions and local codes.

However, lightning is a tremendously powerful force that can damage any and all electrical or mechanical systems in a home. For those living in a high lightning density area, consideration should be given to the installation of a lightning protection system to protect the entire home from lightning.

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CONTRACTOR QUESTIONS

What are the benefits of using CSST flexible gas piping?
CSST is flexible, so it easily snakes through walls and around obstacles without the need for multiple joints. With rigid pipe, routing around each obstacle requires a joint that needs to be fitted and checked for leaks. With CSST, fittings are only needed at the ends of each run. Because a CSST gas piping system has fewer joints, there are far fewer potential leak points. Advanced CSST piping is available to provide enhanced lightning protection without additional bonding, except where required by local codes.

Why is it important to bond CSST piping?
Bonding gas piping to the electrical service is the proper way to provide electrical protection to the gas piping system. Bonding prevents a possible electric shock hazard if people contact the gas piping. Also in the event of a lighting strike, bonding to the electrical service ensures the electrical potential rises and falls at the same level as other components in the system. Because the voltage difference is equalized, the possibility of arcing is reduced or eliminated. All legal cases claiming that a fire was caused by an indirect lightning strike producing a hole in CSST piping have been cases where the CSST system was not properly bonded. Proper CSST installation is covered in the OmegaFlex installation guide.

Who is recommended to perform this work?
A registered electrician is the most qualified person to inspect and perform bonding.

What information will my electrician need?
The information an electrician must know is covered in the CSST manufacturer’s installation guide and local code requirements.

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CODE QUESTIONS

What is the current code status of CSST piping?
CSST is approved for use as a gas piping material in all national model building codes, including the National Fuel Gas Code, the International Fuel Gas Code, and the Uniform Plumbing Code, and is approved for use in all 50 states. U.S. buildings codes currently require ‘direct bonding' of CSST.

What is the approval status of black iron pipe?
While black iron pipe is an approved material in national model building codes, it is not listed by any national standard nor tested by a third-party laboratory. In fact, most black iron pipe is imported from Asia with minimal or no documentation.

Are codes the same for gas piping nationwide?
The major codes are the National Fuel Gas Code (NFGC), the International Fuel Gas Code (IFGC), and the Uniform Plumbing Code (UPC). The model codes are published every three years with changes that go through a public comment process. The states adopt the different editions of the model codes at different times. These codes are adopted by the states, either in full or with some changes. So determining what code is in effect in any one state or city will require research into the legislative and regulatory actions of the government in adopting the model building code. 

Is direct bonding required in the gas and electrical codes?
Yes and No. “Direct” bonding refers to running a dedicated bonding wire from the gas piping service entrance to the electrical grounding system. In the current edition of the National Fuel Gas Code and the International Fuel Gas Code, CSST must be bonded to the building’s electrical ground using a minimum 6-AWG wire. In contrast, the current edition of the National Electrical Code (NEC) permits the use of the equipment grounding conductor (the third ground wire from a gas-fired appliance) to serve as the bonding wire. As a result, there is a conflict in the two model building codes. All CSST manufacturers require the installation of a 6-AWG bonding wire to the building’s electrical ground for standard CSST products. If the CSST uses a conductive jacket, then the use of the 6-AWG bonding wire is not required by the manufacturer. Qualified installers should consult local code requirements for their installation.

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20 Years of Safety

As the only gas piping technology approved by ANSI and other national standards, Corrugated Stainless Steel Tubing (CSST) has been installed in millions of homes with an outstanding safety record.

Rigid Pipe Kills

Two natural forces affect gas piping: earthquakes and lightning strikes.