Changes to how corrugated stainless-steel tubing is installed in gas piping systems are now part of the 2015 model building codes — the National Fuel Gas Code (NFPA 54) and the International Fuel Gas Code — and should make it easier for contractors to install CSST as gas piping. However, as these codes have not been adopted yet, installation of CSST is still an issue plumbing contractors need to be aware of.

“Code enforcement organizations such as the National Fire Protection Association are constantly improving the standards for proper installation and operation of CSST,” notes Michael Buchanan, director of research and development at Valencia Pipe Co., maker of Home-Flex. “Every year brings more knowledge of what is the best design and installation of CSST and its components. A great deal of the past CSST improvements to the NFPA 54 centered around the bonding of CSST, which is important to prevent a possible electric shock and reduce the risk of damage from a lightning strike.”

The CSST direct-bonding requirements in the 2015 model codes limit the bonding conductor to 75 ft. and allows the bonding clamp to be attached to the rigid pipe or fitting component anywhere on the gas piping system.

“Prior versions of the code required the bonding clamp to be located on the rigid pipe or fitting component between the fuel service entrance of the facility and the first section of CSST,” explains Craig Barry, vice president of marketing at Flex-Tek Group, parent company of Gastite, the maker of FlashShield. “This update will often result in shorter and simpler bonding wire routing. A shorter bond wire length will perform better, and is easier and less costly to run.”

Information also was added to the code that any additional grounding electrodes used shall be grounded to the existing grounding system.

These changes were the result of a research study by the Gas Technology Institute, says Bob Torbin, director of codes and standards at OmegaFlex, maker of TracPipe CounterStrike.

“The research determined the most significant variable affecting bonding effectiveness is the length of the bonding conductor, not its location,” he notes. “The GTI also determined that in one- and two-family homes, a single clamp is all that’s required somewhere on the piping system.”

Dave Edler, senior product engineer at Ward Mfg. Co. (maker of WARDFLEX and WARDFLEX II) adds: “Several manufacturers joined in the research project to provide information to the standards council to show that the bonding of CSST is effective in mitigating damage caused by indirect lightning.”

These indirect lightning strikes can result in a power surge to a home that can damage gas piping systems and cause a fire. The National Association of State Fire Marshalls created a website,, to provide information for homeowners on the CSST in their gas piping systems and how it should be installed.

Homeowners shouldn’t only be worried about lightning strikes, Torbin says, since only a small fraction of home fires are caused by lightning. “Bonding is a proven methodology for minimizing damage from electrical arcing no matter what the cause — power surge, lightning strike or electrical system malfunction,” he explains. “And bonding is good for all gas piping — whether steel, copper or corrugated — to protect all the metal in the home from electrical damage.”

Because states have not adopted the newly released 2015 model building codes governing CSST installation, plumbing contractors need to do their homework before installing any gas piping. It can take three to six years before a state adopts a model building code. In each installation in each jurisdiction, contractors need to know which version of the building codes applies, what amendments have been approved and what product he or she is installing.

“Model codes can be adopted as is or adopted with modifications,” Edler explains. “Some municipalities may choose to enforce the bonding requirements, some may not. It’s completely up to the local jurisdictional authority to determine what is adequate for its municipality.

“One of the first things we state in our design and installation guides and training courses is that the local authority having jurisdiction can supercede or override the manufacturers’ requirements. It has the ultimate say in how the product should be installed.”


Arc-resistant products

Some manufacturers have developed CSST with arc-resistant black jackets, or black CSST, which would not need the additional bonding clamp and wire mandated for yellow CSST.

“The main reason Gastite made the decision to only sell black CSST is that the demand from our installer customer base has shifted to the FlashShield product line over the past several years because of its superior performance in simulated direct lightning strikes,” Barry says.

Installation requirements for Ward’s Wardflex II, which includes a black conductive coating on the outside, say the product must be installed with the same minimum bonding requirements as black pipe, Edler says.

The Canadian Standards Association updated its ANSI LC1 CSST standard to include performance requirements for these arc-resistant jacketed products, Tobin notes. Yet the model codes do not distinguish between yellow and black CSST, thus requiring additional bonding for all CSST piping.

            “OmegaFlex feels comfortable whether or not its product gets bonded to the ground, which is why the company no longer sells yellow TracPipe CSST in the United States,” he explains. “We can’t guarantee local enforcement or know what code is being enforced or what local amendments have been executed. By only selling the black product, we insulate our customers from these kinds of enforcement problems. Exclusive use of the black product is inevitable in the plumbing industry.”

To clear up any confusion within the industry — and especially with installers — OmegaFlex believes the model building codes should require bonding for allgas piping because in many homes that use steel pipe and copper tubing it is common to have appliance flexible connectors made of CSST. And the fuel gas code requires that CSST should be protected no matter how short the length.

Another case for bonding requirements for all gas piping materials concerns metallic flues used for appliance venting — for furnaces, water heaters or fireplaces. “If lightning hits the vent, which is common, that energy is going to go right to the gas piping system,” Tobin says. “If the gas piping is steel or copper, it’s going to damage the equipment and may perforate the flex connector because there is no pathway to the ground.”

To make sure contractors are properly installing CSST for their clients, they should take advantage of the training provided by CSST manufacturers. Many have developed technical bulletins on the subject and all have included the new bonding requirements in their design and installation guides. And technical support staff is available to answer any CSST bonding questions.