Corrugated stainless tubing employed for gas piping: manufacturers, sources, installation specifications & building codes. Field report of CSST gas leak. CSST gas piping protection measures.

This short article describes CSST: corrugated steel pipe tubing employed for gas piping in buildings. Since 1990 CSST has been used within many buildings both in exposed and enclosed areas to set up new gas system piping. The content discusses CSST uses, sources, installation specifications, and safety precautions to guard the gas piping from damage by abrasion, puncture, lightning strikes or other hazards. Gas piping codes and industry causes of CSST are included.

Our page top photo, provided thanks to Carson Dunlop Associates, a Toronto home inspection & education firm, illustrates an improper installation of standard yellow CSST gas piping – routed in ground contact inside a wet area. Yellow “Standard” CSST gas pipin galso requires special electrical ground bonding to minimize chance of damage & leaks in regions of high lightning strike activity.

Newer black or dark-jacketed CSST gas piping (shown below, adapted from GasTite’s FlashShield CSST sales literature) currently sold by most manufacturers may not require special bonding.

Black CSST gas piping, adapted from GasTite’s FlashShield sales literature cited in this post.

Watch out: Let’s avoid a reason for confusion: CSST used as gas piping runs in buildings will not be the identical product as the flexible gas connector tubing (shown below) employed to actually connect gas appliances to the gas supply system, and various installation and product protection measures are needed. CSST gas piping is commonly used to route natural gas or LP gas supply using a building as the flexible gas tubing shown below is designed specifically for your connection of gas appliances to the gas piping system.

Look for corrugated stainless tubing (CSST) used as gas piping in buildings constructed inside the United states or Canada after 1990 and also search for it in older buildings where gas piping was newly installed or modified since 1990. CSST is additionally placed in other countries.

Collapsing building © Daniel FriedmanStandard “yellow” or newer black CSST might be recognized in (usually) long runs between your building gas source and its reason for use at gas appliances. The gas appliance connector itself (shown in the photo just above) might be connected directly in between the end in the CSST and the appliance, or the CSST may terminate or be combined with black iron gas piping inside the same building.

CSST gas piping is run in both exposed locations and thru building cavities for example walls, ceilings or floors.

How many homes have CSST installed? We had trouble relating industry estimates around Census data and United states Energy Information Agency data, but it is obvious how the piping is positioned in many homes in Canada, the United States, and Japan.

In accordance with the CSST Safety Website (below), corrugated stainless-steel tubing is placed in about 500,000 new homes annually. Since the U.S. Census Bureau and United states HUD February 2015 New Construction Data news release reports a seasonally adjusted annual rate of the latest construction in the United states of about one million homes, that demonstrates that one half of brand-new homes are increasingly being designed with CSST gas piping.

Or maybe if we look at the February housing start data this means that almost 100% of brand new homes use CSST gas piping – which sounds a bit dubious. In 2014 the United states EIA reported that 27% of most Usa homes were supplied with gas and fewer than 1% with many other gases.

I’m a dwelling contractor in Wisconsin, I might like more details on oval tube utilized for gas piping in buildings. It appears as if manufacturers don’t require it to be secured or strapped very much by any means. ‘m uncertain just what the codes say concerning this. I’ve seen it snaked almost everywhere without support — and what follows is a story of one consequence (quoting from an e-mail to your manufacturer):

I wonder when you could produce a concept about support and protection requirements for CSST. I recently came back from helping my Brother-in-Law with just a few issues in the Condo in Boston — he experienced a sprinkler pop on the winter, so most of the drywall would have to be removed to dry things out. When the restoration contractor removed one part of drywall, the scent of gas poured out. CSST ended up being snaked through floor trusses and had looped up in a location, wherein a pneumatic nail through the wood flooring installation had punctured it.

Presumably, it offers leaked considering that the building was constructed (ten years ago), and been a hazard the entire time. Any “gas” smell people might have noticed was probably masked by the scent of the garage, for the reason that leak is in the ceiling above the garage.

Reading a couple of manufacturers’ installation guides, there doesn’t appear to be a requirement to SECURE the gas line at all — it really must be supported every 8′ or so horizontally, right? Within my Brother-in-Law’s condo, the gas line was snaked throughout rather than really strapped anywhere, while it was protected by nail plates at stud and joist penetrations. Is this acceptable, according to your guidelines and any applicable codes?

I ask, because checking this out could be covered by insurance, if it’s seen as a hazard or not around code or manufacturer’s specifications. Thanks, J.

The manufacturer’s reply was essentially how the CSST should be kept 3″ away from finished surfaces or protected by nail plates if also within 5″ of some constraint (like a penetration by way of a framing member). Beyond that, it provides an “escape” for nail penetrations. This did not avoid the leak I described, since the dexopky14 looped up and was hit by a pneumatically-driven flooring nail… CSST appears like a fantastic thing — easy to install, etc. I wonder when you would do an article onto it?

The background and field connection with CSST use within The United States led to concerns about possible pitting, corrosion or perforation in the original yellow CSST gas piping in areas where lightning strikes were common. Kraft and Torbin (2007) explained that arcing between poorly-grounded CSST gas piping and other nearby metal pathways build a potential that could encourage electrical arcing problems for the CSST gas lines. Such lightning-related electrical arcing can weaken and even perforate the gas piping resulting in dangerous gas leaks.

The danger of arcing problems for CSST is increased in areas where lightning activity is greatest and where CSST is not well bonded to some grounding system.

The authors demonstrated that lightning-related electrical arcing damage risk to CSST can be reduced by direct-bonding in the gas piping system for the building’s electrical ground system: the amount of the electrical charge from an indirect lightning strike was reduced (within their study) from 97% in the charge to 20% by direct electrical bonding on the building’s electrical ground system. Their 2007 report concluded by using a recommendation for direct ground bonding of CSST like a proposal on the National Fuel Gas Code. In 2009 a similar authors reported that CSST could perform acceptably but made important and detailed strategies for the earth bonding of CSST gas piping systems.

Goodson in a patent application (2009) also reported on the potency of direct bonding of both yellow and black CSST gas piping to lessen the potential risk of damage from indirect lightning flashing. Goodson explained that CSST was generally not much of a good electrical ground, thus lending importance to the “direct bonding” discussion for this particular gas piping system. Stringfellow (2013) continued to report on electrically-induced gas distribution piping.

Currently (2015) the makers have pretty much switched to a improved, stronger CSST gas piping whose design contains a protective outer jacket and for which extra manufacturer-specified ground bonding is not required. I feel that only Ward will continue to produce the yellow CSST accessible in the Usa

In accordance with Jim Narva, executive director of your National Association of State Fire Marshals, that association is centering on informing homeowners of the requirement for retrofit ground bonding of older CSST installations.

OPINION: I agree that CSST should be shielded from damage, including or possibly especially after it is run through building cavities where, hidden from view, it’s otherwise too simple for a future building occupant or worker to shoot a nail or screw with the material. One could believe that excluding concerns for corrosion, similar worries pertain to (and customarily prohibit the usage of) flexible copper tubing when employed for gas piping: it is far from routed within building cavities. Instead in those situations it’s common to use steel piping for such gas lines.

From the CSST installation example specifications listed here you’ll realize that the makers typically require numerous installation details to assure safe reliable operation in the gas piping system, including nail plates, flexible corrugated steel armor in some locations, support, as well as other measures. Some local jurisdictions further detail CSST gas piping installation specifications like where and how it might be routed.

Below at left is an example of a regular steel gas pipe routed via a wall cavity during building renovations of a New York Home. And also at below right you can observe the traditional differ from flexible copper tubing to CSST tube once the gas piping system needed to penetrate the property wall.