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Standard yellow CSST Gas piping hazards (C) InspectPedia & Carson Dunlop Associates TorontoCorrugated Stainless Steel Tubing (CSST) Gas Piping
What is CSST, where is it used, how do manufacturers want it to be installed?

Flexible gas piping CSST:

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

Our page top photo, provided courtesy of Carson Dunlop Associates, a Toronto home inspection & education firm, illustrates an improper installation of standard yellow CSST gas piping - routed in ground contact in a wet area. Yellow "Standard" CSST gas pipin galso requires special electrical ground bonding to reduce risk of damage & leaks in areas of high lightning strike activity.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

- Daniel Friedman, Publisher/Editor/Author - See WHO ARE WE?

CSST Gas Piping: Corrugated Stainless Steel Tubing

Article Contents

What is CSST Gas Piping & How is it Identified in Buildings

CSST or Corrugated Stainless Steel Tubing is a flexible gas piping system that has been in use in the U.S. since 1990. In Japan the system has a decade more experience.

"Standard Yellow CSST" such as shown below (adapted from csstsafety.com) may appear in homes where gas piping was installed or modified since 1990.

Standard yellow CSST gas piping needs special electgrical ground bonding - see www.cssafety.org

Through csstsafety.com the National Association of State Fire Marshals and the CSST industry recommend that homes where gas piping has been installed or modified since 1990 be inspected for the presence of yellow CSST and that the electrical ground bonding in those homes be inspected.

[Click to enlarge any image]

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 article.

Watch out: Let's avoid a point of confusion: CSST used as gas piping runs in buildings is not the same product as the flexible gas connector tubing (shown below) used to actually connect gas appliances to the gas supply system, and different installation and product protection measures are required.

CSST gas piping is used to route natural gas or LP gas supply through a building while the flexible gas tubing shown below is specifically designed for the connection of gas appliances to the gas piping system.

Gas appliance connector tubing (C) Daniel Friedman

Where is CSST Gas Piping Being Installed?

Look for corrugated stainless steel tubing (CSST) used as gas piping in buildings constructed in the U.S. or Canada after 1990 and also look for it in older buildings where gas piping was newly installed or modified since 1990. CSST is also installed in other countries.

Collapsing building © Daniel FriedmanStandard "yellow" or newer black CSST can be recognized in (usually) long runs between the building gas source and its point of use at gas appliances.

The gas appliance connector itself (shown in the photo just above) may be connected directly between the end of the CSST and the appliance, or the CSST may terminate or be mixed with black iron gas piping in the same building.

CSST gas piping is run both in exposed locations and through building cavities such as walls, ceilings or floors.

How many homes have CSST installed? We had trouble relating industry estimates with US Census data and U.S. Energy Information Agency data, but there is no doubt that the piping has been installed in many homes in Canada, the United States, and Japan.

According to the CSST Safety Website (below), corrugated stainless steel tubing is installed in about 500,000 new homes each year. As the U.S. Census Bureau and U.S. HUD February 2015 New Construction Data news release reports a seasonally adjusted annual rate of new construction in the U.S. of about one million homes, that suggests that half of all new homes are being built with CSST gas piping.

Or if we look at the February housing start data that means that almost 100% of new homes are using CSST gas piping - which sounds a bit dubious. In 2014 the U.S. EIA reported that 27% of all U.S. homes were supplied with natural gas and less than 1% with other gases.

Still, the system is in active use in the U.S. and Canada and continues in use in Japan.

Fire & Safety Measures to Protect CSST Gas Piping from Damage &Leaks

Standard yellow CSST Gas piping hazards (C) InspectPedia & Carson Dunlop Associates Toronto

Reader Question: report of gas leak from punctured CSST Gas Piping

[At left, a new CSST gas piping installation, incomplete, is illustrated, courtesy of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].]

I'm a dwelling contractor in Wisconsin, I would like more information on Corrugated Stainless Steel Tubing (CSST) used for gas piping in buildings. It seems like manufacturers don't require it to be secured or strapped very much at all. 'm not sure what the codes say about that.

I've seen it snaked all over the place without support -- and here is a story of one consequence (quoting from an email to a manufacturer):

Email sent to ProFlex Technical Assistance

I wonder if you could give me an idea about support and protection requirements for CSST. I just came back from helping my Brother-in-Law with a few issues in his Condo in Boston -- he had a sprinkler pop over the winter, so a lot of the drywall had to be removed to dry things out.

When the restoration contractor removed one section of drywall, the smell of gas poured out.

CSST had been snaked through floor trusses and had looped up in one location, where a pneumatic nail from the wood flooring installation had punctured it.

Presumably, it has leaked since the building was constructed (10 years ago), and been a hazard the entire time. Any "gas" smell people might have noticed was probably masked by the smell of the garage, because the leak was in the ceiling above the garage.

Reading a few manufacturers' installation guides, there doesn't seem to be a requirement to SECURE the gas line at all -- it just has to be supported every 8' or so horizontally, right? In my Brother-in-Law's condo, the gas line was snaked all over and not really strapped anywhere, although 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 may be covered by insurance, if it's seen as a hazard or not up to code or manufacturer's specifications. Thanks, J.

The manufacturer's reply was essentially that the CSST needed to be kept 3" away from finished surfaces or protected by nail plates if also within 5" of some constraint (like a penetration through a framing member). Beyond that, it has an "escape" for nail penetrations.

This did not prevent the leak I described, as the CSST looped up and was hit by a pneumatically-driven flooring nail... CSST seems like a great thing -- easy to install, etc. I wonder if you would do an article on it?
Thanks J.

Reply:

Our reply to reader J. begins immediately below

Lightning Strike Hazards and CSST Gas Piping Leaks

The history and field experience of CSST use in North America led to concerns about possible pitting, corrosion or perforation of 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 create a potential that may encourage electrical arcing damage to the CSST gas lines.

Such lightning-related electrical arcing can weaken or even perforate the gas piping leading to dangerous gas leaks.

The risk of arcing damage to CSST is increased in areas where lightning activity is greatest and where the CSST is not well bonded to a grounding system.

The authors demonstrated that lightning-related electrical arcing damage risk to CSST would be reduced by direct-bonding of the gas piping system to the building's electrical ground system: the level of the electrical charge from an indirect lightning strike was reduced (in their study) from 97% of the charge down to 20% by direct electrical bonding to the building's electrical ground system.

Their 2007 report concluded with a recommendation for direct ground bonding of CSST as a proposal to the National Fuel Gas Code. In 2009 the same authors reported that CSST could perform acceptably but made important and detailed recommendations for the ground bonding of CSST gas piping systems.

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

Currently (2015) the manufacturers have pretty much switched to an improved, more durable CSST gas piping whose design includes a protective outer jacket and for which extra manufacturer-specified ground bonding is not required. I think that only Ward continues to produce the yellow CSST for sale in the U.S.

According to Jim Narva, executive director of the National Association of State Fire Marshals, that association is focusing on informing homeowners of the need for retrofit ground bonding of older CSST installations.

... we are focused on a safety campaign to make homeowners aware of the need to bond yellow CSST. It is estimated to be in about 6-8 million homes where it was installed before bonding was a code requirement or manufacturer installation instruction

Between the early 1990’s when it was introduced in the US market and the mid 2000’s when the requirements came about is the target we are trying to reach and unfortunately no one knows where those 6-8 million homes are in the US. - private email, Narva to Friedman, 14 April 2015

Nail or Screw Puncture Risks with CSST Gas Piping

Steel gas piping new installation (C) D Friedman E Galow

Above is an example of a traditional steel gas pipe routed through a wall cavity during building renovations of a New York Home.

OPINION: I agree that CSST needs to be protected from damage, including or perhaps in particular when it is run through building cavities where, hidden from view, it's otherwise too easy for a future building occupant or worker to shoot a nail or screw through the material.

One would think that excluding concerns for corrosion, similar worries apply to (and generally prohibit the use of) flexible copper tubing when used for gas piping: it is not routed within building cavities. Instead in those situations it's common to use steel piping for such gas lines.

Change from flexible copper to steel gas piping at wall penetration (C) Daniel Friedman

Above you can see the traditional change from flexible copper tubing to steel piping when the gas piping system had to penetrate the building wall.

In the CSST installation example specifications listed below you'll see that the manufacturers typically require a number of installation details to assure safe reliable operation of the gas piping system, including nail plates, flexible corrugated steel armor in some locations, support, and other measures.

Some local jurisdictions further detail CSST gas piping installation specifications such as where and how it can be routed.

But CSST is indeed in widespread use as gas piping in both exposed and hidden locations. Here are some typical protective measures specified by CSST tubing manufacturers cited in the references above.

CSST Gas Piping Installation Code, Safety & Protection Features

Local CSST Gas Piping Specifications Extending the Model Codes for Improved Safety

The following example is excerpted from a local Oklahoma Building Code for Rogers County, Appendix H, , Subsection "Policy for installation of Corrugated Stainless Steel Tubing (CSST)", in Appendix H-17General Information and Responsibilities for One & Two Family Residential Construction, - retrieved 14 April 2015, original source: http://www.rogerscounty.org/planning/zoning%5CAH.pdf -

CSST Gas Piping Bonding suggestion for Oklahoma's Rogers County

[Click to enlarge any image]

CSST Gas Piping Bonding suggestion for Oklahoma's Rogers County

CSST Gas Piping Codes, Specifications, Industry Trade Associations

CSST Gas Piping Safety Research, Patents, Studies

  • Durham, Robert A., and Marcus O. Durham. "Does Corrugated Tubing Lightning Catastrophic Failure?." Industry Applications, IEEE Transactions on 48, no. 4 (2012): 1243-1250.
    Abstract

    In conducting analysis of systems that have failed as a result of lightning and transients, the authors have observed repeated incidences associated with corrugated flexible tubing (CFT). Corrugated stainless-steel tubing is one of a group of flexible pipes used for low-pressure gas.

    This tubing is increasingly used not only in processes but also in laboratories, warehouses, and office facilities for distribution of heating gas. These products were designed with mechanical properties in mind.

    The design does not directly consider electrical characteristics; however, since these piping systems are constructed of conductive metals, they will have electrical properties.

    Despite the observed tendency of this piping to fail during lighting and transient events, there has been no coherent hypothesis for the phenomenon of CFT failure due to lightning. This paper will address the electromagnetic response of these tubing systems.

    Ten electrical properties are correlated to the impact of lightning and transients on materials such as corrugated tubing.
  • Durham, M. O., and R. A. Durham. "Lightning dangers on corrugated tubing carrying hydrocarbons." In Petroleum and Chemical Industry Conference (PCIC), 2010 Record of Conference Papers Industry Applications Society 57th Annual, pp. 1-9. IEEE, 2010.
  • "Industry PR Efforts Prompt Media Coverage of CSST / Gas-related Lightning Fires", Flash Notes, The Lightning Protection Institute, 25475 Magnolia Dr., POB 99, Maryville MO 64468, Tel: 660-582-0429, Email: LPI@lightning.org, Website: Lightning.org (Summer/Fall 2007), - retrieved 14 April 2015, original source:http://www.lightning.org/wp-content/uploads/2012/10/Flash_Notes_Summer-Fall_07.pdf

    This article cites a 2007 press release distributed "in conjunction with the 2007 NFPA World Safety Conference on June 4 2007". That press release was titled "Lightning Fires Linked to Problem Gas Tubing", 6/4/2007
    Quoting:

    A class action lawsuit against four manufacturers of a relatively new type of fuel gas piping has identified the installation of a lightning protection system as a remedy for the fire risk associated with CSST (corrugated stainless steel tubing) gas piping systems. CSST is a type of flexible piping that has been widely used in homes and commercial applications in recent years.

    Unlike traditional, heavy-walled gas pipes, CSST is extremely thin and therefore susceptible to damage from lightning. Lightning traveling on the CSST can burn holes in the tubing and allow gas leakage and fire. In worse [sic] case scenarios, such leaks have led to catastrophic gas explosions.

    The CSST has been found to be susceptible to damage from direct and even indirect nearby lighting strikes.

    CSST has been widely used in recent years because it is easy to install. According to the National Fire Protection Association (NFPA) however, no tests on the effects of lightning on CSST were conducted prior to its approval for use. One CSST manufacturer has acknowledged that the installation of a lightning protection system addresses the hazard associated with CSST, yet homes with CSST are rarely equipped with lightning protection systems. ...
    ...
    "Lightning does not have to strike a building directly in order for the CSST to be affected," explains Guy Maxwell, president of the Lightning Safety Alliance. "The reports of CSST related fires that I have seen involved strikes that were near the structure."
    ...
    In March 2007, the four defendants in the Class Action suit filed in the Circuit Court of County Arkansas reached a Settlement. Under the guidelines of the settlement, owners of structures in the U.S., in which CSST was installed prior to September 2006, can obtain vouchers to defray the cost of mitigating the CSST hazard.

    Remedies identified by the settling parties include installing a lightning protection system and/or making bonding and grounding connections to certain systems in a structure.
    ...
    The deadline to enter a claim under the CSST Settlement is September 5, 2007. For more information call 1-800-420-2916 or visit the website at www [dot] csstsettlement [DOT] .com.
    NOTE: the above website is no longer functional. Do not bother trying it as it's simply an advertising site. Editor, 4/14/2015.
  • Kraft, Brian, and Robert Torbin. "Effectiveness of Direct Bonding of Gas Piping in Mitigating Damage from an Indirect Lightning Flash." (2007).
  • Kraft, Brian, P.E., & Torbin, Robert, P.E., "Evaluation of CSST Gas Piping Subjected to Electrical Insult." Rising Tide Consulting, L. L. C., and L. L. C. Cutting Edge Solutions. (2009).
    Excerpts from the article's Executive Summary:

    Recent events have shown the proclivity of corrugated stainless steel tubing (CSST) to become physically damaged (through electrical arcing) when installed in close proximity to other metallic systems that are simultaneously energized by a lightning strike but not equally bonded to the grounding electrode system.

    This has raised concerns within the electrical community about the general capability of CSST to withstand other electrical insults associated with the “normal” use of electricity. This report summarizes the engineering analysis performed to address these concerns regarding the performance of CSST under electrical insult.

    Considering current installation practices and code requirements for residential construction, electrical service and fuel gas piping systems, the most probable (and severe) electrical insults were determined to be fault current and indirect lightning strikes. The damage modes associated with CSST and these insults were identified as: resistance heating in conductors, resistance heating in connectors, mechanical damage in connections, and arcing between conductors.

    Excerpts from the article's Conclusions:

    It was determined that the primary electrical insults that required evaluation were the application of a fault current to the gas piping and the application of high voltages and currents due to indirect lightning strikes.

    The ability of the material, (tubing, fittings and electrical connectors) to function safely and to resist damage from associated currents, voltages, and arcing was examined.

    Based on this evaluation and testing, the CSST materials and product investigated were found to be capable of performing acceptably well when exposed to anticipated electrical insults that may occur within a residential or light-commercial building.

    The article continues to list of important recommendations for direct bonding of the CSST tubing to reduce arcing damage.
  • Rousseau, Alain, and Mitchell Guthrie. "Direct Lightning Withstand of Corrugated Stainless Steel Tubing for Gas.", 2012 International Conference on Lightning Protection (ILCP), Vienna, Austria. - retrieved 13 April 2015, original source: http://seftim.clic-droit-tech.com/publications/ICLP/ICLP_2012_CSSTinvestigations.pdf
    Abstract

    Corrugated stainless steel tubing (CSST) is used in many countries throughout the world as a practical way to distribute gas within houses and other installations. CSST has become very popular in some countries as it is a very thin and thus flexible tube that allows for easy installation in crawl spaces, inside walls, and in the attic.

    A link between lightning activity and fires involving CSST piping has been reported in the United States as early as 2003.

    Damages documented to CSST generally result in one or more holes in the wall of the pipe leading to a release of gas into the structure with no fire to fire with minimal damage and in some cases complete destruction of the structure. Many experts have studied this subject and many scenarios have been established to explain the failure modes.

    A few reports exist and are summarized in the paper. This paper will then mainly concentrate on case studies and on test results for one scenario that has been almost ignored: partial lightning current flowing
  • Stringfellow, Michael F. "Causes of residential lightning fires: Electrical arcs are at the root." Industry Applications Magazine, IEEE 19, no. 3 (2013): 60-66.
    Abstract:

    This article presents evidence that a major cause of residential lightning fires is electrical arc-fault current. Such arc-fault currents are a common result of both direct and indirect lightning strikes. These faults result from lightning overvoltage damage to the insulation of electricity supply conductors and appliances.

    Many of these overvoltages appear to be caused by indirect lightning strikes, and a small fraction of these events also result in damage to fuel gas systems, especially thin, metallic, flexible gas lines. Fuel gas leaks resulting from this electrical damage may contribute to the fire hazard.

    The absence of any lightning protection on residences with exposed metallic roof penetrations is considered a major factor.

CSST Patents Aiding in Finding the History of CSST Gas Piping Usage

  • Albino, Mark. "Corrugated tubing fitting." U.S. Patent 5,799,989, issued September 1, 1998.
  • Albino, Mark, and Edwin E. Pike. "Preassembled fitting for use with corrugated tubing." U.S. Patent 6,079,749, issued June 27, 2000.
  • Albino, Mark. "Underground piping system." U.S. Patent 6,315,003, issued November 13, 2001.
  • Duquette, Scott, and Brian Coppola. "Sealing devices and methods of installing energy dissipative tubing." U.S. Patent 8,399,767, issued March 19, 2013.
    ABSTRACT
    Sealing devices are provided along with methods of installing energy dissipating tubing. An aspect of the invention provides a sealing device for connecting an energy dissipative tube having a length of tubing, a first resin layer surrounding the outside of the tubing, a conductive layer adjacent to the outside of the first resin layer, and a second resin layer surrounding the conductive layer and the first resin layer. The sealing device includes one or more penetrating members configured to penetrate the second resin layer and establish electrical continuity with the conductive layer.
  • Goodson, Mark E. "Method of preventing electrically induced fires in gas tubing." U.S. Patent 7,562,448, issued July 21, 2009.
  • Goodson, Mark E. "Device for Preventing Electrically Induced Fires in Gas Tubing." U.S. Patent Application 12/971,802, filed December 17, 2010.
  • Goodson, Mark E. "Leak prevention method for gas lines." U.S. Patent 8,251,085, issued August 28, 2012.
  • Lininger, Thomas B., Steven M. Powell, and Nicholas Novak. "Secondary contained csst pipe and fitting assembly." U.S. Patent Application 12/064,539, filed August 22, 2006.
  • Mau, Andrew E. "Self-flaring, split bushing pipe fitting and hose assemblies employing same." U.S. Patent 6,173,995, issued January 16, 2001.
  • Treichel, Steven A. "Fitting for use with corrugated tubing." U.S. Patent 6,276,728, issued August 21, 2001.
  • Treichel, Steven A. "Sealed fitting for use with corrugated tubing." U.S. Patent 6,695,353, issued February 24, 2004.

Sources of CSST Corrugated Stainless Steel Tubing, Plastic Gas Piping, Underground Gas Piping, & Installation Manuals

  • GasTite, Inc., (manufacturer of FlashShield™ system Corrugated Stainless Steel Tubing (CSST). Gastite Division 1116 Vaughn Parkway Portland, TN 37148 Telephone 800-662-0208 Website: www.gastite.com, Email: gastite@gastite.com

    [This is a metallically-shielded 0.010 wall thickness Annealed 304 stainless steel CSST system that meets LC1024 & LC1027. No additional manufacturer-bonding is required. black tubing product promising superior lightning protection.].
    Quoting:

    FlashShield™ Corrugated Stainless Steel Tubing (CSST) supplies natural gas or LP gas to appliances. FlashShield is a reliable, lightning-resistant system that can be installed in all modes of construction. Flexibility and no additional bonding means quick and easy installations: FlashShield® installs 30-70% faster than traditional piping methods.

    Tubing material: ASTM A240 Type 304 321 Stainless Steel

    Tubing jacket material: UV resistant Polyethylene complying with requirements of ASTM E84 Index for Flame and Smoke.
  • GAS SUPPLY INSTALLATION BLUE BOOK - NY [PDF] (2015) National Grid
  • GASTITE FLASHSHIELD PIPING MANUAL [PDF] Gastite underground gas piping: Website: www.gastite.com Tel: 800-662-0208 Email: gastite@gastite.com
  • HOME-FLEX FLEXIBLE CSST GAS PIPE MANUAL [PDF] Home-Flex underground gas piping Website: homeflex.com Tel: 1-661-257-3923
  • Metal-Fab, Inc. (manufacturer of Diamondback CSST gas piping)
    Website: www.mtlfab.com
  • Omegaflex, Inc. (manufacturer of TracPipe and CounterStrike CSST gas piping), Omega Flex Incorporated, 451 Creamery Way, Exton, PA 1 Tel: 610.524.7272 Toll Free: 800.355.1039. [No additional manufacturer bonding requirements].
    Website: www.tracpipe.com
    Quoting:

    TracPipe® CounterStrike® is a patented CSST innovation based on our existing TracPipe® CounterStrike® CSST product, but that is engineered to significantly decrease the potential for lightning induced damage to fuel gas piping systems. TracPipe® CounterStrike® has been designed with a proprietary jacket material in place of the standard yellow jacket.

    This black jacket has energy dissipating properties that will help protect the TracPipe® CounterStrike® stainless steel pressure liner as well as other fuel gas system components if the TracPipe® CounterStrike® becomes energized due to lightning.
  • HomeFlex INSTALLATION MANUAL [PDF] Valencia Pipe Co., - original source: http://homeflex.com/downloads/HOME-FLEX_Installation_Manual.pdf
  • PSE&G, GAS APPLIANCE and GAS PIPING [PDF], (2021), PSE&G Construction, New Jersey, USA, TEl: 800-722-0256, retrieved 2023/07/07, original source: nj.pseg.com/-/media/pseg/global/gathercontentdocuments/7-2-1upgradesandnewinstallationsnew/gas_appliances_gas_piping.ashx
  • PSE&G, GAS APPLIANCE SAFETY [PDF] PSE&G Construction, New Jersey, USA, retrieved 2023/07/07, original source nj.pseg.com/safetyandreliability/gassafety/gasappliances
  • Parker Hannifin, Corp. (manufacturer of Parflex CSST gas piping) Website: www.parker.com
  • Pro-Flex, LLC (manufacturer of ProFlex CSST Flexible Gas Piping) Website: www.proflexcsst.com
  • Titeflex Corporation (manufacturer of the Gastite System CSST Corrugated Stainless Steel Tubing) Website: www.gastite.com/index.html=
  • TracPipe, CANADIAN FLEXIBLE GAS PIPING DESIGN GUIDE & INSTALLATION INSTRUCTIONS [PDF] Original source: https://tracpipe.ca/wp-content/uploads/FGP_001_DI_Guide.pdf
  • TracPipe FLEXIBLE GAS PIPING DESIGN GUIDE and INSTALLATION INSTRUCTIONS [PDF] (2016) TracPipe, CounterStrike, from Omega Flex, Inc.,
    Excerpts:
    The TracPipe® CounterStrike® CSST (corrugated stainless steel tubing) flexible gas piping material must only be installed by a qualified person who has been sucessfully trained through the The TracPipe® CounterStrike® gas piping installation program.
    ...
    The jacket on the The TracPipe® CounterStrike® CSST shall not be removed, altered or modified in any fashion including full or partial painting or coating of the surface and the mounting of adhesively attached plastic or paper labels without the express consent of OmegaFlex®.
  • Ward Manufacturing, Inc. (manufacturer of Wardflex and Wardflex II CSST gas piping) Website: www.wardflex.com/index.htm

...


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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2022-11-17 by Dennis - use CSST to supply a standby generator ?

Generac-generator gas connection not permitted - cited & discussed at InspectApedia.comCan you use CSST to supply a standby generator as long as it is a dedicated line and has excess supply capacity for the generator.

On 2022-11-18 by InspectApedia (Editor) (mod) - Can csst be used outside. Can csst be supported on the bottom of floor joists in basement.

@Dennis,

As Mark Cramer says ... it depends.

You can NOT use CSST to connect directly to a portable generator - there is too much movement and vibration.

The photo, from a Generac generator manual provided in our articles on that topic, shows a prohibited flexible connector (that example isn't CSST) at a generator..

We have not found "CSST" mentioned at all in the backup electrical generator installation manuals that we reviewed.

PLEASE SEE this Q&A and our detailed reply now at

GAS SUPPLY for ELECTRIC GENERATORS

Thank you for a helpful question.

On 2021-10-05 by Earl D. - ok to use CSST outdoors?

Can csst be used outside. Can csst be supported on the bottom of floor joists in basement

On 2021-10-05 by inspectapedia.com.moderator (mod) - yes in some versions of CSST outdoor use is permitted

@Earl D.,

Yes there are version of CSST sold for outdoor use.

Yes CSST can be run under a floor

BUT in both cases the CSST product selected must be the right one for the installation and you must follow the manufacturer's instructions.


Details:

Unlike traditional, heavy-walled gas pipes, CSST is extremely thin and therefore susceptible to damage and contact with sharp objects, dirt and debris, or harmful substances is to be avoided.

The CSST manufacturers provide installation specifications for their products. Most model and enacted building codes require that just about any building component, equipment or device should be installed in accordance with the manufacturer's instructions.

CSST must be installed by a qualified professional and in accordance with the Manufacturer's Design and Installation (D&I) Guide, including bonding and grounding of the system.

Both of your questions can be answered by following manufacturer's installation directions and by discussing with a qualified professional.


Bottom line: CSST flexible gas piping is indeed sold in versions that are rated for outdoor use.

Of course there are protection, routing, electrical grounding and other requirements for such piping to be safe and functional.

Be sure to read those and the applicable standards that are given in the article above on this page as well as manufacturers own installation instructions.

 

Question: is this gas piping using flexible lines safe and proper?

Flexible CSST routed through building wall - improper unsafe (C) Inspectapedia.com KahnI inspected a bi-level yesterday and came across the attached picture.
Picture is from the lower level laundry / boiler room.

I have not seen gas piping installed in this method.

There was an oven installed at the adjacent kitchen.

Per client, the home was filed as a mother daughter home but does not have approval (C of O) for gas range installation.

Other than the legal aspect. I am concerned that it may be a safety issue.

Please advise - DovBer Kahn 2020/04/20

  • Dov Ber Kahn, a home inspector in Rockland County, NY has contributed photographs of various building features. Mr. Kahn is a licensed home inspector in New York and New Jersey, and can be reached at Website: Kahnbhomeinspectors, Tel: 845-445-8234, Email: kdovber@googlemail.com

Moderator reply: NO

Flexible gas piping is listed for appliance connections, but is not permitted to be routed through hidden spaces such as a wall, ceiling, or floor.

Watch out: The concern is for mechanical damage or puncture and a subsequent gas leak, asphyxiation or explosion death of occupants.

The photo suggests installation by an un-qualified installer.

See details at FLEXIBLE GAS CONNECTOR INSTALL

On 2020-05-22 by Jon Raleigh

I have a townhome built in 2006. I am selling it and buyer wants CSST bonded. It has 6 units. The gas supply is on the east end and the electric panel is on the west end. My unit is on the middle.

How can the CSST be bonded when it’s not near my unit or the electric panel?

On 2020-05-22 - by (mod) - How can the CSST be bonded when it’s not near my unit or the electric panel?

Joe

Forgive my griping but this sounds like a possible example of the OPM problem. Someone, probably a home inspector, is spending your money to reduce their risk - it's a great deal for them as your money is "free" to them.

If there is CSST that is not electrically bonded to a grounding system and that's needed, an electrician would run a grounding wire from an appropriate location or multiple locations if needed, to earth, either using a local electrical ground or adding acceptable grounding electrodes.

If I were seller of such a property and if I were willing to make such an allowance to a buyer, I'd ask my attorney to offer a reasonable contribution to the cost of the job. $250. My OPINION is that for such items an allowance, rathe rather than doing the work, is a better deal for both buyer and seller.

For the seller, you avoid getting dragged into an abyss of unknown hassle and expanding costs.

For the buyer, she can be certain that the work is both done properly AND that the work was performed by someone who is accountable to her. Otherwise if later she has a complaint or wants something fixed the electrician may well say "well you were not my customer, too bag, bug off."

The OPM problem is explained at OTHER PEOPLE's MONEY

On 2019-12-10 by Dennis - Can US code flexible stainless steel tubing be used in Canada?

Can US code flexible stainless steel tubing be used in canada

On 2019-12-11 - by (mod) -

Dennis

CSST is code-approved in Canada - though must be installed by a qualified installer. You'll want to find something like "Listings: CSA 256532 / IAPMO 7660" regardless of whether the CSST was made in the U.S. or Canada

Look for a CSA code stamp or label on the product.

Examples include

HomeFlex INSTALLATION MANUAL [PDF] Valencia Pipe Co., - original source: http://homeflex.com/downloads/HOME-FLEX_Installation_Manual.pdf

TracPipe, CANADIAN FLEXIBLE GAS PIPING DESIGN GUIDE & INSTALLATION INSTRUCTIONS [PDF] Original source: https://tracpipe.ca/wp-content/uploads/FGP_001_DI_Guide.pdf

Also see

CAN-CGA-B149.1 Natural gas installation book used in Canada.

CAN-CGA-B149.2 Propane gas installation book used in Canada.

On 2018-06-24 by Burt - how to fix a leak in damaged CSST Gas Piping?

what is the best practice for fixing a punctured CSST line? Can plumber split in a joint connector, or does the whole line need to be replaced?

On 2018-06-24 - by (mod) -

For an isolated leak replace just the leaky section.

If conditions such as overheating have damaged the entire piping then ... ick ... wider replacement is probably needed.

On 2018-04-09 by Russell Is cast legal for commercial application?

Is cast legal for commercial application in Illinois?

On 2018-04-09 - by (mod) -

'm not aware of any cast iron gas piping in modern use.

If you meant to type CSST, yes it's legal.


On 2015-11-03 by Mark - alternative to CSST tubing for high stress installations?

Is there such a thing as a 1" gas non corrugated flex connector tube for a commercial kitchen range on wheels that is code compliant?

Something that would not fatigue like the standard corrugated gas flex tube would. They want to be able to easily move the range for cleaning. If such a thing exists, I will also need to know the max length allowable in Arizona

On 2015-11-04 - by (mod) -

Mark I don't know for sure what you're asking.

When you cannot use a labelled, listed flexible connector use the type of iron pipe and fittings that your local code officials will insist upon.

There are flexible stainless steel LP / NG gas connector tubing products sold for use in high heat or stressful installations.

Watch out:

1. unless there is easy working space and access to the connection side of the kitchen range you cannot make a reasonable installation without providing a flexible connector as you'd have no way to install or remove the appliance

2. a gas range on wheels sounds inherently dangerous to me and may be improper as movement risks gas leaks and a fire or explosion even if you found a non-metallic flexible gas line

What does your local building department say about this range?

On 2018-04-09 by Russell

@Mark,
Yes and fastened to wall has quick coupler connection


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