Flexible gas connector installation: how to select & install a flexible connector for gas fueled appliances or heating equipment.

This article summarizes manufacturer's advice for the selection & installation of flexible gas connector tubing to assure adequate gas flow to support the input BTUH rating of the connected appliance, and to avoid some common sources of gas leaks such as stretching, vibration, or mechanical damage to the tubing.

Flexible Gas Appliance Connector Installation Procedures & Warnings

The manufacturer typically warns of the following safety hazards when using flexible gas connector tubing, mostly in the form of "Do Not" admonitions:

• Install a gas supply line shut-off valve
  
   between the end of the gas supply line and the point at which the flexible gas connector will be mounted to the gas supply.
  
  Our photo (left) shows an un-coated stainless steel corrugated flexible gas connector line connected directly to the iron pipe natural gas supply line. This is a poor installation as there is no shutoff valve installed.
• When you see an error like this you should be alert for other amater workmanship measures that may be improper or unsafe.
• Select the proper flexible gas connector size
  
   (in diameter) necessary to support the input BTUH rating of the appliance, and in accordance with the length of tubing. A table of lengths and tubing diameters and BTUS is provided below.
  
  There you will see that the BTU flow rate capacity of tubing is reduced for smaller tubing diameters, longer tubing lengths, and somewhat by the number of tubing bends.
• Do not install flexible gas connector tubing much longer than is needed
  
   to safely install and remove the appliance.
  
  Excessive tubing lengths may mean extra bends and kinks, reduced tubing flow rate capacity, and extra risk of vibration damage in some locations.
• Do not install flexible gas connectors in multiple or ganged sets
  
  use a single flexible connector line between the appliance and the gas supply connection point.
• Do not use flexible gas connectors longer than permitted 
  
  by local building codes.
  
  Typical maximum gas connector line length is six feet, or three feet in Massachusetts and possibly some other jurisdictions. Check with your local building department.
• Do not re-use flexible gas connectors, fittings and valves;
  
  they are designed for use only on original installations.
  
  The concern is that removal and re-use of a connector tubing and additional handling may damgae it, making it unsafe for re-use.

• Do not use flexible gas connectors with appliances that are mounted on rollers, casters, or wheels 
  
  that permit the appliance to move readily about. Flexible gas connector tubing is intended for limited movement after installatin.
  
  Repeated bending, flexing, extreme vibration, stretching, can cause metal fatigue, cracks, holes and dangerous gas leaks.
  
  Photo at left: coated corrugated flexible stainless steel gas connector tubing. We know from the color that this will be 1/2" I.D. tubing - see the table below.
  
  OPINION: We note, however that flexible tubing will be flexed or bent to and fro when moving the connected appliance, such as a gas-fired clothes dryer.
  
  Watch out against extreme movement, kinks, bends, or punctures that may occur due to vibration such as that induced by a clothes dryer vibrating such that the connector rubs against another surface.
• Do not connect a flexible gas connector line directly to an LP gas tank.
  
  To avoid dangerous over-pressures, fire, or explosion he appliance must be connected through a gas pressure regulator, never directly to a gas tank or other gas source (that will be at higher pressure).
• Do not use flexible gas line connectors on appliances in moving vehicles 
  
  such as campers or RVs.
  
  Use of these connectors is permitted, however, in stationary, permanent "mobile homes" such as those mounted on a foundation and not intended for regular movement or relocation.
• Do not use flexible gas connectors if the part has been in a fire;

Notes to the table above

1. * = not permitted in some jurisdictions such as Massachusetts

2. Straight tubing length capacity in BTUs per Hour is based on the assumption of natural gas at 0.64 specific gravity with a heating value of 1,600 BTUs per cubic foot of natural gas.

This is a BTUs per Hour figure for natural gas consumption rate.

Note that at GAS BTUH, CUBIC FEET & ENERGY we point out that a standard figure of the number of BTUs in a cubic foot of natural gas is 1,050 BTUs.

For propane, the heat value per cubic foot of vapor of LP gas (at atmospheric pressure) is 2,516 BTUs

Naturally all quotes of the heating value in BTUs of a given volume of a fuel in gas form must make an assumption about the gas pressure and temperature or use a standard temperature and pressure figure STP.

1KBTUH = 1SCFH (standard cubic feet per hour).

Multiply the BTUs shown in the table by 0.632 to convert to standard capacity of 50 pa (0.02 in water column) pressure drop. Some reduction in gas flow rates will be imparted by the number of bends in the tubing - keep tubing bends as gentle and as few as possible.

3. Watch out: this table is adapted from tubing manufacturers' instruction sheets. Be sure to check the tubing specifications and applications and installation instructions provided by the specific maufacturer of the tubing that you are purchasing.

4. Adapted from product literature from BrassCraft Gas Products, 39600 Orchard Hill Pl, Novi, MI 48375, United States +1 248-305-6000, Website: http://www.brasscraft.com/

Flexible Gas Connector Codes, Rules, Research

• ANSI Z21.69/CSA 6.16: Connectors for Movable Gas Appliances

• Canada - CLEARANCES FROM GAS, PROPANE AND ELECTRIC RANGES [PDF] Original source: Alberta: safetycodes.ab.ca/Public/Documents/Safety%20Tips%20%E2%80%93%20Clearance%20from%20Gas,%20Propane,%20and%20Electric%20Ranges.pdf
• CAN/CSA B149.1: Natural Gas and Propane Installation Codes.

• CSA listed to ANSIZ21.75 /CSA 6.27 standard “Connectors for Outdoor Gas Appliances & Manufactured Homes” (file #204593)

• CSA listed to ANSIZ21.24 /CSA 6.10 standard “Connectors for Gas Appliances” (file #204593)
• IFGC - CHAPTER 4 GAS PIPING INSTALLATIONS | 2018 International Fuel Gas Codehttps://codes.iccsafe.org/content/IFGC2018/chapter-4-gas-piping-installations
• IRC - CHAPTER 24 FUEL GAS | 2018 International Residential Code | ICC https://codes.iccsafe.org/content/IRC2018/chapter-24-fuel-gas

• BrassCraft GAS APPLIANCE CONNECTORS FLOW CAPACITY CHARTS [PDF] (2016) BrassCraft Mfg. Co., Novi, MI 48375-5331 USA Website: www.brasscraft.com retrieved 2020/10/14 original source: https://d2cl5to9q9oami.cloudfront.net/doc/375.01_GasApplianceConn_FLW.pdf
• BrassCraft ProCoat® STAINLESS STEEL GAS CONNECTORS [PDF] https://api.ferguson.com/dar-step-service/Query?ASSET_ID=3109966&USE_TYPE=SPECIFICATION&PRODUCT_ID=1619782 retrieved 2020/10/14 original source: https://api.ferguson.com/dar-step-service/Query?ASSET_ID=3109966&USE_TYPE=SPECIFICATION&PRODUCT_ID=1619782
  
  Note: ProCoat connectors are certified for indoor & outdoor use.
• STENQVIST, Foodservice Gas Appliance Safety, [PDF] Plumbing Systems & Design NOVEMBER 2011 original source: media.wattswater.com/PlumbingDesignbytheNumbers.pdf
  
  Excerpt: Heavy-duty, commercial grade, flexible appliance gas connectors are used where the gas connection is located at the rear of the appliance and flexibility is required to hook up the unit ...

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2022-09-10 by Evan - Gas connection piping hookup in Canadian RV

Hi there . I'm a full time RVer on its own lot up here in Alberta Canada. It gets like - 40 Celsius here at times during the winter .. and the cost of propane and electricity went through the roof last spring and so I bought a olympian wave 8 ( 8000btu max) catalytic heater .

Apparently I need to hardpipe a line into my 37 ft fifth wheel ( that's what the propane company said . Requires a gas fitter they said . I do want to be safe ( yes I will allow ventilation) is there a easy way to do this ? I have a large 400lb tank that goes into the tree where the propane bottles would go .

Can a copper line replace the hose and come up into the trailer through the floor and then I can connect to the heater ? This heater would be much more efficient..but I realize there are hazards to it . It burns oxygen in the space. What would be the best way to hook it up?

If it is hooked up to the tree there is less issues with the cold freezing as smaller bottles won't work in extreme cold very well . Can you help ? Would copper or another pvc type gas line be easily hooked up ? I have a gas fitter friend at work that can do it .

On 2022-09-10 by InspectApedia-911 (mod) - Flexible copper is often used for LP gas connections and piping

@Evan,

Flexible copper is often used for LP gas connections and piping.

Yes, you need a trained plumber or technician to do the work to be sure that it's safe.

DO NOT even think about using a heater that can consume oxygen you need to live in a space without:

1. being certain that the installation and use follow all of the manufacturer's instructions including their safety warnings

Confirm that this is the right manual for your heater, then see this CAMCO OLYMPIAN WAVE CATALYTIC HEATER MANUAL [PDF]

AND check with the manufacturer to be sure you're using this heater safely:

Camco Mfg. Inc.
121 Landmark Drive / Greensboro, NC 27409 USA
Phone: 800-334-2004 / fax: 336-668-2049
www.uscatalytic.com · info@camco.net

2. ensuring that you have working CO and smoke detectors as well as an adequate supply of combustion air to the heater.

Making a mistake can be more expensive than those terrible gas bills.

 

On 2021-07-31 by mak.church (mod) - code prohibiting gang connecting flexible gas connectors?

@Jacobt,
Above on this page, under the section:

Flexible Gas Appliance Connector Installation Procedures & Warnings

you'll see a number of manufacturer warnings and safety hazards listed including:

"Do not install flexible gas connectors in multiple or ganged sets - use a single flexible connector line between the appliance and the gas supply connection point."

If you have additional questions about any codes specific to your area, check with your LOCAL building code enforcement official.

That person will have final authority as to what is legal for your situation.

On 2021-07-30 by Jacobt

What is the code pertaining to prohibiting gang connecting flexible gas connectors?

On 2020-11-25 by (mod)

I use blue Leak Lock or a similar sealant that is specifically rated for use on oil and gas fittings

On 2020-11-25 by Paul H.

Can you use teflon plumbers tape to connect gas fittings or is there a specific tape/sealer for the purpose?

 

On 2020-10-13 by Dominic - ok to use a flexible CSST gas line outdoors ?

Can you use Flexible appliance connector from the riser to the black pipe stub out outdoors?

On 2020-10-14 by danjoefriedman (mod)

Dominic,

Thanks for the question about whether or not we can use CSST or equivalent flexible gas line connectors outdoors.

Short answer: there ARE some flexible gas appliance connectors listed and approved for outdoor use including some BrassCraft products like the company's ProCoat® stainless steel gas connectors.

See connectors that are CSA listed to ANSIZ21.75 /CSA 6.27 standard “Connectors for Outdoor Gas Appliances & Manufactured Homes” (file #204593)

Details:

Some flexible gas connedtor products are rated-for and approved for outdoor use.

You'll find them at

GAS PIPING, FLEXIBLE CSST

where "CSST" refers to "Corrugated Stainless Steel Tubing"

From that article we note this warning:

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.

So

Bottom line: you would NOT use a typical flexible indoor appliance corrugated gas appliance connector tubing outdoors. But there are some flexible tubing products that are approved for that use.

On 2020-07-12 by chris - ok to cap a flexible gas connector when not in use?

is it ok to cap a flexible gas connector when not in use? would shut off valve and put gas pipe insulating tape on cap fitting.

On 2020-07-12 - by (mod) -

Chris,

If the gas valve is ahead of (before) the flexible gas connector, that's the most important thing- closing that valve.

The safest would be a cap on the outlet opening on that gas valve itself.

On 2020-07-14 by Anonymous

thanks Dan -- yes, valve is closed.

My problem is the valve is located on the ceiling (in the basement), then the pipe extends about 4 ft. to the wall and then down behind the drywall to service a ventless fireplace which was mounted inside a hearth (one of those removable ones). the opening to the back wall inside the hearth is where the pipe ends, and the flexible pipe connected to the ventless unit begins.

it's not only difficult to cap where the solid pipe connects with the flex because it's cemented on with pipe cement, but its far enough behind the drywall that I can't get a wrench on it (forget about leveraging the wrench!).

I'm thinking my only option is after ensuring there are no leaks in the flex pipe... cap the end of the flex pipe, and push it back behind the drywall. then put a piece of drywall over the spot. the valve remains off, of course, and so no gas is flowing to the flex pipe.

I'm thinking if there's a way to "lock" that valve in the off position, it would be added safety measure. An electric fireplace is going into the mantel, but I want to be able to remove it and reconnect the gas unit in the event of a prolonged power outage in the winter.

I know this is not 100% safe if someone were to turn on that valve, AND ALSO, somehow the pipe behind the wall or the flex pipe developed a leak .. .but I'm thinking it's very, very safe, and keeps open option to easily re-connect gas unit. I'm interested in your thoughts and any other added safety steps I could do to resolve this. thanks for your help, Chris

On 2020-07-14 by (mod) - never bury a gas shutoff behind drywall

I would be very nervous about burying a gas valve behind drywall and even though we both agree that off should really mean off. And of course covering a shut off valve on a gas line behind drywall is likely to be a red flag to any Code Compliance inspector.

I would prefer to have capped off the piping if it's not going to be used. Take a look at the whole piping arrangement to see if you can intercept the gas supply and cap it off in a more accessible location well ahead of the problem location.

On 2020-07-15 by Chris

thanks -- I thought you might say that, and I guess that's why I haven't gone ahead yet. I think it would be 99.9% safe the way I was thinking of doing it, but it's not worth taking a risk for that .01% chance. thanks for your help. -- Chris

 

On 2019-07-23 by Wayne Nader -building inspector told us that we need to protect the yellow jacketed flexible gas lines behind the cooking appliances

We have a commercial mobile kitchen that we are setting up semi-permanently for a home shelter.

The building inspector told us that we need to protect the yellow jacketed flexible gas lines behind the cooking appliances (flat top, grill, etc.) because hot grease can eat through the flexible gas lines and cause a gas leak. I have never of this problem before. Is there anything to what he is saying? He said that we needed to provide proof that he is wrong.

On 2019-07-23 - by (mod) -

Wayne,

Thanks for the interesting question. I suspect that the building inspector has some experience or basis for his opinion. Proving the absence of a problem is more difficult than claiming that one exists.

Most inspectors would want to see a code citation or perhaps scholarly research articles.

See

STENQVIST, Foodservice Gas Appliance Safety, [PDF] Plumbing Systems & Design NOVEMBER 2011 original source: http://media.wattswater.com/PlumbingDesignbytheNumbers.pdf

The author in turn cites

1. NSF International

2. ANSI Z21.69/CSA 6.16: Connectors for Movable Gas Appliances

3. ANSI Z223.1/NFPA 54: National Fuel Gas Code

4. CSA B149.1: Natural Gas and Propane Installation Codes

5. International Fuel Gas Code

6. Local codes and standards

Excerpt: Commercial vs. Hard-piped and Residential Connectors Heavy-duty, commercialgrade, Fexible appliance gas connectors are used where the gas connection is located at the rear of the appliance and fexibility is required to hook up the unit (see Figure 1).

They are designed to stand up to the demands of a commercial kitchen and allow a more hygienic environment by providing easy access around the equipment.

Their use increases effciency and reduces operating costs, allows appliances to be set closer to the wall, and provides ease of mobility for cleaning and maintenance.

They also meet updated code requirements, including

ANSI Z21.69/CSA 6.16: Connectors for Movable Gas Appliances and

CAN/CSA B149.1: Natural Gas and Propane Installation Codes.

Rigid or hard-piped connections are made to withstand physical damage; however, they are not practical for movement, and this immobility increases the chance of fire due to the buildup of oil, grease, and other fammable materials.

Equipment with hardpiped connections is difficult to clean and maintain on a regular basis, which presents the potential for food contamination. Also, hard-piped connections do not comply with NSF certification.

On 2019-03-08 by Bob Yehlen. - correct BTU rating for CSST Natural Gas should be in the order of the 1,000 to 1060 BTUs.

Your flexible gas connector sizing info has natural gas listed at 1600 BTUs per cubic foot of natural gas. I'm not sure where you got that info but I believe it is incorrect. The correct BTU rating should be in the order of the 1,000 to 1060 BTUs.

If you could Supply me with the information you got this number of 1600 BTUs from so I could contact them ASAP.( if indeed this was the number they supplied you I would like to have a little discussion with them).

On 2019-03-09 - by (mod) -

Bob:

Thank you for an important question I'll review the data sources. I have to go check ... I could be mistaken. Thank you for asking.

You'll also want to see the citations both in this article and that the references that are at the end of the page

Take a look at GAS BTUH, CUBIC FEET & ENERGY

where we cite authoritative sources and state (among other figures)

One cubic foot (0.028 cubic meters) of natural gas contains about 1,050 BTUs

Thank you for pointing out some confusion on this.

I'm reviewing and clarifying or correcting the article above as appropriate.

The 1600 number cited in a note in the table above came from the source we cited in note 4

BrassCraft Gas Products, 39600 Orchard Hill Pl, Novi, MI 48375, United States +1 248-305-6000, Website: http://www.brasscraft.com/

Below is a copy of the company's original information on the flexible gas connector piping. Click to see an enlarged view and you'll see that I quoted them accurately.

IMAGE LOST by older version of Clark Van Oyen’s useful Comments code - now fixed. Please re-post the image if you can. Sorry. Mod.

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Continue reading  at GAS PRESSURES LP vs NATURAL GAS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see FLEXIBLE GAS CONNECTOR INSTALLATION FAQs - questions & answers posted originally at the end of this page.

Or see these

Recommended Articles

• GAS APPLIANCE CONVERT LP-to-NATURAL GAS
• GAS BTUH, CUBIC FEET & ENERGY
• GAS COOKTOP INSTALLATION
• GAS METER CODES & CLEARANCE DISTANCES
• GAS PIPING, VALVES, CONTROLS - home
  • FLARE FITTINGS
  • FLEXIBLE GAS CONNECTOR INSTALL
  • GAS CONNECTOR for BBQ GRILL
  • GAS PIPING, FLEXIBLE CSST
  • GAS PIPING CLEARANCES, CODES & DEFECTS
  • GAS LEAK DETECTION, LP / NG
• GAS PRESSURE FLOW INADEQUATE
• GAS PRESSURES LP vs NATURAL GAS
• GAS REGULATORS & APPLIANCE / HEATER CONTROLS
• GAS REGULATORS for LP TANKS
• GAS SUPPLY for ELECTRIC GENERATORS

Suggested citation for this web page

FLEXIBLE GAS CONNECTOR INSTALL at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to GAS APPLIANCES, PIPING, CONTROLS

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