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Flexible gas connector corrugated tubing, stainless steel - with defects to be discussed (C) Daniel Friedman LP Gas & Natural Gas Flexible Connector Install
Installation, inspection & safety warnings for flexible gas connectors used with appliances & heating equipment

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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.

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Flexible Gas Appliance Connector Installation Procedures & Warnings

Flexible corrugated gas connector tubing, stainless steel, un-coated, missing shutoff valve (C) Daniel FriedmanThe manufacturer typically warns of the following safety hazards when using flexible gas connector tubing, mostly in the form of "Do Not" admonitions:

Coated stainless steel gas connector for appliances or heaters (C) Daniel Friedman

Table of Flexible Gas Connector Lengths & Diameters vs. BTUs

Tubing Inside Diameter Tubing Color Code Tubing Lengths in Inches vs. Capacity in BTUH
(1000 Input BTUs per Hour of the Appliance)
12" 18" 24" 30" 36" 48"* 60"* 72"*
1/4" Purple
Morado
48.0 43.8 40.0 36.4 33.4 28.3 24.9 23.1
3/8" Green
Verde
102 93.1 85.5 77.1 71.1 60.5 53.2 48.1
1/2" Gold (yellow)
Dorado
180 164.2 150 136 125 106 93.2 86

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

 




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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 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 2020-10-14 by danjoefriedman (mod)

Dominic,

Short answer: generally not but 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)

Please find your question and my detailed reply now near the bottom of the article above on this page. You may need to clear or refresh your browser cache to see the updated page. We welcome your further photos, comments, questions.

On 2020-10-13 by Dominic

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

On 2020-10-14 - by (mod) -

can flexible gas line appliance connector tubing be used outdoors?

BrassCraft ProCoat stainless steel gas connectors approved for both indoor and outdoor use  - cited & discussed at InspectApedia.comDominic

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

Short answer: generally not but 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:

There are indeed some products that 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 2020-10-13 by Dominic

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

On 2020-07-15 by Anonymous

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 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 2020-07-14 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 2020-07-12 - 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 2020-07-12 by chris

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 2019-07-23 - by (mod) - building inspector told us that we need to protect the yellow jacketed flexible gas lines behind the cooking appliances

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 2019-07-23 by Wayne Nader

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 2019-03-09 - 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.

On 2019-03-08 by Bob Yehlen.

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).


...

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