Teflon Tape on Flared fittings

shannon185July 27, 2007

This past week a friend of mine asked me to connect the gas line of her new gas dryer since the company delivering it does not do this anymore. I had hooked up my gas oven a couple of weeks ago and saw that a number of forum discussions indicated that you should not use Teflon tape on the flared ending of the flexible pipe.

Now the fun begins, when I arrived to help her out, everyone including the delivery guy, said I needed to use Teflon tape everywhere including the flared endings.

To make a long story short, over my concerns the delivery guy ended up connecting the line using either Teflon (gas) tape or pipe dope on the flared endings.

Am I wrong about the this matter and should she have any concerns about this? Thanks

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I'm not sure, but being a gas line it had better be right, correct, and code.

    Bookmark   July 27, 2007 at 12:33AM
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Creative Homeowner - Dream ~ Design ~ Create.

This website for homeowners and flared fittings makes no mention of any tape or dope.

    Bookmark   July 27, 2007 at 1:59PM
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Just what got tape applied?
The threads in a flare fitting are NOT tapered and do not need to be sealed.
The seal is between the flared end of the pipe/tube and the tapered face of the other side of the fitting.
All the threaded collar does is supply force to create a seal between the opposite tapers of the two ends.
Putting anything in this taper results in a worse seal, not a better one.

    Bookmark   July 27, 2007 at 8:20PM
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Thanks brickeyee. The tape was applied to the threads of the flared end, the end that the threaded collar fits over.

Will this make it likely to leak?


    Bookmark   July 28, 2007 at 1:38PM
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Applying the tape to only the threads of a non-tapered fitting will not cause a leak. It is the inside bell of the tube and the outside angled portion of the fitting, where the bell of the tube makes contact, that you need to keep clear of tape or other debris.

    Bookmark   July 28, 2007 at 7:54PM
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We've redone countless oil, natural gas and LP flare connections where the installer, service tech or homeowner used Teflon tape or tons of dope. While most of these connections aren't leaking, we pull them apart to make sure nothing is on the metal to metal flare connection and to make sure the surfaces of the flared connections are in good shape. Some people use tape because they don't know any better, and some use it because they had a leak, so either way it raises a red flag.

    Bookmark   July 29, 2007 at 9:50AM
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I have found numerous leaks in flare and compression joints with tape applied by the original installer. Removing all traces of the tape and tightening the fitting properly almost always solves the problem.

    Bookmark   July 29, 2007 at 3:33PM
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Metal to metal connections come in a wide variety of styles. a flared fitting is just one. All M to M connections will benifit from lubrication both on the threads and on seal surfaces. They all will tend to leak if chunks of teflon or other solid stuff gets on the seal surface. Most pipe dope contains shreded or powdered teflon or other fillers. don't get them near the metal to metal seal surfaces. dope or tape just on the threads is ok and may help the seal, but it's safer just to not use them at all.
grease may be used and will help the metal seat and seal better. Grease on the threads helps to get more force to the seal area. Just make sure it has no solids mixed in. Rub a little between your finger and thumb and if it feels or looks the least bit gritty, don't use it.

Brass and copper are relatively soft and have pretty good lubricity even without any grease. They will normaly make up and seal pretty reliably even without grease. Steel flare fitting definitely will benifit from being greased. Stainless steel flare fittings almost require a grease with good anti-galling properties to function.

    Bookmark   July 31, 2007 at 11:13PM
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I'd be curious to know if the selling outlet knows that their delivery guy is telling people how to make connections and is actually making connections. I bet their insurance company would go nuts.

    Bookmark   August 1, 2007 at 12:02AM
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I wonder if that delivery guy wouldn't have to have a plumber's license and/or a gas ticket to legally make that gas connection?

    Bookmark   August 1, 2007 at 12:53AM
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Puting tape on flare joints is like putting tape on joints that have a rubber sealin it .The tape takes to much space on the thread,therefore you dont need any.

    Bookmark   August 2, 2007 at 2:25PM
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