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I'm replacing a faulty regulator on my gas grill. When removing the old regulator, I noticed there appears to be some sort of compound on the threads.

Here is a picture of the threads with the old regulator still partially attached: Regulator still attached

And here is a picture of the threads without the old regulator attached: Regulator not attached


  • What is that substance, and where can I get it?
  • Is it required in order to protect against LP leaks?
  • Are there any tricks or gotchas to know about when applying it?
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3 Answers

up vote 7 down vote accepted

Just got back from the hardware store with this:

Thread Seal Tape for Gas

It's apparently similar to Teflon tape that you would use on a water fitting, but made specifically for gas.

There is also a compound available, but I chose to use the tape because I was told that the compound can be a bit messy.

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According to Wikipedia, you can get teflon tape in different colors to match the use. en.wikipedia.org/wiki/Teflon_tape#Types –  Jay Bazuzi Jul 31 '11 at 19:17
The tape above is fine, use 3 or 4 complete wraps. If you use a liquid dope, be absolutely sure it is LPG rated and apply it with a acid brush. –  shirlock homes Jul 31 '11 at 20:18
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Use of thread seal tape does not work on the fittings that screw directly into an aluminum propane regulator. I don't know if the changes in seasonal temperature cause the aluminum to contract and expand (or something else) but six months later the fittings will be loose and leaking. I suggest using a hardening compound.

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The tape you purchased is the correct tape for gas fittings. However, the fitting in your picture is a flared fitting. PTFE (Teflon) tape/pipe dope is only necessary on pipe thread fittings.

This is because pipe threads are tapered - as you tighten the fitting, the threads bind together and deform slightly to create a seal. The pipe tape/dope helps lubricate the threads and make a better seal.

With a flared fitting like your photo shows, the flare at the bottom seats in a mating flare inside the female fitting. The threads are only there to draw the two together.

Using tape on the flare fitting may not cause any problems, but I would not take the chance, especially with gas. If any tape gets under the flare or prevents the nut from tightening down fully, you're going to have a leak.

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