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Thread: How Do I Cap A Gas Pipe?

  1. #1
    Join Date
    Mar 2007
    New Albany, MS

    How Do I Cap A Gas Pipe?

    I have a wood burning fireplace that was converted to a gas insert that I'm converting back to wood burning. I've had a chimney sweep clean it and inspect it. He removed the insert for me and capped off the fitting inside the fireplace, but he wasn't licensed and bonded in my city to remove the gas pipe. The pipe enters the ash dump from outside the house and is all plumbed with regular threaded black iron pipe. If it was water I would have no problem at all in removing the pipe and capping it off outside, but I've never worked with gas before. I hate to call a plumber out for something that will take 15 or 20 minutes, so any advice would be appreciated.

    Obviously I'll need to shut off the gas at the meter, which will kill my gas water heater (the only other thing that uses gas in my house.) I'm very familiar with relighting it. Is there anything else I have to watch for?
    - Chris.

  2. #2
    Join Date
    Oct 2006
    NW Indiana
    I know they make teflon tape specially for gas installations. The regular teflon tape is white, and I think for gas usage, it is yellow. Some will argue that either will work. I prefer to err on the side of safety, and use the yellow. Do not use galvanized pipe for gas. I should have added that you will want to check for leaks when you're finished. Do that by dabbing a soapy water on the threads where it could leak. If you see bubbles, it's leaking.

    Last edited by Ed62; 02-11-2009 at 02:27 PM.
    Do you know about kickback? Ray has a good writeup here...

    For a kickback demonstration video

  3. #3
    Join Date
    Oct 2008
    Spokane Washington
    Shut off the gas at the meter, (Obvious) remove all piping necessary back to area desired. Use the yellow Teflon tape, because it is approved and has consistent thickness, or use Teflon pipe dope. Use a black pipe CAP do not use a plug in a fitting.(some jurisdictions do not allow the use of pipe plugs on gas piping due to the plug possibly cracking the fitting if tightened to tight.)

    Turn the gas back on and use a 50%mixture of dish washing soap and water and spray all piping connections that have been disturbed. If no bubbles show up, go to the meter and turn on the gas and observe the lowest meter needle for movement for five minutes, if you have no movement of the meter then the piping system is sound and you can relight the pilots on the water heater or any other appliances.

    another concern on the fireplace is that the damper is normally removed or pinned open when a gas insert is installed, you may want to have it reinserted or made so that it can be closed when you are not burning your fireplace. An open fireplace will double the infiltration of outside air to the house

    The question of using normal or yellow Teflon tape has to do with the thickness of the tape. The yellow tape is thicker and meets specifications set by the AGA for gas piping.

    Functionally you could use the white tape if you used enough wraps to get the thickness of the yellow tape but it is not approved for use on gas piping and could possibly cause a question in case of a fire on you insurance.
    Last edited by master53yoda; 02-11-2009 at 04:07 PM.

    If you don't want to know, Don't ask

    If I could come back as anyone one in history, It would be the man I could have been and wasn't....

  4. #4
    Join Date
    Jan 2003
    Atlanta, GA
    I can't add much, you've got some good replies already. The only thing that I would add is that my success rate with the pipe dope is better than with the teflon tape. The pipe dope is messy and will probably cost a little bit more, but worth it IMO. It's not a hard job, just follow the instructions above and take your time.

    Good luck.

  5. #5
    Join Date
    Jan 2007
    Winchester, Ca
    Quote Originally Posted by os1kne View Post
    I can't add much, you've got some good replies already. The only thing that I would add is that my success rate with the pipe dope is better than with the teflon tape. The pipe dope is messy and will probably cost a little bit more, but worth it IMO. It's not a hard job, just follow the instructions above and take your time.

    Good luck.

    I would agree with pipe dope. We have installed our gas piping in the new home and used the dope. Tested with air in accordance with the local code and passed the test and signed off by the inspector. Held air for 24 hours, no leaks.
    Raggy and Me in San Felipe

  6. #6
    Join Date
    May 2005
    Paso Robles, Calif, USA.
    make sure you use a black pipe cap. I don't know why but galvanized pipe is not used for gas.
    Opportunity is missed by most people because it is dressed in overalls and looks like work. - Thomas Edison

  7. #7
    White teflon usually has a density of 0.4 vs. yellow tape density of 1.8.

    Around here yellow is code for gas pipe.

    I take care of several luxury condos built in the late 70's.

    The plumber used white teflon to pipe gas to all the fireplaces.

    They just finished replacing ALL the gas piping in all the units due gas leaks caused by teflon tape failure. If you use tape, use yellow.

    My dad was a master plumber and used pipe dope for gas, aways.
    You might think I haven't contributed much to the world, but a large number
    of the warning labels on tools can be traced back to things I've done...

  8. #8
    SARGE..g-47 Guest
    I ran a feeder line off my fireplace starter by T'ing at the fireplace.. over the ceiling of my shop and down a pole in the center. Then connected a space heater myself. I checked it with soapy water as mentioned. All was well but..

    I called my plumber and gas man to come over and double check behind me. He repeated the procedure and checked all fitting and declared it certified. He gave me a reciept and I paid him $40 which was a pre-arranged amount for checking behind me.

    Did I feel that my work checked out OK and the heater was ready to light? Yes... but... in case of house fire caused by gas in the future I wanted a certification that the work was inspected and certified by a qualified person that was authorized to do so.

    Why.. I was told to do so by my State Farm agent who is a life-long friend. If there were a house fire caused by a gas leak you could have problems if the fact you did it yourself and you are not certified to do so in my state. I can't afford to replace a house out of pocket.. they can.. They want someone to certify it I understand and had it done in that manner as $40 now out of pocket or $100,000 + latter out of pocket is a pretty large gap that's hard to fill.

    Just me I suppose...

  9. #9
    Join Date
    Jan 2003
    Atlanta, GA
    Sarge has a pretty good idea. We all like to save money by doing home improvements ourselves, but working with gas is probably the one thing that can have catastrophic results very quickly - and it's also something that most DIY people won't do enough to get good at. We'd hate to lose our home, just because we were trying to save a few dollars.

    If we have a leak with a typical water plumbing DIY project, we tend to know about it before it's a big problem - and we clean up the water and try again.

    With gas, it's easy to have a big problem before you realize that there's a problem.

    Good luck!

  10. #10
    Join Date
    Aug 2003
    Maryland, USA.
    Does the pipe have to be moved far away from the fireplace even before it's
    capped so the pipe doesn't heat up when you start a fire?

    I guess you could argue that with the pipe capped, you've eliminated oxygen
    from the fire equation (heat+fuel+oxygen=fire).

    Just wondering if this is necessary, too. I have no idea.


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