Fixing Tiny Gas Leaks

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by jdf405, Aug 14, 2008.

  1. jdf405

    jdf405 Electrical Engineer

    Messages:
    47
    Location:
    Los Angeles Area
    Hello,

    I'm looking for advice on fixing a very small natural gas leak. In advance of my final inspection I did a leak test on my NG system. I lost about 0.2PSI from 10PSI in 15 minutes. I spoke to an inspector and he said there is a zero tolerance on the leak test.

    I've done some fairly extensive searching with the soapy spray bottle and found a very tiny bubbling culprit, right smack in the middle of the system (threaded black iron). I would have to cut out the piece and install a L&R - no unions allowed in the crawl space. The problem I'm anticipating is that I don't have any wiggle room to install the L&R - the pipe that would be removed is very short and is constrained between two unmovable objects.

    I guess I have two questions:
    1) Is there something that can be applied to the exterior of the joint to inhibit leaking? Or is there some way to inhibit leaks w/o unthreading?

    2) I've never used a L&R - how much room do I need to install it? What is the tolerance on getting the length right? Any other general L&R advice? All I need to do now is replace one tiny leaker with two big ones!

    Thanks in advance for your advice.
    -Jonathan
    Last edited: Aug 14, 2008
  2. Terry

    Terry Administrator Staff Member

    Messages:
    15,298
    Location:
    Bothell, Washington
    There is nothing you can put on the outside to seal it with.

    You can either start at one end and work you way back, which is what I normally do, or you can use the fitting you are talking about, I only installed one of them, it worked.

    It took more time to find the crazy wrong threaded connection, than it would have taken to disassemble are reassemble.


    There is zero tolerance on gas. Gas kills.
    Last edited: Aug 14, 2008
  3. Left-right couplings always require a specific nipple that comes with the coupling.


    Make the run a little shorter near where you plan on installing this so that you have wiggle room to get the two pipes together and wind into the fitting.


    I'm moving 1.5" gas line in the next couple weeks, all of which will be 12' off the ground.

    It's going to suck and I have to use a left/right coupling to make the changes.
  4. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    You put her together, now take it apart. Lot of work but it's in the crap happens department.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,049
    Location:
    Cave Creek, Arizona
    gas leak

    1) Is there something that can be applied to the exterior of the joint to inhibit leaking? Or is there some way to inhibit leaks w/o unthreading?

    What are the limits on your liability insurance? If you 'patch' the leaks the patch could fail someday. Gas line integrity is not something you worry about until the test is over, and then forget about it. If that were the case, just rig the gauge.

    2) I've never used a L&R - how much room do I need to install it? What is the tolerance on getting the length right? Any other general L&R advice? All I need to do now is replace one tiny leaker with two big ones!

    About 4 1/2" including the L/R 3" nipple. But there is more to installing a L&R nipple than just screwing it in. You have to insure that both sides tighten equally so neither side leaks.
  6. jdf405

    jdf405 Electrical Engineer

    Messages:
    47
    Location:
    Los Angeles Area
    Thanks for the info everyone. I've since found a couple of other extremely tiny leaks in the part of the system that is original to the house. I'm going to have to un-do the entire system - new & old - to fix those.

    I've been using Rector Seal on my threads - seems to work pretty well. Any other tips on getting a leak proof system on the "first" try? Torque on the fittings (1/2 & 3/4)?

    Regards,
    Jonathan
  7. SteveW

    SteveW DIY Senior Member

    Messages:
    1,052
    Location:
    Omaha, NE

    In what way is it working well?
  8. jdf405

    jdf405 Electrical Engineer

    Messages:
    47
    Location:
    Los Angeles Area
    Its working well on the new pipes I've put in, as opposed to the old pipes that are leaking that were held together with 1955 bubble gum...
  9. Terry

    Terry Administrator Staff Member

    Messages:
    15,298
    Location:
    Bothell, Washington
    Rectorseal is good.
    They have soft and the Teflon.
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,049
    Location:
    Cave Creek, Arizona
    leaks

    Use the correct sized wrench and the proper sized person to use it.
  11. Terry

    Terry Administrator Staff Member

    Messages:
    15,298
    Location:
    Bothell, Washington
    I think of this when I change out shutoffs under a kitchen sink done with old gavlavized.
    Sometimes it's all I can do to remove the old pipes.
    And then I feel it for days.
  12. jdf405

    jdf405 Electrical Engineer

    Messages:
    47
    Location:
    Los Angeles Area
    Terry - that brings to mind - when would it be better to use the soft versus Teflon Rector Seal? I called the company and couldn't get a straight answer...
  13. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    There is a danger that when using teflon based products, you may have a tendency to over tighten the joint. This happens because teflon lubricates very well. It is in fact possible to tighten the joint so much that the fitting breaks. Of course most of us get a feel for it after a while but I have seen a bunch of leaking teflon tape joints leak because they were tightened so much the teflon no longer sealed the joint. I like plain old rector-seal for mst everything and a product called gas-tite for gas piping.
  14. MACPLUMB 777

    MACPLUMB 777 TROJAN WORLDWIDE SALES RP

    Messages:
    679
    Location:
    Houston, Texas, United States
    Fixing Gas Leaks Before They Go Boom ! ! !

    I Always Use Teflon Tape Then Coat It With Rector Seal Teflon Paste Being Aware Not To Over Tighten
    Using A 14" Pipe Wrench Instead Of 18" Or 24" On 1/2" And 3/4" Pipe

    Only Use 18" Wrench On 1" Or Above Pipe
  15. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    I only use 12" wrenches on 1/2" & 3/4" pipe. I wouldn't trust my gorrilla arms with larger wrenches on little pipes.:eek:
  16. MACPLUMB 777

    MACPLUMB 777 TROJAN WORLDWIDE SALES RP

    Messages:
    679
    Location:
    Houston, Texas, United States
    Gas Leaks

    There You Go ! !
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