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Best Pipe Dope For Black Iron Gas Pipe

JerseyDIYguyJerseyDIYguy Member Posts: 24
edited May 2018 in Gas Heating
The title more or less says it all. I'm relocating a bunch of 3/4" black iron natural gas pipes that feed my boiler. I've used Oatey dope in the past (I used their conventional, non-teflon dope for gas pipes) and had decent results, but I'm wondering what the pros prefer. I have lots of big-box home stores and smaller hardware stores in my area, plus Amazon.

Thanks in advance.


  • GroundUpGroundUp Member Posts: 960
    edited May 2018
    Might depend on your inspector, if applicable, but I prefer Permabond LH150 anaerobic sealant myself. I use it on everything from 7" gas to 200 psi hydro, copper to SS on threads under 2" and can count on two hands the amount of leaks that needed fixing in the 10 years I've been using it. Code here says no tape on gas, although most do it anyway, and only a handful of inspectors will actually enforce it. Have had quite a few in the local metro comment on the Permabond, as there are no PTFE strands to get in the line. It's expensive but worth every penny IMO. Will never buy anything else for small bore
  • ratioratio Member Posts: 2,329
    @GroundUp, how is that stuff coming apart?
  • IronmanIronman Member Posts: 5,562

    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
    Dan FoleySolid_Fuel_Man
  • GroundUpGroundUp Member Posts: 960
    ratio said:

    @GroundUp, how is that stuff coming apart?

    It can be tricky on small brass or short sch 40 nipples as they will egg before the seal lets loose, but I've found a bit of Mapp heat will loosen the grip enough to get the joint apart almost every time. Everything else does well if you have enough wrench, but I draw the line at 2". Once it's been heated a few times my 225lbs hanging on a 24" wrench with a 2ft cheater doesn't quite do it anymore lol.

    @Ironman that Gasoila is what my company buys, best dope I've ever used with Rectumseal 5 coming in a real close 2nd. I keep one of each on my truck for the bigger stuff
  • The Steam WhispererThe Steam Whisperer Member Posts: 489
    We've been using Blue Monster dope. Thier tape works so well that we decided to use thier dope. No Tape on gas threads!
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • EYoderEYoder Member Posts: 58
    I've found LeakLock is some of the best stuff I've ever used.
  • Solid_Fuel_ManSolid_Fuel_Man Member Posts: 1,954
    Another vote for Gasoila.

    Never tried leaklock on gas, will have to try it next time. Gasoila is not easy to clean up....
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • RomanPRomanP Member Posts: 102
    Code says no Teflon. So I use either blue monster tape( which is rated for NG, and has no Teflon), or there’s that special yellow tape for gas. Then I use MegaLock over the tape. Haven’t had an issue even with bigger threads( 2.5-4”)
  • Steve MinnichSteve Minnich Member Posts: 2,535
    I assume most of us deal with 1/2 psi or less? You almost have to be trying to get a leak.
    PHC News Columnist
    Minnich Hydronic Consulting & Design, LLC
  • george_42george_42 Member Posts: 81
    the difference between the color of different sealing tapes has to do with their thickness. white teflon tape is thinner and considered general purpose ; yellow tape is thicker and is approved for gas use in some places ( it is also teflon ) ; blue monster makes their tape thicker than the white and jus colors it blue , but it is also teflon.
  • Steve MinnichSteve Minnich Member Posts: 2,535
    I respectfully disagree. I use a white teflon tape all the time that is extremely thick. It comes with my supply house's name on it but it's every bit as thick as Blue Monster. I've been using it since the mid 90's. Tried all the others and see no reason to switch.
    PHC News Columnist
    Minnich Hydronic Consulting & Design, LLC
  • RomanPRomanP Member Posts: 102

    Nice catch, man! You made me research and all of them are Teflon. I checked blue monster applications and it is rated for NG. I mean I also checked it few years ago when I started using it.
  • ratioratio Member Posts: 2,329
    Sometimes it's hard to find the overlap between mfgr's acceptable uses and Code permitted uses.
    Steve MinnichSolid_Fuel_Man
  • Solid_Fuel_ManSolid_Fuel_Man Member Posts: 1,954
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
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