Galv pipe vs balck iron/ teflon tape

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Riosman, Feb 26, 2007.

  1. Riosman

    Riosman New Member

    Messages:
    23
    Location:
    San Diego
    Two questions

    1. The inspector said to never to use teflon tape on gas pipe. Use dope. He stated never to use teflon tape on pipe threads
    True?

    2. Gas pipe under a raised floor: Galvanzed or black iron?
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,318
    Location:
    New England
    There is a teflon tape approved for gas (I think it is yellow?), but most people use pipe dope. But, you do what your local inspector wants...
  3. leejosepho

    leejosepho DIY scratch-pad engineer

    I have heard gas should never be in galvanized because of the possibility of internal flaking that can cause havok in valves.
  4. kordts

    kordts In the Trades

    Messages:
    551
    Location:
    exurban Chicago
    That was back in the day, now galvanised is o.k. for gas.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,255
    Location:
    Cave Creek, Arizona
    pipe

    galvanized is not only proper for gas, but is required in some situations, such as exposed outdoors. The main reason for using black pipe is that it is cheaper.
  6. leejosepho

    leejosepho DIY scratch-pad engineer

    Whew, I am sure glad to hear that! In a few minutes, I am headed over to install a new blower motor in a widow's furnace, and I have been afraid to tell anyone that the last time I was there I had noticed the incoming gas line is galvanized!
  7. Rancher

    Rancher Guest

    And if you bury it it has to be wrapped anyway.

    Rancher
  8. Rancher

    Rancher Guest

    I'd always heard it was because a piece of the tape might break off and plug up an oriface.

    Never did make sense to me.

    Rancher
  9. leejosepho

    leejosepho DIY scratch-pad engineer

    I know of a situation where someone should have never been allowed to use pipe dope. He used so much and gooped it so heavily around the very end of the pipe that the water in the house tasted just like the stuff for several months afterward.
  10. coz

    coz New Member

    Messages:
    91
    Location:
    MA
    I heard what rancher heard...plugs up gas valves
  11. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,255
    Location:
    Cave Creek, Arizona
    buried

    You cannot legally install black pipe underground even if it is wrapped, unless it first has a factory coating applied to it.
  12. toolaholic

    toolaholic General Contractor Carpenter

    Messages:
    874
    Location:
    Marin Co. Ca.
    4 TIGHT wraps of teflon tape than pipe dope. with this you will be able to back off a fitting 90 degrees and NEVER have a leak. teflon put on LOOSLEY is what causes problems
  13. Rancher

    Rancher Guest

    Is this a new change to the code?

    Rancher
  14. markts30

    markts30 Commercial Plumber

    Messages:
    630
    Location:
    Phoenix, AZ
    It is in the 1994 UPC - so I don't know if it qualifies as NEW...
    sec 1211.5 and 1211.7
  15. jfkopper

    jfkopper New Member

    Messages:
    16
    At least one state's plumbing code forbids the use of galvanized pipe for fuel gas plumbing. (Whether this prohibition is scientifically valid---I don't know.)

    As always, best to do what the AHJ requires.

    Be safe,
    /kop
  16. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,255
    Location:
    Cave Creek, Arizona
    rule

    It has been the rule since at least 1970, and probably a long time before that.
  17. FredC

    FredC New Member

    Messages:
    19
    Tape Vs Dope + new gas water trap questrion

    I was told 2 wraps of yellow teflon + dope on balck pipe. Never heard of that before & always used Rectorseal alonefor balck pipe. Is this OK or should you stick with one vs the other?

    Do you need to install 3" long drip trap at the end of a vertical line going to a cooktop for propane??????
  18. mrclean

    mrclean New Member

    Messages:
    2
    Have always been told that drip leg lengths dont really matter....more a matter of preference with the local inspectors around here. And, the only gas piping we can bury is soft copper.
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