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  1. #14
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    Jan 2008
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    windy city
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    we do here all the time, and do it sparingly. a little teflon or never sieze as Amick stated, will facilitate future disassembly

  2. #15
    Join Date
    Dec 2001
    Location
    Ocean Pines, MD
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    Union Unions.

    I use it, mainly on the backside and a dab on the threads. I too wondered why the old guys did it till one had the patience to explain to me that it was a union, meant to be taken apart and the sealant wasn't a sealant but a lube to help take apart.

  3. #16
    Join Date
    Jul 2009
    Location
    st louis mo
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    334
    This practice comes from the unions, I was once doped myself, but I wised up and got undoped. but most of the unions today dont have to be doped, because they go through a predoping process,(apprenticeship), and that usually lasts a lifetime.But sometimes a union startes to become undoped, and then they will have to be taped.

  4. #17
    Join Date
    Sep 2005
    Location
    Atlanta GA area
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    21,766
    As I understand it, the purpose of pipe dope (thread compound) is to lubricate the threads to tighten a little more with less torque applied. The sealing ability is secondary.

    And as such, I can see using it on the coupling ring of a union. I could also see this as Union (organization) pride in their work.

    I learned today in this thread (well thought about it)... the joint compound would also act as an anti-seize compound. Good idea.

    Given the idea of lubricating the joint to apply more torque, I can see why some folks use it on flared connections ('B' nuts as we called it in aviation maintenance).

    The part in NY state about not allowing flex gas connectors is a new one to me... shows that code requirements can get goofy sometimes. However I am sure they have a good reason for it, and will defend it with zeal if challenged... governments do that you know.
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  5. #18
    Join Date
    May 2000
    Location
    Rochester, NY, USA
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    14,511
    [QUOTE=ga-hvac-tech;5160762]
    As I understand it, the purpose of pipe dope (thread compound) is to lubricate the threads to tighten a little more with less torque applied. The sealing ability is secondary.
    this debate could go on for a life time, some folks (scientists) believe pipe dope lubricates, some think pipe dope seals? some folks think it does both.

    I have run literally MILES of black steel pipe from 3/8th" to 4", both as high pressure air line and as gas line. I have used Victalic fittings and I have welded fittings. If you put a union together correctly you should never have a need for pipe dope on the matting surfaces or connecting threads.



    The part in NY state about not allowing flex gas connectors is a new one to me... shows that code requirements can get goofy sometimes. However I am sure they have a good reason for it, and will defend it with zeal if challenged... governments do that you know.
    I don't know of any place in NY where a flex connector is allowed to a furnace or HWT. I have been working with steel pipe since the early 80's and it has always been hard pipe. But that has been in the 5 counties around Rochester, I really shouldn't comment about the rest of the state
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  6. #19
    Join Date
    Dec 2001
    Location
    Ocean Pines, MD
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    7,034
    Quote Originally Posted by mike dixon View Post
    This practice comes from the unions, I was once doped myself, but I wised up and got undoped. but most of the unions today dont have to be doped, because they go through a predoping process,(apprenticeship), and that usually lasts a lifetime.But sometimes a union startes to become undoped, and then they will have to be taped.
    You should try putting a little effort to some positive contributions into these discussions, or any discussion at this site. Your main track record here so far has been to try, and I do say try, to be a SA.
    It's getting old.

  7. #20
    Join Date
    Feb 2004
    Location
    New Mexico
    Posts
    5,739
    Unions are ground joint connections and the threads have nothing to do with leaks. If they leak it's either loose or the ground joint failed.
    Pipe dope is a lubricant not a sealer. There are sealers also but usually a tapered thread, like pipe threads, won't require them.
    I've known guys that put Loctite on about everything. Even copper flares. Never knew why when a couple drops of oil do just fine.
    "What Fools these mortals be"....Puck

  8. #21
    Join Date
    Dec 2001
    Location
    Ocean Pines, MD
    Posts
    7,034
    It wasn't Loc-Tite. Teflon type. Like I said, just a dab. I'm reading with interest opinions and will probably learn somethin. But in our area, you can watch things corrode so we do what we can.

  9. #22
    Join Date
    May 2000
    Location
    Rochester, NY, USA
    Posts
    14,511
    there is ONE guaranteed way to "seal" NPT threads.

    Use Teflon tape and then put pipe dope over the Teflon tape. This is about the only way you can run anti-freeze through screwed pipe without leaks. An old pipe fitter told me that trick. Just use caution because you can screw fittings together so far that you will crack the fitting.
    I only drink a little, but when I do
    I turn into another person and THAT person drinks a lot

  10. #23
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    2,520
    I was taught 31 yrs ago to dope the threads on the union, it makes it easier to come apart. Have run into enough undoped and ones I had put in earlier to know it works. It wouldn't do anything to seal the union as that is done at the seat.

  11. #24
    Join Date
    May 2007
    Location
    Dry as a bone Tucson
    Posts
    4,544

    Pipe dope

    I learned how to make up pipe joints 32 years ago while working on drilling rigs---
    1. clean your joint
    2. swab with dope
    3. apply some twine at the base
    4. make up the fitting
    5. quit tightening when the twine squeezes out.
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  12. #25
    Join Date
    May 2000
    Location
    Rochester, NY, USA
    Posts
    14,511
    Quote Originally Posted by ACFIXR View Post
    I learned how to make up pipe joints 32 years ago while working on drilling rigs---
    1. clean your joint
    2. swab with dope
    3. apply some twine at the base
    4. make up the fitting
    5. quit tightening when the twine squeezes out.
    that what she said
    I only drink a little, but when I do
    I turn into another person and THAT person drinks a lot

  13. #26
    Join Date
    Apr 2001
    Location
    san jose,ca.
    Posts
    5,285
    Here in san jose ca. flex conn. is requierd. But then i`ve gone through a 7.3 earthquake that the w/h & furnace danced a jig on the platform.

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