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Sealing large pipe threads

David Sutton_2
David Sutton_2 Member Posts: 63
i have had great luck with this.. just a good cotton kite string, wrapped with teflon the the blue goo, gasoilla, i use this on all my steam headers with great success


  • Wayco Wayne
    Wayco Wayne Member Posts: 615
    I've had some trouble

    with large pipe thread connections that seep after a while. I used 3 or 4 wraps of teflon tape and pipe sealer but still have the periodic problem. Came upon a product today and used it. It seemed to do a fine job. It's called Locktite-55. Looks like dental floss but more stringy. Reminded me of the hemp that veisman sends with their boilers. I think I'm going to use it for a while and see what happens. Does anyone out there have some experience with it to share? WW

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  • I use a

    wire brush on all pipe threads, an old copper fitting brush on the female threads 2 or 3 wraps of teflon, then regular rectorseal on the male threads. you will never have leaks. bob
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  • Rich_2
    Rich_2 Member Posts: 40

    I have used the "dental floss" it worked ,but I find it annoying, still think tape & permatex is great
  • Steve Ebels
    Steve Ebels Member Posts: 904
    We use

    Teflon tape, a good heavy mil variety. Not the hardware store stuff. Over top that we apply Leak Lock from Highside Chemical. It's a hardening type, alcohol based sealer. The teflon seems to allow enough slip to let the thread get to the proper depth in the fitting and the leak Lock definitely seals things up. Not good for taking them back apart, but they sure don't drip.
  • bill clinton_3
    bill clinton_3 Member Posts: 111
    stringy stuff

    We've been using it with great success. We put on a little more than the instructions say. Which makes it harder to screw down well, but no leaks.

  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
    2nd the Rectorseal

    Above 2" I get weeping leaks with the teflon dope that works so well on smaller. The Rectorseal seems to lube very well for that last ½ rotation.
  • kevin_5
    kevin_5 Member Posts: 308
    me too

    I have used the stringy dental floss, and thought it was a little "ugly" in that the joint looked a little "hairy" compared to the smooth look of tape, but it didn't leak, so I decided who cares if it's a bit hairy? I have also used teflon with rectorseal over the top and that works for me also, but the string is faster. Kevin

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  • flange
    flange Member Posts: 153

    i like to use the blue pipe dope, works real well and you know youve been there.
  • joe_15
    joe_15 Member Posts: 3

    one word EXPANDO i am not sure the who makes it but workes great one problem its never comeing back apart
  • ronLD
    ronLD Member Posts: 8

    Yes expando is the best for big pipe threads.been useing it for years on 4",6" etc joints.Mix it up with water to a paste and brush on threads and fitting.Make up joint and let dry for 24 hours and garanteed no leaks.
  • Tony Conner
    Tony Conner Member Posts: 549


    We've tried it for pipe in a tobacco plant we do work in (Can't use teflon tape, dope with teflon in it, or teflon anything.) It does work, but you need that 24 hours. That makes it unsuitable for anything maintenance related - production people want everything back in service NOW.

    We've tried any number of pipe dopes that claim to be good for steam temps up to 366*F or over, but we get leaks in about 1 joint in 10. And many of those leaks are on factory nipples into factory threads. Good nipples too - A106B sch 80 seamless into 3000# forged steel fittings or screwed 150# or 300# steel flanges. Very frustrating.
  • Tom M.
    Tom M. Member Posts: 237
    be careful

    I came across a product like that but didn't buy it because of the temperature rating. I don't remember exactly what it was, but I know it was too low for steam.

    Tom M.
  • kevin_5
    kevin_5 Member Posts: 308
    The Obvious choice.

    One more idea, it's been discussed here before but it bears repeating.
    RTV silicone works great even on damaged threads, and it's super easy to get apart if you ever have to. It's also set up in about 15-30 minutes depending on temperature so you're back in business NOW.

    I don't care how unorthodox or untraditional it sounds. Bottom line is, it works. Comes in clear, blue, copper, red, black, etc... so you might find one that looks professional enough for the most discriminating taste.
    Do it right and you can't see it anyway.It's been tested around the world for years in automotive gasketing applications. Chances are it's sealing most of the water and oil (without even using a gasket)in the truck you drove to the job.I don't use it very often but I don't really know why. Habit I guess. The only thing automotive it can't handle is gasoline. Kevin
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  • munchkin-man
    munchkin-man Member Posts: 247
    Teflon tape & Virgin teflon pipe joint sealer

    has proven to work fine for many years in my personal applications and now at Heat Transfer Products we use it on any thing that needs to be sealed. In most cases we do not have to use teflon tape in addition to the sealent. On large diameter threads it is suggested that one use both teflon tape and pipe joint sealer.
  • Tony Conner
    Tony Conner Member Posts: 549
    Is It Good...

    ...for high pressure/temperature steam applications? We've recently tried Megaloc, and it says it's good to 400*F on the can. but the "leaker" rate we get with it is about the same as any other non-teflon pipe dope. The steam piping in question isn't nearly 400*F either, it's about 350*F, max. It goes on a nice blue, and within minutes of having the steam turned on, it "cooks-out" to beige. And almost always, something leaks. Loctite makes a range of products as well, but most of them run out of gas at 300*F.
  • John Abbott
    John Abbott Member Posts: 356

    teflon tape 5 wraps on up to 2" 8 or 9 wraps on larger up to 6" then lubricate with Palmolive liquid dish washing detergent.Don't laugh until you try it.We use 1/2"teflon up to 3/4" pipe 3/4" up to 2" and 1" above.

  • Big Ed_2
    Big Ed_2 Member Posts: 18
    If you don't want it to leak.......

    .....use lamp wick and pipe dope.
  • kevin_5
    kevin_5 Member Posts: 308
    High temp RTV is 600degrees

    I think. I used it for years (and still do)in automotive applications. Think of it as a rubber loc-tite that fills all gaps in threads and dries to a flexible rubbery state. It's vibration proof.
    It can be easily taken apart, and brushes right off of threads with a wire brush. It's not gummy, sticky, or messy to remove. This is NOT the same as the big tubes of silicone you seal windows with. The RTV stands for room temperature vulcanizing. It dries much quicker for one thing.
    It's about 3 to $4 dollars a tube at any auto parts store. Put one in your tool box, it will last a long time.
    One of the more common applications is thermostat housings on engines. I'm not saying it should replace the "normal" way of doing things, but if you have a joint somewhere and you want to make SURE it NEVER leaks, this stuff won't let you down. Kevin

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  • Big Ed
    Big Ed Member Posts: 1,117
    John does the Palmolive......

    ......help with the lubrication or help seal the threads ? Please tell me more....

    P.S. Reminds me of a safe boating tip.Palmolive is great for removing the rainbow from a oil slick. Just incase you see the Coast Guard comming your way while your having engine problems.....
  • kevin_5
    kevin_5 Member Posts: 308
  • MikeB34
    MikeB34 Member Posts: 155

    You didn't say steam or water, but for high temp RTV silicone works everytime.For water, I also did a stint as a spriklerfitter, and we use a product called "superdope" Its an anarobic dope that "hardens to pipe burst strength" (thats from the label) A real pain in the kieshter to remove, but we pump it up to 200PSI operating pressures, and it dont leak.
  • jerryb
    jerryb Member Posts: 113

    For HI-TEMP above 450% i used flake graphite mixed with engine oil and PULLLLLLLED AND PULLLLLLLLLED to tighten everything up also very LARGE BIG BIG CHAIN WRENCHES WITH CHEETERS.Love the new pipe compounds,but try the flake graphite.
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