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1 1/2" threads won't seal

I've got 1.5" male threads coming off a buffer tank. I am threading a reducing bushing onto it but the connection keeps failing a pressure test. I'm using 5 wraps of blue monster teflon and tightening with a 24" pipe wrench. I've tried a couple times with no luck. These are the largest threads in the system... does teflon not work well on larger threads? any recommendations?

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 20,434
    Only the obvious ones, I'm afraid. Is the reducing bushing really round? Are the threads cut properly? Does it bottom out before the threads seal (threads again -- cut far enough into the fitting). Ditto on the male threads on the tank fitting.

    And one less obvious -- are both NPT? I've hit that one, like an idiot...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 13,112
    Try regular Teflon tape and wrap it tight. Put some pipe dope on the male threads and dope the female threads as well. Crank it up tight.

    Use whatever dope you have , I like Rectorseal True Blue. On the can it says to dope the inside threads on anything larger than 1 1/4"
    ChrisJ
  • hot_rod
    hot_rod Member Posts: 18,195
    It is possible to over-tightens fitting and either pull the thread or expand, maybe crack the fitting. Teflon and a large wrench can tempt you to overdo it :)

    Is the nipple round, no shipping damage?

    If you can get both male and female completely clean, Loctite will seal most anything. The super glue of fittings.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • the_donut
    the_donut Member Posts: 374
    I third pipe dope. If I really want a good seal I will use blue monster tape 3 wraps with dope on first few threads both make and female.
    ratio
  • Dennis
    Dennis Member Posts: 101
    Try a nipple and a reducing coupling. Bushings are all made in China possibly the compression part of the bushing is not tapered correctly.
    Just do it, right.
    kcopp
  • JUGHNE
    JUGHNE Member Posts: 10,279
    How does one thread a reducing bushing onto a male nipple? :)
  • HomerJSmith
    HomerJSmith Member Posts: 1,923
    edited March 2018
    If the connection is permanent, I would use J-B Weld or lock-n-seal (loctite) which can be undone. Even J-B Weld can be undone if heated hot enough.

    I think he means coupling, but I have been wrong before.
  • jumper
    jumper Member Posts: 1,911
    JUGHNE said:

    How does one thread a reducing bushing onto a male nipple? :)

    My question as well.

    Another question is against what pressure do you want to seal?

    Something that worked for me sometimes is to dope the male thread and grease the female thread. Also I never use extreme force on anything threaded. I don't understand why short (stubby) wrenches for larger sizes are so unusual.
  • HomerJSmith
    HomerJSmith Member Posts: 1,923
    edited March 2018
    'hot rod' says, "It is possible to over-tightens fitting..."

    Myself, I always tighten a fitting until it busts and then give it one more turn.
    ratioSuperJ
  • the_donut
    the_donut Member Posts: 374

    'hot rod' says, "It is possible to over-tightens fitting..."

    Myself, I always tighten a fitting until it busts and then give it one more turn.

    Making sure you use a small wrench with a pipe on the handle for maximum egging.
    SuperJHomerJSmith
  • GroundUp
    GroundUp Member Posts: 1,495
    Permabond LH050/150 or Loctite 565/567 have gotten me out of more trouble than I care to admit. I all but gave up on tape and dope (never bare tape, just don't do it) on 2" and less many years ago and can literally count on one hand the amount of leaks I've had since- this is a fulltime job. Of those few leakers, all of which were fixed with more tightening or some heat. Used to use X-Pando for the real stubborn ones back in the day, but that will never come apart again if it doesn't fix it. If the nipple or fitting is egged enough to kill sealing, it won't thread on either IMO. Just ordered another case of Permabond on Thursday, I love it
  • hot_rod
    hot_rod Member Posts: 18,195

    'hot rod' says, "It is possible to over-tightens fitting..."

    Myself, I always tighten a fitting until it busts and then give it one more turn.

    Two grunts on anything 1" or smaller, 3 grunts for larger sizes up to 3"

    Up to 1-1/4" I use this 14" Reed aluminum offset style pipe wrench for assembly. I have worn out 3 or 4 of theses over the years. Sometimes a cheater for disassembling :)
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Solid_Fuel_ManratioHomerJSmith
  • MikeL_2
    MikeL_2 Member Posts: 392
    On stuborn connections I like to use ball or string wicking first, 3 / 4 wraps of quality Teflon, and then a coating of pipe joint compound........
  • ratio
    ratio Member Posts: 3,332
    hot rod said:

    Up to 1-1/4" I use this 14" Reed aluminum offset style pipe wrench for assembly. I have worn out 3 or 4 of theses over the years. Sometimes a cheater for disassembling :)

    This.

    Around here, I noticed that the gas company guys (& gals!) use an 18" offset wench for pretty much everything, so I picked one up. It seems to be able to get in to more places that a regular wench. I'm not completely sure, but there might not be a case where only a standard wench will work.

    And Aluminum all the way!

  • JUGHNE
    JUGHNE Member Posts: 10,279
    A brass coupling would have a little stretch to it and perhaps mate with the nipple a little better especially if the nipple is SS.
  • rick in Alaska
    rick in Alaska Member Posts: 1,396

    Try regular Teflon tape and wrap it tight. Put some pipe dope on the male threads and dope the female threads as well. Crank it up tight.

    Use whatever dope you have , I like Rectorseal True Blue. On the can it says to dope the inside threads on anything larger than 1 1/4"

    I would have to look it up again, but i am fairly sure it is against the plumbing code to put pipe dope on the inside of a female fitting. As you tighten the pipe in, it pushes the pipe dope into the inside of the fitting, which as you all know is not good.
    I can just hear what Icesailor would be saying right know if he heard someone saying to dope the female threads. It would be in all capitol letters!
    My method is like some others here. I use Megalock dope on the threads, followed by at least four wraps of Monster tape, and depending on the thread, more dope on the outside.
    I haven't had to deal with many straight threads yet, so have not had to use wicking, nor have I ever even seen the stuff. I hope to continue that trend.
    Rick
  • HomerJSmith
    HomerJSmith Member Posts: 1,923
    I was taught to dope the female connector if it was larger than
    1-1/2", But I do 1-1/4" too. You only have to do, sparingly, a couple of threads. I gave up using Rectumseal for the newer sealants.