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Thread: Leaking Threads using Teflon Tape

  1. #1
    DIY Junior Member mtyakker's Avatar
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    Default Leaking Threads using Teflon Tape

    Recently installes a Lako's Twist to Clean filter between my preasure tank and water softner. It was reccomended to me on this site to reinstall using unions on each side of the filter so that I could remove the entire unit in order to replace the internal filter. The Lako's has 1.5 inch male threads. I am installing the Teflon in the correct, clockwise direction, I have used thin and thicker teflon, I have used as little as three to as many as 6 revolutions of tape, no matter what I have tried I can not stop the leak. If I continue to tighten the fitting down ,and I am using a large pair of Channel locks by the way, the leak does not stop. I am completely stumped as to what to try next. Any advice would be appreciated.

    These are pvc unions, it's npt the union I am having a seal problem with, it is where I am threadind the female portion of the union onto the male threads of the Twist to Clean, always seems to be leaking at the bottom.
    Last edited by mtyakker; 09-16-2013 at 04:49 PM.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    You do NOT use pipe sealant or tape (it's not Teflon, it's generic PTFE) on unions! THey seal with a metal to metal connection of the ends. Tape in there can get in the way and prevent that. Some people do put a small dab of sealant on the mating surfaces, but it's not required to get a good seal.
    Jim DeBruycker
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    DIY Senior Member dj2's Avatar
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    It's difficult to say without looking at it, as it could be one or more of many reasons. When you are dealing with PVC connectors, over tightening is not always the answer. There could be ab issue with the thread. Or the tape. Hard to say. What kind of union do you have? metal unions don't need tape.
    I see your frustration, just call a handyman plumber.

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    DIY Senior Member Smooky's Avatar
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    For PVC a thread sealent might work better.

    http://www.homedepot.com/p/Hercules-...6202/100112544

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    DIY Senior Member craigpump's Avatar
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    I ALWAYS install a union with the male headed in the direction of the flow. On the rare occasions we have a weep, usually an existing union, we put a small amount of RectorSeal on the face and then retighten the union.

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    Moderator & Master Plumber hj's Avatar
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    quote; I ALWAYS install a union with the male headed in the direction of the flow.

    I haven't heard any one say that in the past 50 years. And at that time it was only one "plumber" who had a few other odd ideas.
    Licensed residential and commercial plumber

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    Jack of all trades DonL's Avatar
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    Quote Originally Posted by Smooky View Post
    For PVC a thread sealent might work better.

    http://www.homedepot.com/p/Hercules-...6202/100112544

    That may work fine.

    The only time I have had problems is when using the made in China fittings and they do not tighten properly because the Pipe sizing is off.

    And it takes a lot of tape to get a leak proof connection.

    Sometimes I will just Glue it if it is not bottoming out, and it is PVC to PVC, but then there is no turning back. If it is bottoming out you can cut some of the male thread off.

    As far as the PVC unions go, the ones will the O-Ring do not leak at the union, and I use O-ring Super Lube.


    May be best to get a different Union, that matches the threads of that filter.


    Are them Twist II Clean filters any good ? Made in China ?
    Last edited by DonL; 09-17-2013 at 08:58 AM.
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    DIY Senior Member craigpump's Avatar
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    I'm sure we have all developed our own practices over the years, but this was passed down to me by my grandfather who was a P1 here in Ct for years.

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    Jack of all trades DonL's Avatar
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    Quote Originally Posted by craigpump View Post
    I'm sure we have all developed our own practices over the years, but this was passed down to me by my grandfather who was a P1 here in Ct for years.

    It it is better to have a plan, Than no plan at'all.
    Theory only works perfect in a vacuum.

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  10. #10
    DIY Junior Member mtyakker's Avatar
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    Yes, I am very pleased with the performance of the unit, however I am getting silt up from my well that is still getting through the 140 mesh filter, but the backwashing/self cleaning part works very well.

  11. #11
    Sprinkler Guy Wet_Boots's Avatar
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    It might be that the male threads are a wee bit deformed, or undersized. I worked with some deliberately-off-spec female threads on PVC valves, that required a major overdose of teflon tape wraps on the mating male threads, being this was before modern plastic-compatible paste dopes.

    That Hercules pipe dope looks like an equivalent to the Megaloc I mentioned.

  12. #12
    Moderator & Master Plumber hj's Avatar
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    quote; Obviously we want it repaired at no cost to us, but we do not trust the original contractor to perform quality work.

    AN "old wife's tale". I install the union in whichever direction it will be easiest to tighten the "union nut".
    Licensed residential and commercial plumber

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