Plastic to plastic threaded fittings... use teflon or not?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by DavidTu, Aug 7, 2010.

  1. DavidTu

    DavidTu Member

    Dec 3, 2009
    Seattle, WA
    On a boat's fresh water system I had to replace a threaded hose fitting. I put on teflon tape thinking it would help seal better but no matter how tight I screwed the fittings together I still get drips. Now I am wondering if w/ plastic to plastic threaded fitting connectors, is using teflon causing the problem? (Any other ideas why it'd still leak?--it cannot be further tightened)
  2. jimbo

    jimbo Plumber

    Aug 31, 2004
    San Diego, CA
    One to two wraps max of tape is ok. Main cause of leakage on plastic threads is overtightening. Hand tight plus one/half to one full turn...that's it. You have proabably already distorted the threads.
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  4. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona
    quote; Hand tight plus one/half to one full turn...that's it.

    I have never seen a plastic thread NOT leak if that procedure was followed. I tighten them until they are TIGHT, regardless of how many turns it takes.
  5. RinconVTR

    RinconVTR Member

    Sep 1, 2009
    Not using tape will not only allow leaks, but it can also "weld" the plastic together making disassembly almost impossible.
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    This type of thread is tapered and seal between the threads, you MUST use something, either tape or a pipe dope rated for use on the plastic pipe you have. Under an ideal world, 1/2-turn after finger tight MIGHT work, but don't count on it.
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