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

    Joined:
    Dec 3, 2009
    Location:
    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

    Joined:
    Aug 31, 2004
    Location:
    San Diego
    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

    Joined:
    Aug 31, 2004
    Occupation:
    Plumber
    Location:
    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 New Member

    Joined:
    Sep 1, 2009
    Location:
    Wisconsin
    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

    Joined:
    Sep 2, 2004
    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    This type of thread is tapered and interference...to 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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