compression fittings

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by don metzinger, Jan 7, 2007.

  1. don metzinger

    don metzinger New Member

    Messages:
    47
    I recently had to re-use the old ferrules when installing some replacement valves and had trouble getting them to re-seal, finally got them set. Is it adviseable to use eiter teflon tape and or paste over old ferrules? I have never had any problems with new ones. Does anyone use tape or paste with either new or old?? Thanks - Don
  2. kordts

    kordts In the Trades

    Messages:
    551
    Location:
    exurban Chicago
    Do not use anything on compression fittings, maybe a drop of oil.
  3. don metzinger

    don metzinger New Member

    Messages:
    47
    Thanks, I was told to not use anything and have followed that advise but was wondering why? - Don
  4. norcal1

    norcal1 Plumber/Owner

    Messages:
    91
    Same reason you shouldn't fix a leak with duct tape. :)

    BTW: I like to use a little plumber's grease on the threads...
  5. Randyj

    Randyj Master Plumber

    Messages:
    1,047
    Location:
    Alabama
    Because once the first connection is made to the ferrule it is like a finger print....virtually every fitting is different and the odds of getting the same old one EXACTLY in the original place at the exact same angle is very low odds so you can bet on having a leak. Sometimes you can tighten extra good to stop the leak but you may damage the nut or the fitting/valve... The ferrule is a soft metal but it still is hard to get it to seal once it is deformed by the original compression.
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,294
    Location:
    Cave Creek, Arizona
    ferrules

    Tell that to the hundreds, and thousands, of ferrules I have reused by just connecting the old nut to the new valve. Tighten them with a 15/16" open end wrench and you will not distort them and will not have to overtighten them.
  7. Randyj

    Randyj Master Plumber

    Messages:
    1,047
    Location:
    Alabama
    hj... me too...but the guy wants an explanation... maybe I should edit that post to be a little more liberal... I definitely would not take a ferrule off of a pipe and re-use it on another pipe. Maybe I got up too early this morning.... time to get out to work... I've got to re-key a whole house and run 250' of conduit underground for multiple phone lines.... might be a long day. Too bad I don't get intelligent and stick to just one occupation...but then I don't pass up a buck!
  8. SteveW

    SteveW DIY Senior Member

    Messages:
    1,052
    Location:
    Omaha, NE

    The reason is that the seal is actually made by the ferrule mating with the spherical female part of the fixture, and NOT by the threads. Teflon tape or thick pipe dope can interfere with the ability of the nut to fully thread far enough on the male threads to adequately compress the ferrule.
  9. don metzinger

    don metzinger New Member

    Messages:
    47
    Thanks, I appreciate all the info. - Don
  10. SteveW

    SteveW DIY Senior Member

    Messages:
    1,052
    Location:
    Omaha, NE
    You're welcome! I learned that little fact, along with dozens of others, on this site - great place to check in on regularly.
  11. I'm not a pro plumber, but I've been DIYing it for more than 50 years.
    Who says that you can't use anything on a used ferrule?
    I've been smearing used ferrules with a small dab of caulk for years to seal them (with new and old nuts). Works like a charm. No leaks. No problems.
    Mike
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