Pipe Dope, Plumbers Putty, or Teflon Tape?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by vistaman, May 3, 2008.

  1. vistaman

    vistaman New Member

    Messages:
    35
    Any general rules for using which, when, why? Or the opposite, why /not/ to use which, when? :)

    Thanks...
  2. hj

    hj Moderator & Master Plumber Staff Member

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    26,815
    Location:
    Cave Creek, Arizona
    ?

    They are used for different purposes so you cannot lump them together. Dope and tape are to join pipes to fittings. Putty is to seal a "clamped" joint.
  3. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,358
    Location:
    Yakima WA
    Pipe dope is a gooey paste that is used on threaded pipe joints. Teflon tape is used for the same purpose, and some plumbers use both at the same time. Plumbers putty is use when installing sink drains. It is a soft putty that will compress to seal between the flange and the sink. Some new materials require silicon, but that's another question. My personal, repeat personal, preference is pipe dope on water and gas joints, Teflon tape on air fittings. There are two grades of Teflon tape, the familiar white tape for water and the less familiar yellow for gas. The yellow is thicker than white.
  4. jimbo

    jimbo Plumber

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    8,997
    Location:
    San Diego

    Well, there is also pink teflon tape, and of course green.
  5. bombjay

    bombjay New Member

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    62
    Remodel work, I do paste over tape.Then I bump the thing and get a leak on the old galvanized down the line anyhow!
  6. crw1957

    crw1957 New Member

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    3
    I use tape. Sometimes tape and dope. Tape is great for PVC threads. I use dope on threads that require some lubricant to make them thread together easier as well as seal them. Megaloc brand works on PVC pipe as well as galv. and copper. As stated earlier, I sometimes use tape and dope on the same fitting when it absolutely cannot leak, like the last joint of the day and my daughter has a dance recital.
    Tape can also be used as packing. I wrap it around stems under the packing nut in stead of string packing or grafite.
  7. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    Generally I use tape for water pipe threads and dope on gas. I only use Gasoila dope.It works on plastic for the rare need. Lately I have been using tape and dope on water heater nipples. The threads have been bad lately on the junk coming from overseas and I do not want to take apart finished work to fix a leak.
  8. vistaman

    vistaman New Member

    Messages:
    35
    Good stuff, thanks guys!
  9. I remember a time when I was using wicking and the old nasty grey ProDope. Now I'm using tape and Megaloc on all threaded metal fittings, dope only on pvc.
  10. vistaman

    vistaman New Member

    Messages:
    35
    Do you choose one over the other for certain types of joints? Megaloc seems like a good choice for all joints. If it truly performs as Megaloc says it does, why use tape at all?
  11. Why use tape? Because I hate taking apart my work because of a leak. I haven't tried Megaloc without tape on brass or copper threads. I'm kinda old-school, believing the teflon tape is there to allow you to thread things together easier and the dope is the thread sealer. Does tape seal joints? Yup, I'll admit I've seen stuff taped-only and sealed. Does dope with teflon in it perform as well as tape and dope? Probably, but I'm not taking any chances. Tape and Megaloc are a combo that work for me, that I'm comfortable with, and that I don't have to go back on call-backs for.
  12. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    I dislike working on pipe that megalock was used on.

    Hard to take apart, if a soft set dope is used right it won't leak but will be easier to take apart...like when installing gas heaters.
  13. vistaman

    vistaman New Member

    Messages:
    35
    This has been interesting for me. I'm an amateur/DIY'er and I'm going to re-plumb my lav and its drain next week. I'll probably use tape for the faucets, as I always have in the past. I've got a new tailpiece, p-trap, trap-arm, all in chrome pipe, for the new vanity.

    In this particular case, would those joints be better done with tape, dope, megaloc, or some combo?

    I thought I recalled reading somewhere in this forum that sometimes a bit of putty on those joints (slip joints) was also helpful. Do you guys have any comment on that method?

    Thanks...
  14. Furd

    Furd Engineer

    Messages:
    446
    Location:
    Wet side of Washington State
    ONLY tapered pipe threads require a thread sealant. Slip nuts, compression fittings, flare fittings, ground-joint unions and any fitting that has a gasketed surface does not need any thread sealant and the use of a sealant is often the cause of leaks.
  15. vistaman

    vistaman New Member

    Messages:
    35
    Then, for assembling lav drain to tailpiece, then tailpiece to trap, then trap to trap-arm, then trap-arm to wall drain outlet, all of which are slip joints with a gasket/washer, use only teflon tape, or use nothing? And no leaks if done properly? :confused:
  16. Furd

    Furd Engineer

    Messages:
    446
    Location:
    Wet side of Washington State
    I don't recall ever seeing a threaded tailpiece that had any kind of sealant on the threads.

    As for the rest, which is all assembled with slip joints, no Teflon or anything else. Be sure the tapered end of the gasket/washer is pointed into the receiving pipe and the flat side is against the inside of the nut. Just slightly more than hand tight should not leak.

    The one possible problem that might arise is if you need to cut any of the pipe/tube for length. If you use a hacksaw be sure that it does not "jump" and leave scratches in the pipe/tube. Deep scratches under a slip nut washer WILL cause leaks.
  17. Interesting. I was always taught to dope all unions. So all traps, tailpiece washers, and all that...all doped. I've had sink traps assembled by others that were tight, but no dope, and leaking. I've disassembled and doped and retested and all OK.
    And my preference for Megaloc is it's approved for plastic pipe (while some other dopes aren't) and easily washes off clothing.

    Hey, ask 10 plumbers and you'll get 10 different answers. Every person has to try different methods and see what works for them. As individuals, there is no hard, fast rule for all to adhere to. What works for me may not work for you.
  18. vistaman

    vistaman New Member

    Messages:
    35
    Well now I'm /totally/ confused :)
  19. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    Drain tubing should never need anything except the slip nut if it is installed right and the tubing is round and smooth.
  20. vistaman

    vistaman New Member

    Messages:
    35
    I appreciate your patience. Can you help this amateur and define "installed right"? Plumb and level and straight I know. Round and smooth I understand :) More than hand tight, or snugged up, or... ?
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