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Tape or Pipe Dope

TonyBal_2 Member Posts: 54
I am getting close to replacing traps on Rads and curious what thought is re using sealant for 1/2" pipe near Rads and thermostatic traps.

Ive seen Rectorseal sealant with teflon white (t plus 2)
Rectorseal yellow "soft set" 5

white tape and yellow (gas) tape. some tape is thicker than others. thicker is better?

Megaloc...?? w/Kevlar..

did i read somewhere to use both tape and dope?

Not sure of best product. any thoughts appreciated.


GN Homemowner


  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    tape or dope?

    i think the difference between tape and dope is the ease of separating the joint later. basically the thread sealant is misnamed--it should be called thread lubricant. i use teflon tape with a drop of dishwashing liquid [on the female thread] over brushed clean threads, and have never had a problem undoing the joint later.

    it's a different story for 6" steam main. on that you probably need both dope and tape.

    remember, if your system is working as originally designed and installed, you should only be hold only a few ounces of pressure inside the system.--nbc
  • Sealant or lubricant ?

    I dunno ......... I would never try to seal a joint with WD-40 or 5W-30 :) Yep , the sealant does lubricate some . But it's also sealing the joint tight .

    I use both Teflon tape and Rectorseal Yellow . Just 2 wraps of 1/2 inch tape on the fitting and paint the Rectorseal over the Teflon . You'll be able to take the fitting apart real easy down the road .
  • Mitch_6
    Mitch_6 Member Posts: 549

    If it is not a natural gas line, I put the dope on the male end first so it does not come off with the tape. Then I make one wrap around with the tape.

    Old day's dope then wicking.

    I like the T2 Teflon past since it is easier cleanup than regular rectorseal, tough threads I use the traditional rectorseal since it seals better.

    Real tough threads I use a coated wicking.

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  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    I have

    been doing the 4-5 wraps of teflon, then dope. I dab some dope inside fittings over 1 1/4. I switched from Rectorseal 5 to Megaloc about 10 years ago and am very happy with it and the wife is very happy it washes out of my clothes. Plus, it smells better than R5 :)
  • hot_rod
    hot_rod Member Posts: 21,815
    check out the 3 wrap

    teflon tape product from Mill-Rose. Two or three wraps of this extra thick product is all you need.

    Start back two threads and use some teflon paste on the end. This gives excellent lube and sealing, especially on rough threaded pipe or fittings.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Timco
    Timco Member Posts: 3,040

    I use some "gorilla" tape that is blue, and even some pink tape, but it looks terrible sticking out of a fitting that is visible. White looks best. Use both tape & dope.

    Just a guy running some pipes.
  • michael_34
    michael_34 Member Posts: 303

    I like using both tape and dope. A little bit of dope on the tape helps give a little more torque on the threads. It lubes the joint to get tighter.
  • Paul Fredricks_9
    Paul Fredricks_9 Member Posts: 315

    I could swear I've always heard only Teflon on steam. Did I hear wrong?
  • paul zeszotarski
    paul zeszotarski Member Posts: 33

    i use both tape and dope. i use the dope first then put the tape on. i also dope the inside on the female side just to be sure.
  • Personal preference

    I do just the opposite; tape, then dope.

    There was one time where I used ABS glue. It was late in the afternoon, no tape or dope to be found and far away from home or any supplier. Worked fine.
  • Paul Fredricks_9
    Paul Fredricks_9 Member Posts: 315

    On water I use a thin coat of #5, followed by 1 1/2 wraps of Teflon. Always worked well. Seen too many steam jobs with dope running down the pipes after things get steaming.
  • MikeyB
    MikeyB Member Posts: 696

    I was taught to use spoolwick/lampwick and either real tuff or prodope on top of the wick, especially when re-connecting into old fittings that have been stretched out, always seemend to seal better then teflon tape alone.
  • Paul Fredricks_9
    Paul Fredricks_9 Member Posts: 315

    Old fittings are a different story. Haven't done any in a while, but was taught to use wicking with pro dope and teflon. I have real tuff, too messy.
  • I use tape then No 5 Rectorseal

    But most important is to wire brush the male and female threads before applying the tape and dope. Use your old copper fitting cleaning brushes to clean out the threads and see how smoothly the joint goes together. You will never have leaks, even the small ones where you connect to the water heater, where you never see water- just mineral deposits, are eliminated.

    Thanks, Bob Gagnon

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  • Bill Clinton_6
    Bill Clinton_6 Member Posts: 35
    pipe sealing cord

    For six or seven years now, we've been using Loctite 55 thread sealing cord...modern version of wicking. Never used on steam but I bet it would be good there too. No leaks in all that time. Europeans, apparently use it. If you look close at euro threads, it's clear they don't even try for and "interference fit" metal to metal seal. Teflon will work on Euro threads, but cord is much better.

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