Tape or Dope?

deek

I'm sure everyone has their preferences but I was wondering which people prefer and why.  My background in aviation makes me lean towards teflon pipe dope because I have seen tape contaminate systems and cause failures in gyros in particular.  But these are in joints that are often disconnected for servicing so my argument really doesn't apply to plumbing a boiler.

Love to hear your 2 cents.

Cheers

Derek

Steve Whitbeck

Both

I first wrap the threads with 4 layers of regular teflon tape and then coat them with pipe dope. ( It is very important that the tape stays back one thread from the end of the pipe because it can partially block the pipe when threaded in if it hangs over the end)

Paul Pollets

Opposite

I do it just the opposite...first a light coating of pipe dope to the threads, then the tape. This way the dope doesn't get on anything. I also use gas fitters tape or heavier mil teflon... less wraps required.

Mark Eatherton

In the GOOD old days...

My dad told me they use to use goose grease as the thread lubricant. Of course in those days, all threads were the same and properly pitched, and the threads self sealed. Today, NONE of the threads have the same pitch, and subsequently require a "sealant" in order to close the deal.



I triple dope. Paste, 4 to 5 wraps of thin tape, and final coating of paste (your choice).



Overkill, fer sure. But the cost of having to drain a system down, and fix a leak is not insignificant.



I "recycled" an HTP 120 gallon tank on my solar system at Hydronicahhh, and the cold water connection had a slow leak. That's why I got it in the first place. So, being cautions, I used a new sealant/lubricant that is commonly used in refrigeration system, and it STILL leaks... My friend, Der Heatmeister told me I need to take it apart, rough up the threads, and use hemp on the threads to seal it up.



My water up there is SO hard, I suspect it will self heal, and on last inspection, actually appears to be doing so.



My $0.02 worth :-) Keep the change.



ME

hot_rod

another option

We assemble a lot of brass fittings that have Euro style straight threads. We use Loctite bolt and nut thread locker. A few drops, screw it together finger tight, wait a few minutes and it is set. It does not dry or harden on the outside so wipe excess off with a rag.



I've tried some on steel pipe threads and it works well also.



IF you need to disassemble a fitting, heat it slightly with a torch to soften the set and screw it apart.



The beauty of a straight thread is you can stop anywhere and end up with an exact lay length, no guessing to where the fitting will tighten.



The fittings need to be clean and dry, clean off any pipe dope with a wire brush and rag.



Some of the Euro manufacturers that still send straight threads over here, now include a small squeeze tube of this Loctite sealant.



Beats winding hemp



hr

zacmobile

silicone twine

Viessmann sends a little spool of loctite silicone impregnated twine with their indirect tanks, it seems to work well. Normally I use lead dope (it actually has pulverized lead particles in it that mash into the threads) then pink teflon tape, that's the thicker stuff, stay away from the white as it shreds and can contaminate the system as deek mentioned.

AlexS

tape or dope.....

When I worked with Steamfitters, we used lampwick, then dope, then a couple wraps of tape.  Time consuming, but no leakers. 

j a_2

I think

A properly pitched thread should turn into the female fitting 3 1/2 to 4 turns by hand.  before it starts to tighten....Try it......Anything else is suspect and needs checking especially if gas is involved...For obvious mechanical reasons....To deep to weak.It also helps keep your pipe measurements correct and keeps things on the level...Often we get pipe or nipples that require tipping.. ...I return them if I don't like them...As for so called Teflon tape I think that name is used incorrectly..DuPont I believe has the name  teflon...Anything else is not Teflon..goggle it...Never have I used tape on gas only have I used a soft set sealant...As a word of caution never tighten a gas fitting once it is set and sealed, disconnect and reseal it...The so called Teflon I believe is used to assist to  disassemble,and not seal....Wicken is a great option and still used in steam piping assembly, along with the pipe sealent of your choice...Ja

Plumdog_2

I'll vouch for Loc-Tite

Those Triangle Tube Phase III Indirects used to give us fits leaking out of the bottom (usually) boiler connection. No amount of doping and wrapping worked all the time. Now they are shipped with a tube of thread sealer like Hot Rod described, you just apply it and screw it snug but not real tight, and it seals. I learned the hard way. My apprentice made me take one apart and clean it all out after I had applied tape and teflon paste, as I usually do. I should pay attention more.

deek

Loctite is my friend...

I cant think of a bad product that is made by loctite.  Really a great company.  My dirt bike is entirely held together by that magic stuff!  Has anyone used loctite 565?  Its the recommended goo for my ss dhw tank.  There is a big placard on the side stating it as a requirement.  Guess I'll try it.

Thanks for the ideas.

hot_rod

545

is the other type we use on fittings. It is not a thick viscosity like the other number.