Plumbers tape or Pipe Dope, does it matter?

JackW

As some of you know I'm redoing my radiant heating system in my Morton building and I can't thank you all enough for the help. I'm still in the process of setting it up, with your help, when I got to thinking is one better then the other (plumbers tape or pipe dope) in a closed circuit radiant heating system?
Thanks,

Steamhead

Putty? You mean "pipe dope", right?

JackW

Steamhead yes I do. Thank you for the correction.

mattmia2

dope is more convenient. i find for some reason brass threads don't seal as easily as steel and usually end up using both on brass, especially brass to steel/iron

teflon tape is more substantial so it will seal a larger gap in the peak/valley interface of threads

nothing beats single strand wicking for a stubborn set of threads that won't seal

GroundUp

Both, or anaerobic sealant like Loctite 567 or Permabond LH150. Gas I'll use dope only

MikeL_2

I agree with mattmia2; string wicking is my go to sealant. I occasionally use single strand wrapped over with quality teflon. When I started in the plumbing trade ( 1960's ) we used multi strand ball wicking on all tubular slip joint connections........

Intplm.

I have become a big believer in the Blue Monster Style teflon tape.
It is almost the only thing I use on any threads now. I have yet to have a leak.
I have used it on plastic, black malleable, brass, copper, stainless.
I am totally impressed with this product. And I don't impress with newer products easily.
When I mention above that I have yet to have a leak, that's not entirely correct. I was using it like the white teflon and used to many wraps around the threads. Cracked the fitting.
I read the directions and it says to use three wraps around the threads. I was using more than what the directions stated.
I like the product enough that it is almost all that I use.
Still have a can of pipe dope at the ready, but don't use it very often.

JackW

Intplm that is the brand that I am using glad to hear it's working well for you. I have copper to stainless, copper to cast and copper to plastic.

Intplm.

JackW said:

Intplm that is the brand that I am using glad to hear it's working well for you. I have copper to stainless, copper to cast and copper to plastic.

Are you in need of installing dielectric fittings between those foreign metals?

jerryb46

Just a bit from the past,when i started a job first thing in the morning i would reach for a spool of QUICK WICK and and awl and have it hanging right over head,Leaks can drive you crazy and cost money!!

JackW

IntplmI I have them between the boiler and copper lines but was wondering if I shouldn't put them between the SS manifold inputs and the copper lines. What do you think? Thanks.

JackW

jerryb46 what did you do with the QUICK WICK and awl?

Gilmorrie

I use either Teflon tape or pipe dope, depending upon my mood - and both work fine. My usual pipe dope from Ace Hardware contains a bit of Teflon. I slightly prefer dope because tape could produce crumbs, when threading or unthreading the joint, that might plug small opening in the system. Also, I hate it when I drop a roll of tape and it unspools. I never have used both tape and dope on the same connection.

Purists maintain that neither tape nor dope is really a pipe sealant - it is a lubricant that helps a threaded pipe joint to be tightened to achieve the interference fitting between standard tapered threads. However, I think either tape or dope may help in future disconnection of threaded joints, if ever necessary.

Intplm.

JackW said:

IntplmI I have them between the boiler and copper lines but was wondering if I shouldn't put them between the SS manifold inputs and the copper lines. What do you think? Thanks.

I would use dielectric fittings when there is a change in joined metals. It is what I have done for many years. Some use brass fittings as a alternative. But this is a lesser alternative in my humble opinion.

Ron Jr._3

We us both Teflon and thread sealant for all water or steam joints. Using one of the other has caused us leaks otherwise.

I wouldn't consider these sealants a lubricant. So is motor oil or even butter. But see if a joint will be water tight using either !

mattmia2

A tapered pipe joint definitely requires a sealant, no matter how much you crank it down there is always a gap between the tip of one thread and the valley of the other thread. the dope or tape seals this gap.

Intplm.

mattmia2 said:

A tapered pipe joint definitely requires a sealant, no matter how much you crank it down there is always a gap between the tip of one thread and the valley of the other thread. the dope or tape seals this gap.

@mattmia2 I like that explanation.
What I was taught many years ago, was that pipe dope and teflon tape is used to fill any imperfections on the threads. No matter how slight that imperfection might be.
If the imperfection is there, what's inside the pipe will find it and leak it's way out.

mattmia2

I was trying to find a good drawing, i've seen it before, but there is a small spiral groove in the joint formed by the space between the peak of one thread and the valley of the other. unless they are special self sealing threads that are designed to interfere with each other and deform, there will be a microscopic gap that the tape or dope seals.

mattmia2

I would like to know why i seem to have problems with brass. maybe it is because brass is less malleable than iron/steel or copper

mikeg2015

> @Intplm. said:
> (Quote)
> I would use dielectric fittings when there is a change in joined metals. It is what I have done for many years. Some use brass fittings as a alternative. But this is a lesser alternative in my humble opinion.

My research when installing a indirect tank on my steam boiler shower SS (esp 316L with more nickle) and Copper we’re close enough on the table that it didn’t matter. Some indirect mfg recommend against dielectrics even in the install manuals.


I newer to pipe fitting. But at my work, all brass only gets tape and all threaded gas fittings get dope only. For steam in my own house unused tape and dope as the dope acts like a lubricant and makes it easier to tighten larger pipe... at least it seemed like it to me.