Teflon Tape and Sealant at the Same Time

[WorldPeace]

Hello, everyone,

This is for domestic hot water. I noticed a new plumber was using teflon tape and sealant at the same time. My understanding was that you use one or the other. And, that if you use both at the same time, it actually creates a bad seal.

I wanted to be sure before I mention this to the plumber.

Thanks.

 

[James Henry]

It's mainly an intuition thing. I've seen sprinkler fitters use tape and dope on every joint because to fix a leaking threaded joint you have to unthread part of the piping system to reach the joint that is leaking. the plumber may have felt that the joint had a high risk of leaking and he didn't want to take a chance or it was in an awkward area, or an area that would cause a lot of water damage. I've never heard of using tape and dope at the same time causing a bad seal.

 

[Sponsor]

 

[Terry]

I use tape and dope often on threads for water.
With plastic fittings, tape only.
Brass, steel and copper, dope, tape, tape and dope. It all works.
For gas, dope only.

 

[Fitter30]

You will also notice tape starts 1.5-2 treads back dope will give the tape some lube make it easier to tighten.

 

[Jeff H Young]

we all have preferences its common for some guys to use both . but also very common for many guys to only use one or other.
I use both in many situations We ran 5000 foot 2inch black sch 40 screwed pipe for oil, grease , antifreeze at a mech shop 6 wraps Teflon tape and keytite dope on every joint per my bosses orders which I 100 percent agreed with I probably would have done the same but let him make call. we did have a few leaks had to use left -right nipples and couplings . It was pretty successful though.
tape and dope is fine for gas too, but most white tape is not listed for gas (maybe none of the white tape can be used on gas)

 

[WorldPeace]

Thanks for your opinion, guys. I really needed to know what is commonly perceived by people in the profession.

I remember reading something many years ago, stating that using both at the same time actually makes the seal worse because it prevents the specific mechanism each uses to seal threads. It was something about there isn't enough space within the threads to fit both. So, if you do use both, you end up pushing the tape out and things start to clump. Something like this.

If I can find the paper, I will post it here.

 

[Terry]

If I can find the paper, I will post it here.

Papers are nice, but we've been doing this for decades. It's nice that someone took the time to wonder what we are all about, but don't worry, we're making it happen.
A piece of paper isn't going to convince us out in the field daily that what is working isn't really working. It's working.

Peace brother.

 

[Jeff H Young]

Thanks for your opinion, guys. I really needed to know what is commonly perceived by people in the profession.

I remember reading something many years ago, stating that using both at the same time actually makes the seal worse because it prevents the specific mechanism each uses to seal threads. It was something about there isn't enough space within the threads to fit both. So, if you do use both, you end up pushing the tape out and things start to clump. Something like this.

If I can find the paper, I will post it here.

This is exactly how its done in the profession we are all over the place whether to use it or not how many wraps all of that there is no agreement. 3 or 4 guys respond with 100 years plus experience. we might be all wrong but feel comfortable in how we've been doing our jobs. whether my way is best or another guys variation is better I don't know, but I think I could trust a few of them to screw pipe together and believe they have been successful at it. but share whatever you find on the topic.