Pipe Dope, Plumbers Putty, or Teflon Tape?

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JeffNC

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?

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.

But you just did lump 2 of them together.
 

JeffNC

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Here's my opinion. I'm not a licensed plumber, but I do a fair share with bathroom remodels and other light plumbing installation and repair, and I have a background in several sciences.

Clearly the putty is a different category, and you've figured that out by now.

The issue is dope vs. tape, and frankly most of the answers even by pro plumbers make no logical sense. If you think about what's happening with the materials, using them together is pointless.

Let's say you're one of those that uses both tape and dope. So first you put your tape on, then the dope. Well, what happens when you screw that joint together is that one side of the threads has only tape touching it (the tape basically keeps the dope from touching that side), and the other side has dope touching it. They can't both be best.

Both are lubricants. Both help seal the micro gaps in the joint to resist water leaks. But they can't both be best at that job - only one or the other are. Use only the one that is best. That one will touch both sides of the threaded joint.

Personally, I think the best lubricant and the best long term sealant is pipe dope. I use this on shower arms, threaded nipples, and female PEX adapters on threaded shower valves. On any connection where there is a compression or gasket seal, it only gets in the way and gunks things up (except maybe as mentioned by Jeff Young above - then a small amount is acting strictly as a lubricant). If those leak, there is a different problem, such as a little piece of debris, crack, misalignment or other issue that needs to be corrected first.
 

DirtyJerz

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Based on some recent stuff I did my thinking is tape is going to be more helpful in closing bigger “gaps” because you can wrap it around multiple times to bulk up the male side of the pipe. Threading the female end on will at most “cut” into the tape and leave the bulk in place. With dope I feel like if you put on too much, the front end of the female pipe will just push it forward instead of filling in the gaps.

But maybe that doesn’t make any sense either. I agree that doing both seems unnecessary.
 

JohnCT

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Here's my opinion. I'm not a licensed plumber, but I do a fair share with bathroom remodels and other light plumbing installation and repair, and I have a background in several sciences.

Clearly the putty is a different category, and you've figured that out by now.

The issue is dope vs. tape, and frankly most of the answers even by pro plumbers make no logical sense. If you think about what's happening with the materials, using them together is pointless.

Let's say you're one of those that uses both tape and dope. So first you put your tape on, then the dope. Well, what happens when you screw that joint together is that one side of the threads has only tape touching it (the tape basically keeps the dope from touching that side), and the other side has dope touching it. They can't both be best.

Both are lubricants. Both help seal the micro gaps in the joint to resist water leaks. But they can't both be best at that job - only one or the other are. Use only the one that is best. That one will touch both sides of the threaded joint.

Personally, I think the best lubricant and the best long term sealant is pipe dope. I use this on shower arms, threaded nipples, and female PEX adapters on threaded shower valves. On any connection where there is a compression or gasket seal, it only gets in the way and gunks things up (except maybe as mentioned by Jeff Young above - then a small amount is acting strictly as a lubricant). If those leak, there is a different problem, such as a little piece of debris, crack, misalignment or other issue that needs to be corrected first.

When I was installing my new oil tank, the instructions that came with the tank required that both teflon tape *and* pipe dope be used simultaneously. Seeing as how the firomatic valve had to face out from the tank on a 90 and there's no guarantee that the valve will face the correct direction when fully tightened, the dual method of sealing seems to make sense. One thing's for sure, you don't want to find out you have a leak at the bottom of an oil tank after you fill it.

John
 

John Gayewski

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Based on some recent stuff I did my thinking is tape is going to be more helpful in closing bigger “gaps” because you can wrap it around multiple times to bulk up the male side of the pipe. Threading the female end on will at most “cut” into the tape and leave the bulk in place. With dope I feel like if you put on too much, the front end of the female pipe will just push it forward instead of filling in the gaps.

But maybe that doesn’t make any sense either. I agree that doing both seems unnecessary.
The dope helps the threads slide across the tape.
 

Eman85

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Just for grins I'll throw my 2 cents worth in. My trade background is in automotive, so there's plenty of sealing misconceptions and magic potions available there too. I was always successful at sealing tapered pipe threads using a teflon based thread sealer. Then for some reason the world started turning the wrong direction and trying to get tapered pipe threads to seal became a challenge! Not too many years ago the water heater in my shop started leaking and I decided to replumb the shop with PEX as it had CPVC that I was afraid of bumping and having it crack, which it did in the past. I bought all high quality brass fittings and a can of Megalock dope. Plenty of tapered pipe threads on the heater and the shutoff valves that is used brass NP to PEX fittings on. Every fitting leaked a little. I disassembled every one cleaned and taped then doped and fixed every leak. I'm now in the tape + dope group when it comes to tapered pipe threads.
 

Elton Noway

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Two years ago I had to run 75 feet of 2" black steel pipe gas line in a crawl space with only 14 " of clearance. The threads on the pipe ends were dinged up, ruff and sharp. I'm also considered old school... so... with no desire to have to go back into that hell hole to check and retighten over twelve connection points to fix a leak or repair a failed inspection I wrapped the first 4 or 5 threads with a couple turns Blue Monster Gas Guard PTFE tape followed by a coating of PTFE thread sealant. (With dope alone it was a struggle to get the connections as tight as I wanted. To me anyway... the tape serves to lubricate the threads and dope to ensure a good seal. Because a little is good and a lot is better I charged the line to 75 psi and let it sit for 3 days. No drop in psi.
 

Jeff H Young

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Two years ago I had to run 75 feet of 2" black steel pipe gas line in a crawl space with only 14 " of clearance. The threads on the pipe ends were dinged up, ruff and sharp. I'm also considered old school... so... with no desire to have to go back into that hell hole to check and retighten over twelve connection points to fix a leak or repair a failed inspection I wrapped the first 4 or 5 threads with a couple turns Blue Monster Gas Guard PTFE tape followed by a coating of PTFE thread sealant. (With dope alone it was a struggle to get the connections as tight as I wanted. To me anyway... the tape serves to lubricate the threads and dope to ensure a good seal. Because a little is good and a lot is better I charged the line to 75 psi and let it sit for 3 days. No drop in psi.
That works for me which one lubricates or seals can be argued but no leaks is what matters
 

sky view

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DIY'er looking for opinions on PFAS in plumbing tape. We are repairing part of our system and trying to avoid adding carcinogens to our well and bodies. I realize that leaking joints are a problem but I would really like to have the cleanest water I can. I've taped all the joints to the tee on the pressure tank but am debating taping the rest of the joints. We are using a Shurflo 5050 positive displacement pump because we have a small solar system and it works well with batteries. It's 55 PSI Switch/Bypass, 5 GPM.

I don't need to create headaches for myself but I'm am trying to be proactive.

 

Tuttles Revenge

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DIY'er looking for opinions on PFAS in plumbing tape. We are repairing part of our system and trying to avoid adding carcinogens to our well and bodies. I realize that leaking joints are a problem but I would really like to have the cleanest water I can. I've taped all the joints to the tee on the pressure tank but am debating taping the rest of the joints. We are using a Shurflo 5050 positive displacement pump because we have a small solar system and it works well with batteries. It's 55 PSI Switch/Bypass, 5 GPM.

I don't need to create headaches for myself but I'm am trying to be proactive.

Interesting take on it. I don't have any answer to that. The wetted portion of the threaded area has got to be pretty minimal, but how minimal is too much?
 

Reach4

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DIY'er looking for opinions on PFAS in plumbing tape.
I had not heard of this.

It seems to me that this is a good reason for buying good PTFE tape, figuring that the cheapest could be made from anything that looked right. The Oatey pink looks good to me, but there are other good name brand tapes.
 

Jeff H Young

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PFAS is that a typo ? PTFE a lot of good ones out there . Cancer ? I have no knowledge on that had it once couple years ago hoping the chemo did the trick
 

sky view

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I had not heard of this.

It seems to me that this is a good reason for buying good PTFE tape, figuring that the cheapest could be made from anything that looked right. The Oatey pink looks good to me, but there are other good name brand tapes.

"PTFE, or polytetrafluoroethylene (promise you don’t need to remember that), belongs to a subgroup of PFAS called fluorinated polymers, and PTFE is by far the most popular one in the group; it makes up approximately half the market."

"As awareness around the problematic effects of PFAS chemicals has started to grow, the notion of PTFE as safe to use has persisted among its proponents, even though there is not much evidence for anything, really. There are still many unknowns when it comes to the effects of PTFE, as is often the case with chemicals."
 
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sky view

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PFAS is that a typo ? PTFE a lot of good ones out there . Cancer ? I have no knowledge on that had it once couple years ago hoping the chemo did the trick

Experts said the findings were 'frightening' given the scale of the problem and the link between the toxins and serious health conditions like cancer, infertility, birth defects and hormone issues
 

John Gayewski

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The tape doesn't contaminate the water. The wetted surface of a joint that has been taped is going to be beyond tiny, if any at all. Then you'd have to break the surface down into the water. This isn't realistic.

Experts said the findings were 'frightening' given the scale of the problem and the link between the toxins and serious health conditions like cancer, infertility, birth defects and hormone issues
The issue have been when these companies dump it into the water or runoff from manufacturers. Not related to using tape on water pipe. More like the Teflon coated pans that you scrape up and eat from.
 

sky view

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The tape doesn't contaminate the water. The wetted surface of a joint that has been taped is going to be beyond tiny, if any at all. Then you'd have to break the surface down into the water. This isn't realistic.

The issue have been when these companies dump it into the water or runoff from manufacturers. Not related to using tape on water pipe. More like the Teflon coated pans that you scrape up and eat from.
I understand what you are saying, in my area it's been sludge applied to agricultural fields contaminating wells and ground water. I realize the tape is a small contact point, however I'm trying to reduce any potential contamination due to existing health problems.

My original question was really can I make threaded unions without tape or dope without them leaking, not to ignite controversy about PTFE and PFAS.

And for what it's worth - we don't use Teflon pans for just that reason.
 

Weekend Handyman

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I understand what you are saying, in my area it's been sludge applied to agricultural fields contaminating wells and ground water. I realize the tape is a small contact point, however I'm trying to reduce any potential contamination due to existing health problems.

My original question was really can I make threaded unions without tape or dope without them leaking, not to ignite controversy about PTFE and PFAS.

And for what it's worth - we don't use Teflon pans for just that reason.
I am not a plumber. I have heard old plumbers say they used to use soap to lubricate the threads back in the day. I don’t know if that works or not. In my house (where I have to live with the consequences of any leaks) I use tape then dope for anything that is pressurized and just tape for anything that is not.
 

John Gayewski

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The answer is yes you can make a joint without tape, but you can't consistently be confident that you won't have a leak. If you gonna attempt it be prepared to redo done stuff and probably deal with a nagging drip. The quality of threded joints isn't consistent enough to make a lot of connections without tape.
 

Eman85

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If you keep the tape and the dope back a couple of threads there wouldn't be much if any exposure to the water.
I understand the concern of contaminants and being proactive is good. The true sad part is we've screwed the pooch on this and I really don't see anything turning it around. I can't have a well where I live in a rural county because of dumping at a private landfill that contaminated the ground water, no cleanup just monitoring so we can know just how contaminated it is. Of course no liability for the polluter as it's part of a corporation and untouchable.
No matter what your water flows through it's going to have some effect on your final drinking water. We will all now depend on science to try and provide us with "acceptable" drinking water and breathing air.
 
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