Pipe Dope, Plumbers Putty, or Teflon Tape?

[Terry]

I've never had a problem using tape on CPVC threads. You don't want to thread into a plastic (CPVC or PVC) fitting though. I prefer the plastic male adapter to thread to a female fitting. They do make a stainless reinforced CPVC fitting though which works well.

 

[Oldman Ludicrous]

Thanx. I'm new at the game- at least with PVC.
(heh- ask me about computers sometime. Fifty+ years as a techie -everything from S360/370 to Raspberries)
Your 2nd pic above is confusing. -
a ¾" CPVC male adapter? Looks like a male brass thread into a female CPVC.
Anyhow, I'm gonna fit my male adapters onto the brass ball valve with some Oatey white dope,
and then glue the slip-on ends to the original CPVC pipe. And hope it doesn't leak.
If it does? Well, simply saw off another inch of the old CPVC, and try again. Maybe with Teflon tape. I think I can do this at least 10-15 times before I run out of pipe. -)
If worse comes to worst, I'll glue a CPVC end-stopper onto what's left of the original CPVC and call a professional plumber!

 

[Sponsor]

 

[Michael Young]

Any general rules for using which, when, why? Or the opposite, why /not/ to use which, when?

Thanks...

NEVER use tape on gas appliances or gas piping!!!
Always use about 4 spins of teflon tape on your threaded fittings
Some people use teflon tape with a little brush of pipe dope (kinda overkill)
I rarely use plumbers putty. I usually use clear silicone instead. Fewer leaks.
and yes, I know you guys use plumbers putty. But silicone works better

-mike

 

[Mr Andy]

Drain tubing never need anything except the slip nut which installed in the right way then the tubing is round and smooth which can spend 2 year easily without any damage if You face problems then use plumbing services

 

[Jadnashua]

As an aside, Teflon is a trademark owned by Dupont. Dupont does not make PTFE tape, so it's technically not teflon tape...

When you have a pipe that needs something like tape or pipe dope to make a seal, either or both will work as long as you're using the right stuff for the pipe and material used in the pipe.

 

[Travis K]

Here is a big Don't do. Don't use pipe dope or Teflon tape or should I say PTFE tape on compression fittings. Like the fittings on 1/2 angle stops that use a compression fitting onto bare copper pipe. You should put a drop or 2 of light weight oil on the threads and ferrule. This will reduce friction and give you a better seal buy allowing the torque to go into the compression and not the threads.
Also, no tape or dope on those braided supply lines. And don't over tighten them either.

 

[Reach4]

Here is a big Don't do. Don't use pipe dope or Teflon tape or should I say PTFE tape on compression fittings. Like the fittings on 1/2 angle stops that use a compression fitting onto bare copper pipe. You should put a drop or 2 of light weight oil on the threads and ferrule. This will reduce friction and give you a better seal buy allowing the torque to go into the compression and not the threads.
Also, no tape or dope on those braided supply lines. And don't over tighten them either.

Pipe dope on the threads and even the ferrule is fine, and I think desirable. And it takes more wrench torque than most amateurs think. Fear of crushing the pipe with your pair of 6 inch wrenches is misplaced in my non-pro opinion.

I strongly agree-- no tape.

 

[AndrewM]

I'm no professional, but I get into a decent amount of plumbing with all the remodel work I do. Since I started using grey mega tape topped with pipe dope I very rarely have a leak. Pipe dope alone doesn't give me enough 'cushion' to get that elbow or shower arm pointed the right direction. I'd rather overkill than disassemble.

 

[Caryncbreeef]

I know pipe dope is not recommended for plastic as it can negatively interact with it. I actually read that today when working with a plastic shower drain - it said silicone only.

 

[Reach4]

I know pipe dope is not recommended for plastic as it can negatively interact with it. I actually read that today when working with a plastic shower drain - it said silicone only.

A lot of pipe dopes are specifically recommended for plastics. Check the label.

 

[Tuttles Revenge]

Here is a big Don't do. Don't use pipe dope or Teflon tape or should I say PTFE tape on compression fittings

Why?

 

[wwhitney]

Pipe dope on the threads and even the ferrule is fine, and I think desirable.

For a compression joint, the design is for the ferrule to seal to the pipe and to the beveled edge of the fitting. As such, the threads are not part of the seal, and pipe dope on the threads just seems like a bad idea. The drop of oil on the threads is to reduce friction, allowing you to more easily compress the ferrule on the pipe. You could try using pipe dope as a lubricant, but the oil is better.

As to pipe dope on the ferrule, it shouldn't be necessary. The ferrule should be able to seal to the pipe and the fitting on its own. If the ferrule or fitting bevel is a little damaged, pipe dope on it could be a temporary solution to allow you to get it to seal, but really you should replace parts as required to get a proper seal without dope.

At least, that's my understanding of the theory, and so I would say pipe dope is not desirable. Flared joints and ground joints are similar, although I've not heard of using oil on those threads.

Cheers, Wayne

 

[Tuttles Revenge]

Pipe dope, T-Tape, and the drop of oil are all performing the same task.. reducing friction. not creating a seal.

 

[wwhitney]

Pipe dope, T-Tape, and the drop of oil are all performing the same task.. reducing friction. not creating a seal.

But since pipe dope and t-tape are also capable of creating a seal, they are not as effective as the drop of oil.

And if by creating that seal on the threads (filling the thread space somewhat), they prevent the threads from being tightened as fully as they could be with oil or nothing, thereby reducing the clamping pressure on the ferrule, they could actually cause a leak.

That last part, I think, is the real reason, it took me a while to get there.

Cheers, Wayne

 

[Weekend Handyman]

For a compression joint, the design is for the ferrule to seal to the pipe and to the beveled edge of the fitting. As such, the threads are not part of the seal, and pipe dope on the threads just seems like a bad idea. The drop of oil on the threads is to reduce friction, allowing you to more easily compress the ferrule on the pipe. You could try using pipe dope as a lubricant, but the oil is better.

As to pipe dope on the ferrule, it shouldn't be necessary. The ferrule should be able to seal to the pipe and the fitting on its own. If the ferrule or fitting bevel is a little damaged, pipe dope on it could be a temporary solution to allow you to get it to seal, but really you should replace parts as required to get a proper seal without dope.

At least, that's my understanding of the theory, and so I would say pipe dope is not desirable. Flared joints and ground joints are similar, although I've not heard of using oil on those threads.

Cheers, WayneI am not a plumber.

Any worries about using oil with plastic pipe? I would be afraid it would eat pex if it was to get in the wrong place.

 

[Reach4]

Here is how I picture it. The olive (ferrule) is changed in shape during tightening. That is done by slopes compressing the olive, and some sliding happens. If there is sliding, some lube may be beneficial. Just my mental model. But some people recommend some dope on the olive. When I redid a leaking compression fitting, I applied some Rectorseal #5. Now is that the reason the re-did joint did not leak? or was it because I applied more torque to the nut, not worrying about crushing the copper. We will never know.

Now would some grease have been as good or better? Won't know that either. If the pipe dope did it's sealing thing, that would seem to be good too.

https://terrylove.com/forums/index.php?attachments/compress_rigid-png.53952/

 

[Reach4]

Any worries about using oil with plastic pipe? I would be afraid it would eat PEX if it was to get in the wrong place.

I don't know of anybody lubing PEX. But if I had threaded plastic pipe, I would use pipe compound (that was safe for plastic) and ptfe tape both. That I have done. Avoid female plastic threads but there are good exceptions for that. For example, schedule 120 PVC couplings are quite good if you get the torque right.

 

[Tuttles Revenge]

I use a single wrap of T-Tape on the threads of the angle stop. I don't think its taking up space enough to stop a nut from tightening all the way and I know from experience that it works. Tape is something that's already in my tool bag which a bottle of oil certainly wouldn't be. A bottle of oil might be a good homeowner trick, but T-tape and pipe dope are what someone in the field will use. All of which will work fine.

Any worries about using oil with plastic pipe? I would be afraid it would eat pex if it was to get in the wrong place.

Yes, I would worry about that if you were using a compression valve on PEX or CPVC. A single wrap of t-tape is inert.

 

[wwhitney]

From Brasscraft's instructions on compression stops https://d2cl5to9q9oami.cloudfront.net/doc/425.04_WaterStops_INS.pdf

COPPER COMPRESSION INLET
Be sure to shut off water before starting.
For use with type L or M copper only.
1. Place compression nut and sleeve onto the copper tube.
2. A drop of general purpose oil will make tightening easier.
3. If using a drop of oil or thread sealant be sure the threads are clean of any debris and that sealant is also free of any metal debris. DO NOT USE a putty, gasket material or thread seal tape.
4. If using a thread sealant, apply a thin even coat to the male compression threads only taking care not to get thread sealant on the compression ring or sealing surface. IMPORTANT: Excessive thread sealant may cause joint to fail.
. . .

The last three items above are identical in the instructions for PEX.

Cheers, Wayne

 

[wwhitney]

And Dahl's instructions from the web page of one of their valves randomly selected https://www.dahlvalve.com/products/mini-ball-valves/supply-stops/copper/supply-stops-611-33-31.php

"COMPRESSION ON COPPER PIPE: Do not use pipe dope or PTFE tape. Pipe must be clean, de-burred, round, & cut square. Slide nut, then ring, then valve onto pipe. Tighten firmly with small wrench. DO NOT OVER-TIGHTEN. . . ."

Cheers, Wayne