Liquid teflon tape

richierich

Bronze Supporter
Jul 12, 2013
582
Long Island, NY
#1
I called Pentair to ask a question about my filter and the rep told me that it's better and easier to use liquid teflon tape instead of regular white tape for all the male threadings on the filter. Is there a certain brand or type that you all use? I currently have oatey great white. Is that ok? Is that considered liquid teflon tape? Also, if I use oatey great white (assuming that's liquid Teflon tape) should I also use Teflon tape in addition or is that not necessary
 

CJadamec

TFP Expert
Apr 29, 2016
2,194
Quaker Hill, CT
#2
Any paste or liquid pipe thread sealant will tell you what type of pipe it is rated for. Read the package carefully and make sure you are using a sealant approved for PVC/plastic pipe. Some sealants contain solvents that will damage PVC/plastic pipes.

Another thing to be careful of is liquid sealants can make it much easier to over tighten a pipe fitting and increase the risk of splitting the female fitting.
 
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richierich

Bronze Supporter
Jul 12, 2013
582
Long Island, NY
#3
Thanks. When you bring the equipment in for the winter and then back outside next spring, do you wipe away the thread sealant and redo onto clean threads? Or do you just leave it as is
 

CJadamec

TFP Expert
Apr 29, 2016
2,194
Quaker Hill, CT
#4
Any time you undo a threaded connection you need to clean the threads best you can and reapply new sealant. PVC threads are very soft and can be easily damaged while trying to clean them. That lesson I have learned the hard way. You would be much better off by using unions that seal with O-rings rather than unthreading and rethreading pipe over and over again. Pipe threads are tapered and every time you reinstall the pipe the male end goes further into the female end. Over time you will wear out the tapper of the fitting and be faced with leaks that will never seal.
 

dschribs

Well-known member
Mar 14, 2013
363
CT
#6
Unions are used w pvc to easily connect two pvc pipes or pvs pipes to a filter and/or pump. They can be disconnected by simply unscrewing them for disassembly.



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pooldv

Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
Aug 10, 2012
24,993
DFW, TX
#9
You shouldn't use teflon tape and pipe dope. Only one or the other is needed.

Pipe dope is also called thread sealant, pipe joint compound and others. Permatex, Oatey, Loctite and others each have a version. The key is that it is teflon based. Teflon is what is needed to seal the threads.
 
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richierich

Bronze Supporter
Jul 12, 2013
582
Long Island, NY
#10
I had read on some of the threads people use both with great success. Is there a downfall to using both tape and thread sealer? I've never used tape before and I'm worried that I will do it wrong.
 

pooldv

Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
Aug 10, 2012
24,993
DFW, TX
#11
It is important to wrap the tape on the threads the same direction that it will screw into the fitting so it doesn't get unrolled and bunched up.

As for using one or the other or both, that is what I've always heard, use one or the other, not both. I've always used just teflon tape on water lines and pipe dope on gas lines. So, I decided to do a little research and apparently it is just another one of those things where everyone has their way of doing it and they always have because the person who taught them did it that way. :)

There doesn't seem to be any downside or concensus that I could find here or on plumbing websites except that if you use both then put the tape first, which makes good sense to me. So, I am going to change my advice to this:

I prefer to use teflon tape only because it is neater and cleaner and always works fine. Or you can use a teflon based pipe dope. Or if you want to be extra cautious you can use teflon tape first and then a little pipe dope on top as an extra precaution.
 

CJadamec

TFP Expert
Apr 29, 2016
2,194
Quaker Hill, CT
#13
There are some reasons for not using both but for the average home owner they will generally not come across those situations.
The exception to that is if you are doing work on a gas pipe at your house. Tape shouldn't be used on threaded gas pipe as it can cause havoc with regulators if lil bit get into the gas pipe.
There was some debate for a while as to teflons roll in the thread sealing world. Tapped pipe threads are well tapered so that as you screw them together the opposing tapers will create a metal on metal seal. Anyone who has split a threaded female PVC fitting knows the power of this tapered fit all to well. The main purpose of Teflon in thread sealers is actually to lubricate the threads so it's easier to get the joint tight enough. Many old plumbers will insist this is the only function the Teflon performs. The current School of thought is that the Teflon will melt under the friction of the threads and help seal minor imperfections in the joint.
Pipe dope comes in two flavors mostly. Hardening and non hardening. Hardening sealers are generally found in 1000+psi fittings in air and hydraulic systems. You would definitely not want to have tape and dope on that type of joint. Non hardening dope is the most common and with thicken over time but not really harden. Again the primary reason for the pipe dope much like the tape is to lubricate the joint so that you can achieve an interference fit on the threads. Pipe dope more so than tape with fill imperfections in the threads and because it is so viscous act as a seal.
In general any professional pipe fitter will utter many unkind words about a joint that has both dope and tape on it.

Finally the pressure of the system, what the pipe is made of, expected operating temperature, and fluid in the pipe must be considered when picking a joint sealer.
 

jasnovanorder

Bronze Supporter
Jul 2, 2015
201
Hamilton Michigan
#15
It is important to wrap the tape on the threads the same direction that it will screw into the fitting so it doesn't get unrolled and bunched up.

As for using one or the other or both, that is what I've always heard, use one or the other, not both. I've always used just teflon tape on water lines and pipe dope on gas lines. So, I decided to do a little research and apparently it is just another one of those things where everyone has their way of doing it and they always have because the person who taught them did it that way. :)

There doesn't seem to be any downside or concensus that I could find here or on plumbing websites except that if you use both then put the tape first, which makes good sense to me. So, I am going to change my advice to this:

I prefer to use teflon tape only because it is neater and cleaner and always works fine. Or you can use a teflon based pipe dope. Or if you want to be extra cautious you can use teflon tape first and then a little pipe dope on top as an extra precaution.

That is what i like about the liquid. No worries about bunching just an even coat on the threads and its good to go