rogersmithiii
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Pipe dope or Teflon tape?
Air connections. Pipe dope or Teflon tape?
- Thread starter rogersmithiii
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Lucid Moments
Well-known member
I have used both with pretty much equal success.
stonesfan68
Well-known member
I wrap the threads with Teflon tape and then give them a light coat of Rectorseal pipe dope.
most of the time I use tape . don't overtighten, it can cause leaks.
toyotadriver
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Any time I want a threaded connection to not leak, I wrap the threads with pipe tape and then cover that with pipe dope. Once I started doing that, I haven't had a leak since.
Nthill93
Well-known member
I never have luck with the blue monster dope always leaks. Never an issue with tape
BlakeTheCarGuy
ALLIANCE MEMBER
I haven’t used the goop stuff on fittings for air stuff but I use the liquid Teflon tape. It’s so much easier to use then losing my patience with the actual tape lol.
When I did plumbing & heating in High school many years ago, I remember the teacher ( who was a licensed plumber) saying, "most leaks in threaded pipe result from overtightening the joints, causing the fitting to stretch, resulting in the leak.
Back in the day I believe that to be true. now with cheap import stuff, I think it's both. but over the years I have had very little trouble with sealing threaded joints
Back in the day I believe that to be true. now with cheap import stuff, I think it's both. but over the years I have had very little trouble with sealing threaded joints
Xcursion88
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Both...
Galvanized pipe..(3/4").
Use Teflon tape...then dope.
Tighten up...leak free for a very lllooonnngggg time
OP
rogersmithiii
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Liquid teflon tape?
Pipe dope is ideal for air compresor lines. I think the reason many people think it's more leaky is that pipe dope doesn't reduce the coefficient of friction for the threads as much as teflon tape does, so the same pipe wrench force when tightening pipe dope fittings will not be as tight as a fitting tightened with teflon tape on the threads. You also have to be careful with teflon tape. Ideally don't wrap the first thread of the male threads, or let the teflon tape wrap down over the end of the male pipe at all when making fittings. If you do, pieces of the tape can come off later on down the road and end up traveling within the pipe system and possibly plug something up. That's more of an issue with hydraulic systems, but it can happen in compressed air lines too. There are some small orifices and valves within air tools and air line pressure regulators. You don't have that potential issue when using pipe dope.
If you are careful with the installation, pipe dope on top of a couple wraps of teflon tape is what many often now do these days. That gives you the pipe dope benefits for the beginning of the threads, along with the teflon tape benefits for the bulk of the threads and to help reduce friction and help you get a nice tight joint more easily. It also often does a better job of sealing poorly cut threads.
Another consideration is that many modern pre-threaded pipes come with threads that aren't super well done. Especially if the pipe itself was made in China like you often find at places like Home Depot. They might not be taper threaded enough, so you don't get the proper overall desired thread engagement for a good seal, they can be threaded too much so the fitting bottoms out before the tapered threads bind tightly, or else the threading die sometimes leaves too much of a cutting ridge on the threads where the die is stopped and reversed at the factory. That's often caused by trying to continue threading by using a die with chipped teeth in it so there are sections of the finished threads with two steps worth of cut in one place. That ridge can smear, displace, scrape, or bunch up the teflon tape or pipe dope while the pipe is being threaded and prevent a good seal. It can also create a leak path even if everything else is done right. I guess what I am saying is that even if you do everything right the pipe can still be hard to seal if you are using pipe that was threaded poorly from the factory. Your main issue could be that the threads need to be chased or cleaned up first with a better quality threading die.
Lastly, for the teflon tape method to be successful you need to always wrap the tape in the proper direction so that the tape tightens down instead of bunching up as the female fitting is screwed on top of it. If you make sure the threads are well formed and you use the proper techniques, either method or a combination of both at the same time will work just fine.
If you are careful with the installation, pipe dope on top of a couple wraps of teflon tape is what many often now do these days. That gives you the pipe dope benefits for the beginning of the threads, along with the teflon tape benefits for the bulk of the threads and to help reduce friction and help you get a nice tight joint more easily. It also often does a better job of sealing poorly cut threads.
Another consideration is that many modern pre-threaded pipes come with threads that aren't super well done. Especially if the pipe itself was made in China like you often find at places like Home Depot. They might not be taper threaded enough, so you don't get the proper overall desired thread engagement for a good seal, they can be threaded too much so the fitting bottoms out before the tapered threads bind tightly, or else the threading die sometimes leaves too much of a cutting ridge on the threads where the die is stopped and reversed at the factory. That's often caused by trying to continue threading by using a die with chipped teeth in it so there are sections of the finished threads with two steps worth of cut in one place. That ridge can smear, displace, scrape, or bunch up the teflon tape or pipe dope while the pipe is being threaded and prevent a good seal. It can also create a leak path even if everything else is done right. I guess what I am saying is that even if you do everything right the pipe can still be hard to seal if you are using pipe that was threaded poorly from the factory. Your main issue could be that the threads need to be chased or cleaned up first with a better quality threading die.
Lastly, for the teflon tape method to be successful you need to always wrap the tape in the proper direction so that the tape tightens down instead of bunching up as the female fitting is screwed on top of it. If you make sure the threads are well formed and you use the proper techniques, either method or a combination of both at the same time will work just fine.
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Never liked tape, always used pipe dope. Since I discovered RectorSeal T Plus 2 dope, never have any issues. Though it is a bit messy and damn hard to get out of clothes!
rectorseal.com
And I agree with Tools4Me - Chinese parts and supplies can be a real pain. Quality control and tolerances can be iffy.
RectorSeal T Plus 2
Features PTFE enriched For use with potable water (hot or cold) Lead free and contains no other metals Lubricates and protects threads Formulated for plastic and metal pipe
And I agree with Tools4Me - Chinese parts and supplies can be a real pain. Quality control and tolerances can be iffy.
The last 34 years of my "indentured servitude", aka working life, were doing heavy industrial instrumentation - covering hydraulics, pneumatics, electronics, etc - and Tools4Me just covered everything you need to know, as well as (or better than) I've ever seen.
'Nuff said... Steve
'Nuff said... Steve
steaks&anvils
Well-known member
I thought the pvc pipe cement was all you needed? 
JackOfDiamonds
Well-known member
"pipe dope" is very unspecific. What does that actually mean? There must be dozens or hundreds of thread preparations out there. Which one is "pipe dope"?
I used to build paintball guns semi professionally. I never saw the end of issues causes by little threads of teflon tape that escaped from taped connections. It put me off of tape forever. Plus the tape is a pain to use anyway.
I standardized on using a drop of blue loctite 242 on all pipe thread connections, even 1/8NPT. Never leaked, seals more or less instantly, very easy. Never any problem getting joints apart. Others in the business did the same thing.
I used to build paintball guns semi professionally. I never saw the end of issues causes by little threads of teflon tape that escaped from taped connections. It put me off of tape forever. Plus the tape is a pain to use anyway.
I standardized on using a drop of blue loctite 242 on all pipe thread connections, even 1/8NPT. Never leaked, seals more or less instantly, very easy. Never any problem getting joints apart. Others in the business did the same thing.
seagullplayer
Well-known member
Tape, no mess. Easy to carry in the tool box or on the tool belt.
Xcursion88
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I have a 4 bay shop I plumbed for air and every fitting got teflon tape and pipe dope.
There are are probably 35 plus fittings..not one single leak.
There are are probably 35 plus fittings..not one single leak.
plinker
Well-known member
Loctite 545 is ideal. Tape doesnt agree with me much. I've noted that the quality of pipe threads vary's a lot anymore by COO, and on the made in china air compressors I've seen in the last ten or so years they use a clear (super?)glue on the threads.
Liquid teflon sealent have worked fine for me (loctite 565 & 567, & Permatex equivalent). I had gotten a jar of this blue Gasolia sealant from somewhere and liked it as well. https://www.amazon.com/dp/B00CRKWAXQ/?tag=atomicindus08-20
Liquid teflon sealent have worked fine for me (loctite 565 & 567, & Permatex equivalent). I had gotten a jar of this blue Gasolia sealant from somewhere and liked it as well. https://www.amazon.com/dp/B00CRKWAXQ/?tag=atomicindus08-20
I actually used epoxy on some crappy threads for a friend's cheap tire inflator that leaked like a sieve
oldwino
ALLIANCE MEMBER
For air lines I use yellow teflon tape. Never had a leak. Usually use Rectorseal 5 on waterlines with no tape
This
timgunn1962
Well-known member
Pipe Dope is not a phrase that seems to be used as much in the UK as in the US, where it seems to be a generic term for any product that is applied to threads in a liquid state. This is unhelpfully vague, as others have pointed out.
There are many different products that are applied in the liquid- (or paste-) state. Some remain liquid permanently, others set over time.
I tend to use anaerobic pipe seal on pretty much anything I intend to be permanent, with the precise product being dependent on the pressure and the perceived permanence required.
Back in the mid-1980s, I spent several months chasing down leaks on industrial hydraulics. The "best" fix for leaking threads, whether tapered or parallel, was to depressurise the system, back out the thread about half-way, give it a good dousing with brake cleaner (the system was usually still warm, so it evaporated off quickly. We used brake cleaner because it was a fraction of the price of the Loctite-branded stuff), apply plenty of Loctite 542, tighten the thread, wait a while, restart and check the leak was no more.
The Loctite method was the most boring and effective one. It avoided all the excitement associated with draining down hundreds of gallons of hydraulic oil, all the excitement of avidly watching things through the next few pressure cycles and hitting the e-stop if things got spurty, and about 90% of the cleanup associated with any of the other methods.
When I started playing with pneumatics, rather than hydraulics, I tended to stick with what I knew worked. Loctite 542 worked well, but was a bit too "strong" for threads in mixed metals that included brass and Aluminium. 577 worked well, but was much easier to undo. Then every supplier and his dog came up with their own brand of anaerobic seal, often in different strengths/grades. I find all of them work very well. They are easy to apply, don't leak and, if chosen appropriately, allow disassembly. It can be a minor pain to clean the threads for reassembly.
There are many different products that are applied in the liquid- (or paste-) state. Some remain liquid permanently, others set over time.
I tend to use anaerobic pipe seal on pretty much anything I intend to be permanent, with the precise product being dependent on the pressure and the perceived permanence required.
Back in the mid-1980s, I spent several months chasing down leaks on industrial hydraulics. The "best" fix for leaking threads, whether tapered or parallel, was to depressurise the system, back out the thread about half-way, give it a good dousing with brake cleaner (the system was usually still warm, so it evaporated off quickly. We used brake cleaner because it was a fraction of the price of the Loctite-branded stuff), apply plenty of Loctite 542, tighten the thread, wait a while, restart and check the leak was no more.
The Loctite method was the most boring and effective one. It avoided all the excitement associated with draining down hundreds of gallons of hydraulic oil, all the excitement of avidly watching things through the next few pressure cycles and hitting the e-stop if things got spurty, and about 90% of the cleanup associated with any of the other methods.
When I started playing with pneumatics, rather than hydraulics, I tended to stick with what I knew worked. Loctite 542 worked well, but was a bit too "strong" for threads in mixed metals that included brass and Aluminium. 577 worked well, but was much easier to undo. Then every supplier and his dog came up with their own brand of anaerobic seal, often in different strengths/grades. I find all of them work very well. They are easy to apply, don't leak and, if chosen appropriately, allow disassembly. It can be a minor pain to clean the threads for reassembly.
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Downwindtracker 2
Well-known member
I echo the comment about the poor quality of pipe fittings available, even from industrial supply unless a good brand is specified. Working in industry,for air lines, I used Teflon tape mostly , three wraps only in correct direction, leaving a single thread exposed for easy starting. Some brands of tape are garbage, very frustrating to use.They are best tossed very far away . The odd time, I would use a Locktight product, a white liquid in a tube. I found it messy, so it wasn't very often. But on stainless steel piping I had to use both if I didn't want a leak.