Teflon tape

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HoppyMcHopster

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So I've never actually thought about using teflon tape on fittings until I've read through numerous posts and install instructions for cooler MLT's. Now that I've "learned" about them I was wondering what the proper application is? Should I apply them on all fittings or only on ones that aren't exposed to wort (ie outside fittings)?

For example, If i have a coupler inside my MLT that has a barb on it, should I apply teflon to the barb fitting even though it will be exposed to the wort?
 

Phyrst

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It's safe to be in contact with the wort, but just use it on threaded fittings. Going around the threads twice is all you need.

Don't use it on barbs. You really don't need a great seal on the inside fitting of your MLT anyway. I mean, it's hooked up to a stainless steel hose or copper manifold with holes in it. You just need a good enough seal that grain can't get in there. (Re-reading your post I suspect you already knew this.)
 

audger

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At the very least you should wrap the tape around the threads of ANY metal to metal connection. I use it on plastic threads as well.
no. tape is for use on tapered threads only (NPT). flared, compression or other fittings = no tape. you can cause leaks by using tape where its not required (tape can prevent a compression fitting from threading on far enough to compress the joint/seal)
 
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HoppyMcHopster

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audger said:
no. tape is for use on tapered threads only (NPT). flared, compression or other fittings = no tape. you can cause leaks by using tape where its not required (tape can prevent a compression fitting from threading on far enough to compress the joint/seal)
My 3/8" barb has a 1/2" male NPT that connects to a 1/2" coupler inside my cooler MLT. So teflon should be used in this case? Same goes for the barb in the outside connected to my ball valve?
 
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HoppyMcHopster

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Phyrst said:
It's safe to be in contact with the wort, but just use it on threaded fittings. Going around the threads twice is all you need.

Don't use it on barbs. You really don't need a great seal on the inside fitting of your MLT anyway. I mean, it's hooked up to a stainless steel hose or copper manifold with holes in it. You just need a good enough seal that grain can't get in there. (Re-reading your post I suspect you already knew this.)
You may have misunderstood. I wasnt implying to use them on the barb itself rather the NPT on the opposite end
 

zachattack

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no. tape is for use on tapered threads only (NPT). flared, compression or other fittings = no tape. you can cause leaks by using tape where its not required (tape can prevent a compression fitting from threading on far enough to compress the joint/seal)
This is correct. Only tapered threads, so in this case any NPT fittings. With CGA, compression, etc. PTFE tape will interfere with a proper seal and potentially damage fittings.
 

Rbeckett

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PTFE Tape is food safe. I use it on every threaded fitting in every thing I build except for pure O2 and Acetylene. Those two gasses are extremely reactive so I dont use teflon on them. Otherwise I wrap a couple of turns on in the correct direction and assemble my fittings as usual. The tape will seal small drips and leaks in just about any low pressure application. Higher pressures (above 40 PSI) require a little more forethought and malice to prevent leaks. But since we dont use even medium pressures it is just fine on nearly any fitting except your regulator to tank connection. Good luck and hope this helps.
Bob
 

zachattack

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So you only need it for npt, not bpt threads? :)
I believe some British Pipe Thread is tapered, some isn't? Like audger said, you want to use PTFE on any tapered threads.

And yes, PTFE is one of the most inert materials there is. No worries about food contact.
 

jfrizzell

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HoppyMcHopster said:
You may have misunderstood. I wasnt implying to use them on the barb itself rather the NPT on the opposite end
I believe he meant no need to use it on the threaded end of the barb fitting on the inside of your mash tun. No point since any leak would be in the same direction of wort flow.
 
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HoppyMcHopster

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jfrizzell said:
I believe he meant no need to use it on the threaded end of the barb fitting on the inside of your mash tun. No point since any leak would be in the same direction of wort flow.
Ok so I misunderstood him. That makes sense.
 

thargrav

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You should not use teflon tape on CO2 regulators even though many do. The tape is not rated for 1800 PSI (max high pressure side pressure).
 

Bobby_M

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I've never seen a pressure rating on PTFE tape. The only reason I could see it being an issue is if you used too much and prevented the threads from fully deforming into each other. In a high pressure application, I'd put exactly one rotation on just for lubrication purposes. Brass is usually soft enough that any other lubricant on the threads would do the same function.
 

zachattack

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You should not use teflon tape on CO2 regulators even though many do. The tape is not rated for 1800 PSI (max high pressure side pressure).
PTFE tape should not be used on CGA fittings (fittings used on gas cylinders). If you need to lubricate your CGA threading to get it to properly seal, it means that the fitting is damaged and should be replaced.

Here's more info:
http://risk.arizona.edu/healthandsafety/labchemicalsafety/WhentouseTeflontape.pdf
http://en.wikipedia.org/wiki/Thread_seal_tape

I've never heard of PTFE tape having a pressure rating either, but I don't know that for sure.
 
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There is no pressure rating on PTFE tape. I asked my local Swagelok rep, who I am tight with, and he's never heard of such a thing.

My father, who was a ChemE for 35 years in industry, also never heard of such a thing either. I am an MS ChemE and I've never run across this in 15 years on the job.

The only thing I can think of is Swagelok branded tape is thicker than normal Home Depot tape so that might be slightly advantageous. But pressure rating? Someone is high if they think anything of the sort.

As others have said, Teflon tape is only to be used on NPT fittings. It has no place on anything else.
 

audger

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the reason there are no pressure ratings on tape, aside from the fact that the way you apply the tape is so variable, is because tapered pipes should never be used to carry anything higher than a few dozen PSI in the first place. if you need to hold hundreds of PSI, you should be using a more positive seal.
 

zachattack

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the reason there are no pressure ratings on tape, aside from the fact that the way you apply the tape is so variable, is because tapered pipes should never be used to carry anything higher than a few dozen PSI in the first place. if you need to hold hundreds of PSI, you should be using a more positive seal.
This is not correct. I've never heard of tapered pipe, but fittings using tapered threading such as NPT can easily be purchased rated to 3000+ psi, and I've seen specialty sources that will sell NPT fittings rated to 15,000 psi.
 

Bobby_M

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Yeah, I'm not a union pipe fitter or anything like that but I'm confused by a few statements in this thread. Why do they offer NPT fittings rated for 3000psi + then? I understand that you wouldn't want to pack the threads with teflon because it could blow out or at least cause and incomplete mesh, but other then that, the tape is not bearing any of the pressure.
 

zachattack

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Yeah, I'm not a union pipe fitter or anything like that but I'm confused by a few statements in this thread. Why do they offer NPT fittings rated for 3000psi + then? I understand that you wouldn't want to pack the threads with teflon because it could blow out or at least cause and incomplete mesh, but other then that, the tape is not bearing any of the pressure.
I'm not a union pipe fitter either, but (like Irrenarzt) I am a MS chemical engineer and I work with these type of fittings daily. There are plenty of statements in this thread that are just plain wrong. Compressed gas can be very dangerous! Please make sure you know the proper procedure for any fitting you use, and if you're unsure, ask a professional.

I regularly plumb gases at significantly higher than "a few dozen psi" using NPT fittings, this is what they're built for. Look at a gas regulator, there's a short piece of pipe connecting your compressed gas tank to the regulator: one end of the pipe has a CGA fitting to connect to the tank, the other end has an NPT fitting to connect to the regulator. That NPT fitting sees 2500+ PSI all day.
 

Bobby_M

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I think it's just a case of people seeing some specific warning, such as the one not to use tape on the CGA coupling, and incorrectly applying that warning to the pressures involved rather than the specific coupling design. The one I see far more often is people putting tape on the threads of a flare or compression nut. That actually makes it worse because it could delay the detection of a leak at the actual pressure bearing surface as the tape may hold for a short time while you're doing your soap test.
 

thargrav

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the reason there are no pressure ratings on tape, aside from the fact that the way you apply the tape is so variable, is because tapered pipes should never be used to carry anything higher than a few dozen PSI in the first place. if you need to hold hundreds of PSI, you should be using a more positive seal.
The entire pressurized gas industry has used tapered thread fittings for years. You can buy pipe, ball valves, and a host of other fittings - all with tapered thread fittings, with pressure ratings up to 4500 PSI!

One thing you will not see is any of the main stream companies using Teflon tape to assemble their regulators.
 

FTG-05

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The entire pressurized gas industry has used tapered thread fittings for years. You can buy pipe, ball valves, and a host of other fittings - all with tapered thread fittings, with pressure ratings up to 4500 PSI!

One thing you will not see is any of the main stream companies using Teflon tape to assemble their regulators.
So what do they use then?
 

zachattack

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So what do they use then?
Pipe dope is often used (http://en.wikipedia.org/wiki/Pipe_dope). It's a little quicker to apply than PTFE tape, and the end result is basically the same. You never want to use both on one fitting! If you ever have a plumber over your house, chances are they'll use pipe dope, especially for natural gas connections. It's a little messier but as I said, quicker. IME PTFE tape is neater to apply and much neater to remove when you re-use a fitting, and I prefer it in the lab.

Red Loctite (the Loctite 262 referenced above) is a thread locking compound and is not intended for use as a thread sealant / pipe dope... Loctite makes other products that are proper thread sealants.
 

clockwise

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lol.... so confused

I'm just going to put my PTFE on the tapered ends and be done with it. What pressure do the "highs" on my C02 regulator coming from my 10# tank actually see?

Unrelated, slightly related:

Also, when my professional friend came over to run my natural gas line to my kitchen stove we used plumber tape (not sure what kind) AND some white pipe dope. This is wrong?
 
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