Thread seal tape

[HighStateToke]

When it comes to the task of sealing threads on a closed loop system, many of us know that yellow PTFE tape is the go to. Yellow PTFE tape is specifically designed for sealing threads on lines containing gas. Being made from PTFE, this tape is chemically inert and capable of keeping your systems leak free, as they should be.

Various brands of yellow PTFE tape also contain 1% pigment.

Now..what is this pigment made made from?

Would love to hear everyone's thoughts. Also on the topic of lubricants used in the production of PTFE tape.

 

[flatslabs]

I found an interesting article about the development of RoHS certified PTFE tape for the aerospace industry which has quite a bit of information about the removal of cadmium being used in yellow pigment prior to 2006. I haven't finished reading the whole paper yet, but it seems there are a few manufacturers who make pigment-free ptfe tape

 

[HighStateToke]

Interesting, I'd love to read that if you have a way of sharing it.

I have also heard from various sources that green PTFE tape, suitable for oxygen lines, must be free of oil/lubricants. Makes me wonder about the rest.

I've come across the following tape, which is made from PTFE and nickel, 90%/10% respectively.

http://www.buyfittingsonline.com/mrthreadtape.aspx

Thoughts?

 

[HighStateToke]

http://www.restek.com/pdfs/308-02-001.pdf

I am unable to copy directly from the pdf, but for those who care, read the description paragraph after clicking on the link.

It sounds like green PTFE tape is the best choice for reducing contamination, although, the pigment issue remains. Having some reassurance that the pigment cannot leech out from the tape would be nice, but I doubt it.

 

[HighStateToke]

I found an interesting article about the development of RoHS certified PTFE tape for the aerospace industry which has quite a bit of information about the removal of cadmium being used in yellow pigment prior to 2006. I haven't finished reading the whole paper yet, but it seems there are a few manufacturers who make pigment-free ptfe tape

Found it.

https://www.techneticsgroup.com/bin/RoHS_PTFE_Tape.pdf

 

[BigJohnny]

I like Masters Pro Dope personally.

downside is that it can get very messy very fast in the hands of inexperienced users, and can take a bit longer to apply if you want to be careful and not get it all over the place.

 

[HighStateToke]

I like Masters Pro Dope personally.

downside is that it can get very messy very fast in the hands of inexperienced users, and can take a bit longer to apply if you want to be careful and not get it all over the place.

In the case of using pipe dope, I would imagine that bits of dope becoming loose from the velocity of flow would be a huge problem.

 

[HighStateToke]

Where's that wolf when you need him..

 

[pharmco]

I'd heard that GrayWolf remark he makes use of both PTFE tape and PTFE paste, but I would love to hear a more detailed version of his thoughts on the matter.

 

[Jdubba]

anyone know if the white ptfe tape Paramount Supply sells is rated for gas?

 

[ple1ades]

The white and yellow tapes are the same ptfe the yellow is just thicker.

 

[Chonkski]

The white and yellow tapes are the same ptfe the yellow is just thicker.

How did the cold trap work out ple1ades?

 

[HighStateToke]

The white and yellow tapes are the same ptfe the yellow is just thicker.

Yellow is typically of a higher density as well.

 

[Gray Wolf]

On the smaller sizes, I found just yellow tape adequate, or even more wraps of the thinner conventional tape, but with the larger sizes we experienced both leaks and galling, so now fill the threads on the male piece with PTFE paste and then wipe it smooth with the top of the threads, before applying two layers of PTFE yellow tape.

That has mostly stopped our threaded connection leaks at shakedown, which was the major issue on our first Mk V. We also haven't had to replace any galled stainless fitting since then.

We also tried the stainless PTFE tape to address the galling issue, but alas, it was not the panacea that we hoped for.

 

[pharmco]

Any worries on the dislodgement of PTFE paste?

Or is running solvent through it dry sufficient to ensure that no more ptfe paste will find its way into product?

I was considering using this paste: "Gasoila Soft-Set Pipe Thread Sealant with PTFE", but I noticed it had isopropyl alcohol and Ethylene Glycol Butyl Ether on the MSDS. I assume those dissipate after the first use?

 

[Gray Wolf]

After the initial flushing run, pickup from tightly compressed pipe joints should be minimal, given that is the part of the NPT thread under the greatest compression.

PTFE is non reactive in our gastric juices and so it too shall pass, but Ethylene Glycol Monobutyl Ether is a known carcinogen, so there is no acceptable exposure.

Check out Rector Seal food grade.http://www.rectorseal.com/index.php/rectorseal-food-grade-anti-seize-lubricant/

 

[BigJohnny]

In the case of using pipe dope, I would imagine that bits of dope becoming loose from the velocity of flow would be a huge problem.

When you apply it to the thread correctly none of it ends up inside the pipe.

Bits could definitely be a problem if you go all bat shit crazy and cover the entire thread in gobs of dope.

Generally you only need a small amount of paste on the first 3 threads, then when you screw them together it will pull the dope away from the inside of the tube.

 

[BigJohnny]

Any worries on the dislodgement of PTFE paste?

Or is running solvent through it dry sufficient to ensure that no more ptfe paste will find its way into product?

I was considering using this paste: "Gasoila Soft-Set Pipe Thread Sealant with PTFE", but I noticed it had isopropyl alcohol and Ethylene Glycol Butyl Ether on the MSDS. I assume those dissipate after the first use?

Pipe dope (PTFE paste is the same thing I think) isn't affected by solvents in my experience, and I've used it pretty extensively in some really harsh environments/chemicals/pressures.

The ISO and ether are what keep the paste in liquid form. it evaporates in order to cure the paste, so yes, it will dissipate once the paste is dry.

 

[pharmco]

Loving the information, friends. That's all the go ahead I need to snag up some better pipe dope and get to work.

Good info on the Ethylene Glycol Monobutyl Ether, Gray Wolf! My spidey sense was telling me it was bad juju, or at least to be avoided.

 

[BigJohnny]

Masters Pro Dope also contains Ethylene Glycol Monobutyl Ether.

If I'm not mistaken that SHOULD evaporate once the paste has solidified.....but would like some confirmation on this, however like I said, the paste is not susceptible to solvents (I could use clarification on that if something specific does react with it) so in essence there shouldn't be any traces of it in the end product?

Also, as I mentioned, when applied correctly the paste doesn't end up inside in the pipe. I'm always careful to wipe off any residue that made it's way on to the end of whatever fitting I'm screwing in. This way I can ensure that there are no gobs or even bits that will end up inside the pipes.



That's why it's VERY IMPORTANT to only apply paste the the first 2 or 3 threads, and only enough paste to just fill the space between the threads.

Once it's tightened in you should have only a small bead of paste on the outside of the fitting and nothing on the inside.

It is common though to have a big gob form on the outside of the fitting sometimes. generally this doesn't affect anything inside.

Is all this "inside/outside" nonsense making sense?