Air brake connections- Teflon paste or Teflon tape?

[Reworked LMTV]

What is the DOT standard for NPT connections on air brake systems? Teflon paste or Teflon tape or either?

 

[NDT]

I say paste. Never seen teflon tape used on trucks.

 

[juanprado]

usually the red stuff

 

[shotty]

Curious to hear the responses, I've never had good luck using the paste on my air compressor lines at home...

 

[NDT]

A master plumber once told me that the purpose of teflon tape or the teflon pipe sealant is to lubricate the threads so you can get the connection tighter.

 

[coachgeo]

usually the red stuff

you mean red (medium?) loctite? I have heard this before too... but was expressed to use lighter than normal on smaller ones; esp. brass fittings that might round off when trying to remove

 

[runk]

A master plumber once told me that the purpose of teflon tape or the teflon pipe sealant is to lubricate the threads so you can get the connection tighter.

And if you are using stainless, to keep it from galling or friction welding together.

 

[juanprado]

The red stuff is typically oe applied and used by haldex and bendix.

Ndt is spot on. Not only used to seal threads as most pipe threads do that on there own but to prevent galling and seizing by lubricating the threads.

I just recently overtightened an oil pressure switch and cracked it flush on the block. I had used white brush on permatex sealer. Fitting came out easily with easy out. Might have been a totally different outcome otherwise.

 

[juanprado]

you mean red (medium?) loctite? I have heard this before too... but was expressed to use lighter than normal on smaller ones; esp. brass fittings that might round off when trying to remove

No. Not 271 or ? Thread locker. This thread sealer maybe 569 if memory serves me .....
Different purpose. Those are anti vibration.

 

[Reworked LMTV]

"red" Loctite 492145 545 Pneumatic/Hydraulic Thread Sealant, but it is only compatible with metal. The air brake control manifold npt connections from Haldex appear to
be nylon.
https://www.amazon.com/dp/B003XZB54O?tag=duckduckgo-exp-b-20&linkCode=osi&th=1&psc=1

 

[Reworked LMTV]

I spoke with Haldex this AM. Nice guy. He stated that the only approved sealant for the composite manifolds is pipe dope, or PST565. NO TEFLON TAPE. NO RED LOCTITE.

 

[M35A2-AZ]

If you use the tape you may get little parts of the tape in your air system, use paste.

 

[juanprado]

I spoke with Haldex this AM. Nice guy. He stated that the only approved sealant for the composite manifolds is pipe dope, or PST565. NO TEFLON TAPE. NO RED LOCTITE.

Interesting but their fittings come with a "red" teflon/dope already pre applied on new items.

 

[M35A2-AZ]

Parker fitting come with the "red" sealant on them also.

 

[juanprado]

So I spoke to Henkel tech support who is the parent of permatex/loctite.

The red is actually what they call burnt orange. It is sold to preauthorized centers in bulk and they apply it. They do not sell the same product in the retail or automotive/hardware markets.

Some additional information provided:
"So we have many anaerobic thread sealants. They are chemically very different than the pre-applied product. First of all, they do not dry on the thread, so you apply and assemble right away. Secondly, the pre-applied thread sealant is a non-curing product, so it can actually be adjusted. Our liquid/paste anaerobic products cure once, and if you move them, you've lost the seal "

Their preferred solution for pipe thread sealant is 567. So the OE applied stuff can stand to be adjusted after the fact but not the stuff we have access to. I suspect 565 or 567 or pipe dough will be fine as additional preventative.

 

[Reworked LMTV]

So I spoke to Henkel tech support who is the parent of permatex/loctite.

The red is actually what they call burnt orange. It is sold to preauthorized centers in bulk and they apply it. They do not sell the same product in the retail or automotive/hardware markets.

Some additional information provided:
"So we have many anaerobic thread sealants. They are chemically very different than the pre-applied product. First of all, they do not dry on the thread, so you apply and assemble right away. Secondly, the pre-applied thread sealant is a non-curing product, so it can actually be adjusted. Our liquid/paste anaerobic products cure once, and if you move them, you've lost the seal "

Their preferred solution for pipe thread sealant is 567. So the OE applied stuff can stand to be adjusted after the fact but not the stuff we have access to. I suspect 565 or 567 or pipe dough will be fine as additional preventative.

I'm not sure these are the correct products IF you are replacing your Haldex Midland brake manifold control with the latest version. The newer products are NOT a metal manifold. They are a plastic composite. These two sealers appear to be metal to metal.

 

[brianhk91]

I guess 565 is OK since Haldex approved it, but be aware that the TDS for both 565 and 567 say "This product is not normally recommended for use on plastics (particularly thermoplastic materials where stress cracking of the plastic could result). Users are recommended to confirm compatibility of the product with such substrates. "

 

[juanprado]

I did not inquire about plastic/abs? application.

 

[Awesomeness]

Always use liquid/paste thread sealants for pneumatic fittings, because the little shreds of tape will cause malfunctions in pneumatic controls (e.g. the pilot passage on a solenoid is very small, and easily clogged). Tape is only for liquid plumbing systems, but even then once you have the liquid/paste around there is almost no point in ever using tape again.

Permatex High Temp Thread Sealant is a good single choice to keep around: https://www.permatex.com/products/t...high-temperature-thread-sealant/?locale=en_us