Thread sealants on NPT and others?

[mikester]

I started using heavy teflon tape on NPT. I've found the dried liquid teflon dope crumbling on disassembly making contamination as much of an issue as using the thin teflon tape which shreds. The thick stuff doesn't shred and stays on when changing hoses and fittings.

 

[nyone]

I’ve always used Teflon tape on NPT pipe/fittings, and always will

Teflon can and will get into the hydraulic system and clog valves and such. I have personaly pulled it out of places it shouldnt be.

I use loctite 456.

 

[LouNY]

I have used Teflon tape for NPT joints from the late 70's on to today. On Stainless Steel pipe I use Teflon tape and a nickle anti-seize. Tape on the male never-seize on the female (Chesterton spray Nickle used to be the best) those connections could be made up and loosened and re tightened, that does not happen much with SS npt fittings or actually SS threads of any kind. I do use squeeze tubes of teflon pipe dope also at times.

 

[truckdiagnostics]

i like like tight 5452

LOCTITE® 5452

LOCTITE® 5452 is a purple, thixotropic, anaerobic-curing thread sealant liquid designed for sealing threaded fittings in hydraulic and pneumatic systems. The thixotropic nature makes it suitable for large diameter pipes, and the sealant contains no fillers or particles that can interfere with a...

next.henkel-adhesives.com

There are other similar products. teflon based anything big no no.

 

[BnRidge]

Another vote for Loctite 545. I've used teflon tape and tpfe paste for many fittings, until I encountered several high pressure leaks on NPT fittings that would not seal. Use the primer/cleaner to create a clean metal surface. It starts to congeal on contact, and will harden in minutes.

 

[SilentJ]

I don’t know that there’s a “right” answer with NPT. Pipe threads seal by deforming the threads EVER so slightly … Teflon tape actually functions as a lubricant more than as a sealant. Reducing friction between threads to achieve the right torque.

There is certainly a right answer with JIC and O-ring fittings. The seal is created by
-the two tapers coming together in the male and female (JIC)
-or the o-ring being squished “just enough” in O-ring boss or face seal
In either, the threads are just there to clamp. Threads hold the connection mechanically but there is no sealing done at threads.

If you THINK glopping stuff on threads in such instances “helps”… it’s at best a band aid for a damaged fitting or cut oring that needs replaced. If fluid is even GETTING to the threads when tight, you got bigger problems, and spackling over the threads isn’t a proper repair. Or safe.

If you’re worried about fittings coming loose, you don’t have a loctite issue, you have a torque issue. Or you have a hose installed with a twist in it that’s trying to loosen your connection under vibration or whatever

 

[newbury]

Looking on Amazon:
Loctite 545-36 ml Bottle (PN: 492145) $24.79 ($20.49 / Fl Oz)
Loctite 5452™ Fast Cure Thread Sealant, Purple, 50mL Tube - $95.28 ($56.38 / Fl Oz)
Is the only difference the speed of the cure?

 

[WranglerX]

Simple rule is tapered threads usually require thread lube or sealant, straight threads do not require thread lube or sealant because "seal" is not at the threads.... I always seem to have bad results with tapered threads I use various forms of sealant and tape and always seem to have to work fitting 2-3 time to get a seal... Good luck on whatever form you decide to use....

 

[truckdiagnostics]

As for Parker...... way back. A parker rep suggested we switch to Fel-pro 51454. It is a 250ml bottle. Had to go down to the tool box to check. Had it forever.

We were having Teflon accumulate in the pressure compensator on there pump. When we switched it solved a lot of leak issues also. Some engineers are a trip. You flat out can't assemble the hydraulic hoses on a piece of equipment and use a torque wrench on everything. It is about feel. The younger guys working assembly don't have the touch. They were either too loose or most were over torqued.

We increased the education on the shop floor at the time also. We basically had to teach, "tight" So, what really fixed it ...

The solution would be to design it more better and switch to steal lines. That would require more work on there part. Lot easier to say well, "if you just torque it right get the flex on the hose right. It will work fine" I don't know how may times I have stood there with engineering watching, proving that it can't be done that way. "Just because it worked in 3D CAD, means nothing, down here in the real world"

The sealant on the straight tread is being used as a thread locker.

So, the Loctite or felpro product gives the shop floor one product for more applications.

 

[5030]

I’ve always used Teflon tape on NPT pipe/fittings, and always will

I do as well but I never wrap the tape over the last 1/16" of the threads.