Hose Fitting Sealents

[Hendey T&G]

I've read some say only use pipe joint compound on threads. Is there a special hydraulic compound or will any brand do? The Oatey ordinary plumbers pipe joint compound I have says good to 10K PSI with liquids.
What's the consensus on the yellow teflon tape made for contact with gasoline and oils?
Of course, not letting any get in the system.
Thanks

 

[WranglerX]

Sealants should only be used on tapered thread fittings (NPT and such), and straight fitting usually seal with a metal to metal flair contract or an "O" ring.....

Teflon tape and I don't get along, I use a general purpose thread seal and that in its specification cover a long list of what it is approved to be uses as.....

When Applying paste sealant or tape always leave at least first 1-2 treads clean....

 

[Hendey T&G]

Thanks for your reply. I should have said mine are NPT.

 

[EddieWalker]

Thanks for your reply. I should have said mine are NPT.

Are you sure? I'm no expert, but I've never seen a NPT pipe fitting on a hydraulic line.

From what I understand, hydraulic lines do not use sealant or tape. The reason is that those products are VERY BAD for hydraulic pumps if they get into the system.

On all my tractors the hoses are Flare Connections that force metal to metal contact to create the seal, or Flat Face fittings that use O rings to create the seal. I have a large selection of O rings for my hoses when I replace them.

 

[Tinhack]

Are you sure? I'm no expert, but I've never seen a NPT pipe fitting on a hydraulic line.

I'm no expert either but they're as common as JIC fittings. Nearly all the premade lines from places like TSC and Surplus Center come with NPT ends unless you order otherwise. I stock the ends myself. Shown below are 1/4" NPT.

 

[etpm]

Loctite makes at least 2 thread sealants for hydraulic fittings using tapered threads, 545 and 5452. Look them up.
Eric

 

[kennyd]

I'm no expert, but I've never seen a NPT pipe fitting on a hydraulic line.

Sadly, NPT is used in hydraulics all the time. It should be outlawed!

A paste with PTFE in it, or a dedicated sealant like one of the Loctite product is best, we sell and use this in our shop:

High Pressure Hydraulic Thread Sealant Medium Viscosity - BoltOnHooks LLC

hydraulic thread sealer, vibra-tite

www.boltonhooks.com

 

[etpm]

Sadly, NPT is used in hydraulics all the time. It should be outlawed!

Yeah, I feel the same way. While tapered threads have their place I hate to see them used in places where disassembly is likely. Tapered threads tend to gall and are often not made well so folks tend to over tighten them to attain a good seal. Straight threads, or parallel threads as the Brits call them, can be of lower quality finish wise and it doesn't matter since the thread is not doing the sealing. And since fittings that use straight threads don't rely on the thread for sealing they are less likely to be over tightened and less likely to have gobs of tape or dope applied that then extrudes into the fluid or air path.
Eric

 

[mikester]

I prefer using the thick teflon tape over liquid thread sealant these days. I find the liquid stuff tends to dry out and crumbles on disassembly making more of a contamination issue than the tape. Don't put tape past the threads. Thick tape doesn't shred like the thin stuff.

 

[EddieWalker]

This is the first that I've ever heard of NPT threads on hydraulic lines. My oldest tractor is a 1988 Case Dozer, and my next oldest is a 1998 New Holland Backhoe. Neither of them use NPT threads on their hydraulics.

Is it an age thing, or is it for lines that do not have a lot of pressure?