Teflon tape on hydraulic fittings

[/pine]

Just built a hydraulic chainsaw for the tractor. All taper to taper NPT threads used Loctite 545. All swivel NPT to taper NPT used no sealant. These allow easy assembly and service of component parts. No leaks.

The NPSM fittings used on valves, cylinders etc. also make it simple to order hoses...with the NPSM the end(s) of the hose can be straight male pipe thread (NPT)...the mechanical joint eliminates the need for sealant and re-using the fittings (NPSM) is not a problem....

Female Pipe Swivels (NPSM)

The National Pipe Straight Mechnical (NPSM) female fitting has a straight thread and an inverted 30? seat. The male fitting has a straight thread and a 30? internal chamfer. A properly chamfered NPTF male will also seal with the NPSM female.

www.discounthydraulichose.com

 

[npalen]

I totally agree with using NPT on a hydraulic system only when no other choice. Hydraulic systems actually should use NPTF (dryseal) threads which have thread crests and roots designed to eliminate spiral leakage. NPTF = Dryseal American National Standard Taper Pipe Thread

The "Dryseal", in my estimation, is saying no "dope" needed.

Another issue with NPT or NPTF is that the taper can crack castings if over torqued and that can happen when trying to get a street ell, for example) facing in the needed direction.

 

[npalen]

http://greensladeandcompany.com/wp-content/themes/greenslade-theme/pdf/articles/threads/Threads%20-%20NPTF%20Taper%20Thread%20Gaging.pdf

Just some info on how the dryseal threads work.

 

[LD1]

Loctite 545. If you work on hydraulics....have a bottle on the shelf and quit second guessing everything

 

[npalen]

Loctite 545. If you work on hydraulics....have a bottle on the shelf and quit second guessing everything

Not sure what you mean by "quit second guessing everything".

 

[LD1]

Not sure what you mean by "quit second guessing everything".

Dont second guess your choice of sealer. Or sealer vs lubrication, or teflon vs non, or tape good or bad.

NPT are the only hydraulic fittings that need anything. ORB, ORFS, NPSM, JIC....all need nothing.

Keep a bottle of 545, and if you are working on hydraulics and they are NPT, use it. Save the PTFE paste or tape for water lines, gas lines, shop air, etc.

 

[PHIL850]

Teflon tape is for sealing tapered threads.
Hydraulic fitting's don't seal via the threads.
If you're using teflon tape on hydraulic fittings, you're either trying to patch something in the field to hold on till you can get it to the shop and properly fixed OR you don't know what you're doing.

there are tapered fittings on some hydraulic units (NPT) my model 75 loader is one item that uses these.

 

[npalen]

Dont second guess your choice of sealer. Or sealer vs lubrication, or teflon vs non, or tape good or bad.

NPT are the only hydraulic fittings that need anything. ORB, ORFS, NPSM, JIC....all need nothing.

Keep a bottle of 545, and if you are working on hydraulics and they are NPT, use it. Save the PTFE paste or tape for water lines, gas lines, shop air, etc.

http://tds.loctite.com/tds5/Studio/ShowPDF?pid=545&format=MTR&subformat=REAC&language=EN&plant=WERCS

Question on the 545 cure time: The graphs in the product info above all talk about "breakaway strength" in regard to cure time, temp etc. I would normally be interested in cure time in regard to sealing hydraulic pressure rather than "breakaway strength" which I understand as resistance to "coming loose" mechanically.
What is your advice on normal curing time prior to using to prevent leakage? I ask because I'm normally needing to "get back on the road" after fixing a leak, so to speak.

 

[Smokeydog]

Tapered thread hydraulic connections are common on tractors and AG equipment.

EA makes the point of explaining that they use taper thread fittings on their wicked grapple cylinders because they are bigger and stronger. Yes it takes more time, special sealer but makes a better, tougher product.

 

[npalen]

Tapered thread hydraulic connections are common on tractors and AG equipment.

EA makes the point of explaining that they use taper thread fittings on their wicked grapple cylinders because they are bigger and stronger. Yes it takes more time, special sealer but makes a better, tougher product.

That's the first I've ever heard of NPT being used because they are "bigger and stronger" but I suppose it may have some merit.