Hydraulic Fittings Won't Seal

[huffman102833]

I'm having trouble getting fittings to seal and I'm starting to wonder if they're not compatible with the hose. I've attached pictures of the male and female ends. If you notice, the male side has a recessed flat "rim" that seems to indicate something may sit flush against it. This isn't present on the female side. I've tried liquid teflon with no success.

Specs for hose: "1/2 in. MNPT"
Specs for fittings: "1/2-14 NPTF"

 

[bigdeano]

The recessed tapered seat on the male fitting is used with a female swivel fitting. The seal is made on the taper seat and not on the pipe threads. It's not used with a standard female fitting, which seals on the threads. Try a different thread sealer. I use Loctite 242 thread locker if the threads are clean and dry. If you use something that doesn't harden like those Teflon liquids it will probably be pushed out by the high pressure.

 

[/pine]

The hose end appears to be NTPF...it's tapered thread that fits NTP female(requires sealant) or NPSM female swivel (mechanical joint, no sealant required)

It looks like the fitting on the cylinder may be SAE/ORB on both sides of the 90... if that is the case you will need an adapter from male pipe to male SAE/ORB....

...if the open end of the fitting on the cylinder is indeed male pipe (NTP) the hose just needs to be tightened more with sealant...but if it's SAE/ORB it is straight thread and the NTPF hose end can damage the fitting...

Steel Fittings - DiscountHydraulicHose.com

 

[huffman102833]

Thanks for the responses. Here are links to the actual parts.
Hose- 1/2 In. x 24 In. Long Hydraulic Hose, Swivel End
90- 1/2" Adj. O-Ring x 1/2" Female Pipe | Agri Supply 18653
Quick Connects (which are also leaking)- Hydraulic Quick Coupler, 1/2-14 NPTF

I'm okay with buying different parts if I need to, I just want to make sure I'm getting the right thing.

 

[/pine]

Thanks for the responses. Here are links to the actual parts.
Hose- 1/2 In. x 24 In. Long Hydraulic Hose, Swivel End
90- 1/2" Adj. O-Ring x 1/2" Female Pipe | Agri Supply 18653
Quick Connects (which are also leaking)- Hydraulic Quick Coupler, 1/2-14 NPTF

I'm okay with buying different parts if I need to, I just want to make sure I'm getting the right thing.

OK the hose should work OK...just need sealant and torque...

IMO this would be a better choice:
6901-08-08 | #8 SAE/ORB Male x 1/2" NPSM Female Swivel 90°

 

[huffman102833]

OK the hose should work OK...just need sealant and torque...

IMO this would be a better choice:
6901-08-08 | #8 SAE/ORB Male x 1/2" NPSM Female Swivel 90°

Great. I'll order a couple of them. How about the quick connect? Is there a better alternative there as well?

 

[Discount Hydraulic Hose]

So the leak is between the male and female fitting in the photos, or at the base of the 90 degree on the cylinder? Does the male feel "loose" when you screw it into the female? Could be a mismatch of threads..

 

[huffman102833]

So the leak is between the male and female fitting in the photos, or at the base of the 90 degree on the cylinder? Does the male feel "loose" when you screw it into the female? Could be a mismatch of threads..

The base of the cylinder seals fine. It threads down to the base and seals with an O ring. My problems are on the hose side. Both to the 90 and to the quick connect on the opposite end.

 

[bigdeano]

Just use a better thread sealer. No need to replace the parts.

 

[kthompson]

Not a thread expert but there is the pipe threads and there is another thread that will screw together with it but they are NOT compatible. Under load they can leak and even blow apart. If you are paying attention very carefully and try wiggling the two fittings you should pick up on more movement than is normal. I have run into this with two different hyd cylinders due to just assuming same threads on all hyd cylinders and they are NOT. When both of mine failed it was a major failure (in regardless to how major the oil leaked) with little notice. I do not think the sealant is your issue but the fittings are not the same thread type.