Tape or Thread Dope on Hydraulic Connections?

Stoneman44 · Jan 5, 2020

Hello All,

I ve recently installed a new FEL on my tractor. To save a little cash, I bought hoses and connections from our local Rural King. Some of these connections are leaking. I ve tightened them as much as I, and my 6 -5", 250lb son-in-law, can.

I ve read that it s not wise to put any tape or substance in the connections. However, in some of the "old" loader connections, I can see tape, and there is no fluid leaking.

What s everyone s thought? Yay or nay?

Thank you!

4520BW · Jan 5, 2020

You can use tape just dont put it on the
end threads.

714_run · Jan 5, 2020

use pipe dope or they will leak

john in la · Jan 5, 2020

Hydraulic hoses do not seal by the threads.
They seal by the seat on the end of the hose matching the bore of the fitting.
But hey if a little tape solves your problem have at it.

Bob · Jan 5, 2020

Tape is just fine as long as you CAREFULLY install it so it's never closer than a couple of threads from the end of the male fitting.

There's lots of good "thread pastes" out there, here's one I'll have very good luck with:

<img src = "https://www.zoro.com/static/cms/product/prev/Z0-ED_fo5oy.JPG">

Steve@Advance · Jan 5, 2020

I've used tape on hydraulics with no ill effects.

The trick is to wrap the tape slightly away from the leading thread so none gets into the oil.

Something like a loader, with a manual valve, gear pump, is a very forgiving system. A little tape will not interfere with the workings of the system.

What is the country of origin of your tractor? One of the most common causes of taper thread leaks is mixing NPT and BPT fittings. They are close enough to thread together, but different enough to damage the threads and leak.

If this had been done, when the fittings are removed, there will be metal shavings coming out with the threads. This id far more detrimental to a hydraulic system than a little thread tape!

At this point not much can be done other than clean it up with the correct tap and find the correct fittings. Or put a bunch of tape on and hope for the best.

Case Nutty 1660 · Jan 5, 2020

tape is fine and works even with oil on the threads,, like said below Only on the threads though and only two wraps max,, ,, older hyd systems it does not affect, But some of the newer systems do not like it at all,, the dope works If you clean every part to be completely free of any oil other wise they leak,, I hate thread dope for that reason,, also easy to over tighten them with tape so do not use full strength on tightening

moresmoke · Jan 5, 2020

On NPT fittings that screws directly into
a valve with no swivel nut, the best thing
I have found is Loctite 545. The threads
need to be clean of oil, and the sealant
needs a bit of time to set before being
put in service.

glennster · Jan 5, 2020

locktite 549 or 569 are for hydraulic fittings here is a link
poke here

9001ron · Jan 5, 2020

Depends on the type of threaded connection. Pipe thread joints need a
sealant of choice -- typically I use Teflon tape and wind it on in the
direction so it dosent "unravel" as the fitting is threaded together.
When they say dont put it on the ends of the treads they mean -- dont
have any that gets into the area where oil will flow -- takes some
practice . Small amounts of Teflon tape or other sealant can get into
bad places and cause trouble . Just think of how many times a drop of
oil circulates in that system when you have it running - that bit of
tape will eventually get where it can do the most harm.
Other types of threaded connections such as flared or oring type
connections dont need sealant.

Hobo,NC · Jan 5, 2020

Pipe dope acts as a lubricant and a sealant with chines threads, tread interference may be the issue dope them for that little extra lubricant so you can tighten them before thread interference comes into play...

I gave up on pipe tape because of this issue...

the tractor vet · Jan 5, 2020

It depends on what your working with . If it is standard pipe then i use a paste made for hyd. , None of the rest need tape or dope . If your working with a J I C fitting don't go hog wild on tighting the fitting for all your worth as you can damage the seal . If your working with PIPE mqake sure you get pipe and fittings rated for hyd. , the black pipe ya buy at the big box stores today are not even rated for compressed air let lone something pushing over 2000 psi.

Traditional Farmer · Jan 5, 2020

I use the yellow teflon tape on NPT fittings never have a problem sealing if done correctly.

MJ in the UK · Jan 5, 2020

Hi Stoneman, if it is your David Brown tractor you have put the loader on it will
have JIC hose connections.MJ

37chief · Jan 5, 2020

I use good old standby aviation permatex. Stan

oldfarmkid · Jan 5, 2020

Had an instructor years ago tell us teflon tape was to ease threading of connection. Not designed as a sealant. Anyone else out there hear the same info?

Mike(NEOhio) · Jan 5, 2020

In addition to wrapping in the direction of the threads you should start wrapping high on the threads and work toward the end so the tape edge doesn't curl back as it enters. This isn't usually an issue with 1/2 inch tape on fittings under 1/2 inch. Stop 2 threads from the end.

rustred · Jan 5, 2020

there is so many fittings out there like ORB, JIC, BSP, these do not require anything on the sealing surfaces. on pipe threads you can use Teflon tape or the Teflon in a tube. plus the jic fittings are a fitting that don't require a lot of torque to tighten it. in hard to get at places I will put a little drop of blue locktite on the threads to keep the fitting from loosening. its not the threads that are doing the sealing as you know its just that these fittings like to loosen from vibration. you do not say what fittings you have that you are haveing trouble with. plus overtightening the pipe threads in a cyl. you will just spread the threads and of course you will have a leak. not much info here to go by and lots of guessing. no info on what hose connections you are talking about.

Brown Swiss · Jan 5, 2020

Only on pipe thread, then my mind wonders
what you have for fittings? All too often
I have seen people try to install pipe
into ORB, or vise versa, they just didn't
know any better!

Brown Swiss · Jan 5, 2020

Then also jic and ORB are the same thread but won't work if installed!

Brendon-KS · Jan 5, 2020

Being that this is on a loader I'm assuming that the hose size is something between 1/2" and 3/4". If this is correct you would not have any hydraulic connections that would require an
unusual amount of torque. For example, a 1/2" connection takes something in the 50 lb-ft range depending on style of thread. A 3/4" connection would only be around 80 lb-ft. If you have
connections that are leaking after being tightened like you describe chances are very good that the couplings are damaged.

Rule-of-thumb is to use tape or dope on connections where the sealing happens within the threads, such as with tapered pipe threads. This is to prevent galling the threads as well as to
aid in sealing. If the sealing happens somewhere other than in the threads, such as with ORB and JIC, no teflon is required.

paul · Jan 5, 2020

Are you with the common pipe thread hose connections?

Or the o ring type?

The common pipe connection I?ve always heard don?t use tape it can get in the hose and plug things up. So nearly every hose connecting I?ve seen has tape on it..... I
guess I use tape and am very careful to keep the tape back a couple threads from the tip.

Paul

Jim.ME · Jan 5, 2020

The still unanswered question that determines the need for any pipe dope or tape:

Stoneman44,

What are the threads types of both sides? And are you absolutely certain that is what they are? You may be trying to put mismatched threads together.

paul · Jan 5, 2020

Yea I?ve never done anything like that... nope, can?t prove it anyhow.

There are a lot of ?standard? ways to connect hyd hose and several of those o ring types look pretty close to a pipe.

Then, put an o ring connection together and forget the o ring..... that never happens either....... more often tighten too tight and burst the o ring......

Paul

Jim.ME · Jan 5, 2020

Stoneman44,

What is the loader? New or used? What is the tractor? Where and what connections are you making to save money? Just the supply and return hoses, or every hose on it? There may be some clues for the guys as to what the threads might be in those answers also.

old · Jan 5, 2020

Are you 1000% sure you have the correct hose fittings?? There are 3 plus types and if you have NPT but tried to use flare type then will tread up to each other some times but leak. There is also the type with the O-ring plus a number of other type fittings. You have to have the correct type fitting or they will leak. When I replace a hose I take the old hos with me and match the n fittings up by size and look. And yes when I can I buy from the local Orscheln's farm and home to save some $$

Plus I NEVER use tape or dope on the fittings

Stoneman44 · Jan 5, 2020

Sorry, I should have been more specific. I m using 1/2" NPT fittings on a DB885 w/a Case Model 55 loader. I m having NO leaks where I ve joined directly to the loader or the power beyond box.

All connections are good to any hard line on the loader. My problems are where I ve had to use female fittings to join two lengths of hose together.

Jim.ME · Jan 5, 2020

(quoted from post at 21:44:46 01/05/20)
Sorry, I should have been more specific. I m using 1/2" NPT fittings on a DB885 w/a Case Model 55 loader. I m having NO leaks where I ve joined directly to the loader or the power beyond box.

All connections are good to any hard line on the loader. My problems are where I ve had to use female fittings to join two lengths of hose together.

It is likely you don't have leaks at the valve body because the hose end goes into a swivel adapter. If you look at the inside of the adapter and the end of the hose fitting you will see they have a seating arrangement where they meet. They seal internally, not by the threads. The adapters should be NPST (National Pipe Straight Thread), the threads are not tapered but are the same pitch as NPT (National Pipe Tapered Thread). NPT seals on the threads. The hose end threads are likely tapered to work with NPT but as both the hose end fitting and coupling you are using are steel, they are not conforming to each other as easily and are not sealing well in the threads. You will need to use thread sealant of some type to stop the seeping. Loctite 545 is one I have used in industrial applications on steel fittings. Loctite TIGHT is another good one. Everyone will have the pipe sealant and/or tape they think is best. My thoughts are you will need something for tape and/or sealant where you used the couplings between hoses. JMHO.

Stoneman44 · Jan 6, 2020

Thank you all for your responses and expertise! I will report back once I've completed the repairs.

Skyhighballoon(MO) · Jan 10, 2020

Tape or Thread Dope on Hydraulic Connections?

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