How to torque a hydraulic fitting

[Furu]

May be a dumb question but the only dumb question is the one that is not asked.

My question is how to torque a hydraulic fitting but the question generally is when you can't get a socket torque wrench on a bolt/nut/fitting how do you torque it to a specific setting. Using crows feet and a normal torque wrench and math I think it could be done with some degree of error due to angles changing but is there a better/simpler method. Of course one can always tighten it till it feels right but that doesn't always turn out well.

 

[RickB]

A crow's foot socket positioned 90 degrees to the beam of a torque wrench requires no math calculation. Practice will give good results; that is knowing how tight 'tight' really is. You won't get a torque wrench near many hydraulic fittings anyway. Here are fitting torque guides:

http://www.pirate4x4.com/tech/billa... Hydraulic Hose and fitting Torque values.pdf

 

[Baby Grand]

This document came in the box of my new (in 1975) SK 3/8 torque wrench:

http://www.srtorque.com/Downloads/Instructions/857313D.pdf

Hope it helps!

-Jim

 

[Monster5601]

Here is yet another resource for the math:
Torque Wrench Adapter Extended Calculation - Engineers Edge

May be a cut-a-way socket could work, like the ones used to remove oxygen sensors from the exhaust system. Doesn't seem practical though, the rigidness of the hydraulic line and diameter to nut size of the fitting would require a very long socket. Just thinking...

 

[wdchyd]

Here's a few videos that may help....

Tompkins Adapter Assembly Videos - Tompkins Industries Hydraulic Adapters And Fluid Power Products

 

[Egon]

Some type of fittings may use a criteria that involves the number of turns after finger tight snug.

 

[Soundguy]

wow.. I must be doing it all wrong.

I just put em in till they feel good and go.. and that accounts for npt, orb and jic.... I better start getting high tech and get the TW out..

soundguy

 

[Gary Fowler]

I am with SoundGuy, I have never used a torque wrench on hydraulic couplings. Just tighten till it is snug. Hydraulic fittings dont take a lot of torque to be leak tight so a bit more than snug is about all you need. If it leaks, which I have never encountered, tighten it a bit more.
If you are built like a young Arnold S. then maybe you need to torque everything, but I have found that after a few years of practice and knowing how much it takes to twist off a bolt, experience is better than torqueing. Torque wrenches dont take into consideration the friction factor and sometimes you can reach specified torque and the bolt will still be loose whereas a really well lubricated bolt may be overly tight when torqued to the max.

 

[BethesdaEC]

I have often joked that the best way to properly torque a bolt without a torque wrench is to tighten it until the head snaps off then back off a quarter turn.

 

[Soundguy]

... or to tighten till just before it breaks off..


soundguy

 

[nspec]

How about 'blue dot spec'? Tighten until you see the little blue dots when your straining

 

[wdchyd]

I'm with most of you guys....for me it's more of a feely meely thing....snug is good, reefed is not.....

 

[RickB]

I supplied the torque chart for the benefit of the OP. But like the rest of you with some experience, I can truthfully say that I have never used a torque wrench on a hydraulic fitting of any type.

 

[Soundguy]

I pretty much 110% figured that on the torque chart. after spinning as many bolts and fittings in and out as you have done in your service carear and home projects one just pretty much learns where a fitting feels good, or knows when they feel a bad threaded hole, bad threads on a fastener.. or one that is just ready to break off. ( Of course i had to learn it by breakeing quite a few of them off ). I wish the previous owner of my 950 had known where to stop... never seen soo many broke bolts and fittings and studs on a single tractor could have been a demonstration display unit for hard drills and extractors at a fastenall store..

good luck to the OP.

soundguy

 

[Furu]

As the op., I have also always just tightened most things to feel, hydraulic fittings included, I had never even seen very many specs on torque for a hydraulic fitting until last week. As I reviewed the installation on some equipment the manufacturer repeatedly calls out a torque spec on each fitting and there are a lot of them. More than 50 total and about 10 different values. Since as I age I have seen more and more things that have bitten people in the *** because they either break or strip threads or back off because they are too loose I have become less trusting of the feel and more a believer in specs and thought that I might try a different method this time than I have previously done. I have wondered what some "shaved ape" was thinking on some occasions when I dealt with some bolt that they tightened a bit more than necessary. I also wonder if our litigious society has caused manufacturers to spec things to limit liability.

 

[Soundguy]

I think you nailed it. spec it , and leave the liability to the dealer or user.

and yeah.. I've had many a tractor that instead of the owner buying a 25 cent gasket.. or making a free one, they instead glued the flanged plug in with hardning gasket sealer or gorilla snot, then hired an ape to tighten the bajeebers out of it.

soundguy

 

[Tractor Seabee]

In my younger day I overhauled a lot of machinery, engines, compressors, pumps, etc. We always used a torque wrench on bolts/nuts directly related to moving parts or containing pressure such as cylinder heads. We found by experience that standard box and open end wrenches have engineered lengths that if you tighten w/o extraordinary measures it is hard to over torque any bolt/nut they fit. If it still leaks you can push a little harder. This holds true with tubing fittings also. Some manufacturers of special fittings provide a go/nogo guage that fits between the nut and the fitting wrench flats. Other wise we always used a flare nut wrench on the nut and a open end wrench (adjustable wrenches are a no-no, usually can't get in the space anyway) on the wrench flats of the fitting spaced them apart about 2" and squeezed with one hand. When it would go no more it was tight. Always worked. I have a Kubota BX25 and have no place I cannot use that system effectively. Not backing up the fitting can most always cause a leak elsewhere. Once a pipe thread is tight, backing off just little bit can cause a leak. Over tightning flare fittings can destroy their integrity by thinning out the tube flare. Do not try to make your own flares on tube unless you have a double flaring tool of the right flare angle. Your friendly hyd shop guy will do a professional job.

Ron

 

[EMB5530]

I have often joked that the best way to properly torque a bolt without a torque wrench is to tighten it until the head snaps off then back off a quarter turn.

Ive always joked about the same anytime someone asks me how tight.:thumbsup:

 

[Egon]

We found by experience that standard box and open end wrenches have engineered lengths that if you tighten w/o extraordinary measures it is hard to over torque any bolt/nut they fit. If it still leaks you can push a little harder.

Just remember those of us that getting older and frailer seem to require longer handled wrenches!:thumbsup:

 

[5030]

wow.. I must be doing it all wrong.

I just put em in till they feel good and go.. and that accounts for npt, orb and jic.... I better start getting high tech and get the TW out..

soundguy

I don't need no steenkin torque wrench either.....:laughing: