High pressure hydraulic tube replacement

[tomjelly]

I just got in a 150 ton hydraulic press with a pump that operates at up to 6000 psi. The tube that runs from the dump valve to the cylinder was removed before it came to me. The fittings are male 1-3/16" thread major diameter, 12 tpi thread with a 45 degree flare angle, and the rest of that circuit is plumbed with 7/8 tubing with long steel flare nuts. In checking the interwebs I see no high pressure fittings with 45 degree flare angle, everything is 37 degrees so it appears the closest thing is a JIC fitting as shown here:

304 - 37 JIC Long Flare Nut | HydraulicsDirect.com

I've read that SAE fittings with 45 degree flare should have the same thread specs- but I can't seem to find any...or any 7/8" OD tubing available anywhere I've looked so far, and it looks like if I convert down to 3/4" fittings and tubing not only is the working pressure even in stainless about 5000 psi-a little low- even that would have a .104 wall thickness, which I don't know if I'd be able to flare. 7/8" tube would need to be even thicker. So I see hose might work, but I see DIN 4SH and SAE R15. both working pressure 6000 in 3/4". Are these functionally and dimensionally the same hose? Do they use the same fittings? Anyone make custom lines to dimension in steel? (60" long with one 90 degree bend) It is an up acting press and relies on gravity to retract the cylinder so although the pressure line from the pump is smaller, presumably the line from the control valve to the cylinder needs to be kept relatively large so it will fall at a reasonably fast rate as it dumps to the reservoir.

Hydraulics guru needed....

 

[john.k]

You can get hydraulic steel pipe fittings that grip smooth tube without need for flaring....Ermeto is one name comes to mind.....otherwise ,just weld or silver solder on fittings ....or flare the steel tube ....If you dont know what to do,get one of the onsite hose repairers to come round and measure up ....itll cost ya ,tho.

 

[Cole2534]

I believe I'd buy up the req'd fittings and tube then weld it out myself. TIG root, because that's how my pressure vessel experience tells me to do it, then MIG or TIG fill. As for the 90, I'd fab that from some steel stock.

From a totally different angle- my formore coworker worked HP nitrogen stuff, 25,000psi was common for these guys, and their solution was HEAVY wall tube. Machine all the features directly into the tube wall.

 

[magneticanomaly]

You could try these folks Pipe Fitting Manufacturer: Stainless Steel & Weld Fittings | CPV

 

[Robert R]

You can get hydraulic steel pipe fittings that grip smooth tube without need for flaring....Ermeto is one name comes to mind.

Your local Swagelok distributor can supply the correct tube fittings for the .109" wall pipe. Their ferrule type fittings have the same pressure rating as the thick wall tubing.

It will be easier to use a elbow fitting with a tube connection on one end and a male thread fitting on the other end rather than attempt a bend.
They do have pipe thread, straight thread, and 37 deg taper ends for the elbow. You will need to look elsewhere if your 45 deg fittings are welded onto the cylinder and cannot be removed.

Their catalog shows a suggested allowable pressure rating of 4300 psi for .109" wall 7/8 diameter annealed carbon steel tubing with a tensile strength of 47,000 psi and a maximum applied stress of 15,700 psi.
The numbers are taken from a ANSI code specification.

The allowable pressure is based on a safety factor of 3.

 

[deltap]

Look up hss(high strength steel) tubing. You can get required pressure rating with thinner wall for better flow rate. For small amount best go to hydraulics shop.

 

[adammil1]

Can you pull out the 45 deg fittings and see what's underneath them? Chances are it's an SAE port, otherwise it's going to be NPT. Once you figure out the port those 45deg fittings are in you will be in a lot more common territory tossing them out and using something else.

As others mention if you want tube probably best to go either compression or the other system that is nice is ORFS (o-ring face seal) as you can buy braze on ends that are easy to use. 37deg flare is industry standard but to go with tube you need to have a flaring machine which isn't worth it for a 1 off.

Tube will still need tube benders too and can be a skill/art itself.

I were in your shoes I would probably go to my local hydraulics shop and consider doing it in hose to the ends of their choice.

Careful about pressure ratings. I don't have the sizes memorized but JIC and SAE at the bigger sizes top out around 2500ish. Now with that being said there's also a 4x factor of safety built in but 6000psi is up there. I have always thought that the SAE must put such high factors of safety in there to protect the guys on say a backhoe where an impact or load shift may cause huge spikes and have always wondered if one can run much higher if protected by a true relief valve like in a pumping situation.

I have certainly seen people run -32 JIC all day long at 2000-3000psig not knowing any better when the book only says 1500psig but I don't know how wise it really is.


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[tomjelly]

I'm still waiting for a call back from the manufacturer to see if I can get a replacement part- it might not still be available. If I can't get that you are right I'm going to remove the 45 flare fittings from the cylinder and valve (99% sure they are NPT ports) and then talk to my local hydraulic shop. I can make the part in EMT conduit for him to duplicate, one 90 bend and one offset, or 2 45s. I might be able to do it in hose but I'd rather have tube. If he can't do it I'm going to just plumb it with class 6000 forged carbon steel pipe fittings. Of course the parts are going to have to come from a few places as I've been looking and no one seems to have street elbow, 45s, pipe, and unions all from the same source. I'm also not sure about threading the pipe- I haven't read yet if I can do it with Ridgid pipe dies or if I'll need to do it in the lathe.. Looking like $300+ in pipe and fittings. Hopefully I can avoid the hassle of doing it in pipe.

 

[idacal]

I have been using schedule 160 pipe for my larger hydraulic runs 1" type stuff. that not at 6000 but at 4000 frequently and 5000 sometimes. over 5/8s tubing its hard to bend with hand tools i use heat on pipe to bend it were it needs to be then weld ends on.

 

[adammil1]

I'm still waiting for a call back from the manufacturer to see if I can get a replacement part- it might not still be available. If I can't get that you are right I'm going to remove the 45 flare fittings from the cylinder and valve (99% sure they are NPT ports) and then talk to my local hydraulic shop. I can make the part in EMT conduit for him to duplicate, one 90 bend and one offset, or 2 45s. I might be able to do it in hose but I'd rather have tube. If he can't do it I'm going to just plumb it with class 6000 forged carbon steel pipe fittings. Of course the parts are going to have to come from a few places as I've been looking and no one seems to have street elbow, 45s, pipe, and unions all from the same source. I'm also not sure about threading the pipe- I haven't read yet if I can do it with Ridgid pipe dies or if I'll need to do it in the lathe.. Looking like $300+ in pipe and fittings. Hopefully I can avoid the hassle of doing it in pipe.

I think you will probably regret doing that in screwed pipe. Can you weld and do socket weld fittings it would be far easier? Also look at the O-ring face seal system the way the braze on ends work is very nice. If you can't bend the tube, buy 90 unions and cut straight sections and do 90's. I think I would rather that to cut and thread NPT all day long especially when trying to get it all to line up to fixed points.



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[tomjelly]

Thanks yes, I'm hoping I can avoid all of it by getting the OEM replacement. Still waiting on an answer, I need to call for a third time tomorrow as its been over a week now with no callback.

 

[Cole2534]

I think you will probably regret doing that in screwed pipe. Can you weld and do socket weld fittings it would be far easier? Also look at the O-ring face seal system the way the braze on ends work is very nice. If you can't bend the tube, buy 90 unions and cut straight sections and do 90's. I think I would rather that to cut and thread NPT all day long especially when trying to get it all to line up to fixed points.



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And welding avoids the 99% chance that the NPT will leak.

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[Peter from Holland]

Are you sure it is 7/8 Not 22mm

Peter

 

[tomjelly]

Yes, measure quite a bit larger than 22mm and is from a year 1973 USA made machine

 

[e-fishin-c]

I make hyd tubes, but .875” tubing is not common,
looked in my stock and found one .875 x .095” wall, 73” long.
Bending is not an issue as I have dies for .175” and 3.00” radius plus I have a few #14 JIC nuts and sleeves.
But the big issue is the working pressure for the material here is only good for 1995 psi (using a 6:1 burst ratio), .875 x .095 has a rated catastrophic burst of 11,943.
UPS shipping could be an issue too cuz I think it may max out size requirements.
If the tubing adapters could changed to #12 JIC I do have thicker wall and plenty of nuts and sleeves for .750” carbon steel tubing.
6000 psi is a lot to ask for unless safety factors are changed.

 

[tomjelly]

Thanks, I finally got someone at the factory who is checking now to see if the tube from the new ones will fit mine, and if they changed to 37 degree flare. I believe it must be a thicker wall tube. If it doesn't work out I may get back to you!

 

[e-fishin-c]

I do also have plenty of .750” x .120 and have the capability to put on a 37 deg flare and bend.

 

[tomjelly]

That would be the right stuff, maybe even .105