Material for hydraulic hard lines, Copper-Nickel or only steel?

[joea99]

While i ponder getting custom hoses made JIC flare at each end, for a rather tight space, I wonder making them out of steel or copper-nickle would be feasible. I'd have to by a 37 degree flare kit, which could be handy for other purposes, but wonder about the working pressure.

Seems the copper nickle I can afford has a working pressure of about 2200 PSI, if I translate MPa correctly. That is just over the specs for my tractor.

I am going with 1/4 lines, flex or hard which will only be maybe 1 ft overall length, going from spool valve to bulkhead fittings, from there to top and tilt cylinders. I'd prefer the flow to be a bit restricted, hoping to avoid adding restrictors if they "slam" easily.

So far I've not no definitive answer from the suppliers on working, deformation or burst pressure.

 

[BeezFun]

It needs to be rated above the relief pressure, not just the operating pressure. I would guess your tractor operates at 2100 and relieves about 2500. So I would look for something rated about 3000psi. The copper nickel brake lines I've seen are rated 3000psi, so that would be fine.

 

[oldnslo]

I would be concerned about working pressure of copper nickel especially if carrying a load over rough ground. The bounce can induce some unknown pressure spikes. I used 1/4" steel brake lines for my grapple where was space limited and did not need high flow. Just purchased a couple of 2 foot pieces and bent and flared as needed. These also has a coating on the OD to reduce rust.

 

[ptsg]

I suggest that you go with steel hydraulic tubing or the zinc plated version of that, if you want to deal with painting the tubing. Not only it has to deal with system pressure but it also has to deal with pressure spikes, which can go really high.

This is in metric but it's from a spec sheet of a local hydraulic shop. 6 mm tubing, closest to 1/4", with 1 mm wall has a pressure rating of 3900 psi. With 2 mm wall thickness, it gets a pressure rating of 6200 psi.

 

[joea99]

Thanks for the tips. Any spikes I think are handled by an internal adjustable relief built into the valve, Vents via the tank return, I believe.

The copper-nickle idea was mainly for the "never rust" feature. Stainless would work too, but is quite hard to bend well, from what I read. My experience with zinc coatings and bending those lines has not been pretty. Could have been those were not "plated", but "dipped".

 

[LD1]

The adjustable reliefs on most valves are on the inlet side and not the work ports.

 

[etpm]

Thanks for the tips. Any spikes I think are handled by an internal adjustable relief built into the valve, Vents via the tank return, I believe.

The copper-nickle idea was mainly for the "never rust" feature. Stainless would work too, but is quite hard to bend well, from what I read. My experience with zinc coatings and bending those lines has not been pretty. Could have been those were not "plated", but "dipped".

What are you using to bend the lines? Whenever I have had to bend small diameter stainless, brass, or copper tubing I used a tubing bender and had no trouble with kinking or distorting the round shape of the tube.
Eric

 

[Sportsman762]

I would probably use Stainless lines and look for something with a 3,000 psi working. I would encourage you to go with 3/8" tubing as it will be close to 1/4" hoses in size. Tubing is measured by the OD and hose is measured by the ID. 1/4" tubing is extremely small and will be very very slow, the valve will basically be on or off with no feathering ability. A Ridgid 375 is a commonly used hand flaring tool however for 1/4" or 3/8" tubing I would suspect most flaring tools would work. For fittings Parker TX-S sleeves and BTX-S nuts would be the most economical choice.

Zoro has some reasonable tubing prices.
Strong & Resilient Stainless Steel Tubing | Zoro.com

Fittings for 3/8"

Triple-Lok 6 BTX-S $1.11 Nut | Zoro.com

Order Triple-Lok Nut, 6 BTX-S at Zoro.com. Spend less, save more with competitive pricing on Flared Tube Fittings at Zoro.com.

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Triple-Lok 6 TX-S $0.83 Sleeve | Zoro.com

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This is what is used on industrial equipment all the time and is a proven and durable approach.

 

[kennyd]

Thanks for the tips. Any spikes I think are handled by an internal adjustable relief built into the valve, Vents via the tank return, I believe.

The adjustable reliefs on most valves are on the inlet side and not the work ports.

Correct. When the valve is in neutral, the PRV is not a factor.

 

[joea99]

Correct. When the valve is in neutral, the PRV is not a factor.

That does appear to be the case for this valve.