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Old 07-31-2021, 11:27 AM   #1
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Hydraulic steering tubing sets

Can anyone comment on recommended wall thickness and/or pressure ratings needed for copper or copper-nickel tubing runs in a Teleflex hydraulic steering system on my twin rudder, 2 helm, 44 foot boat?

I've read some threads on this:
Sounds like "refrigeration" tubing is what's recommended by Teleflex if you don't buy from them. So is it wall thickness or pressure rating that makes it qualify as "refrigeration tubing"? I guess thickness and pressure rating are different ways of saying the same thing.
I just don't want to buy a roll of something that's underrated for my application.

Also, I'm hearing that copper-nickel is more corrosion resistant and easier to work with. I'm assuming I don't need to worry about dissimilar metal issues with this since everything is obviously copper compatible? I'm planning on leaving the original copper runs and replace problem runs with copper-nickel. I'm assuming a mixed system like this would be fine?

Also sounds like double flare fittings are best. I've seen the kits for these and the process seems pretty simple and I'm pretty handy. Are these fittings pretty easy to get right after a few practice tries?

My system instructs me to pressurize to around 40 psi so is that the max pressure in the system or does steering under load create higher pressures?

Thanks in advance...
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Old 07-31-2021, 02:08 PM   #2
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On my GB it is refrigeration tubing, along with the fittings. Most commercial AC distributors will have what you need. I think it is slightly thicker wall for higher pressures.

I considered using braided flex or maybe even Pex. But I currently have it as delivered. The copper tubing can be repaired easily.

You did not state why your asking the question.
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Old 07-31-2021, 03:34 PM   #3
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My system of 43 years has all copper tubing. There is a slightly thicker wall but what my boat has specifically I don't know. However I do not buy from suppliers like Home Depot or the like. I go to a proper supplier of industrial materials or refrigeration.

I ONLY use a double flare kit, a now old Weatherhead. It will take some practice to reliably produce a good double flare. THe flares are 45o, NOT 37.

You will need a small smoothing file to ease the exterior edges of each flare before forming the initial part of the flare. You will need a decent countersinking tool also to relieve the sharp interior edges of the tube ID. 3 or 4 flutes. The two can do a decent job but to often a a bit rough and create a burr.
I also suggest a GOOD, Rigid, small tubing cutter.
Either a small vac. to pull any chips out of the tube or a small air tank to blow the chips out. Make sure there is NO debris left or it can very well cause trouble in the system.

Keep the gripper rings in the clamp bars free of copper flakes or the bars will not be able to grip and the tube will slide.

Any systems I have seen are limited to about 1,000PSI but that is a high point or should be. The good copper tubing will easily withstand that. Just support it well, every 8 " or so so it does not vibrate.
If you do need to run lines through air where there is nothing to support it well I have used 3/4" Ply pieces and clamps to secure each line to the other with a solid support and stop individual tubes from vibrating.

The only problems my system had were with the OEM single flares which were POORLY done and many split. Once those were redone the system has been dry for the last 20+ yrs..

I don't think you need cuni tubing unless you simply want it.

I carry some of the tubing, about 15', some brass flare fittings and the flaring kit as part of the boat tool kit.

Even for my diesel stove fuel lines I only use the double flare kit.

Have fun.
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Old 07-31-2021, 04:32 PM   #4
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Helm pump pressure is up to 1000 psi so you should size for it.
On my boat I have all copper tubing except the last foot in flex hose.
However I plan to replace everything with hydraulic hoses sized for the helm pump max pressure.
Why and what I don't like with copper?
1. Subject to corrosion. Even in fresh water I so some corroded parts and considering the pain to access I prefer to avoid the risk.
2. Copper more rigid so more subject to vibration and stress on fittings.
3. Fitting are as good as the guy making them.

Hydraulic hose is a bit more pricey but range between 3 and 10$ per foot (canadian) so not so expensive, fittings are properly crimped and if hose are properly attached it will last longer than myself, peace of mind.

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Old 07-31-2021, 06:06 PM   #5
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If your goal is replacement of existing lines and you have difficult to access places or tight working spaces then I suggest hydraulic hose all the way for a number of reasons. This past winter I tore out all of the 1983 vintage copper.

My plan had been copper all the way. It quickly became apparent that the long runs would require repeated bend and straighten which would work harden the copper. Further Hynautic said to support the copper every 18" to prevent work hardening and failure. This would not have been possible on the longer runs.

My plan then changed to hyd hose from the steering ram to the forward engine room where the autopilot pump, reservoir and TEEs to the helm pumps are located. I would use copper from there.

All good on paper. But I found I still needed to make repeated bend and straighten motions that hardened the copper. Flares had to be made before running the copper on some runs due to extremely tight working spaces. Which meant the lengths had to be exact. Additionally the copper I was able to purchase was not uniform wall thickness often causing the double flares to not form proper "bells". I couldn't shorten to replace bad flares resulting a lot of copper in the recycle bin before I had all the leaks resolved. While none of the hyd hose joints leaked.

Yes hyd hose is more $$$ than copper. But the amount of waste closed the cost gap considerably. And the time I would have saved using hose would have been significant.

Evaluate your entire project on probable success not just the cost of copper vs hose
Some things are worth doing simply because they are worth doing.
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Old 07-31-2021, 08:45 PM   #6
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Second the hydraulic hose. I have encountered cracks and splits with cu tubing. Also agree that bends must be pre-done before installation and if the double flare is off, then the piece is scrapped. Single flares are much easier to do on water lines but even then, the bends must be pre-done.
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Old 08-01-2021, 08:32 PM   #7
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Thanks for the input thus far - very helpful.
Reason for the question:
During my last 3 day outing, I noticed a slow leak had developed where one of the copper lines joined my autopilot pump in the engine room. The autopilot was already defunct so my plan was to remove the pump and cap off the 3 short copper runs to the pump at their source/origin.
I did this and that went great.

On inspection of the remaining lines, everything I can see looks good and is well supported except for a short distance of corrosion on the 3 copper lines running up to the upper helm. It's where they make a 90 deg bend to enter the opening in the engine room ceiling for the vertical run to the upper helm. This area is pictured below before and after treatment with Corrosion Block. But I think their days are numbered.

My plan was to replace like with like: copper tubing with double flare ends. I'd need to learn a new skill by watching more U-Tube videos on making double flares and buy the kit.

But after reading the above I'm wondering if hydraulic hose would be a better option given my inexperience with making double flares. The kit for this is cheap but the potential cost of losing steering could be expensive.

I'm estimating the length of the run to the upper helm is around 15 feet. I had read that long runs of hydraulic hose could lead to changes in steering feel and/or performance due to loosing the stiffness of the copper.

Any opinions on that?
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Old 08-01-2021, 09:05 PM   #8
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I wouldn't trust the copper in your pic.

Regarding loss of performance with hyd hose vs copper, I don't see any loss. But, and this is a big but, I also had both helms, the autopilot pump and the ram overhauled.

Hynautics, now Seastar recommend hyd hose when I described the challenges.

Hyd hose ID is the same as copper refrigeration tubing OD. Loose a little to friction, gain a little to increased diameter.

Regarding double flares. If you go that way buy extra copper to practice with. Buy a quality flare kit, a cheap one will only get you frustration and disappointment. Buy a tubing bender. When you add all that up the difference in cost between copper and hyd hose isn't all that much for the short runs you are talking about.

About the only negative I see to hyd hose is a shorter life. However if this 1983 boat is still running when the hose needs to be replaced I'll be surprised.
Some things are worth doing simply because they are worth doing.
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Old 08-06-2021, 02:04 PM   #9
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THANKS for all suggestions.

Any recommendations on brand or model for a quality double flare tool kit?

Iím not going to make a living with this but donít want to skimp and have leaky connectionsÖ
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