Under water hydraulic hoses

[Ole Anderson]

I have a hydraulic lift for my pontoon boat, it lives in fresh water all year as I store my shrink wrapped pontoon on the lift in the winter also as do many of my neighbors. I love the hydraulic lift vs my previous cable lift. So much faster, no cables to worry about and the key fob remote along with battery operation charged by a 20 watt solar panel.

The downside? I blew a hydraulic hose after only 3.5 years of operation. Three year warranty. Dumped over a gallon of "environmentally friendly" oil in the canal on which I live. Fortunately it happened in the evening and by morning the plume was gone. The hoses above water looked almost new, below water they were just covered with bumps where the outer casing bubbled. One of the bubbles was where the leak occurred. No previous sheen to indicate a leak.

Anyone with a working knowledge of hydraulic hoses used underwater? My local hydraulic shop said he has replaced the hoses on many lifts and didn't believe anyone makes hydraulic hoses with stainless steel interior braid. He does have SS fittings which I intend to have him use. But picking apart a few bubbles didn't reveal any rust on the interior braid. I don't know the mode of failure, could it have been the interior lining failing? We do have zebra mussels which were attached to the hoses, but I don't believe the bubbles were necessarily located where the mussels attached themselves. Wondering if covering the hoses with corrugated electrical automotive wire loom would help?

The lift manufacturer said he never had a hose failure before 5 years and has many lifts out there with 10-15 YO hoses. Of course. Fortunately we have a local outfit that will pluck the hoist out of the water with a pontoon based crane for $125.

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[Jim Becker]

Maybe a smooth wall hose would fair better?

[Ole Anderson]

Maybe a smooth wall hose would fair better? Yes I am thinking a hose with a plastic smooth coating would be preferable, not sure it is available.

[Bill Dufour]

Any idea on pressure? I wonder what oil you are actually using and it's compatibility with the hose designed for petroleum oils.
Bill D.

[Jerry Bruette]

All the hydraulic hoses I've dealt with were made of 3 layers. The inside layer was some type of what appeared to be plastic, possibly PVC. The next, middle, layer was the reinforcing wire and the third layer was the rubber jacket.

If the inner layer fails the material in the hose will leak from the inner layer but may be contained by the outer jacket, that's where the bubbles come from.

At my past places of employment we would have the outer jacket pin pricked and that would let us know that the inner layer had leaked. We didn't do this for hydraulic hoses but for CO2, Anhydrous Ammonia, and high pressure air(850 psi).

One employer didn't pin prick their hoses until I started working there and recommended doing it. I've seen CO2 hoses where the inner layer leaked and the outer jacket held the pressure. This caused the inner layer to collapse essentially shutting off the flow of material. That was a hard one to troubleshoot.

I don't think your leak started from the outer jacket being crusty, but from the inner layer somehow breaking down. Yo could maybe go with a hose that's rated higher than your system pressure and the hose may last longer, the stainless fittings are a good idea too.

[Ole Anderson]

Any idea on pressure? I wonder what oil you are actually using and it's compatibility with the hose designed for petroleum oils.
Bill D.
I have the same concern. The hose is Flexdraulic brand and they note that it is good for many liquids including mineral and polyglycol based hydraulic fluids. I see that many EALs (Environmentally Acceptable Lubricants) include synthetic esters, which may or may not be compatible with the hose lining. I have a call into the hoist maker to ask what oil they use, in an earlier conversation they specifically said it was not a vegetable oil base. I do note that Flexdraulic says to not submerge them in water or expose them to sunlight. Two strikes right there. And they are not compatible with phosphate ester hydraulic fluids. Maybe strike three?

[Tom M King]

I have never seen, or heard of a hydraulic boat lift before. All the ones here are cable hung. I'm very interested in investigating them now, as I like the idea a lot.

It seems like the manufacturer would know what to use. I'm getting ready to build a four slot boathouse fairly soon.

[Jim Becker]

Yes I am thinking a hose with a plastic smooth coating would be preferable, not sure it is available.
All of the hydraulic hoses I've purchased in recent years for the Big Orange Power Tool have smooth jackets...

[Ronald Blue]

We used Eaton Aeroquip almost exclusively. I will attach a link to their hose catalog. My thought is you need to be proactive and change before a failure. The corrosion on the fittings is also concerning. Looks a lot like the fittings I've dealt with on the equipment that gets exposed to road salt. Those are JIC fittings which isn't an issue because it's probably my favorite style. Any type of pipe is the least favorite of all. I will presume you are running at 2000 psi or there abouts. That looks like it is either #6 or #8 hose. That's 3/8" or 1/2". even 2 braid hose is well over the pressures you should be seeing there. 5300 and 4500 PSI operating pressures respectively. Burst pressure is at 4 times that. How long are the hoses in total length? The bubbles on the surface mean that somewhere and maybe several points water infiltrated the protective cover and damaged the steel braid. That is where the pressure is contained. If they are not difficult to access and not terribly expensive planned replacement might be the best way to deal with them.

This will be somewhat confusing but the GH 781 or GH793 are good all around hose series.
https://www.eaton.com/ecm/groups/public/@pub/@eaton/@hyd/documents/content/pct_479318.pdf

[Ole Anderson]

Mine was built by Schneider Fabrication in St, Johns, Michigan. But if you Google Hydraulic Boat Lifts, you may find a seller near you. Others do build a pile mounted hydraulic lift. https://www.schneiderfab.com/

[Ole Anderson]

Talked to my hoist builder. They use Eviron AW46 hydraulic oil which is mineral (petroleum) based. And they are investigating a changeover to a thermoplastic, nylon reinforced hose.

Eviron AW46 is an inherently biodegradable product. Not necessarily a good thing as it will eventually break down but over a very long time, 35% in 40 days. Plant based oils will break down much faster, as much as 100% in 40 days. But plant based oil with an ester base might require a specialty hose.

[Tom M King]

I see why they are not used here. They are a Lot more expensive than the cable systems everyone uses here. These are even made locally. Our water level is maintained within one foot, so no need for floating docks even.

https://doozieboatlifts.com/?gclid=CjwKCAjwkYGVBhArEiwA4sZLuDnwd_9jCDHCkhvqQZk HrV-fe_oslIznGOSQ5uI7aipIkPUsTZbUtxoClqwQAvD_BwE

[Ronald Blue]

Talked to my hoist builder. They use Eviron AW46 hydraulic oil which is mineral (petroleum) based. And they are investigating a changeover to a thermoplastic, nylon reinforced hose.

Eviron AW46 is an inherently biodegradable product. Not necessarily a good thing as it will eventually break down but over a very long time, 35% in 40 days. Plant based oils will break down much faster, as much as 100% in 40 days. But plant based oil with an ester base might require a specialty hose.

ISO 46 is a high quality hydraulic fluid. Every company put's their own identifier on it such as the "Environ AW" title. The key is the 46 though. It's an industry standard. There is also ISO 32 for extreme cold operations. There is synthetic hose that is Kevlar reinforced but the draw back is it is not as flexible. That probably isn't an issue in this application so would be worth exploring. I would also explore that avenue separately. Look for hydraulic shops in the area that may have options available to you. I'm referring to actual hydraulic shops and not a parts store that has a hose machine.

This place came up when I did an online search.
https://www.pirtekusa.com/locations/madison-heights/

[Ole Anderson]

I used Loryco in Pontiac MI to build new hoses while I waited. https://loryco.com/ Disappointed they did not have SS fittings in stock due to supply issues. Couldn't wait. Hose was two wire 5000 psi WP standard design from CSI (Contractor Supply Inc). Oil is Phillips 66 NZ46 mineral based biodegradable. I'm going to slide 3/4" split electrical loom over the hose to protect from zebra mussels and physical abrasion. The rods are chrome plated SS, but had a deposit of scale on them which I am sure is hard on the wipers and seals. I cleaned them up to like new with 30 Second Outdoor cleaner followed by muriatic acid and a light wiping with an abrasive pad followed by a light pressure wash and a spray of WD40 white lithium grease.

[Ole Anderson]

And after a heavy spray of WD40 white lithium grease on the fittings, I'm ready to have it put back in the water this afternoon.
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[Kev Williams]

You might consider finding some small screw-on zinc anodes and some stainless cable and hang them around your tee's- if the corrosion is due to stray current or other electrolysis related issue, the anodes will corrode first...
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[Bill Dufour]

Note that stainless steel in still water is not great at resisting corrosion. The chemistry needs wave action or water flow to work.
Bill D

[Scott T Smith]

We replace a lot of hydraulic hoses on equipment here at the farm and sawmill. Invariably, they go bad when the outer jacket gets damaged, and allows moisture to seep into the wire reinforcement. Once the wire reinforcement rusts through, pressure will cause a blowout where the reinforcement is gone.

What I would suggest you do is install a layer of 2 or 3 ply heat shrink tubing the entire length of the hose before installing it under water. Some heat shrink has a heat activated adhesive inside and that would be even better. You can source it online from Del City and others.

The additional layer of protection should help protect the jacket and keep moisture away from the wires, thus prolonging the life of the hose.

I'd also verify that whatever inner lining is used with the hose is compatible with your special hydraulic fluid.

Best of success to you.

[Ole Anderson]

We replace a lot of hydraulic hoses on equipment here at the farm and sawmill. Invariably, they go bad when the outer jacket gets damaged, and allows moisture to seep into the wire reinforcement. Once the wire reinforcement rusts through, pressure will cause a blowout where the reinforcement is gone.

What I would suggest you do is install a layer of 2 or 3 ply heat shrink tubing the entire length of the hose before installing it under water. Some heat shrink has a heat activated adhesive inside and that would be even better. You can source it online from Del City and others.

The additional layer of protection should help protect the jacket and keep moisture away from the wires, thus prolonging the life of the hose.

I'd also verify that whatever inner lining is used with the hose is compatible with your special hydraulic fluid.

Best of success to you. Thanks for the suggestion. Lift is already back in the water and in service. I wrapped the hoses with 3/4" corrugated split automotive electrical loom. It will at least keep the zebra mussels from munching on the hose. Several have told me that blisters on the exterior was likely from a combination of exposure of the outer jacket and failure of the inner liner. At the location of the blister that actually leaked I was surprised to find the steel reinforcement had not rusted.