Galvanic Corrosion - AN Power Steering Fittings - Aluminum and Steel

[bsampson]

I'm doing a hydroboost conversion for brakes, which uses the power steering system. I was planning to use flexible tubing cut to length and AN fittings. I ordered a few plumbing parts not thinking about a problem combining different metals. It was hard enough to find the right fittings at a reasonable price.

I ended up with aluminum fittings, and now to get lines rated at a working pressure 1500 psi+, most ends are steel.

Is there going to be a problem mixing aluminum and steel AN fittings? Or is galvanic corrosion something that wouldn't be an issue for many years?

[Steeveedee]

I'd say probably not, if you keep any electrolytes away from the fittings. I see that you are in snow country (for part of the year). If you drive it and get any road salt on the parts, combined with water you could have issues. I'd spray the completed assembly with a clear coat and give it a visual whenever I did an oil change. It won't corrode from the inside, as it's full of oil.

[HO455]

Are you using hose with an external steel braid or with a rubber external coating? I've built hundreds of hydraulic hoses with internal braid installed on sea going tug boats with no issues unless they were installed on deck. Meaning constant direct salt water exposure. Those fittings we would wrap and seal them against the elements. So with the internal braid hose I would not think twice about it.
The external wire braid hose is a different animal that I don't have experience with so I'm of no help there.
I hope this helps.

[LS short box]

I would double check the PSI you are working with. On a typical power steering pressure side most recommend the Teflon lined SS hose and the correct fitting. All of those use steel fittings. On the return side which is low pressure typical power steering hose can be used or braided SS lines.

[bsampson]

Thanks for the input guys. Re-reading what I wrote, I wasn't as clear as I should have been. I already bought the adapters to go from the stock PS pump, hydroboost, and gear box. These all adapt to AN -6, and are aluminum.

So, I was shopping for hoses and hose ends. As pointed out by LS_Short_Box, anything that supports high pressure has steel ends.

I ended up going with a PTFE hose with braided 304 stainless steel (Russell Powerflex) with steel AN -6 ends. The setup is rated to 2500psi. I threw in the towel on being cheap.

Being AN fittings, they are easy to take apart an check, so I'll do that in a year or two and see if there are any visible signs of corrosion on the surfaces that contact each other.