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Q&As since 1989


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Best Sleeve Material/Coating in Saltwater Environment

We presently use a stainless (304) thin-walled sleeve (7/16" X .028 wall X 1/4" lg.) inserted into a plastic grommet-like device to expand and secure a plastic tube internally in a kayak. The stainless tube is expensive and difficult to manufacture in modest quantities. I am considering replacing it with either an anodized aluminum or nickel plated brass tube of the same dimension. It will be subject to intermittent splashing of saltwater. The tube will be electrically isolated from it's environment. Can someone advise me on the best way to go here?

Dan Kidd
Yankee Engineering, Inc. - Limington, ME, USA
2005

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If the issue is cost savings based on material of construction, I'd forget it and stay with the stainless. Anodizing or nickel plating are additional processes that will not be inexpensive either, and the anodizing may be a questionable solution, since it must remain perfect to be at all satisfactory.

If the issue is that some machining or manufacturing operation is difficult with the stainless steel, you might consider electroforming the sleeve from nickel, which might give you a finished part in a single operation with no machining required at all.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2005

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2005

Naval brass lasts but titanium looks better for longer.
For price, you cannot beat a piece of nylon air line. A dab of epoxy or cyanoacrylate adhesive will bond it sufficiently inside the rubber grommet.

Top RC planes and kites today are made from carbon fiber/epoxy tubing. Search some RC modle airplane or kite suppliers online.

Jack Wells
- Austin, Texas

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Hi Dan,

I'm surprised that no one has mentioned MONEL ... that copper nickel alloy.

Isn't that supposed to be the cat's meow for salt water applications?

For more info goest thou to Special Metals in the USA or Special Metals Wiggin in the UK.

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).
2005

I suggest CP titanium which is immune to such atmospheres.

R. Annakumar
- Chennai, India
2005