Metal finishing Q&As since 1989
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Anodized Aluminum in swimming pool areas
Q. We have previously supplied fittings for use in a pool area made of 316 Stainless however these have corroded even after passivation.
We are considering re-making these in 6082-T6 aluminum and getting them anodized. We are stuck as what to specify in the way of film thickness and whether to get them hard anodized or not. It is important that the fittings do not go too dark grey in color. The fittings are approximately 2m above the pool level but are used in some cases near a steam room and sauna.
In light of the fact that we were advised 316 stainless would be perfectly good for this application we need to be 100% sure that an anodized aluminum finish will not corrode or deteriorate if this is the route we need to take to rectify the problem.
Thanks,
Thomas Braylighting manufacturer - Barrowford, Lancashire, UK
2004
"Corrosion of Metals in Swimming Pool Buildings"
by Moore & Cox
on
AbeBooks
or
Amazon
(affil links)
A. I doubt that the good samaritans who offer free advice here can offer the 100% sure money back guarantee you seek, Thomas :-)
I don't think a steam room or sauna will be troublesome to either stainless steel or aluminum, but the chlorine in a swimming pool is always a problem.
If you hard anodize the aluminum, it will go gray. To keep it shiny, you need to bright dip it and anodize it to just a few ten-thousandths. I don't think that will be an improvement over stainless steel. Why not high quality nickel-chrome plating on brass?
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. In regards to your use of stainless steel for swimming pools, you need to use duplex or superduplex stainless steel alloys which have a very high chrome content- you will have no issues with chlorine then.
Simon Jackson- Dubai, UAE
January 16, 2012
A. You must be using cheap Chinese 318 stainless. You get what you pay for.
Short of a tea stain proper 318 stainless should not corrode away.
- Sydney. Australia
November 1, 2018
Q. We build plate alloy boats in marine grade aluminum. We are trying to determine whether it is at all possible to build a swimming pool from fully welded plate. If so, what coatings would be needed if any? No other metals would be in contact. It would be above ground with wooden deck surround. Outdoors. We are in a hot tropical climate. I am gathering from other posts/threads that this may not be possible unless coated (if even then), but in every other way this is the most viable option for us for a pool, so would love to hear that this could work.
Thanks in advance.
- Fiji
June 21, 2012
A. Hi Amanda.
I haven't heard of this, but that doesn't mean it hasn't been done. Outboard motors are frequently painted aluminum, even for saltwater use, so it sounds feasible to me. I would think that replaceable magnesium anodes would be very beneficial in protecting any aluminum exposed by scratches or pinholes in the coating. I'm certainly a layman when it comes to swimming pools, so consider this brainstorming rather than an authoritative response :-)
Good luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
June 22, 2012
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