Protect Metals submerged in swimming pool
Protect Metals submerged in swimming pool
(OP)
I am going to build and submerge test hardware in a swimming pool. What type of stainless and what type of coating for alumium is recommended for long-term submersion?
Should sacrificial anodes be considered?
Should sacrificial anodes be considered?





RE: Protect Metals submerged in swimming pool
RE: Protect Metals submerged in swimming pool
None of this is built yet, so it's all adjustable.
RE: Protect Metals submerged in swimming pool
RE: Protect Metals submerged in swimming pool
The water in the swimming pool can be contaminated and chlorinated to the extent that even the ordinary stainless steel may corrode in relative short time. The temperature is also important, as it can accelerate the corrosion rate. Sometimes, the small kids in the pool might have an 'accident', contributing to the corrosive contaminants. Birds, algae and other contaminants in an open pool tend to aggravate the corrosion rate. You should also visit a public heated swimming pool and look at the roof supporting structure how rusted it is, perhaps have a look at the stainless steel fittings around the pool, some of them are quite rusted, particularly if they were in contact with some carbon steel components. Most of that rust is due to the vapour condensing on metallic surfaces or worst, submerged in the pool water. The chlorine corrodes everything at the given temperature of this heated pool. So try to be a bit more specific with the pool water chemical composition, particularly in chlorides are present, the water temperature and any other contaminant which could be in the pool and is not normally present in, say potable water. Then you might get in this forum a professional advice on your project.
Cheers,
gr2vessels
RE: Protect Metals submerged in swimming pool
The environment is heated (80 to 100 F)and treated water but does not otherwise see the normal pool loads, i.e. no people, few biologics. So, it probably does not require strong oxidizers to keep the water clear. As a test tank, it will be in use for 20 years or more. The fixture frames can be stainless steel or anodized aluminum but can be easily replaced. The important thing is that the tank envelope last 20 years. I am reading here and elsewhere that I should limit stresses and wear on submerged stainless steel, especially around chlorine/bromine. I can use a non-chlorine treatment that is a less effective treatment because I have no bathers, I'm inside a building, and I will cover the tank at the end of each day. To limit metal stress I can reduce bolted fittings on the inside walls of the tank. And to reduce condensation on other metal surfaces surrounding tank I can have good ventilation followed by covering the tank.
What non-chlorine treatments are recommended?
Is 6 % Mo stainless the recommendation as from CoryPad?
Can I get a 20 year tank in the end?
RE: Protect Metals submerged in swimming pool
You also have to avoid dissimilar metals. A steel nut or bolt dropped in can start localized pitting that can get serious.
If I was doing this today I would look at using 2205. This material is very strong and much more corrosion resistant than 316. It also has a reasonable cost.
For any stainless make sure that the welds are pickled before it is put into service. This includes the weted side of where braces are welded to the outside. If there is any discoloration pickle it.
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Plymouth Tube
RE: Protect Metals submerged in swimming pool
- so it will be the sole and immediate user that will maintain it under your test facility's control, rather than be making a "dunk kit" that gets dropped into a commercial/government open-water swimming pool.
Right?
RE: Protect Metals submerged in swimming pool
Cheers,
gr2vessels
RE: Protect Metals submerged in swimming pool
RE: Protect Metals submerged in swimming pool
Cheers,
gr2vessels
RE: Protect Metals submerged in swimming pool
RE: Protect Metals submerged in swimming pool
The non-chlorine treatment I found is ECOsmarte. They describe it as a "copper ionization technology" and "Oxidation is achieved when water
passes through the titatnium electrode plate with a
low voltage electrical current".
I don't know, but the copper may be corrosive to the stainless steel.
http://www.ecosmartepool.com/spa-treatment.html
RE: Protect Metals submerged in swimming pool
RE: Protect Metals submerged in swimming pool
This little unit look fine. Since you won't have a high organic load in the tank this should be plenty. Don't worry about too much Cu, it would take a heck of a lot to cause problems.
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Plymouth Tube