Seawater Corrosion vs. Magnisium Sulfate(Epsom Salt)

[houdini16]

I am trying to find out how corrosive Epsom Salt water is compared to Sea saltwater. This information if for a sensory deprivation tank, and there are not a lot of pumps or heaters designed for pools and spas that are capable of saltwater, most pumps have stainless steel shafts at the least, there are luckily some all Titanium heaters. Do you know what the corrosive differences are if any between the two.

Can stainless steels be used with a saltwater filtration system? If so which ones?

Water is stagnant except for during business hours it cycles for 15 min. every hour. There is 800 pounds of epsom salt in 150 gallons of water.Yes 800.

Thanks Guys, CHEERS.

 

[EdStainless]

Mg sulfate should be a lot less corrosive than seawater.
You need to use a pure enough grade that there is no chloride in it.
In industrial applications they use 316L stainless clear up to the boiling point in 26% solutions.

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[houdini16]

Most people use Pharmaceutical Grade Epsom Salts
I havent looked up the difference in sea water vs Mg Sulf.
But you think even this Extremely high concentration will still be ok?

Ive seen some mfgs use stainless, but wondered if they just didnt do any research, 316 is fairly expensive, do you think 303 or 304 would work, or no way?

Also most pumps Ive seen with stainless pump shafts say that it is stainless and for saltwater, but I work at a machine shop and as far as my research, stainless shafting is only made from a SS that can be hardened, usually 440 which is crap as far as corrosion. I thought about just buying the pump, turning the shaft down and pressing a new turned Titanium piece over it, and machine it to the original size.

 

[houdini16]

CHeck this out and tell me what you think.

http://www.parrinst.com/doc_library\dealer\Stain.pdf

 

[strider6]

houdini

have a look at these data:

http://books.google.it/books?id=KXw...onepage&q=magnesium sulfate corrosion&f=false

and also:

http://www.outokumpu.com/applications/corrosion/view_details.asp?name=MA04

as you can see 302, 303, 304 SS are resistant in concentrated Mg Sulfate.
Regarding the question on seawater corrosion, SS 316 is not a recommended material for this service due to the low resistance to pitting, crevice and also stress corrosion cracking.
in pharmaceutical they use SS to avoid any possibl e contamination of the product.

hope this help

S

Corrosion & Rust Prevention Control

 

[EdStainless]

Never use 303. It is the free machining grade and will often rust in air.
You probably could use 304, but I suggested 316 based on it's superior resistance to chlorides.
If you are building a tank then you should either use a non-metallic or use a lean duplex grade (LDX2101, ATI2102).
These alloys are much stronger than 304/316 so you could use thinner material. It would save metal cost and fab cost.

As for the pump I would again suggest non-metallic as much as possible. There are many pumps out there with cold worked Nitronic shafts that work fine.
While your starting solution will not be corrosive I am concerned about trace chlorides and long term effects.

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