Tanks - Aluminium Vs Stainless?

Aluminium could suffer from the fact that it is a very reactive metal. It could be vunerable to electrolytic or galvanic corrosion from stray electric currents or contact with other incompatible metals. If aluminium is to be painted it must be primed with the correct primer. Internal coating would almost certainly need to be a much more hi tech coating than paint. They do make boat hulls of aluminium though!
For most porposes stainless steel should require no protective coating.
 
read a thread on eng tips, if you use copper pipe to supply aluminium tank the copper sulphite can cause pitting corrosion to tank
 
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the copper sulphite

[/ QUOTE ] I am not sure where you are getting your copper sulphite from but ceratinly copper and aluminium are not compatible and galvanic corrosion of the aluminiun will be likely.
 
Maybe the debate is whether a metal tank is the best option these days, given the developments in plastics. In your earlier posts, I think you raised the possibility of having a tank made by Tek Tanks. Definitely worth pursuing as it avoids some of the downsides of both SS and Ali, with no significant negatives except maybe cost - although the costings I got for the last two tanks I had made were little different between SS and Tek Tanks, maybe because of the irregular shapes and number of fittings.
 
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it was copper ions

[/ QUOTE ] Thats better. The effect is going to be small but probably cumulative and the amount of copper in the water will depend very much on the composition of the water and also on flowrates in the supply pipewok. Turbulance and high velocities can have a very dramatic effect on copper pipe. If copper pipework or brass fittings are connected to an aluminium tank high corrosion rates are likely . that was my initial thought.
 
I have just replaced one of my water tanks with a tec tanks type (made in Barcelona by a british guy) I would reccomend this type of tank, excellent and strong, no corrosion probs.
 
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a tec tanks type ............. I would reccomend this type of tank

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Good job you are not answering an exam question. We were asked to consider aluminium vs stainless steel Recommending plastic will get you no marks. /forums/images/graemlins/grin.gif

Possibly the best solution in the long run though.
 
How fire resistant are the plastic tanks?

Twin aluminium 50 litre tanks installed 15 years ago, unpainted and unlined, connected with standard plastic diesel hose to filters then steel pipe. No problems to date and still look like new.

Avagoodweekend......
 
Dunno. I've had mild steel, stainless steel and plastic, all without problem.
You can get a mild, or stainless steel tank made, to dementions, probably aluminium as well. A plastic tank probably needs to be moulded, so not practicable for one, or ten.

Do the sums, any sheet mettal worker should be abe to knock a tank together, steel ali, or stainless. For plastic, I think it will have to be standard, or a very expencive mould.

Either way, it should last for 20 years, maybe longer.
 
Haydn, where you bin?? You were into plastics!!

They can make any shape of plastic tank nowadays, (dunno about round) from pattern without a mould, they can weld it together, wiv some special gear, that's how they made my tank to fit. A 60 gallon one at that! He's (the chap in barcelona)also gonna make me a black water tank and all the fittings etc. /forums/images/graemlins/grin.gif
 
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Hallberg Rassy use stainless steel for theirs.
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And it's a mistake. Our Najad had a stainless steel holding tank. 15 years later and it corroded through. Urine is very corrosive to stainless steel. (Corroded through in the most bottom corner where there is always some sewage left.)
Lots of articles on the web about it. I'm not sure if Hallberg still use stainless. I think a lot of manufacturers wisened up.
 
If I was buying a new HR then that is one thing I would change on the spec. I wouldn't want to go through that hassle again. If I was buying a second hand HR I would be suspicious of the holding tank. It's always possible I suppose that they now use medical grade stainless steel and some owners may have the heads discharge permanently diverted to go straight overboard.
 
Stainless will eventually fail at the welds (something to do with the what happens to the Chromium in the stainless), but is considerably more durable than aluminium IMHO.

Having just replaced an aluminium holding tank that had rotted through in a few years, I would favour plastic every time.

Hope that satisfies the examiner...../forums/images/graemlins/grin.gif
 
No intentions of using stainless, "proper" plastic one for me, made to fit hole available and fully EU/World accepted etc, and all that horseshit!!
 
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