Does an INOX reservoir start corrosion?

[Karantanec]

The question is straighforward. When using an INOX reservoir with copper waterblocks, does corrosion occur?

[jaydee]

You mean stainless steel resivoir?

[Karantanec]

Originally Posted by jaydee116

You mean stainless steel resivoir?

Yes. INOXidable steel (in my case type A.316) has usually added CrNiMo or other elements.
Same applies for fittings or alike - can I use such steel in a waterloop combined with copper?
I would really like a definitive answer to thi topic.

[redleader]

Stainless steel tends to have things like Zinc in it to stabilize the Iron's tendency to corrode in the presense of water. I'd imagine it wouldn't hurt copper, but I've never tried steel so i don't know.

[AngryAlpaca]

Copper is stronger (or whatever the term is) than steel so the only risk for corrosion (I think stainless gets rid of this) is to the reservoir, not to the blocks.

[Moony]

But the waterblocks will become reduced in the reaction and a layer of crap will form on them

[pHaestus]

copper in the waterblocks will be reduced? Not going to happen

[Cathar]

Had a loop using a passivised 316 SS filter mesh. After 3 months, the mesh was fine. Not a hint of corrosion. That was using the more highly anodic silver as a block, rather than just regular copper.

Thing is, so long as the 316 is not contaminated in any way, it'll be okay. You'll find out pretty quicky if there's a problem though.

[Karantanec]

Originally Posted by Cathar

Had a loop using a passivised 316 SS filter mesh. After 3 months, the mesh was fine. Not a hint of corrosion. That was using the more highly anodic silver as a block, rather than just regular copper.

Thing is, so long as the 316 is not contaminated in any way, it'll be okay. You'll find out pretty quicky if there's a problem though.

Hmmm...
What do u mean by contaminated? The steel itself or impurities from outside?
WOuld the use of some anti-corroding agent in the coolant quarantee safety?

[Cathar]

Originally Posted by Karantanec

Hmmm...
What do u mean by contaminated? The steel itself or impurities from outside?
WOuld the use of some anti-corroding agent in the coolant quarantee safety?

Contaminated, as in the steel itself as a result of its manufacture.

If the steel is fine, and there's a very good chance it will be, you won't need corrosion protection. If it isn't, then you basically need to treat it about the same as you would treat bare aluminium in a copper loop, which would mean at least a 25% concentration mix of anti-freeze/corrosion inhibitor.

[bigben2k]

The short answer is: yes it'll corrode (as with all metal combinations, but perhaps not as fast as you think).

The long answer would involve looking at a galvanic chart, and observe the different potential between SS and copper. Otherwise everything else has been covered.

[Karantanec]

Originally Posted by bigben2k

The short answer is: yes it'll corrode (as with all metal combinations, but perhaps not as fast as you think).

The long answer would involve looking at a galvanic chart, and observe the different potential between SS and copper. Otherwise everything else has been covered.

Would corrosion occur only on the stainless steel or would the copper elements get damaged too?
WHat METAL other then copper should I use then to make a reservoir?
WHat exact coolant mixture should I use, which prevents corrosion and doesnt lower the cooling properties? I hear anti-freeze hinders heat transfer.

A friend of mine implied there could be a way to circumvent corrosion between materials by connecting them with a copper wire outside the coolant (so the wire would make kind of a short-circuit between the reservoir and waterblocks, preventing the reaction through the fluid.
Any info on that?

[Butcher]

Brass or copper are good for not having a reaction with copper.

[redleader]

Originally Posted by Karantanec

Would corrosion occur only on the stainless steel or would the copper elements get damaged too?
WHat METAL other then copper should I use then to make a reservoir?
WHat exact coolant mixture should I use, which prevents corrosion and doesnt lower the cooling properties? I hear anti-freeze hinders heat transfer.

A friend of mine implied there could be a way to circumvent corrosion between materials by connecting them with a copper wire outside the coolant (so the wire would make kind of a short-circuit between the reservoir and waterblocks, preventing the reaction through the fluid.
Any info on that?

Won't help. He confused about how the battery effect works. The reaction isn't directly between the two materials, but rather between one piece of metal and dissolved ions in the coolant. Having a common potiential between the two metals doesn't affect the dissolved ions.

[bigben2k]

Redleader is correct.

http://www.thelenchannel.com/1galv.html

The copper would take the bite here, unless there's a finish on it, maybe.

[Butcher]

Depends if the 316 has been passivated or not. Active 316 is very much more anodic than copper, almost as much as as Al.

[Titan151]

Remember,

You need to have a metallic path in order for anything to happen in the first place. If you are not sure of this take a resistivity measurement between the waterblock and the radiator. Also, as you can see on the chart in the above link, the two metals are not that far apart. In short, the potential difference between the two metals is not very substantial so any problems should be minor. One other thing going for you is the use of distilled water. DW has a relatively high resistivity which will further inhibit the corrosion rate.

If you are still concerned about this, you could electrically isolate the radiator from the waterblock. Of course this may not be an option depending on how it is installed. Perhaps the thing to do would be to take it apart after a month and give it a good ol inspection.

edit - guess I should add that the above info primarily pertains to the presence of corrosion between disimiler metals.

[AngryAlpaca]

The reaction isn't directly between the two materials, but rather between one piece of metal and dissolved ions in the coolant. Having a common potiential between the two metals doesn't affect the dissolved ions.

You need to have a metallic path in order for anything to happen in the first place. If you are not sure of this take a resistivity measurement between the waterblock and the radiator. Also, as you can see on the chart in the above link, the two metals are not that far apart. In short, the potential difference between the two metals is not very substantial so any problems should be minor. One other thing going for you is the use of distilled water. DW has a relatively high resistivity which will further inhibit the corrosion rate.

If you are still concerned about this, you could electrically isolate the radiator from the waterblock. Of course this may not be an option depending on how it is installed. Perhaps the thing to do would be to take it apart after a month and give it a good ol inspection.

How do you plan to electrically isolate the radiator (we're talking reservoirs, by the way) from the water block? Not have water flowing through them? That won't work very well.

[Titan151]

Originally Posted by AngryAlpaca

How do you plan to electrically isolate the radiator (we're talking reservoirs, by the way) from the water block? Not have water flowing through them? That won't work very well.

The four parts of the corrosion cell are the Anode, Cathode, Electrolyte, and a Metallic path. By eliminating one you blow the circuit. In this case the water is the electrolyte. So yes, it isn't very effective to take this out of the loop. By isolating the reservoir from the waterblock you eliminate the potential for dissimilar metal corrosion between the reservoir and the block. They may as well be on two different sides of the ocean.

I'm not saying that he should isolate it, but if he wanted to he would simply need to install it with dielectric fittings, some rubber or something of that sort. Like I said it may not be possible depending on his installation method. If it is something that would be easy to do, then what the hell go for it.

[Titan151]

Originally Posted by redleader

Won't help. He confused about how the battery effect works. The reaction isn't directly between the two materials, but rather between one piece of metal and dissolved ions in the coolant. Having a common potiential between the two metals doesn't affect the dissolved ions.

This is the same exact thing as what I previously discussed except now the corrosion cell is taking place on a single object. Here the circuit takes place when one area of the same metal becomes more anodic compared to another area. This causes a potential imbalance on the metal surface. The anodic area (say a spot on a waterblock where the paint is missing), provides current to the cathodic area around it. Over time this can result in metal loss at the anodic area. Eventually you can get pitting and all of that action. This often happes with poorly galvanized or poorly anodized materials. As it starts to wear off the exposed areas form a corrosion cell with those areas that are still covered. Here, the electrolyte could be condensation, water inside the reservoir, steam, or who knows what. So to eliminate the problem you have to cut part of the circuit. Since this occurs within a metal you are somewhat limited to your options. Typically the problem is solved by removing the electrolyte or insulating the anode from the corrosion (by recoating).