Steel Tank Stand Chemistry Question

[GBRsouth]

@Randy Holmes-Farley, I have heard, that when in contact with steel/iron, aluminium acts as a sacrificial metal in oxidising first through electrolysis.

1. Is this information correct?

2. Could intentionally connecting aluminium to a steel stand be an effective means of preventing iron oxidation used in conjunction with normal powder coating methods.

I know it is not the normal in tank chemistry, but would love to hear your thoughts on this.

Thanks in advance.
Mick.

Anyone else who feels they are qualified to answer this question, your input is welcomed too.

 

[Lasse]

Normal sacrificial anodes are made of zinc - but what I have seen lately - even aluminium is used. Once I was a shipyard worker - we always mounted zinc anodes directly on the steel in the tanks that contained oil and everywhere else where there was a risk of rust. Here in Sweden - I can find this type of anodes in shops for recreational boats

Sincerely Lasse

 

[GBRsouth]

@Lasse thank you for the reply. I'll have a look in boat shops here and see what I can come up with.

 

[Randy Holmes-Farley Verified Community Expert]

@Randy Holmes-Farley, I have heard, that when in contact with steel/iron, aluminium acts as a sacrificial metal in oxidising first through electrolysis.

1. Is this information correct?

2. Could intentionally connecting aluminium to a steel stand be an effective means of preventing iron oxidation used in conjunction with normal powder coating methods.

I know it is not the normal in tank chemistry, but would love to hear your thoughts on this.

Thanks in advance.
Mick.

Anyone else who feels they are qualified to answer this question, your input is welcomed too.

What are you trying to prevent?

Sacrificial anodes will only work if they are exposed to the same corrosive solution.

For example, if you bolted zinc to steel and put the whole contraption into seawater, the zinc will corrode first.

But if you splash seawater onto a piece of steel that somewhere else has a piece of zinc attached to it (that doesn't get wet), then the zinc won't do anything.

Also remember to be sacrificial, these metals dissolve into the corroding solution. If that gets back into the tank water, you may find elevated aluminum or zinc. Folks have had issues from corroding metal parts just above the water.

 

[GBRsouth]

@Randy Holmes-Farley thank you for your reply. You've corrected my understanding of how a sacrificial metal would or would not work.

I was wrongly under the impression that the sacrificial metal would work even if it wasn't the part in contact with the salt water, as long as it was in contact with the iron/iron alloy.

Thanks for setting me straight.

Mick

 

[Randy Holmes-Farley Verified Community Expert]

You're welcome.

Happy reefing.