Aluminum tank

[Lister]

Do you see any problems with the ethanol mix in regular gas and aluminum tanks?
Thank you
Lister

[michael pierzga]

They say that its corrosive ?. I dont know, we dont run boats on corn cobs over here. The typical repair of a non integral alum tanks that I see is corrosion from the outside.

Be sure that the exterior is well coated with primer , that the tank is mounted on heavy gauge welded tabs and that the tank is dry and ventilated on the outside.

http://www.nmma.org/assets/cabinets/...tion_Paper.doc

[Lister]

Thank you Michael. I was concerned also with the interaction inside the tank with the new coming 15% ethanol and the aluminum. Your link about the ethanol is quite informative, enough to be cautious of the aluminum tank.
What a piss poor gasoline we have over here. Sad to say but I prefer to eat the corn than to put it on my tank
But I keep in mind your outside recommendations.
Lister

[michael pierzga]

If youre considering plastic tanks Oceanlink has a huge selection of stock tanks

http://www.oceanlinkinc.com/tanks/gas-diesel.htm

[Lister]

Nice link, thanks
Lister

[CatBuilder]

From the NMMA:

Aluminum Fuel Tanks

In the case of aluminum tanks, aluminum is a highly conductive metal that relies on an oxide layer for its corrosion protection properties. Low levels of ethanol, such as E10 (10%), are usually not a problem in aluminum tanks because the oxide layer provides a good measure of protection. The problem occurs when the ethanol content is increased.

There are two mechanisms that occur with ethanol. Both mechanisms are a result of the hydroscopic property of ethanol, meaning it absorbs water. The more ethanol in the fuel, the more water there will be in the fuel tank. Water not only causes the tank to corrode, it also causes the corrosion particles to clog fuel filters, fuel systems, and damage engine components. The corrosion rate can be accelerated under a number of conditions if other contaminating metals are present such as copper which may be picked up from brass fittings or as a low level contaminant in the aluminum alloy. Chloride, which is a chemical found in salt water, will also accelerate corrosion. In the long term, corrosion can perforate the aluminum to produce leaks that would cause fuel to spill into the bilge and end up in the environment. In the worse case it could cause a fire and/or explosion hazard. Boat fuel tanks are often located under the deck next to the engine where the operator might not be aware of a leak until it was too late. .

The second mechanism that can occurs with the increased use of ethanol based fuel in aluminum tanks is galvanic corrosion. Gasoline fuel is not conductive, but the presence of ethanol or ethanol and water will conduct electricity. The galvanic process that occurs to aluminum trim tabs, stern drives, shaft couplings, etc. will occur within the aluminum fuel tank. Boat builders are able to protect exterior aluminum boat equipment with sacrificial anodes known as zincs. Sacrificial anodes are not a feasible option for the interior of a fuel tank.

[Lister]

I thought galvanic reaction was only on salt water.
I never saw a galvanic reaction on a boat on a lake, they don't have artificial zinc either.
But I can be wrong, I don't know much about that subject.
Lister