Re: Fuel tank out - should I paint it?
Re: Fuel tank out - should I paint it?
I did the research for you. Here is the advice on the fuel tank....from the aluminum fuel tank experts:
Tanks installation | installation and Maintenance Repair
Any Aluminum tank should be mounted so that moisture will not collect on any surface. One of the most common mistakes is mounting a boat tank on a sheet of plywood, foam, rubber or some other material that absorbs moisture. Ideally the tank should have air circulating around it on all sides including the top and bottom. To allow air under the tank requires using brackets that raise the tank above the mounting surface. Another common mistake is foaming the tank in. There are Federal Regulations and American Boat and Yacht Council (ABYC) standards that must be met to foam in a boat tank. One of the most significant of these is that the foam must bond tightly to the surfaces of the tank. This is to prevent any moisture from collecting between the foam and the boat tank wall.
If a tank is mounted properly, easy to get to and inspect, it will probably last 20 to 25 years without leaking.
Problems with boat tanks are primarily problems of improper installation, not the material itself for tanks - aluminum. Properly installed, aluminum boat tanks will usually outlast the life of the powerboat.
For under the deck replacing Boat Tanks, tanks should not be just sitting on a bare plywood deck. They should be supported at intervals which allow air flow around the tank.
You may need to build frames under the boat depending on the amount of the span between stringers. Use wood shims on the inside of the stringers if necessary to guide it into the right position. If the Boat tank is more than two feet wide, not recommend this, simply Install the frames before glassing. For mounting the deck - The best method is to fasten heavy, fir ledger strips to the side of the stringers. Its probably best to cross bolt through the stringers rather than using screws, if possible. That this has to withstand the weight of the fuel with the boat slamming, so you need to make them very strong. Then heavily fiberglass or epoxy the ledger strips so they dont rot and set the fully glassed deck on top.
The Next step, you will need at least two tubes of 3M 5200 adhesive sealant, and you will literally glue the plastic strips to the tank bottom . Apply the adhesive so that the entire surface of the plastic is coated with 3M 5200 adhesive and will not leave any gaps or crevices for water to get into.
Allow 24 hours for the 3M Marine 5200 Adhesive Sealant to set up before setting the tank in the correct place.
The Next step, apply two 1/4" wide beads of 3M 5200 Adhesive Sealant along the length of each strips/plastic/ that are now glued to the tank bottom .Note, the strips do not get fully bedded, because fuel tanks expand and contract as they are filled and emptied and depending on temperature.
important rules:
• Never allow salt water and absorbent material to come in contact with the Aluminum tank.
• Make sure that straps or whatever securing devices you use don't cause crevice corrosion.
• Do not use rubber strips which is cathodic to aluminum and will cause galvanic corrosion.
•Do not use plain steel - galvanized only.
•It is the best to use only stainless steel pipe fittings for the fuel supply. Do not mix a variety of metals.
• Make sure that wherever the tank is sitting on is a flat stable surface, always use the hull stringers and never the bottom of the boat hull.
• Boat Tank should not be so deep in bilge that its going to be in constant contact with bilge water or salt water.
Tanks corrosion | Aluminum
Aluminum is self-protecting material , so long as the surface gets adequate air exposure. Severe corrosion is almost always caused by water plus a lack of oxygen. As long as the aluminum fuel tank has a good airflow around all surfaces, contact with water, fresh and salt, will not damage it or a very long time.
Aluminum Tanks are very corrosion resistant, and mostly affected by salt water and other corrosives found in the marine environment.
Aluminum Fuel tanks don't corrode because they get wet, tanks corrode because at some point something is in contact with the tank that traps water between it and the tank. The average life of an aluminum tank is 15-20 years.
Tanks should be stored empty, or if being stored for max a few months, co-inhibitors and stabilizers can be added to the fuel to prevent phase separation.
If you store the tank this way, it should be completely enough.
Aluminum Boat Tanks, Paint Or Not!?
The painting process for aluminum is so-complex that painting a fuel tank is simply not worth the trouble, If the metal is kept dry and clean the oxide will reform and again protect the aluminium. For this reason aluminum boat tanks are generally NOT painted.
In fact "aluminum boat tanks are almost never painted"!
