Clearcoat new tanks?

[emlesnick]

Any thoughts on wether it is advisable to clearcoat new tanks for rust prevention?

I have new tanks of both SS and aluminum for the fuel.

One person suggested eastwood exoarmor

Eastwood Company : Search Results for Exoarmor

Any thoughts?

Thanks!

[Diesel Bill]

Originally Posted by emlesnick

Any thoughts on wether it is advisable to clearcoat new tanks for rust prevention?

I have new tanks of both SS and aluminum for the fuel.

One person suggested eastwood exoarmor

Eastwood Company : Search Results for Exoarmor

Any thoughts?

Thanks!

When I was a young dude working on unrep tankers for fueling the navy ships,
on occasion we had to go down into the tanks that were empty and washed out with sea water to muck them out. the tanks had some kind of coating on them (epoxy?) Any way the coatings were sloughing off in large sheets and falling to the bottom of the tanks. We were carrying Diesel and jet fuel mostly. Not sure what you could coat the tanks with that wouldn't break down and loose adhesion.
Later on sailing commercial tankers we had to clean out the potable water tanks and same thing encountered, coatings sloughing off the walls of the
100 ton capacity tanks.
Make sure whatever you put on the tanks will not cause problems later.
Let us (me) know what you find and end up using.

[emlesnick]

Well it would just be on the outside. What Im concerned about is that eventually the sealer will crack and moisture will get in behind and oxidation will be worse that if just left to air. Idk I really never even thought of clearcoating them until now....I REALLY don't ever want to see these tanks again

[HopCar]

I don't think either stainless or aluminum tanks will benefit from coating. The aluminum tanks in my boat are almost thirty years old. When they fail it will be from the inside.

[DeepFrz]

No, don't coat metal tanks. The longevity of metal tanks depends on proper mounting. That means mounted so that air can circulate around them and moisture can not be held against the metal. It also means keeping them clean and free of water on the inside.

[Cheechako]

Originally Posted by emlesnick

Well it would just be on the outside. What Im concerned about is that eventually the sealer will crack and moisture will get in behind and oxidation will be worse that if just left to air. Idk I really never even thought of clearcoating them until now....I REALLY don't ever want to see these tanks again

Not too sure. As you mention, any break in the coating with lifted/bubbledareas could cause entrapped moisture in that area. But my gut says coat them, but with something not too brittle... not epoxy. Aircraft tanks are coated.
Are any tanks under floor? Those go bad very often. You need a way to rest them on something that allows air... not rubber pads or wood 2 x 4's without something to raise them off the wood /rubber. Dri dek?
I wonder if Cosmoline would be good? (CRC 5-56 spray) Military spare parts are often coated in that. It's gummy like lanolin and not easy to remove without solvent.


A couple thoughts from my experiences:
-7 year old SS under floor tank had holes in it the size of pencil erasers.
-15 year old SS tank covered with a thin layer of fiberglass did not.
-12 year old Aluminum tanks with no coating and in a raised dry bilge had pin holes in the bottom corners. Both tanks.
Based on that I would be tempted to put a coat of boat cloth/ fiberglass on.

[emlesnick]

Almost all of these tanks are in the bilge under the floor.

The gameplan is to boatlife abs plastic to the tank and the plastic will brace against closed cell foam to cushion against the hull

[Cheechako]

I think best is to keep any flat surface away from the tank. A honey comb would be perfect I suppose. maybe this?

[emlesnick]

Agreed. Best way I can figure is to stagger this padding system around tank hoping for good air flow around tank and nothing that can hold moisture actually touching the tank.

Of course they are going under the engine room floor in a super tight space in the turn of the bilge but this is the best plan we've been able to come up with.

[DeepFrz]

I will suggest that you read this article.
Diesel Fuel Tank Design | | PassageMaker

[emlesnick]

"Aluminum tank manufacturers often offer to coat their tanks with corrosion-inhibiting epoxies. This may be tempting, but, in my opinion, it is more cosmetic than functional. Aluminum is quite corrosion resistant on its own, provided it is exposed to circulating air and is not repeatedly exposed to stagnant water. If the epoxy coating on a tank becomes damaged (a single nick or scrape is all it takes), then corrosion can gain a foothold, and it can progress in an especially aggressive manner. You’ve probably seen this type of corrosion occur around fasteners on painted aluminum structures such as masts, window frames, doors, and hatches. Water works its way beneath the epoxy coating, where oxygen is not present, and this causes the aluminum’s natural corrosionresistant film to break down. The corrosion often attacks beneath apparently sound paint, where it can’t be seen, the only evidence being a bubble or other irregularity in the paint’s surface. Poke it with the tip of a knife or even a fingernail, and the paint falls away, revealing white, sticky (if it’s still wet) hydroxide, the detritus of aluminum corrosion. Thus, my preference is to leave fuel tanks and all other aluminum structures in an uncoated state, as long as their naked appearance can be tolerated."

[HopCar]

Originally Posted by DeepFrz

No, don't coat metal tanks. The longevity of metal tanks depends on proper mounting. That means mounted so that air can circulate around them and moisture can not be held against the metal. It also means keeping them clean and free of water on the inside.

Exactly right. It used to be common practice to foam aluminum tanks in place on smaller boats. They would fail from the outside in less than ten years.

Air circulation is your friend. Don't coat it. Don't foam it.

[CarlF]

Aluminium tanks often corrode at their supports and mounts. Consider having the tank maker weld on aluminium tabs or stand offs that keep the thin tank wall in the air. If that's not possible use a mounting block that won't hold moisture - like hard neoprene rubber. Don't let the tank rest on the fiberglass hull.