polymer lining inside a steel tank

[rebel heart]

Hey guys!

I have a steel fuel tank, about 80 gallons or so, and it's got rust here and there on it because... it's steel.

I'm not really loving the idea of cutting it out and replacing it, and right now the 2000 Yanmar is running like a champ, and there aren't really any dirty fuel problems yet, although I'm going to open up the access port and clean it out the best I can, following some instructions I read on this forum.

That being said, I also heard on the dock that I can ask the boat yard to spray some kind of polymer coating on the inside of the tank, apparently dramatically lengthening the lifespan of the tank, and making it much easier to clean (the latter part I don't get).

So I'm curious.... I have a fuel tank that might be as old as the boat, it's steel, and I'd like to start being proactive with it now before it develops problems.

[DeepFrz]

Sorry I don't have an answer but you might like to post this question on the Metal Boat Society forum.

[Boracay]

Given that the three rules for a successful paint job are preparation, preparation and preparation I cannot see how the inside of a diesel fuel tank could be properly prepared for painting.

[rebel heart]

Originally Posted by Chris31415

Given that the three rules for a successful paint job are preparation, preparation and preparation I cannot see how the inside of a diesel fuel tank could be properly prepared for painting.

That's a pretty valid point.

[Chief Engineer]

neither can the paint.

Sounds like a marina "hose job" waiting to happen.

[mudnut]

Originally Posted by rebel heart

Hey guys!

I have a steel fuel tank, about 80 gallons or so, and it's got rust here and there on it because... it's steel.

I'm not really loving the idea of cutting it out and replacing it, and right now the 2000 Yanmar is running like a champ, and there aren't really any dirty fuel problems yet, although I'm going to open up the access port and clean it out the best I can, following some instructions I read on this forum.

That being said, I also heard on the dock that I can ask the boat yard to spray some kind of polymer coating on the inside of the tank, apparently dramatically lengthening the lifespan of the tank, and making it much easier to clean (the latter part I don't get).

So I'm curious.... I have a fuel tank that might be as old as the boat, it's steel, and I'd like to start being proactive with it now before it develops problems.

Bite the bullit now.Even if ya could coat the inside,it's still gonna keep rusting away.In the longrun what ya do today is not cost effective.Mudnut.

[GordMay]

Application of a protectorant film, inside diesel fuel tanks ,is a highly skilled professional job, seldom worth the cost.

The effectiveness of any coating depends upon the conditions of the surface to which it is applied, the ability of the type of coating to withstand the environment to which it is exposed, the durability of the coating, and both the extent and manner in which it is applied.

If properly applied to the tank, polyurethane coatings, chromate treatments, and epoxy paints may well be effective in delaying or preventing corrosion. The problem with these methods, for repairing a damaged tank, is the difficulty in achieving sufficient adhesion of the film to the base metal, and in applying a uniform and sufficiently thick protective layer free of pores, or "holidays" through which water may penetrate.

Any water penetration will eventually lead to destruction of the film and renewed, or accelerated, corrosion attack of the base metal.

Typically, rusted steel will have a series of small rust craters, along with the layered rust. These craters go deep and are hard to detect. The metal sheet itself might be wasted by only 20%, but the craters could be just hours away from total failure.

Any obvious corrosion activity, including perforations, rust, streaks, pitting, scaling, weld deterioration, cracks, or any structural instability will eventually fail a tank lining.

[mike d.]

rebel heart i was lookinh at a hans christian a couple of yrs ago, and the fuel tanks were bad (rotted thru) i talked to a friend who owns a marina, has been in the bus. all his life in business, handed down from his father, anyway he said the easiest, and most economical thing to do was to cut out the top of the tank/s grind edges smooth and put bladders in there.

[Tspringer]

If the tank can be removed from the boat, then you have excellent permanent solutions.

Take the tank to a powder coating company that does ceramic coatings for racing applications. Tell them the dimensions of your tank as some companies may not have facilities to bake a large tank. The ceramic coating is a powder that is applied by magnetizing it and them blowing it into every nook and crany of the item being coated, then it is baked. The result is an extremely hard coating that is impervious to fuel and/or solvents and is very durable.

I had the fuel tank in my '69 Porsche 911S thus coated and after 4 years it still looks perfect inside and out. I have also had various race car suspension parts ceramic or powder coated and though they take a beating the coatings have not been scratched or rubbed off at all. They are very durable.

If you cannot remove the tank from the boat all this is moot. The process requires that the item being coated be baked at a high temperature, often through several steps of the process.



Terry

[rebel heart]

Originally Posted by mike d.

rebel heart i was lookinh at a hans christian a couple of yrs ago, and the fuel tanks were bad (rotted thru) i talked to a friend who owns a marina, has been in the bus. all his life in business, handed down from his father, anyway he said the easiest, and most economical thing to do was to cut out the top of the tank/s grind edges smooth and put bladders in there.

This seems like a pretty good solution. I suppose there are some awesome ways to lock those bladders in place, and another thing I like about this is that I can have numerous small bladders (maybe three 30 gallons, or something like that) as opposed to one big one.

Definatly something worth considering. Anyone else have any thoughts on these flexible tanks?

IMTRA Marine Products

That certainly would make my life a heck of a lot easier. Maybe two of those 53 gallon tanks (of course I'll size them out before I do anything).

[svHyLyte]

We have flex tanks on our boat and they work well. In your case you'll need to remove the tops of the steel tanks and the baffels and grind the edges as smooth as possible. Than line the tanks with neoprene (wet suite material). To get a baffel effect use several inter connected small flex tanks rather than a single large tank. These can be secured in the hull of the old steel tank with several nylon wire ties at each corner passed through small ring-bolts driven through the old tank's sides. We used a similar arrangement on a poly water tank and it worked quite well.

Good Luck!

s/v HyLyte

[Richhh]

Tank lining with epoxy is pretty common in the maritime and chem process industry.
Interlux offers such 'lining epoxies' from their commercial division. For small lot quantities I use: NSP Specialty Products for both potable water and fuel tankage.
Steel / black-iron tanks usually are attacked on the outside due to plugged limberholes, etc. or develop pin holes in the weld seams .... for fuel tanks I usually cut large acces holes in the top (tank flooded with water while cutting), clean/sand/grind the internals, add cloth/roving to the all the bottom + bottom seams, etc. then overlay (roll-on) with the lining epoxy, apply a bolted-on metal 'sister flange' to what I cut into the top and then epoxy it back together.
The whole job is more efficient and more cost effective for both time and money versus ripping out and replacing with new.

[Alan Wheeler]

There are many coatings available. Butt hey are all useless unless two factors can be delt with. Firstly, you have to remove that rust. Secondly, you have to apply the coatings evenly all around the tank. If you can't do both, you are wasting your time.
There is a product especially made to coat tanks. I can't remember the exact name. It was PRC or PCR of PCM or P?? I can remember the first letter as P. Do a search on "P" and see.........no wait, bad idea ;-)

[cooper]

A diesel tank under normal circumstance shouldnt rust. It is usually due to condensation. The water at the bottom of the tank (under the diesel) has no oxygen. The easiest way to keep condensation at bay is to keep your tank full. Some epoxys but not all are "diesel proof" you have to check with the manufacturer.