Sludge rust at the bottom of my steel fuel tank

[coopec43]

Originally Posted by Cheechako

Yeah, plastic of some sort is great. I have had two aluminum tanks go bad. One SS tank go bad. All of those went bad where they sit on something. Moisture stays in the gap and corrosion eats the metal.

My aluminum fuel tanks sit on the floor bearers (is that what you call them?) but I have sika -flexed plastic (nylon? Marelon? ) strips to the bottom of the fuel tanks where they sit on the bearers. Hopefully that will solve the problem of corrosion?

[thinwater]

Condensation on the roof of large storage tanks is so common that the inspection standard requires the roof be inspected for structural soundness and falling rafters before the tank can be entered. There have been statements made that condensation in a diesel tank is not possible, but the OP's question, industry standards, and the experience of EVERY API and UL tank inspector all support that condensation is common and serious. The "empty tank" test is not valid for a number of physical/chemical reasons.


(I am a licensed API tank inspector and have been in thousands of tanks).


The only way to prevent it is a silica gel filter (H2Out). These have been used in the refining industry for many, many decades. They work.

[zeseb]

Originally Posted by thinwater

Condensation on the roof of large storage tanks is so common that the inspection standard requires the roof be inspected for structural soundness and falling rafters before the tank can be entered. There have been statements made that condensation in a diesel tank is not possible, but the OP's question, industry standards, and the experience of EVERY API and UL tank inspector all support that condensation is common and serious. The "empty tank" test is not valid for a number of physical/chemical reasons.


(I am a licensed API tank inspector and have been in thousands of tanks).


The only way to prevent it is a silica gel filter (H2Out). These have been used in the refining industry for many, many decades. They work.

How would you apply it exactly?

[peter57]

Find a new fuel bag that will fit the void, you can have a lot leeway with the size, the bag always bigger. Cut the top out of the tank leaving beams and lugs to tie the top of the bag too and one or two for the filler and air hose to go through. The beams should hold the bag in if you ever go 180. You could do away with beams if the boat was slipped and lugs welded to the bottom of the old tank to tie the bottom lugs of the fuel bag. lowers the condensation problem. This has been done very successfully after seeing this done, I done it with my fresh water tanks which were originally copper, glued carpet to the inside to line it so the bag would not puncher from cutting out the baffles.

[kapnd]

I understand the OPs dilemma, tearing out and replacing tanks is not fun!
The cheap and non-intrusive solution is to utilize heavy duty, high capacity industrial grade filtration and possibly a polishing system too.
Check out sbmar.com, they sell kits that can handle lots of debris/water, and free advice on setting it up.

[zeseb]

Originally Posted by coopec43

Until last week I had a 1956 David Brown tractor which I bought 30 years ago. The tanks (Petrol and Power Kerosene) were in bad shape so I coated the inside of of one of them with epoxy and ran the tractor on petrol without any problems.

Just now I wanted to know if what I had done had been tried by anyone else and during my research I came across this.

Damon Industries Red-Kote Gas Tank Liner


Maybe the way to go?

I asked for the "Red Kote" option to the vendor directly and this is not an option:

Red-Kote does one thing very well. It coats the entire inside of a gasoline tank that can be removed from the vehicle for a proper job to be done.



We do not recommend using Red-Kote with any tank that has had diesel fuel in it unless it is sand blasted first to remove the shellac.



We do not recommend only coating part of a tank. It will probably peel off starting at the edges.



We do not recommend brushing on Red-Kote. It is not designed to be brushed on and makes a very difficult job.



In spite of our recommendations, people still do these things. A few have no problems, but most do have problems. I understand that you cannot remove the tank to do the job properly, so if you proceed, you do so at your own risk.

[RaymondR]

Since it is steel you can give it a dose of good strong caustic soda or drain cleaner, let it soak for a while then let it dry out and vacuum it out using a piece of 1" poly pipe and a vacuum cleaner. Bang on the top to loosen any rust.

Don't do this with an alloy tank though, it will disappear.

Steel won't rust if there is a coating of mineral oil on it but light mineral oil biodegrades so you need to fill it right to the top regularly.