T&T: Black Iron Fuel Tank Leaking

[Keith]

Here's my experience:
____________________
Fuel Tank Repair



I had developed a little fuel weep in my Starboard fuel tank. This is the 
original tank on a 1986 Krogen 42, hull #99. This was more of a nuisance 
than a problem. about = cup of fuel would leak out per week, and I was using 
sorbent pads to catch it. The fuel was actually coming out of the forward 
bulkhead in the engine room and originally I had thought it was leaking from 
one of the fuel filters which are right there. Once I eliminated this, I 
knew the fuel was coming from the tank somewhere, running forward, and 
exiting from behind the bulkhead.



I hired a local fuel tank repair guy to fix this problem. We first pumped 
all the fuel to the other tank, and then he cut three additional ports so 
that he could access each area of the tanks. There are four baffled 
sections, and I only had one inspection port forward. The main thing we 
found was rust on the upper portions of the inside of the tank, where fuel 
usually never gets, since I don't ever fill that high. This rust would fall 
off to the bottom of the tank, making a layer of crud down there. There was 
very little slime/crud other than that, so he scraped the bottom of the tank 
to clean out all this stuff.



He then cleaned the inside of the tanks with a solvent. I'm not sure what he 
used, but it smelled like MEK or maybe lacquer thinner. I also smelled 
alcohol, so maybe he used a mix. Naphtha would also work well. While doing 
all this, he hooked up a blower to the fill on the deck so it would suck the 
air out through the tank. We left this in place throughout the project. He 
essentially used a cardboard tube to make a riser out of the fill, and then 
put the intake hose from the blower over that.



Once the tank had been solvent cleaned, he used an air grinder with some 
little 3" disks, maybe 60 grit to clean the metal down to bare and shiny. He 
then cleaned with solvent again.



He coated the inside of the tank with some coating he painted on, ended up 
gray. Coated the entire tank from the bottom up to within about 4" of the 
top. He was very secretive about what he used, even removing the labels from 
the cans before bringing them to the boat. He did say it was a fuel tank 
lining used in the aviation industry.



Here is a great .pdf file that explains aviation fuel tank sealers and lists 
three suppliers:

http://www.vansairforce.net/articles/tank_sealant.pdf



Another good one, an aviation fuel tank sealer is at: 
http://www.sacskyranch.com/proseal.htm

PPG Aerospace: http://tinyurl.com/ypwduq





Searching the internet for "aviation fuel tank coating", "diesel tank 
 repair" or "diesel tank lining" will bring up other various repair 
materials. Some are designed to use inside a tank; some are for outside 
repair. Here are a few links:



http://www.nationalsealants.com/Index.html

http://www.hexaflex.co.uk/tuffcote.html

http://prp-porstore.com/merchant.mvc?Screen=CTGY&Category_Code=TankSealers

http://www.pplmotorhomes.com/parts/caulks-sealants/40754.htm

http://www.piperepair.net/index.html

In any case, call the manufacturer to discuss the use with them.



Another candidate comes from www.thinfilmtech.net. They have a product 
called GasPruf that is designed to line / remediate pipelines, petroleum 
tanks, etc. It's basically an epoxy. Here is a note from their spec sheet:

GasPruf 130tm is a unique blend of liquid polymers and proprietary curing 
agents which is able to displace water or hydrocarbons such as gasoline or 
diesel fuel from wetted surfaces in order to make a permanent bond. The 
formulation is solvent-free to ensure safety and maximum technical 
performance. Kevlard* fibers are incorporated for reinforcement and 
viscosity management to achieve high application rates -even under 
hydrocarbon liquids!



I also imagine that you could use things like JB Weld or Splash Zone on the 
outside of the tank, if you can access it and find the leak.



The seals for the new inspection ports were interesting. They were stainless 
steel, with a flat plate for the outside and two half-rings for the inside 
of the tank. He used them as a template to drill the holes outside the 
inspection port. He then threaded the bolts into the two half rings, sealing 
the threads with epoxy. He then made a gasket for the inside and outside of 
the tank, installed the two half rings inside with their gasket, then the 
outside plate with the gasket. The reason for the two half-rings was so that 
they could be passed through the hole. See: http://www.seabuilt.com/



The repair seems to be working perfectly. The leak is repaired and I have a 
new set of inspection ports if I ever need to get in there again.



Keith
_____
"He can compress the most words into the smallest idea of any man I know." - 
Abraham Lincoln
----- Original Message ----- 
From: <TAMPAKOA at aol.com>
>
> If any of you have experience sealing a diesel tank from the inside using
> one of the products or types of products mentioned above I would surely
> appreciate learning from your success or failures. If anyone has had 
> success  with
> any other products  please tell me about it.