Cutting fuel tanks

[michaeld5503]

Hi all, unfortunately we are going to have to replace the fuel tanks on our ketch. 36 years of glassed in steel tanks created a corrosion problem. We are planning on using the ATL fuel bladders so avoiding cutting out floors. ATL recommends cutting a acces hole in top of tank to install the bladders. I know it's diesel, but a little worried about cutting the tank. Anybody have any experience in cutting steel tanks? Jig saw?

[a64pilot]

I won't go into the fuel cell debate as that is another issue, but for cutting into steel tanks, I think I would want an air powered nibbler, and I'd likely fill them with CO2 and have someone watch me from above as I think you can get asphyxiated pretty easy from CO2, it's heavier than air?
On edit, if a nibbler or shears won't work, then an air powered jig saw and a little water flow, probably help the cutting anyway

[UNCIVILIZED]

I gather that your concern is about starting a fire, or explosion when cutting the tank? If so, then so long as you're not using electrically powered tools, you could even fill the tanks with water. If, that is, CO2 would worry you.

[Cheechako]

I personally wouldn't worry about explosion in a diesel tank. But I would likely use a nibbler anyway as I seem to be the guy who the impossible happens to! You cant light a coffee can of diesel by throwing matches in it, no matter how many you throw... try it.

[Tayana42]

We did this same job on our boat about 10 years ago. Actually, I found someone to do it for me. After emptying and cleaning the tank he used a reciprocating saw to cut an access hole in the top of the tank. That was the easy part. The hard part for him was spending hours upside down head first in the tank grinding out the baffles so they would not cut into the new bladder. After that we lined the old tank with Dry deck tiles to cushion the bladder. So far it has worked great for us.

[UNCIVILIZED]

@Tayana42
One might simply cut out the baffles & then do a pour of some substance (foam, resin, or?) to cover the remaining bits of the baffles on the tank floor. Though this wouldn't solve for any baffle bits on the tank walls however.

[Tayana42]

Originally Posted by UNCIVILIZED

@Tayana42
One might simply cut out the baffles & then do a pour of some substance (foam, resin, or?) to cover the remaining bits of the baffles on the tank floor. Though this wouldn't solve for any baffle bits on the tank walls however.

Yes that was the problem. The baffles were welded to the tank walls and required grinding to get them smooth enough for the protection of the bladder.

[Viking Sailor]

Did a 110 gal diesel tank. Got access to one end of tank. Cut large hole using a Sawall with a short blade. Proceed to cut around the top and dropped in to the tank. Then cut and removed pieces of top. From there it was just a matter of cutting and removing the rest of the tank a piece at a time.