Removing A Leaking Fuel Cell

[mlb2992]

I have a 1999 Pursuit 2870 Offshore. Just discovered a pretty large fuel leak in the starboard tank. Anyone have any ideas on cutting out a tank. No way to remove it with out cutting it apart.What are the safest ways...and with what tools??? How do you remove fumes prior to cutting??
Thanks in advance!

[PAR]

Fill it with fumes from a small gas engine, like an air compressor or generator. Use a hose to direct the exhaust gas directly to the filler neck. After letting it blow out all the gas fumes, start cutting with what ever you like, a reciprocating saw would be my first choice. The exhaust gas from the engine, will prevent sufficient oxygen from being present in the tank to form a combustible mixture.

[CDK]

I would rather use a CO2 cylinder or a piece of dry ice. The gas is heavier than air so will stay in the tank while you work on it.
The gas engine produces a lot of water vapor and also CO, which is unpleasant in a confined space.

[mlb2992]

When using the dry ice , does the tank have to be completely empty...or can you have small amounts of gas or water in the tank?? I have been told to use a gallon of bleach, with a large bottle of Dawn dish washing soap and fill it with water to exhaust all the fumes....Which do you think is the best idea.

[CDK]

Bleach and dish washing soap, the guy surely doesn't like you.

With dry ice, water present will immediately freeze solid and stay that way until all CO2 has evaporated. The gasoline will not freeze but thickens and will stay below the flame point for some time. The gaseous CO2 replaces air and fuel fumes. If you need much time cutting or sparking, throw in some more ice if needed.

[Typhoon]

If it's a fibreglass tank, just cut it up with an air saw.

Regards, Andrew.

[PAR]

. . . and hope you don't hit something to make a spark?

[Submarine Tom]

Don't screw up on this one or it'll be the biggest mistake of your life!

Perhaps even your last...

Don't underestimate the danger level you are venturing in to.

-Tom

[TollyWally]

I have an aluminum fuel tank to remove and replace. I've been running it full of water for several months to maintain correct trim until I get around to the onerous task of replacement. I've had a few suggestions including filling the tank with co2. I have considered topping it off with water and cutting it in half with a cutoff wheel on a pneumatic grinder.

[mlb2992]

Got mine cut yesterday...all went well. First I filled the tank with water...added Dawn liquid dish soap to force out some of the air....then dropped in small blocks of dry ice. I used a sawsall with a metal blade and made quick work cutting the top off, then the baffles....now today I'll cut the tank into 2 pieces for an easier removal.

[Carteret]

I have done this on a larger scale many times. I would use a confined space atmosphere meter. This is the hand held device that people test fumes with in man holes and confined spaces. We used to weld on large hydrant fuel systems. We would place the meter in the area, inert with gas (argon) and when the meter would read 0% oxygen cut or weld. A side grinder works well in cutting tanks.

[Typhoon]

Originally Posted by PAR

. . . and hope you don't hit something to make a spark?

Yeah, that fibreglass sparks up pretty bad.
Why does everyone recommend exhaust gases to purge tanks, when they contain unburned hydrocarbons themselves?

Regards, Andrew.

[PAR]

When plowing through 'glass or any material for that mater, you will often come across fasteners, which do spark nicely when hit with a reciprocating blade. I've used this tool hundreds of times on 'glass and sparks are a common thing, when blindly cutting through things Typhoon. You need oxygen in a fairly specific ratio to make gas fumes go off. With exhaust gases flooding the area, including their partially spent hydrocarbons, there isn't enough oxygen for the fire to catch. Plus it's a reasonably easy thing to rig up, though any inert gas will do. I've used nitrogen and argon on occasion when these were handier.

[marshmat]

I've heard the "flood it with engine exhaust" before, and yes, it should work in theory. I don't trust it, though, and will never use this method. There are many other things that could go wrong- if you pump exhaust in while working, it can end up in the worker's lungs; if you shut the exhaust off, air can get back in the tank as you work. Unless you have carteret's system of inert gas tanks and atmosphere monitoring sensors, I'd advise against this option.

The only thing I would trust to displace gasoline vapours from a tank is water, right to the brim. There's very little to go wrong this way.

Originally Posted by marshmat

I've heard the "flood it with engine exhaust" before, and yes, it should work in theory. I don't trust it, though, and will never use this method. .

Daily proven practice worldwide!

The entire tanker fleet is filling empty tanks with inert gas.

Coming straight out of the exhaust of the main propulsion (solids filtered out).

Nothing to fear, and cheap.

Regards
Richard