Flushing Fuel Tank

[Alan Wheeler]

Your Right Richhh, it's Bacterea, fungal and enzymes, not Algae.
I had on my tank cleaning rig, firstly a high pressure water blaster to produce the pressure. On the end of the pressure line, was a special head with multiports, that sprayed around and blasted the walls of the tanks. Then the fuel was pumped via the filtration system.
A device we fitted to the tanksafter the cleaning, was called "Fuel dry".It was a large "sock" filled with a material that you can still find in garden shops today. I think they call it Crystal rain. It absorbs water only, not fuel. We would drop these to the bottom of tanks and once a month would change them over. They can be dryed out and re-used, but we just threw then away.
Simple, No water, no growth. Maybe you guy's have a poorer grade of fuel, but we don't seem to have the same issues of it breaking down. But then, we have sulfur free Diesel. The base product is a high quality low sulfer crude and then it is further processed to remove sulfur and it has very little Aromatic solvents left in them as a result of removing the Sulfur. It's a real pain as it makes seals on fuel systems shrink and leak.

[Richhh]

Best 'laymans' info on fuel storage, shelf life, etc. that Ive ever found is:
http://www.bp.com.au/fuelnews/ADF1402.pdf
shows good incite on metal reactions, storage, intervals for tank cleaning recommendations, etc. The 'stuff' that you were adding may probably be a fuel stability foam ... also discussed in the above URL. Good info.

[Starbuck]

I think if I can get the tank out, it will be much easier to work with. May take it to one of those drive-in self-serve car washes, and blast away, then let it dry really well before reinstallation. "High pressure rinse" is the setting I"m looking for.

[GordMay]

It is true, as RichH says that ”... Unless the polymerized and agglomerated particles (they are NOT 'bugs') are knocked free from the walls no amount of recirculation polishing will remove them ...”.
Which is why: “...The cleaned fuel is returned to the tank under pressure, to power wash (scour) the tank interior ... “.
I’ve used it. It works.

This is a subject that I researched and feel bold enough to claim some expertise. My vessel carries 2000 litres (about 500 US gals) of fuel and I use about 400 per year. I live in the tropics. I was having serious trouble with clogging filters and the colour and visible condition of my fuel was obviously out of ordinary. My filter was being clogged by a brownish substance I assumed to be dirt or rust residue. A sample was examined for me by the BP lab in Brisbane. The residue was alge (bug). The lab recomended the fuel not be used as was and to treat the fuel with a good bio-cide. I also invented a little "fuel polisher" made out of a jar, a filter and a wrecked car part that worked perfect and cost very little. This was 4 years ago and the proof of the success of the system is the fact I have never changed a filter out of normal routine (annually) since. I published the results of my investigations and technics used, 3 years ago and due to continuing inquiry have recently re-published the article.

There is no reason to dispose of the fuel. The process uses the fuel to clean the tank while the fuel is also being cleaned.

For more info see the site for the treatment I used www.fueltreat.com.au and for a free copy of the edition containing the article go to www.thecoastalpassage.com find the button on the home page for issue # 16 and download. The article is on page 7.

I wish to stress, this is not just theory. Four years of perfect operation with excellent exhaust colour, easy starting and no harm to injectors or pumps with fuel that in part is years old.

Cheers

I am going to give Thomas a push into the middle of this (Cause I'm such a nice guy). His tank is older, and has the all too common problem of loose debris. This debri gets stirred up in rough seas, and plugs everything. At one point, after exhausting all other options, he accessed the fuel pick up, and discovered the screen was plugged. He also has an on board polisher, but I will let him tell you about that. I agree whole heartedly about adding an access port. Two if there is a baffle. Less of an issue with aluminum tanks than iron, but it is the only way to get in there, and pull all the gunk out. Creating an access port will require far less removal than pulling the tank, but this does create it's own hazards. A hole saw can create sufficient heat to ignite diesel. I have not cut into an old tank, so I am not what precautions to take, but I am sure some would be in order.

[CaptainK]

You would be two fries short of a happy meal. If ya go cutting away with a hole saw on any tank, without first having the proper ventilation in the room. And inside the tank.

You'll have a very memorable experience of seeing stars and a view of your life flashing before your eyes!!!

Yeah.. old gunk is a problem. In the article I mentioned above, one of the advantages of the system I made was the remote pick-up, that is, I used a 1/2 inch copper tube that I could manually stick into the "coffin corners" of the tank to purposely go after the worst of it (water,dead bug, old rust scale etc) like a vacume cleaner. Then after stirring the **** up I would just let the device run for a while to clear the fuel of the fine mist of debri.

Hole cutting should be OK. A jig saw should do the trick to cut an inspection port as well. In my case I didn't have a port built in and once I worked out my cleaner I didn't think I needed one bad enough to do the work. I have two 1000 litre tanks.

You would be amazed at what you can do with diesel... I had to weld 6 patches on one of my (steel) tanks. 14 foot of welding all up and the tank was about 3/4 full when I did it!! Below the fuel line was interesting hearing the fuel boiling under the weld and having the leaking fuel burning around my wand (mig welder) but can you guess how I did it ABOVE the fuel line??? Think about it.... The winner gets a free edition of TCP!!

Cheers

[CaptainK]

Run to the hills.
Run for your life.

[Alan Wheeler]

Ummm, filled the tank with exhaust fumes??? or blew a CO2 extingusher into the tank top???
Yes, deisel takes a bit to ignite it. A hole saw on a slowish speed is reasonably safe and it is very safe if the tank is close to full. Less air, less chance of a problem. Keep a cutting oil on the saw blade, it cools it and helps cut.
Bob, I am suprised the coolness of the fuel allowed you to get a decent weld??? Hehe and I bet you were a little nervouse at first huh??

From experience, I can say that even if you follow all of the procedures, things do go wrong. I made an 8 gallon Harley fat bob tank once. It was 5 gallons when I started to weld. Oops I can laugh now, but it scared the heck out of me when it popped. No flames, but it jumped 10 feet in the air. Gas had penetrated the metal over the years. Water and CO2 in the tank kept if from burning, and eliminated air space, but when the penetrated steel got hot enough, WOW! Since then, I am a little leary about applying any type of heat to a fuel tank. The aluminum tank with plenty of cutting oil should be safe, but I am not recommending anything.

BINGO ALAN!! You get the prize! I backed my van onto the wharf next to the boat and ran the exhaust via flexible tube into the fuel filler, thus displacing the free oxegen with nice stable non combustable carbon monoxide. I was pretty good with a MIG so had the amp and wire speed well set for work below the fuel line. But yes... I was paying close attention! But above the fuel was the problem as you worked out. It's the O2 that is the worry. Gasoline, or petrol is a whole different game but still not explosive as is commonly understood. Gasoline VAPOUR is an easily ignited and a very fast burning substance however.

Yup K-N a hole saw properly cooled on a diesel tank should be no problem even without displacing oxegen. I like to use metal cutting jig saws myself though.

The moral of the story?? Things that look crazy at a glance may be perfectly reasonable with more information....

Cheers all

[Alan Wheeler]

I've been currentlyrunning some night classes, teaching welding to Adults at a pro level. The one point I have made to them is to not even go there, when it comes to welding and Gas cutting anything that has carried fuel or oil. Unless you know what you are doing, it can really go wrong. Many years ago, two guy's were killed here, welding a fuel tanker on a truck. The interesting thing is, the tank was proffesionaly prepared for the welding by proper industry standard cleaning for such a task. The tank was being welded internally. The thing exploded killing them both. I have seen the results of so many accidents, I just say to people, don't do it, unless you are formerly trained in doing it.
Aside from that, part of the way do do it right is as Bob has pointed out. Without oxygen, NOTHING will burn. Displace oxygen and your safe. You just have to ensure there is no way Oxygen can ever be part of the gas mix.
Oh and 1/4 cup of petrol/Gasoline vapourised, is equal to a stick of dynamite in it's explosive power.

[markpj23]

Inert the tanks first with nitrogen - cheap and easy to do. Can weld on diesel tanks as noted above.. just don't try it on a gasoline / petrol tank unless you don't want your ex to keep collecting that alimony. Car exhaust can be tricky - an uncertain O2 content to worry about...?

For me - I'll inert the tank even for using that sawz-all to cut the access. Worth the price of a nitrogen bottle for peace of mind..

[Alan Wheeler]

For that matter, if it was a mig welder being used, the welding Gas could have been used as well.