Diesel Tank Biomass Removal

I have a significant biomass problem in my stainless steel fuel tanks and I have no way to access the inside of the tanks without radical surgery. After an engine shutdown underway I pulled the pickup tube from the tank and it was completely stuffed with a 12" long biomass snake. The racor filter was clean but the housing was so clogged with biomass that I had to remove it and tear it down completely. There are no access ports for the tanks and there is only 3" of clearance from the top of the tanks to the underside of the cabin sole. Even a local seasoned fuel polisher is not sure if he can access the fuel in the tanks.


Is there an effective fuel treatment that will break this stuff down and allow me to drain it out of the tank? Any other ideas other than major surgery on the boat or trying to cut access ports?

I don’t know of any chemical that will do it. I think you may have to bite the bullet and put in access ports. What about going down through the filler to suck it out?

Maybe clean out the glass portion of the Racor water/fuel separator more frequently?

Our boat sat for a few years before we bought it, so I had to empty out the Racor's glass bowl of granular funky crap quite often the first year. Several years down the road, I never have to empty it anymore.

What is in the cabin above the tank? You might be able to cut an access panel in the deck above the tank to allow an access port cut into the top of the tank?

I have used this with Great success.

Kills bacteria in fuel on contact.
treats 439 gallons on the initial treatment; after the initial 16 oz. it can treat 1920 gallons. Killem is a water soluble product, EPA registered as a biocide for the control of bacteria and fungi growth in oils and refined fuels. Approved for use in California.
Killem Antimicrobial Fuel Treatment FPPF Chemical ... - Auto Value


https://www.autoparts2020.com/fppf.../killem-antimicrobial-fuel-treatment-fpp-00119



Captain F. Lee

Fuel polisher.... either you do it or you can employ a professional.

Once you install the access points on the sole, get the tanks inspected and cleaned.
If you can see the top of the tank, you can no doubt see the tank access ports. Time to do some cutting to the sole.

You might also consider installing a separate fuel polishing system for the future.

I do not know of any PROVEN magical method of desolving the existing mass.

MurrayM said:

Maybe clean out the glass portion of the Racor water/fuel separator more frequently?

Our boat sat for a few years before we bought it, so I had to empty out the Racor's glass bowl of granular funky crap quite often the first year. Several years down the road, I never have to empty it anymore.

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Sounds like the fuel pickup was so clogged that fuel was not getting to the racors.

To add to the above good advice... if you have biomass, then you also have water. No matter what else you do, it will be a continuous struggle until you get ALL of the water out of the tanks.

Ken

Each fuel filler has 2 90 degree turns so no way to get the probe in there. The discharge from the polishing rig could go in there though. To gain access to the top of the tanks, holes would have to be cut through custom cabinetry and setees. I hate to do that but may have to. The current thought is to cut through the the cabinetry directly above the fuel sending units to gain access to the tanks. We do have clear access to one side of each tank. Is there such a thing as a leakproof side access hatch that could be installed reasonably?

Yes, many boats have access panels in the tank sides. There are companies that sell kits to put them in. Search this site and there are recommendations about the kits.

The easiest way would be go through the side of the tanks if you can get to the sides. You can put in access panels that won’t leak. If not then I would cut out the bottoms of the cabinets and setees and put the access panels in the top of the tanks. Then make removable bottoms in the cabinets and setees. Which ever way is easiest is the way I would go.

Side access?? Sounds like a very bad idea.

Find the current tank access ports and cut a hole above the top of tank access ports. I am very surprised, on a boat your size, you do not have existing access points above the tank.

SeaBuilt makes access panels that are designed for either top or side wall installation. I have not seen any issues reported with side wall installation. Search the forum and there are several people that have installed them in the tank sides without problems.

Our boat has 8" side access panels in each of the 4 tanks - allowed easy inspection. And no leaks at all around the round panels. The tanks are covered with the 'punched metal' covered insulation, but with openings for the tank access panels.

Comodave said:

Sounds like the fuel pickup was so clogged that fuel was not getting to the racors.

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This is the bit from the O.P. that I was keying off of:

SeaBreeze said:

The racor filter was clean but the housing was so clogged with biomass that I had to remove it and tear it down completely.

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Side access is not a bad idea, it's very common.

If the fuel tank has the usual 1 1/2 or2 inch fill you should be able to slide a 1 inch reinforced hose into the tank. A large rotary hand pump, as used to empty 55G drums may not be bothered pumping slime.

If you can at least partially empty the tank you can let the fuel stand a day or two and pump off the water.



Return the fuel, blow some low pressure air (a wet or dry vacuum ) to mix the remainder and do this as many times as needed to see mostly clean fuel.

Bio bore or similar might be a help in killing off what life remains.

Inspect the tank , it might have a bottom drain to get much of the water.

So I decided to suck it up and install a 8" access plate from Seabuilt as recommended. The 8" plate requires a 6" hole. I will be mounting it in the side of the tank. Seabuilt said it is very common and they have never had a hatch leak. Cutting the 6" hole through stainless steel will be the hardest part. I ordered a Milwaukee bi-metal 6" hole saw. I hope it is manageable with slow rpms and cutting oil. Anyone have any tips or thoughts on cutting the hole?

It should do it, though carbide would be better. You only have the one hole to do. Yes, cutting oil and especially VERY low rpms - for a 6" 50-60 rpms for stainless. Be patient, keep applying oil and you'll get there.

Ken

You can clean the tanks w/o cutting them open. I've done it many times, mostly for other people. It's a direct result of water the tanks and no fuel conditioner. I use a conditioner every time I fuel, whether I plan on using the fuel right away or not. The right conditioner will kill the organisms and make it easier for a full size Racor to remove the water. Without water, the organisms cannot live.

You can pay a fuel polisher or buy a pump, if necessary a better Racor, kill the organisms, and probably circulate the fuel for several days. Killing a mess like yours will take at least a 3x dose and maybe additional dosing. Until you kill the organisms, everything else is wasted time.
My current boat sat 6 years without any mothballing. It has 4 tanks capable of holding 2000 gallons total. Only the day tank was accessible. I used a 3x dose of Algae-X and I pumped the fuel with the transfer pump thru a 900 Racor with a 30 micron filter between tanks. Later with the engines. I got a lot of water, but never plugged the filter. Now I run a 2 micron. 3 years later during a remodel I entered the tanks and they were clean, no water, no debris.

I currently use Archoil AR6200 I like a little better and have used it to clean tanks for other people.

Yes, cut slowly and use cutting oil. It will be slow but try not to let the stainless heat up or it can harden.

Seabuilt - Access Plate Systems

In our actual

boat the entire tanks had a tick coat of bacteria,
first we remove all we can in 20 lt tanks
after we use ...vacuum witch one done for water
and high pressure water , vacuum, high pressure water , vacuum, high ...
Ok by a hole of 3" you can't clean all the surface but you could remove the major part and less job for the chemical additive (if you choose the chemical solution)
Chemical solution on a big amount of bacteria without try to remove the major part I have some doubt

This evening I started the project of cutting an access port into the first stainless steel tank. There has to be a quicker way. I spent over 1.5 hours trying to drill a pilot hole so I could use the bi-metal hole saw. I used cutting oil, a new bit made for metal, and used slow rpms. After 1.5 hours I still had not even broken through to the interior of the tank. At this rate it will take 20-30 hours just to get the access hole cut and the bolt holes drilled. Someone please tell me there is a trick to this that I’m missing.

All this hassle could be avoided if every boat builder put the fuel take off/pick up at the very bottom underneath of the tank the same as a truck and all these problems would be avoided.

I don’t see that you are doing anything wrong. When I drill S/S I use slow RPMs, heavy pressure on the bit and cutting oil. If you try to drill too fast you can work harden the S/S and then never get through it. I think I was using a new titanium bit if I remember correctly. I would be surprised if the hole saw will cut through the tank side. I would expect to use a sawsall with a carbide blade rather than the hole saw. Did you ask the access port manufacturer what they recommend to cut through a S/S tank?

SeaBreeze said:

This evening I started the project of cutting an access port into the first stainless steel tank. There has to be a quicker way. I spent over 1.5 hours trying to drill a pilot hole so I could use the bi-metal hole saw. I used cutting oil, a new bit made for metal, and used slow rpms. After 1.5 hours I still had not even broken through to the interior of the tank. At this rate it will take 20-30 hours just to get the access hole cut and the bolt holes drilled. Someone please tell me there is a trick to this that I’m missing.

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Stainless steel work hardens. You'll need cobalt drill bits and carbide hole cutter in the size of the hole you're cutting. You already know to go slow and use cutting oil. If you're good with a jigsaw, you can use special stainless steel cutting blades in 24 to 36 teeth per inch range. I really don't like SS when it comes to cutting or drilling. I briefly worked for a company that made food packaging equipment. I'm sure glad I had a big expense account when it came to buying tooling for repairs and modifications.

SeaBreeze said:

This evening I started the project of cutting an access port into the first stainless steel tank. There has to be a quicker way. I spent over 1.5 hours trying to drill a pilot hole so I could use the bi-metal hole saw. I used cutting oil, a new bit made for metal, and used slow rpms. After 1.5 hours I still had not even broken through to the interior of the tank. At this rate it will take 20-30 hours just to get the access hole cut and the bolt holes drilled. Someone please tell me there is a trick to this that I’m missing.

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SeaBreeze - Not sure your level of handiness; if you're having trouble with the metal of your tank I would go find a like/same piece of scrap somewhere to experiment on first to try out a couple things...

This past fall/winter I did both fuel tank and a water tank access ports from SeaBuilt. My fuel tanks are black iron - pretty thick on my jigsaw but certainly not stainless toughness while my water tank is stainless but much thinner. I tackled both in the same manner and both went relatively easy. First, I traced my bolt and hole pattern from the front plate. Then I carefully center punched every bolt hole and my start hole for my jigsaw. After that I started will a small, sharp drill (I think 1/8 was what I used), then stepped up I think 2-3 times to my final size. I go slow slow, use oil, and a lot of pressure. If there isn't curls of metal coming off the bit is not sharp, the initial hit with the center punch didn't set, or you're not going slow enough with enough pressure.

This youtube video shows good technique for stainless steel - its also an example of the same type of technique I describe above for drilling holes. He's drilling in some pretty thick angle, but the principle is the same.

Same thing when you get to using the jigsaw on stainless (or regular steel), turn the speed down, but you won't want to use a lot of pressure or you'll kink the blade.

I didn't take pictures in between, but here are pics of a six inch access port cut into an approx 150 gallon water tank. (Someone had in the past installed a fuel tank style level sensor which eventually rotted and deposited its corroded metal bits on the bottom of the tank requiring a hole to be added so we could clean up the debris hopefully preventing the tank itself rotting through... we'll see! I want to say that marking, drilling, and cutting out this hole took me maybe 45 minutes, but I didn't time it. It is the 6 inch size, not the full 8 inch that I used for the fuel tanks.







On our fuel tank project we really only had settled asphaltene gunk and some corrosion that we cleaned out and did some preventative maintenance on, but I feel for where you are. I spent a couple weeks each on my fuel tanks (laying on one side port, the other side starboard, up over a tranny and a stringer onto part of the hull, reaching up into the tank to clean it) but in the end I have tanks with access ports that I can get to again in the future, or rather then next guy can! I'm pulling for you! I think if you search my threads you can find some more pics of my fuel tank project if your interested. Good luck!

"All this hassle could be avoided if every boat builder put the fuel take off/pick up at the very bottom underneath of the tank the same as a truck and all these problems would be avoided.

Even better would be a bailable sump , sat 4-6 inches in diameter and 6-10 inches deep.

Thin bit and HIGH pressure is the trick to SS.

SeaBreeze said:

This evening I started the project of cutting an access port into the first stainless steel tank. There has to be a quicker way. I spent over 1.5 hours trying to drill a pilot hole so I could use the bi-metal hole saw. I used cutting oil, a new bit made for metal, and used slow rpms. After 1.5 hours I still had not even broken through to the interior of the tank. At this rate it will take 20-30 hours just to get the access hole cut and the bolt holes drilled. Someone please tell me there is a trick to this that I’m missing.

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It absolutely should not be that difficult. You must not have a good quality SHARP drill bit. Many brand new drills bits today are not worth the metal they are made from. Go to a place like McMaster Carr which ONLY sells high quality bits, and buy either a set of drill bits or the particular sizes you need.

These will do it, but the cobalt bits are indeed even better.

https://www.mcmaster.com/8907a14

Ken