Diesel tank cleaning

I have been hired to get an old wooden motorsailer in the water after being out for over 20 years. The 6-354 perkins has been rebuilt and is in place and has been aligned but i expect to have to realign in the water. So I have to hook everything else up, i do plan on replacing all the exhaust hose. But to me the big issue is cleaning out the tanks, there are 2, 1 is easy to get at ,the other very difficult and removing them is not an option so they will need to be cleaned in situ. Here's the problem, they are very nice stainless steel tanks but have no cleanout plates so i will have to cut some in but of course they have baffles which will only allow access to the chamber where I put the cleanout so i may have to install multiple cleanouts which i hate to do as every one is a potential for leaks. Also, on the hard to access tank they would need to go on the vertical face which i don't really like. As an alternative is there some liquid chemical, preferably not flammable that I can just soak the tanks with to loosen the crud on the bottom and then pump and filter until its clean. I would really rather just hire a company to do it but there are none around here.
On another note, the fuel pickups are from the bottom corner of each tank on the aft end while they are connected by a hose and valves at the front, is this legal these days? I've always installed the pickup in the cleanout plate.

Steve.

 

You could cut holes and then make cleanout plates.

 

I did say i will have to install cleanouts, i think i may try soaking with parts cleaner and see if it loosens up the gunk.

Steve.

 

If you can access between the baffles, an industrial detergent and a scrubby pad will clean it. Diesel usually doesn't create the hard varnish you see on gas tanks.

 

Yeah, the baffles i expect will cause a problem though for physical cleaning, i won't really know i guess until i install the cleanout plate. The smaller tank looks like it has 2 baffles so i expect i will only be able to access about 1/3rd but it depends how they made the baffles. Gonzo, you are a surveyor, right? What is the legality of the fuel pickup and crossover pipe coming off the bottom end of the tank. I am planning on moving it to the cleanout plate so i can hold it short of the bottom anyway.

Steve

 

I'm uncertain as to what sides of the tank the baffles are connected, but... might it be possible to cut off say 80%'ish of one side of the tank, so that you get full access to the tank's interior. - With a saw, not a torch (preferably .

Then clean out the tanks, followed by welding on new sides to replace the cut out/off portions. Using a combination of both plug, & lap welding for redundancy.
This would also allow you to put the fuel pick up points where you wish, prior to putting the new sides onto the respective tanks. Followed by your putting clean out ports at the best locations for future cleanings. And as a perk, with that much of one side of the tank removed, you could move the baffles if necessary. So that they're located such that they don't much interfere with future tank cleanings, yet still are placed & configured for optimal tank cleanout.

Or, you could even, possibly, reconfigure/redesign the baffle system such that they work well with new cleanout ports installed in the tops of the tanks, post side reinstallation that is.

I'd figure that spending some time talking with a few, crusty old, tank cleaner/fuel polishers would likely yield volumes of good information. And also that it'd pay to talk to a few mechanics who rebuild engines, & transmissions (especially those who specialize in working on one's in situ) to see what their solvent washes will & wont remove, both with & without scrubbing.

Like the types of solvent baths mfd. with red metal tanks/tubs, with internal screen gratings for the parts being cleaned to lay upon. Which you see tucked into the back corners of & along side walls of auto/mechanic shops.

Worst case, you could always figure out a way(s) to clean out the tanks via small ports, & inspect your work as you go, with flexible fiber optic cameras. Though such would likely be pricey.

BTW, what's in the way of getting to the tank in the tougher location? And is does leaving the obstructions in place truly outweigh the cost of pulling, & reinstalling the tank? Especially given that if you pull the tank, you'll get a good chance to look over it's long hidden sides (and what's underneath of it). Ergo, no nasty surprises about it's structure 2 years from now.

I've found that for the most part, having machinery, etc. off of the vessel to work on it, usually pays for itself in terms of time & ease of access for working on any item in question, yanked out for repairs. Knock on wood.
And that rebuilding the original structure surrounding it's generally one where the time spent thinking about how to un-install & reinstall said item & it's housing is worth more to me than a couple of weeks of skinned knuckles due to poor access with the item in place.
Ditto on the quality of the work done on said item when it's done on a shop's work bench, via that which is done in situ if the item's in a difficult to access location.

Good luck with the project, & let us know; which route you go, & what snags & their respective solutions, as you go about the project.
Ah, also, a few pictures of the proposed project, allowing us to see your concerning tough spots would do wonders in terms of us helping you find a good solution.

 

Thanks, UC, i have been giving this a lot of thought while working on other tasks and have decided to concentrate on the smaller, easier to access tank and see how that goes. It is a simple rectangle with two baffles so i am going to cut in a cleanout plate in the top 6"-8" so i can get my arm in and i will be able to reach all of that cavity to scrub, but before any scrubbing i will try dissolving anything that's there. The boat has deep bilges so, with the pickup coming from the bottom corner i will be able to drain the fuel that's in there into a bucket, from what i can see through the small hole there is (there is a small plate covering a hole i would only consider an inspection hole, about 1"x2") there is maybe an inch of fuel in there. My thoughts are that since the tanks are stainless, not aluminum i can use pretty harsh solvents and since i can drain rather than pump it out it will be safer so i will try gasoline or parts washer fluid which should work i think. When i make up the cleanout plate i will install a new pickup in it with the tube stopping an inch or two from the bottom and put a plug in the old hole or perhaps a valve with a plug so it could serve as a future drain should he ever get bad fuel with water in it. These are very nice tanks actually. BTW removal is not an option.

Steve.

 

Steve,
You're more than welcome. Just a safety tip. And I'm sure you know this, but when you're working on the tanks, whether with solvents or no, make sure that the tanks are well grounded (SIC). Ditto on any tools, aside from hand tools, which you're using too. Meaning, make sure to use 3-prong type cords, etc. I'm sure you know what I mean. That & were it me, given my druthers, most of the time I'd wear a face shield in addition to my safety specs. And have an eye wash station handy as well.

Good luck with, & enjoy the project.
Andy

 

Any chance of hiring a steam cleaner?

Maybe 3 smaller (say 4" round) access plates would allow the lance into each section for a thorough clean and just keep going 'till the 'stuff' coming out the drain hole is clean. might need to drill / holesaw the drain plug hole first.

This will get them clean enough if you do need to weld a flange and drain plug at the bottom though a sniff test (like draeger snap tube) worth doing if you can.

:!:
Also be VERY careful if you decide to MIG or TIG the flange on - the shielding gasses Argon or CO2 are both asphyxiants (Ar is without taste or odour = NO warning) and Heavier than air! They will fill the bilge up... SCBA may be needed if positive ventilation is not possible!
:!:

 

"Mr Muscle" oven cleaner will disolve any oil based gums or tars but is highly caustic so lots of rinsing (ideally pressure wash)

 

To be clear, no welding is going to take place on the tanks, fortunately they already have the fuel pickup in the bottom corner so draining is no problem. Steam cleaning would probably work well. I have thought about putting 3 cleanouts in the small tank but they would want to be at least big enough to get an arm in past the elbow. I cleaned out the poly water tanks on my cat last year and i couldn't get past my elbow so couldn't scrub at all, i ended up soaking with a bleach solution. I am glad they are ss and not aluminum so i can use more caustic cleaners if need be.

Steve.

 

This has the feeling of one of those jobs where semi 'mass production' might be worth it.

If you go and see your local profile cutting/waterjetting/lasercutting company you can get them to make you a set of oval plates and corresponding backing flanges - ideally pre-drilled. Remember that the oval has to allow the backing plate to go sideways through the hole.

If you need 7, 8 or more this will save a ton of time - you can also get them to cut you an extra flange in thicker mild steel to use as a drilling and cutting template.

They may even be able to put your bolts through the hole and weld them captive on the inside flange if you dont have access to a welder. One or two small countersunk screws can be added to ensure the backing flange will stay put if the plate is removed.

 

You may be right regarding having them waterjet cutting and we do have one locally if I need a lot. I have made a few of these before and they are pretty easy to make out of aluminum. They don't need to be oval, I cut the inside ring on the bandsaw and the cut through to cut the inside is what allows you to feed it into the tank, there is no reason for it to be continuous. I can tap the holes for the bolts into the inside ring quickly as I have a air tapping arm. There is a company named Seabuilt that makes exactly what I need but I can make them a lot cheaper for the customer. I will look into waterjet cutting though if I find I need more than a few, which I will know after I cut the first hole and see how dirty it is and how the baffles are installed.

Steve