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Up Topic Welding Industry / General Welding Discussion / Diesel truck bed tank
- - By ason1965 (*) Date 06-09-2008 20:32
If I want to construct/weld my own truck bed diesel tank for my Dodge, what codes should I check other than the obvious things like size, strength, sealed, etc? Any rules and regs. I should be concerned about here in Texas? I am not going to run offroad in my Dodge either :) Got me a Harley for daily commutes and errands.

Parent - By RioCampo (***) Date 06-10-2008 01:16
There is a limit of either 900 or 1000 pounds of diesel fuel before you have to have placards. Not sure about the rest though.
Parent - By NWPAwelder (**) Date 06-10-2008 01:23
How much capacity are you looking to add?  Legally, you can have an auxilliary fuel tank with a capacity of no more than 119 gallons as per U.S.D.O.T. regulationson a one ton p/u.  The tank also has to be certified and carry the proper identification tag.  I know this because I actually used to have a 115 gallon tank in the bed of my truck when I pulled travel trailers cross country but took it out when I came off the road.  Nice tank (polished diamond plate aluminum) complete with transfer pump that mounts on the frame. Gravity feed systems are no longer legal either.
Parent - - By DaveBoyer (*****) Date 06-10-2008 01:44
I think You will want some inteligently placed and designed baffles. Unless the tank is completely full the sloshing fuel can be an issue. This is called "free surface effect" You might want to do some reasearch on it.
Parent - By ason1965 (*) Date 06-11-2008 13:38
Thanks! I was looking to build around a 100 gallon tank. Partly for a project to practice and partly for professional reasons.

Parent - - By thewelder (***) Date 06-14-2008 21:07
HI to "minimized the muvement" of the fuel you have to add at least 3 or 4 dividers, just have havy tacks o n them no weld all arount, the vertical openings has to be stager inside the tank.
Parent - By texwelder (***) Date 06-14-2008 21:44
Or you can cut round holes in the baffels to stop the movement, random holes about 2", that the way I always built the aluminum ones.
Parent - - By sbcmweb (****) Date 06-14-2008 22:05
I'll second that, Dave. All commercial truck tanker trailers have them. Good luck, Steve.

"I'm just a girl....I'm just a girl in the world...That's all that you'll let me be..." (I'm Just A Girl, No Doubt, Tragic Kingdom LP)
Parent - - By texwelder (***) Date 06-14-2008 22:07
The shape of the tank also has a lot to with it.
Parent - - By sbcmweb (****) Date 06-14-2008 23:31
Ohh so true as well!! For all the work that will end up going into it, I would just buy one at TSC for $400. The aluminum alone & bung hole pieces will cost you that & steel won't be a whole lot less at the end of the day. Don't want to rain on anyone's parade, but the labor & fab alone would be a task in itself, and that's if you have all the clamps, layout table & jig pieces to set it up & keep it straight while you tack it up. It would be a horror show to try building it with no setup jigging, on a cement floor crawling around all day on your knees. Big chance it will warp up & or have bulges & valleys if it doesn't line up good when it's being tacked.  It should be TIG welded for the best possible seal as well. Just a few things to think about. S.W. :-)

"Just another tricky day....For you." (Another Tricky Day, The Who, Face Dances LP)
Parent - - By texwelder (***) Date 06-15-2008 01:04
If you did build one, you would be better off have a sheet metal shop bend as much of it you could, then mig it together if you build it out of steel, tig if you build it out of alum. and use as much filler rod on the welds as possible or it will crack.
Parent - - By sbcmweb (****) Date 06-15-2008 03:17
Yep. That would be the way to go. The braking on it shouldn't be any more than $60-100 at the very most. Still say it would be a lot cheaper to buy one. A liquid tight tank holding combustible fuel, to put on your truck, made without fixturing wouldn't be anything I would want to "practice" on as a first time big project. A small one, say for a snowmobile, wouldn't be a problem at all, quite easy in fact. You can control the outcome a lot more when you can set it on a table, clamp it & plumb it up with some straightedges & 2X4X6 blocks. The small pieces wouldn't be prone to warp & misalign.

But a big one......I would probably be pulling what hair I have out of my head 1 hour into it!! :-) You could always make a jig out of a plywood & 2X4 box & overlay the metal on it to get it tacked up. Then pull the box out after it's aligned & tacked. It's still going to suck without good fixturing to set it up though. Getting the final piece on without bowing & warping would be a trick, not to mention the crown the sheet metal itself has that will have to be compensated for if it's a heavy one. There's no way to support it inside unless you put some gussets in to hold it on place. Still, you wouldn't be able to fully weld them to the top piece inside.  Believe me on that one. Been there, done that. I'm not saying it cannot be done, but it all depends on how good you want it to look & what you want to put into it labor wise. Good luck on it though! S.W.

"They hold no quarter.....They ask no quarter.." (No Quarter, Led Zeppelin, Houses Of The Holy LP)
Parent - - By ason1965 (*) Date 06-16-2008 20:07
Thanks all for the good advice. I have a little Tig welding experience, on carbon, chrome and SS pipe mostly. It would be a learning/experience garnering project but the basic materials would be free. What are the advantages of steel vs. aluminum for a gas/diesel truck bed tank? Weight and rust are a couple in favor of AL, I would suppose, are there others?

Parent - - By sbcmweb (****) Date 06-16-2008 20:38
Hi, Dean. Steel would be the advantage in that it's a lot more forgiving & you can weld it with GMAW & come out good & not be welding on it for the next month if you were to weld with GTAW. Weight will, of course be more & rusting can occur as well, but from strictly a fabricational standpoint, steel is going to be a heck of a lot easier to weld, cut & bend without a ton of special tools. AL is great, but you would want to have enough confidence in your welding ability to assure that you don't end up having leaking & cracking problems down the road with 100 gallons of $4.35 diesel in it & on the back of your truck, 300 miles from home!!

If you were to run into a problem doing TIG on AL & had a bad fit up, or a blowout on a critical edge weld, things could get dicey real fast & AL isn't all too forgiving with problems like porosity, burn through, cracking, etc. Stainless would be the bomb, but you're wallet better be fat, or have access to good usable scrap sheet. Bending & shearing it is a nightmare as well if you don't have some heavy machinery to do it with. SS sucks for TIG though, if you don't have a LOT of patience & experience with thinner metals. Sugaring & other problems, including warpage can quickly arise if you're not careful.

I would NEVER want to discourage anyone from a learning project, I just have been there myself taking on ambitious big projects without having all the details mapped out first & then end up with a wicked mess on your hands halfway thru. If the materials are free, I would do it in steel, around 12-14 gauge min. You could easily fabricate it, make some mistakes & still have the ability to fix it without a major headache. That would be my $ .02 on it. Best of luck!! S.W.

"I feel so alone, gonna end up a big 'ol pile of them bones."  (Them Bones, Alice In Chins, Dirt LP)
Parent - By ason1965 (*) Date 06-17-2008 14:24
SW, thanks! I probably will go with Carbon Steel since I have access to enough free plates and stuff to get a tank done. The stuff you say about the relative pain of dealing w/ Al outweighs the gains in weight and lack of rust.

Up Topic Welding Industry / General Welding Discussion / Diesel truck bed tank

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