[jordanjw]

Hey,

machinist by trade by like to weld also. I will be building a new alum gas tank for my friends boat. could you give me some tech help on material selection for this app (5/32 thk), filler rod series and diameter. Tungsten diameter for this material thickness. Also some tip on joint design as the tank will be all welded and no bends. Know of any basic books on gas tank design for boats.

Thanks
Joe

[jordanjw]

no takers?

[jpence38]

I would use a 5052 base metal with a 3/32 5356 filler metal and a 3/32 electrode. I would use a corner to corner joint design so there is 100% weld penetration. I would also consult a book for design and find out what the specifications are for a fuel tank. Not to be stupid or anything but there is a lot more to building one of these things than you may think. Good luck. Hope that helps. Anybody else got any input. I know there are some aluminum boat welders/fabricators in this forum.

[kermdawg]

Can you use bladders in marine tanks like they do in fuel cells?

[jordanjw]

Hey

Guys I really appreciate the prompt and professional replies to my questions on the gas tank. I will admit a gasoline tank for a boat is not my first choice of things to weld but it is for very good friend of mine that has helped me a lot in the past. Time to step up to the plate so to speak. I feel comfortable with my welding skills just wanted to check out the small details. We will be pressure testing it as recommended. Does anyone recommend dye penetrant testing or is that a good test for this type of job.

Thanks

Joe

[joseph.mowery]

What size tank? May want to consider baffles in the tank to keep the fuel from shifting during turns. Nothing like all that weight shifting to the outside of a boat to give the operator a little pucker factor. Also, if you use AL, remember to keep any ferrous material away from the tank. It's a real concern for corrosion in a saltwater setting.

[Otto Nobedder]

Good thought on the baffles. I'd put them in a small tank regardless. It'll keep the fuel pump from sucking air, 'cause there's a lot of sloshing going on in a boat tank.

My material of choice would be 16 ga. 304 SS (316 if for salt water) in a five or ten gallon application, 11 ga. for larger tanks. The baffles can be as thin as you're comfortable welding, whether Al or SS.

You ought to post a picture when it's finished.

Steve

[Otto Nobedder]

You might also consider a small sump below the level of the pickup to trap and drain water, unless this is to be a portable tank.

Steve

[TheExpert]

Thanks for this informative forum. I like Otto Nobedder suggestion. This is also much informative.