Modifying (welding) Transfer-Flow Tank

[Dkevdog]

As some of you have been helping me on know, I acquired a used transfer flow in bed type tank. I deceied to toss the toolboz case that was built around it (the tank is seperate and just bolted inside of it) and create a new diamond plate box for it.



Doing this will require some welding and fabrication of the existing steel tank. I need to extend and relocate the fill and vent tubes, as well as weld some mounting tabs to the bottom.



Question is, I am well aware of the dangers involved in welding on fuel tanks, gas in particular. Do the same dangers apply to diesel tanks?? I didn't think diesel fumes were explosive by spark, but don't want to find out the hard way !!



Kev

 

[Steve Campbell]

IMO....

diesel is way less "excitable" than Gasoline. I ran the exhaust from my truck into the tank for 20-30 minutes before welding. I had no problem.



I have filled empty gas tanks with water before to weld them. Kind of hard to get them dry afterwords before refueling.



Disclaimer..... Remember... . this is the internet... . and you can hear/read just about anything on any subject. Who knows whether it is true or not.

 

[nickleinonen]

pump it full of carbon dioxide or nitrogen... i think if you put in a few pounds of dry ice and let it evaporate it'll fill it with CO2 also...

 

[JohnE]

The welder that repairs diesel fuel tanks for us doesn't care if we purge or not.

We choose to use dry nitrogen to purge tanks and satisfy safety concerns. About any inert gas will function including nitrogen, CO₂ , argon, helium.

We have nitrogen around for testing A/C systems before dropping the freon.

A common source of inerts is the gas off your wire feed welder.



edit forgot the ₂ on CO₂ Besides being deadly, CO will burn

 

[Dkevdog]

Thanks for the reply's. I 'll fill the tank with Co2 just to be safe. Nearly all the welding to be done involves tabs and the outside of the tank. The only critical area is the filler neck and return lines.



Kev

 

[JWChessell]

Welding on fuel tank

My experience in welding on an aluminum fuel (gasoline) tank that had been in use for a few months was to fill it with argon under pressure. We used a second argon bottle (the first was attached to the TIG unit) and a two-stage regulator.



After emptying the tank, removing it from the vehicle and then blowing compressed air through the tank at length to evaporate any gasoline residue, we plugged all the openings with rags or small wooden dowels. We ran a hose from the output side of the argon regulator down the fill-neck of the tank into the interior of the tank, then packed the opening of the fill neck as tightly as possible with a rag, around the hose. Then we filled the tank with argon (pulled out one of the little dowels to make sure the argon would flow in) and after we figured it was full, we replugged the little hole and set the output side of the two stage regulator at about two or three pounds pressure. That way we had constant displacement by incoming argon of any air that managed to seep back into the tank.



Then we started welding. No problems; everything went smoothly, and the repair weld lasted about 200,000 miles -- still have the tank, may use it in the new 3500 if I can find a spot.