cutting down a '90 F150 fuel tank, is it soldered?

[ladykiller]

I do intend to get a smooth sawzall cut, but I don't want to rule out the possibility of needing further fitting.

[ForingaMex]

The guy that fixed my gas tank ran the exhaust in to the tank for about 20 minutes (stick the exhaust pipe into the tank filler hole) than welded away no problem. I friend of mine told me that he has welded on a lot of propane tanks. He said that he would pour some vinegar in to the tank and splash it around, make sure all of the inside surfaces of the tank had been coted and let it sit for about 10 minutes. After that, he said, you could weld on it. I'm not sure gasoline and propane would react the same to vinegar or not. I can vouch for the gas tank repair that it worked, I was there but I'm not sure about the propane tank/vinegar idea. Whatever you do, proceed at your own risk. Be careful.
Jake

[BobbyFord]

When we would weld on Harley tanks, the trick is to stuff a bunch of dry ice in the tank, no boom.

[Skifu]

Ive welded on several fuel tanks.and Ive cut open retired propane pig tanks to make BB-Q smokers out of them,If your gonna do it the same day,or real soon,set the tank behind your truck,and run exhaust gas through it for a couple hours,wash it out first,as good as you want,but run exhaust through it after,this has worked like a charm for me several times,I run a mobile mechanic/welding business from my home.The last one I patched was a big round aluminum diesel tank,I purged it with a farm tractor,and it worked just fine.??

[badboyzkustumz]

if you por-15 the inside of the tank it takes care of the vapor. welding on old tanks isnt that bad as long as you do it right.

[Skifu]

Blow exhaust through it,its simple,and it works.

[zakt]

read this, good info

http://warbuddies.homestead.com/gastank.html

[Skifu]

read this, good info

http://warbuddies.homestead.com/gastank.html

Sure,their trying to scare you into being safe, and thats ok,theres a MIL Spec on how to purge a fuel tank for welding in the field If your away from the shop,Ive seen it,and read it,by using exhaust gas,it has worked for me more than once,it must be done properly,as with all these steps,I cut doors into a 150 gal. propane tank to make a BB-Q smoker,all I did was fill it up with water,and cut away,I also burned it out for a couple days after it was done to burn away any left residues,and to "season" it,I must of burned a truck load of wood in that thing,Then pressure washed it out.but man would it cook,make a big fire in the fire box portion,place the food on the racks,and forget it,come back 2 hours later,or how ever long it takes for the amount of meat,and it would be ready,easy!and it cooked perfect every time.