If I weld a dent puller stud on a gas tank without draining or flushing, will I wake up at the Pearly Gates?
You will, I fixed a Harley tank one night after everyone left the shop, the POOF pushed most of the dent out! And this tank was dry and didn't smell of fuel
Oh, this one was an old shovel tank that had not been used in 20+ years and still popped! And then after I calmed down I tore a hole in it with the stud puller!
If you want to do this safely, first off, make sure there isn't any sludge or varnish in the tank, if so, wire a rag on a stick, pour a quart or so of lacquer thinner in the tank and start scrubbing. After all the glop is mopped up, take the tank to the car wash and spend a few bucks blasting it out with hot, soapy water, once that's done lay the tank out in the yard in the hot sun and let it dry. The last step is to sniff the tank, this is best done by a woman as they can smell things that men can't even imagine.
Or empty it, rinse, and run a hose from your cars tailpipe into the gas tank. This fills it with carbon monoxide which is non flammable .
Why would a guy want to weld on a full tank? Evidently it doesn't leak right? Unless they need a bracket welded on or something. If you blow yourself up I'll never speak to you again.
Put a hose from a running cars exhaust pipe in a drained dry tank for 15-20 minutes. You can then weld on it.
A CO2 fire extinguisher or CO2 bottle off your MIG welder will work will purge it also you 75/25 gas for welding and Aragon or Helium will purge it. I have used all the above with success.
I pulled my Bantam in the garage today and knocked my 1940 Indian Sport Scout onto a spare Flathead block. About a quarter size dent, no puncture. I can just fill it but one stud might pull it out. Thought maybe with a full tank and the cap off it might work. Doesn't sound like it. Thanks guys. Other than that it was a great day.
>>>carbon monoxide which is non flammable . >>> Kindergarten teacher told me it was flammable. Burns to non-flammable carbon dioxide. I saw it on the internet somewhere too. So it must be true. 8^)
Years ago, my boys had a honda50 that had the perfect size tailpipe for a heater hose to slip over it. That heater hose was a nice fit inside the neck of a m/c gas tank and letting the little bike run for ten or fifteen minutes, into an empty tank of course, they were safe to weld on. After I got a tig welder, I just purged the tanks with argon while welding them up.
I used to weld diesel tanks if they were full, but would never even consider a gas tank without being empty flushed and purged with argon or nitrogen.
My buddy did this at the shop he worked at. Using exhaust to purge tanks was SOP there. It always worked, until one time it didn't. Ever shoot a tin can with 12ga buckshot? That's what the tank looked like afterward. He swore that he let exhaust run in the tank for over half an hour. He didn't get hurt, probably not enough fumes to be real bad, but it opened that tank up like a fat kid opens a cookie bag.
I've welded many motorcycle tanks. Normally I just flush with soap and water, hold a torch over the filler and get a mild WHOOSH as it burns off the remaining fumes. And I've done a lot of stud gun dent pulling. The stud and surrounding metal get red for a second, probably the back side too. It might not ignite a full tank, but it might... I'll just fill it, probably need filler with a dent puller anyway.
When I was a kid the “local biker gang” saw me painting cars. One guy stopped by one day and asked me about a simple paint job on a set of tins. I did it he was happy I collected my $10.00 plus supplies. I was only 14 at the time. No real skills with stripes or striping but if they came and helped me I would do it. Had bikers lined up around the block they liked my cheap work and me. I’d they needed a pin hole in a tank brazed up I’d braze it up as long as they brought me a clean tank. So they always brought me clean stuff. Until one guy didn’t. I hit that leaky seam with the torch and that gas tank opened up in my lap like me with a bag of Cheetos. I had just done my last bike paint job! Never saw that guy again anywhere, ever. His associates were pissed.
I welded/brazed/soldered quite a few bike tanks...Flush with acetone, then about 15 minutes air flush with the shop vac. The an ancohol flush, more shop vac. and wave the torch over the filler opening... but a bike tank is about 20% the volume of a car tank...