Originally Posted by Jason Hildebrand
Let's not get carried away here with horror stories, gasoline fumes are a whole lot different than diesel. The original post was a guy asking about welding a small tank not a 10,000gal tanker. Diesel can ignite from welding so obviously u keep a fire extinguisher around for safety, for it to explode it needs a mixture of fuel and air under pressure. Keep the area vented = don't weld the tank with all the caps on, let it breath.
I feel compelled to comment on your statement only for the reason of safety.
I'm not going to debate your extensive experience repairing fuel tanks, from your comment earlier about that you think welders only have fuel tanks steam cleaned to get the fuel out of the crack, I'm inclined to believe its quite limited, but then my opinion is based only on your own words.
To anyone else reading this, you need three things to create a fire and possible explosion...AIR...FUEL...AND A SOURCE OF IGNITION. By removing one or more of these or limiting at least one to the smallest minimum possible is the only safe way to repair any kind of fuel tank, it dont matter what size it is.
While it may seem insane to weld on a tank full of fuel, as was pointed out several times earlier, by having the tank full you are limiting the amount of air inside the tank. To attempt to weld on any kind of fuel tank which is empty and no other steps taken is extremely dangerous.
I suspect the fellow who asked the question in the beginning did so because he was unsure of whether or not he wanted to attempt to repair his own tank. To suggest in a public forum like this, blatant disregards for safety to someone who may not know better, is nothing short of irresponsible.