Auto body repair & detailing: floor pans, air chisel, floor pans

Question
I am looking at replacing my floor pans? I am very handy can weld and do just about any thing. Can you tell me what is involved with this project, what tools re needed. Do we have to seal the metal on the joints with something or will the weld enough to keep out the weather?

Answer
You will need a cut-off wheel or a good air chisel to cut the old metal out. Weld your new pans in, prime and seal, then paint or undercoat.
Are you making your own pans or are you buying new stamped replacements? If you are just patching what you have, then the cut-off tool is easier to trim out the bad metal for a patch. If you are putting in complete floor pans, then you will need to drill out spot welds, then chisel the old piece out.