Calc welding(meter) steel plate on new bottom storage tank

[theraider]

Hi!
I'd like to develop a excel tool for calculate how many meter of welding need for install a new bottom on a storage tank.
The data that I know are:
Steel plate dimensions: 2mtX8mt;
Tank Diameter (in mt);
Tank Bottom (in sq.meter);

Thanks a lot.

[theraider]

Bottom = new floor