Suppose, I have a cylinder made of sufficiently strong materials.  One of the
side is made up of copper sheet (with strong enough welds and joints)
.  Assuming radius r and height h for the cylinder and d the thickness
of the sheet (same radius), what is the safe presssure I can put
inside the cylinder. specifically will a 0.2 mm Copper sheet of area
100 cm^2 hold 8 atms in the cylinder within safe limits ??
Will 10 cm^2 area sheet do the job ?? A analytical formula would be
the best answer. Assume standard grade copper ...nothing fancy...

My guess is yes. An aluminum pop can take several atnospheres.

Does your can contain a valve?  Is it bimetal?  Will it be heat
treated after being formed? Is the fluid inside corrosive? Pure copper
is rather soft assume a standard plumbing alloy.

Read this:

http://www.efunda.com/formulae/solid_mechanics/mat_mechanics/pressure_vessel.cfm