That's an awfully vague request. If you're figuring lifting weights or shipping weights or something of the sort, you really need more specific data.
For relatively thin cylinders, approximately, t=PR/SE +CA, where P is internal pressure, R is radius, SE is allowable stress times joint efficiency, CA is corrosion allowance, with all units consistent. Typical values of SE might range from 12,000-20,000 PSI; CA perhaps 1/8". Thickness would normally be 1/4" or so minimum. These numbers could vary widely, though, depending on the application.