Double-walled barrel and method of its manufacture

A double-walled barrel comprising:

• an outer barrel including
• (a) a cylindrical barrel jacket with an inner surface and a first set of corrugations;
• and
• (b) a top with barrel openings and a bottom, said top and bottom being attached to said cylindrical barrel jacket by a first set of folds to form said outer barrel;
• an inner barrel including:
• (a) a steel container having a second set of corrugations;
• and
• (b) an inner top with barrel openings and an inner bottom, said inner top and inner bottom being attached to said container by a second set of folds to form said inner barrel, said inner barrel being configured and dimensioned to closely fit within said outer barrel and being supported by said second set of folds and said second set of corrugations lying against the inner surface of said cylindrical barrel jacket;
• a connecting flange, said inner top extending upwardly toward said top and contacting said top in a region of the barrel openings, said top conforming to the shape of said inner top and being joined to said inner top by said connecting flange at the barrel opening;
• wherein the region of contact between said top and said inner top is step-shaped with the steps progressing upwardly, in a direction away from said bottom, toward the barrel opening.