Today in 1950, US Patent 2503339 A was issued, an invention of Herbert S. Jandus, for his “Metallic Beer Barrel.” There’s no Abstract, but there’s this description. “This invention relates to double walled containers and more particularly to double walled beer barrels made from sheet metal stampings and provided with a removable or permanent liner made of a material suitable as a container for beer,” and then a few more specific reasons for the metal keg design.

By constructing such a barrel with double walls, a number of advantages are gained thereby. A sturdy construction of sufficient rigidity to withstand the hard usage to which these barrels are ordinarily subjected can be formed of relatively thin sheet material by’ stamping methods, portions of the total structure being made in sections which are subsequently secured together, and yet the total weight can be kept within satisfactory limits. To accompany the advantage of using sheet metal suitable for stamping, provision is made for the lining of the inner shell so that the metal itself need not be one that is especially adapted because of its inertness for the reception of beer or other edible Products.

A double walled construction is readily adapted for the provisions of an opening into the interior shell, larger than the usual filling opening or tap rod opening such as are usually provided in wooden barrels, for example. Such an enlarged opening can be used to facilitate the cleaning and the inspection of the barrel, and may also be used for the insertion and removal of a separate removable liner.