Today in 1957, US Patent 2812876 A was issued, an invention of Michael Karl Goetz, for his “Cover for Tap Opening of Beer Kegs.” There’s no Abstract, although in the description it includes these claims:

This invention relates generally to the field of containers for beer or the like and, more particularly, to cover structure for use on beer kegs to shield and protect the tap opening portion thereof.

It is the primary object of this invention to provide cover structure adapted for protecting the tap opening of a keg from damage during transportation or storage, for excluding dust and foreign matter from the vicinity of such tap opening and for preventing inadvertent displacement of the cork normally employed to seal such opening until the keg is tapped.

It is another important object of this invention to provide such cover structure which may be conveniently and positively emplaced upon a keg and which may be readily removed from the keg when the latter is tobe tapped.

It is another important object of this invention to provide such cover structure which may be manufactured at low cost and in large quantities with a minimum of material and processing.

It is another important object of this invention to provide such cover structure which is adapted, when installed on a beer keg, to not only cover the tap opening of the keg but to effect a positive, protective seal between the cover and parts of the keg surrounding such tap opening.

It is still another important object of this invention to provide such cover structure which may be easily and effectively cleaned for re-use.