Today in 1969, US Patent 3438531 A was issued, an invention of Raymond L. Millard and Arthur W. Tschannen, assigned to the Adolph Coors Co., for their “Plastic Bung For A Beer Barrel.” There’s no Abstract, although in the description it includes this summary:
This invention relates to plastic bungs for beer barrels.
The invention comprises, in essence, a bung plug having a circular wall section sized and tapered to fit a standard bung orifice, and an oversized, tapered, conical skirt at the leading rim of this wall adapted to guide and subsequently lock the hung in the orifice. A seal ring circumscribes and outstands from the wall adjacent to the skirt and is in functional juxtaposition therewith, for the skirt protects the seal from scraping against the sides of the bung orifice until the bung is finally positioned.
It follows that the primary object of the invention is to provide a novel and improved plastic bung which may be fitted into an ordinary bung orifice in a beer barrel and will not thereafter leak.
Another object of the invention is to provide a novel and improved bung formed of a selected type of synthetic resin plastic material which combines the desirable properties of rigidity, resilience and the ability to cold flow at moderately high stresses, and which is formed and proportioned to stress the sealing portion of the bung against the walls of an orifice, by a resilient pressure in the body of the bung, with pressure sufficient to deform and to cold flow the sealing portion to produce a tight, leakproof fit.
Another object of the invention is to provide a novel and improved leakproof bung of such synthetic resin which will reliably seal a hung opening in a beer barrel that is scratched, pitted, marred or otherwise made irregular by use and abuse.
A further object of the invention is to provide a novel and improved bung for a beer barrel which is adapted to be securely fitted into the bung orifice of the barrel with out contacting, sliding or otherwise damaging the sealing portion of the bung against the wall of the bung orifice while the bung is being driven into place in the bung orifice.