Today in 2013, US Patent 8348086 B2 was issued, an invention of William P. Apps, assigned to the Rehrig Pacific Company, for his “Plastic Beer Keg.” Here’s the Abstract:

A beer keg includes a container having a base and a wall extending upward from a periphery of the base. A liner within the container includes a base, sidewalls and a mouth. The base of the liner interlocks with the base of the container to prevent relative rotation therebetween. A valve is disposed over the mouth of the liner.