Homebrewers often use kegs for aging, filtering, and storing beer. These are seldom the standard kegs used by major brewers to transport draught beer to wholesalers, but instead are reconditioned Cornelius kegs (colloquially known as “cornies”) that were originally manufactured to store soda; these vessels are much easier to fill, clean and maintain than standard beer kegs.
These kegs are stainless steel cylinders that hold approximately 5 U.S. gallons of liquid. The keg is filled with liquid via a removable hatch on the top, which is then closed and sealed. Carbon dioxide is added to pressurize the keg via an inlet port on the top and is facilitated by gently rocking the brew back and forth. Liquid is dispensed via an outlet port attached to a tube that extends to the bottom of the keg. Pin-lock and ball-lock fittings (or posts) are the two types of couplings used on the inlet and outlet ports. Coke distributors used pin-lock fittings, while Pepsi distributors used ball-lock fittings. Ball-lock are most used. The pin-lock style is often referred to as a “Coke” keg or style and the ball-lock is often referred to as a “Pepsi” keg or style, though the fittings themselves are removable, serviceable, and contain interchangeable parts.
Homebrewers sometimes use 15.5 U.S. gallon commercial kegs (known as 1/2 kegs) for boiling vessels in creating wort. The kegs are drilled for a drain at the bottom, and the top cut open to create a large stainless steel cooking kettle. Many times, the piece of metal cut out of the top is re-used to create a false bottom for straining wort during the mashing process, as well as to strain the boiled wort when adding hops without using a mesh grain bag.
It is not recommended that kegs be sanitized with bleach. To avoid unpleasant residuals, sanitize kegs with an iodine or oxygen based sanitizer. Sanitizers like Star-San and B-Brite are commonly used. The ball lock valves may be unscrewed using wrenches to allow further cleaning or replacement of O-rings or poppet valves.