Bunghole

A bunghole or bungehole is a hole bored in a liquid-tight barrel to remove contents. The hole is capped with a large cork-like object called a bung. Acceptable usage include other access points that may be capped with alternate materials providing an air- or water-tight access to other vessels. For example a bunghole on a combustion chamber can be used to remove slag or add coal. Bungholes can also be utilized to insert and remove sensing probes or equipment like mixers to agitate the contents within a vessel.

Bungholes were first used on wooden barrels, and were typically bored by the purchaser of the barrel using a brace and bit. Bungholes can be bored in either head (end) of a barrel or in one of the staves (side). With the bung removed, a tapered faucet can be attached to aid with dispensing. When barrels full of a commodity were shipped, the recipient would often bore new bungholes of the most suitable size and placement rather than remove the existing bung. Wooden barrels manufactured by specialty firms today usually are bored by the maker with suitable bungholes, since the hobbyists who purchase them for the making of beer, wine, and fermented foods often do not have a suitable brace and bit.

Closed-head steel barrels and drums now used for shipment of chemicals and petroleum products have a standardized bunghole arrangement, with one 2" NPT and one 3/4" NPT threaded bunghole on opposite sides of the top head. Some steel barrels are also equipped with a 2" threaded bunghole on the side.

Bungholes can be made on the bottom of small boats. The hole would have a small piece of cork (Bunge) in the hole while in use by the owner; when it was not in use the owner would remove the bunge so if unwanted visitors decided to take the boat they would sink. Used mostly in the Renaissance and Middle Ages.