As an expert sommelier and brewer, I have had the opportunity to work with various types of kegs, including the popular corny kegs. When it comes to the size of the thread on a corny keg, it is important to note that Cornelius is a well-known manufacturer of these kegs, and their threading specifications are widely followed in the industry.
Typically, corny kegs manufactured by Cornelius have a threaded 19/32″ 18 threads per inch (TPI) on both the gas and liquid posts. This means that the threads have a diameter of 19/32 of an inch and there are 18 threads per inch. This threading size is consistent for both the gas and liquid posts on the keg.
It is worth mentioning that there are other manufacturers who produce kegs under license from Cornelius, such as Firestone and John Wood. These kegs may have slightly different threading specifications. The most common threading size for kegs manufactured under license is 9/16″ 18 TPI. Additionally, these kegs may have distinct threads for the gas and liquid posts, unlike the uniform threading on Cornelius kegs.
In my personal experience, I have found that the threading on corny kegs is crucial when it comes to compatibility with various fittings and connectors. It is important to ensure that the threads on any keg you are working with match the fittings you intend to use. Mismatched threads can result in leaks and difficulties in connecting and disconnecting equipment.
To summarize the thread size of a corny keg, it is typically threaded 19/32″ 18 TPI on both the gas and liquid posts when manufactured by Cornelius. However, kegs produced under license by Firestone or John Wood may have different threading, most commonly 9/16″ 18 TPI, and may also have distinct threads for the gas and liquid posts.