What is a C x C, Sweat x Sweat, or Solder x Solder valve or fitting?

The three terms listed below are all used to describe the same type of plumbing connection.

Copper x Copper (C x C)
Sweat x Sweat
Solder x Solder

Sweating a pipe refers to soldering the pipe or the joint. Soldering a pipe joint, or sweating a pipe, is accomplished by heating a brass or copper valve or fitting with a propane torch until the end of the fitting or valve is just hot enough to melt metal solder. The heat draws the solder into the gap between the fitting and the copper pipe to form a watertight seal.

The female copper sweat connections are manufactured to be compliant with ANSI B16.18.

CAUTION: When soldering a ball valve it is crucial that you position the valve handle so that the ball is in a partially open position during the soldering process. This is important to avoid the build up of pressure between the valve body and the ball as the heat is applied.

Additional Resources:

https://support.boshart.com/how-do-i-install-a-solder-ball-valve