There are several piping parts that you will encounter in engineering, including sweepolets, weldolets, thredolets, sockolets, elbolets, and nipolets.
Weldolets are 90-degree branch connections for piping that come in reduced or full size. The end connection for this part is suitable for butt welding.
Sockolets are similar to weldolets, but the difference is that the end connection is suitable for socket welding, hence the name.
Thredolets are also for 90-degree branch connections like the first to, but with their ends suited for threaded joints.
Elbolets are a hybrid of the first three parts as they are also for 90-degree connections but with ends that can be used for butt welding, socket welding, and for threaded joints as well.
Nipolets are simply weldolets with an extended pipe body and have the same end capabilities as elbolets.
With special olets, there are latrolets that are used for 45 degree or special angle connections, and coupolets which have threading and are used for low-pressure services along with sweepolets.
Along with sweepolets, these commonly used branch connections are among the most basic ones, so you can expect to come across them regularly in piping.