Olets are fittings used in piping to provide an outlet for a bigger pipe to a smaller one or similar size. The main pipe is called run or header, where the branch connection is fixed. The common types of branch fittings are as follows.
Weldolet: These branch fittings come in a wide range of dimensions, and they have beveled ends on both ends. One side is fitted into the branch pipe while the other side is welded into the running pipe.
Sockolet: This fitting is similar to a weldolet. The difference is that the branch pipe is joined with the run pipe via the sockolet.
Threadolet: These fittings are for low-pressure applications and smaller pipes. The branch pipe is screwed into this fitting and welded on the run pipe to fit it in.
Sweepolet: These are contoured, butt-weld fittings used for long fatigue and low-stress services. To inspect the welded connection, a plumber uses radiographic examinations or non-destructive tests.
Latrolets: These fittings come with butt welds or threaded connections. They branch a pipe at 45 degrees and come in 3000# or 6000# classes.
Nipolet: Nipolets are made with a threaded outlet or a socket weld-on side of the branch. They are commonly used for valve take-offs, vents, and drains.