A pipe fitting is a piping component that is used to join piping, change the direction or diameter of piping or end the pipe. They are a versatile piping component which are necessary in modern piping system.

Pipe fittings can be broken down into several categories:

Branch Connection – Branch connections are used when two or more pipes come together. These can be in the form of a complete fitting, such as a tee or cross. They can also be in the form of an O'let which is a branch connection that is designed to attach directly to the pipe. Branch connections are available in buttweld, socket weld, threaded and flanged.
Cap – Weld caps are used to seal the end of the piping. It might be used when old pipe is being abandoned or with a tee to form a hydraulic elbow. Caps are available in buttweld only.
Coupling – Couplings are used to join two different threaded pieces of pipe. When a coupling is used, it is important not to over torque the piping, otherwise damage to the coupling or union can occur. Couplings are available for threaded pipe only.
Elbow – These are useful when needing to change direction of flow. Typical elbow directions are 45, 90 and 180 degrees. Elbows are available in buttweld, socket weld, threaded and flanged.
Reducer – Reducers are used when the pipe needs to change diameter. Reducers are available in buttweld, socket weld, threaded and flanged.