Which types of fittings require mitres?

Mitres are cuts made at an angle to allow two pieces to join together seamlessly, especially where a change in direction is needed. Elbows and sweeps are specifically designed to change the direction of a piping system. When these fittings are used, such as in a setup that involves bends, creating a mitre ensures that the connection is smooth and fits tightly without disrupting the flow.

In contrast, caps and plugs are typically used for sealing ends and do not require that type of angled fitting. Flanges and valves are connection points and control elements that don't necessitate mitres for alignment or function. Adapters and couplings serve to join two different pipe sizes or types and are generally made to fit without needing an angle. Therefore, the requirement for mitres is uniquely pertinent to elbows and sweeps due to the nature of their application in altering the flow direction.