What type of fitting is used to allow access to a plumbing line for cleaning and inspecting?

A cleanout fitting is specifically designed to provide access to a plumbing line, which is crucial for cleaning and inspecting the pipes. This fitting allows for removal of clogging materials, providing a way to maintain the plumbing system efficiently. Cleanouts are typically installed at strategic points in the plumbing system, such as at the base of vertical stacks or where horizontal lines change direction, enabling plumbers to clear blockages without the need to dismantle the connected pipes.

Elbow fittings, on the other hand, are used to change the direction of a piping system, providing angles typically at 45 or 90 degrees but do not allow for inspection or cleaning access. Saddle fittings connect a pipe to a main line at a branch but do not serve the access purpose for maintenance. Union fittings are designed to connect two pipes in a way that allows for easy disassembly but do not provide inspection capabilities. Therefore, the cleanout fitting is the only choice suited for the purpose of providing access for cleaning and inspecting plumbing lines.