A Pit Furnace is normally used for processing batches or large single components. It is sunk into a pit, and has a lid/plug section which is lifted off and either placed else where, or is connected to a lifting arm that swings it to one side. The size and shape of the furnace will largely depend on the quantity and type off component that is being treated.

Pit furnaces either has exposed elements, or has an internal retort that is used for controlling the atmosphere needed for the treatment required. Most have a fan for circulation that can be fitted in the lid or in the floor (fitting in the lid makes for easier maintenance).

Pit Furnaces have a large scope for possible processes, commonly involving controlled atmospheres, i.e. Endo Gas, Ammonia, Hydrogen, Nitrogen, Etc.

Common processes include:-

Gas Carburising

Nitriding

Hardening

Tempering

Annealing

Stress Relieving