A continuous carbonization method for the carbonization of a continuous, oxidized polyacrylonitrile (PAN) precursor fiber, wherein the precursor fiber exiting the carbonization system is a carbonized fiber which has been exposed to an atmosphere comprising 5% or less, preferably 0.1% or less, more preferably 0%, by volume of oxygen during its passage from a high temperature furnace to the next high temperature furnace. In one embodiment, the carbonization system includes a pre-carbonization furnace, a carbonization furnace, a substantially air-tight chamber between the furnaces, and a drive stand carrying a plurality of drive rollers that are enclosed by the air-tight chamber.