Abstract: An outlet valve for a melt-containing vessel includes a lower insert piece mounted in the base of the vessel having an outlet bore passing therethrough from the inside to the outside of the vessel, and an elongate shaft located above and pressed down upon the lower insert piece. The shaft has a lower face mating with an upper face of the lower insert piece and is rotatable relative to the lower insert piece about a generally vertical axis. The bore through the lower insert piece is offset, at least at its upper end, from the axis of rotation. The shaft has a side opening at the lower end thereof capable of aligning with the top of the bore through the lower insert piece in at least one rotational position.