Abstract: A sliding gate valve assembly adapted for use in the pouring of metals comprises a sliding gate member arranged for sliding movement to open and close an orifice of the assembly through which orifice metal is arranged to flow; the sliding gate member comprises a refractory body in which is provided a nozzle aligned with the orifice in an open position of the gate member and offset from the orifice in a closed position of the gate member; the nozzle has a side wall portion of permeable refractory material; and gas, e.g. an inert gas or oxygen is supplied to the nozzle, through the permeable side wall portion.