Abstract: Undesirable deposits of precipitated alloying materials are avoided in a sliding gate valve apparatus of the type in which gates are sequentially moved to and from operative position between the pour opening of a teeming vessel and a pour tube assembly for conducting molten metal from the valve apparatus, by forming the gates with through-openings whose axes are inclined in the direction of gate movement to and from their operating position in the valve apparatus, and forming the flow passage in the tube holder of the pour tube assembly with an opening extended in the direction of gate movement. The configuration of the particular gate and pour tube holder constructions are also disclosed.