a device for stopping flow of molten metal through a conduit having a longitudinal central passage . a ceramic seal is placed through a wall of a ceramic pipe for preventing flow of the molten metal through the opening in the wall of the ceramic pipe . a nonmetallic plug is located adjacent the ceramic seal . a lever arm adjacent the plug is used for depressing the ceramic seal and the nonmetallic plug vertically into the ceramic pipe through the longitudinal central passage to prevent flow of molten metal through the ceramic pipe .