Abstract: A flame injection throat for a furnace incorporates a furnace structure formed with a flame injection throat opening lined by at least one ring of refractory tiles the adjacent edge portions of the outer faces of selected adjacent tiles are formed with aligned undercut grooves. Pins having enlarged ends are attached to the furnace structure within the throat opening and project into the groove. Locking members fitted into the grooves engage simultaneously the undercut portions of the grooves in the tiles and the enlarged ends of the pins lying within the grooves whereby to hold the tiles to the pins. Each locking member is a block of heat-resisting metal presenting two limbs arranged to straddle a pin projecting into the groove.