An inner nozzle is capable of being mounted onto a tube exchange device for holding and replacing an exchangeable pouring nozzle for casting molten metal out of a vessel. The tube exchange device is constructed of a frame with a casting opening. The frame is configured to be fixed to the lower side of a metal casting vessel and has a first, upper portion and a second, lower portion, joining at a middle section plane defining the plane where an inner nozzle and an exchangeable pouring nozzle form a sliding contact. The upper side portion of the frame receives and clamps in place a bearing surface of an inner nozzle at its pouring position. The lower portion comprises elements for loading and moving along a first direction (X) into casting position an exchangeable pouring nozzle. At least two clamping elements are arranged transverse to the first direction (X).