Abstract: A runner for conveying molten pig iron and slag from a blast furnace of a steel manufacturing facility, is of wholly metallic construction and is hollowly formed to provide a cooling jacket through which water is circulated. Each runner so formed is an individual section in a string of other, similarly formed runners each of which has its own inlet connected to a source of water under pressure, and its own outlet to a suitable drain or reservoir where water temperature may be measured and observed. Water entering each section through the inlet courses through a tube that extends within the jacket substantially from one end to the other end, adjacent the slag channel of the runner, then extends transversely of the channel to the other side of the runner, thereafter extending longitudinally of said other side. The water flows out of the tube, within the jacket, after having extended along both sides of the channel in heat exchange relation to the slag flowing through the channel.