Abstract: A cooling device for a converter opening, such as a Peirce-Smith copper converter, has been disclosed wherein a cooling medium, which is a combustible liquid of high temperature cracking characteristics, is introduced in cooling conduits floatingly disposed in a refractory material lining an opening of a converter, through which, at high temperatures, the contents thereof are discharged. The lower vapor pressure of the cooling medium, the expansion and contraction of the conduit in individual cooling segments and the maintaining of the cooling medium under pressure improves the operation of the converter.