Abstract: A cooling element for a metallurgical or blast furnace having steel tubes integrally cast into a cast iron body to convey a cooling medium. The steel tubes are provided with an additional metallic layer which is composed of Ni, Co, Mn, Ag either individually or as a combination of one or more thereof and a metallic oxide layer composed of one or more metallic oxides provided on the metallic layer. The metallic oxide layer has a free oxide standard enthalpy of formation of less than -145kcal with normal pressure conditions and a temperature of 600.degree. C.