Abstract: In the present invention, many cooling pipes are arranged horizontally at least in any one of the walls or roof of a furnace, to be fitted at the respective ends on both sides with supporting pipes provided outside the furnace, to let the cooling medium flow in one system for high cooling efficiency and long life. The cooling pipes may be arranged in ladder fashion or in a similar way, to keep the splash film stable, thereby preventing the decrease of the thermal efficiency of the furnace.

Abstract: A roof assembly for an arc furnace is disclosed in which a furnace roof ring and a plurality of roof units are assembled together to define a roof section frustoconical in cross section and with a roof top opening, and a roof top made of an electrically insulating refractory and provided with electrode holes closely fitted into the roof top opening. Each sectionalized roof unit comprises a main body cast from cast iron or copper, and a cooling coil embedded in the main body with end sections being extended out of the upper major upper surface of the main body so as to be used as a cooling water inlet and an outlet. In order to ensure the satisfactory high-temperature strength and thermal-shock resistance, the inner major surface of the main body directed toward the inside of the furnace is partially lined with the refractory or corrugated.