Abstract: A scrap preheating system in which scrap metal is preheated and contaminants such as grease removed therefrom by direct impingement of flames upon the scrap. The system includes a tunnel like preheater hood through which a conveyor passes conveying the scrap. The preheater hood includes parallel side walls positioned adjacent the conveyor and a roof assembly in which are positioned a plurality of burners for directing flames upon the scrap. The roof assembly of the preheater hood is formed into a plurality of substantially identical modular roof assemblies which are carried by the side walls and are positioned in side by side relationship along the side walls transverse to the longitudinal axis of the conveyor.