Apparatus for heating steel products

An apparatus (10) for heating steel products (100), comprising a furnace of the direct combustion irradiation type, comprising inside it a path for feeding the steel products (100) which extends between an entry end (110) and an exit end (111) of the steel products (100), an entry aperture in correspondence with said entry end (110) to allow the entry of said steel products (100) into said furnace (11) and an exit aperture (150) in correspondence with said exit end (111) to allow the exit of said steel products (110) from said furnace (11), means for feeding a fuel, means for feeding a comburent comprising oxygen, and burners (40, 41) able to operate the combustion of the fuel and of the comburent, wherein said means for feeding comburent and said means for feeding fuel are configured to feed the comburent and the fuel so that oxygen is in a sub-stoichiometric or stoichiometric proportion with respect to the fuel at least in one part of said apparatus (10), wherein said exit aperture (150) is provided with a sealing device (152) comprising a packing (153) configured to cooperate with a closing door (151) of said exit aperture (150) and inert gas barrier means (155) configured to prevent the entry of air into said furnace (11).