11 Furnaces and industrial furnaces and parts structural thereof and casting furnaces and structural parts thereof for smelting, heating, warming up and preheating, drying, storing, homogenising, alloying, refining, carburising, annealing, casting, hardening, tempering, quenching, cooling and chilling, thermal aging, aging, sintering, tempering, coating and surface treatment, cooling and chilling, thermal aging, aging, sintering, tempering, recycling relating to pyrolysis and for other treatment of objects of iron, steel, metal, aluminium or silicon and scrap therefor and ceramic materials; heating apparatus and equipment for industrial purposes, namely, heating apparatus for liquid or gaseous fuels, heating units for industrial purposes, heating furnaces and structural parts therefor; refrigerators, refrigerating apparatus for industrial purposes in the nature of refrigerating appliances and installations, structural parts of the aforesaid goods; drying apparatus for chemical processing, apparatus for drying in the nature of forage drying apparatus, for industrial purposes, structural parts of the aforesaid goods; including the aforesaid goods for chemical purposes and other treatments or for chemical purposes and/or processes; protective gas apparatus, equipment and furnaces for industrial purposes for heating or smelting, in particular apparatus and equipment for feeding protective gas into industrial furnaces in the nature of gas regulators, Safety accessories for gas pipes, namely, flashback arrestors and reverse flow check valves, gas scrubbers; gas generation or gas treatment apparatus and gas generation installations or gas treatment installations comprised of the aforesaid goods for industrial purposes, namely, electrochemical gas generators, Gas purification machines, pressure regulators for gas installations; heat recovery apparatus and heat transfer apparatus and heat recovery systems composed of the aforesaid goods for industrial purposes, specifically heat generators in the nature of heat regenerators, recuperators for chemical processing and heat exchangers, other than parts of machines and heat recovery systems comprised of heat generators in the nature of heat regenerators, recuperators for chemical processing and heat exchangers, other than parts of machines; heated drying machines, for industrial purposes, namely, Industrial dryers for heating and dehumidifying; drying apparatus and installations, for industrial purposes namely, Industrial dryers for heating and dehumidifying and structural parts thereof