11 Industrial ovens for the treatment of metal work pieces; structural parts and units of industrial ovens, in particular inflow and outflow gates, treatment chambers; transport and conveyor devices, namely, chain conveyors, roller conveyors and belt conveyors for metal work pieces, heating installations, gas production and storage installations; vacuum and atmospheric installations for the treatment of metal work pieces, in particular vacuum heat treatment installations featuring high pressure gas quenching, and structural parts therefore; heat treatment installations, namely, vacuum and atmosphere furnaces, oil quenching apparatus, gas quenching apparatus and liquid salt apparatus for the treatment of metal work pieces and structural parts therefor; gas generators and producers, namely electrical or gas heated endo gas generators, furnace integrated gas generating retorts, in particular generators and producers of inert gas and structural parts therefore; gas circulation installations, namely, electric fans and structural parts therefor; burners, in particular oil and gas burners and heating systems primarily comprised of recuperator gas burners, electrical heating elements for industrial ovens; loading and storage installations for metal work pieces, in particular loading and unloading tables and batch storers and conveyors; ovens, namely, sealed quench furnaces with protective gas atmosphere, low temperature tempering furnaces, low temperature nitriding furnaces and gas generators, namely, endo gas generators and structural parts therefor