Apparatus for lighting, heating, steam generating, cooking, refrigerating, drying, ventilating, water supply and sanitary purposes namely, heat exchangers, steam generators, evaporators, condensers, economizers; Heat exchangers other than parts of machines; Evaporators for refrigeration and steam generating in industrial processes; Gas condensers, other than parts of machines; Heat pumps; Industrial boilers; Steam generators being heat exchangers; Steam heating apparatus; Water heaters for industrial use; Chiller units being parts of water cooling installations for industrial use; Refrigerating apparatus and machines namely, evaporators, condensers, gascoolers, superheaters, economizers