FURNACES AND PARTS THEREOF; RADIATING COMBUSTION CHAMBERS USING GASEOUS, LIQUID, AND SOLID FUEL AND COMPRISED OF REFACTORY MATERIAL; OIL AND GAS BURNERS AND PARTS THEREOF, KILNS AND PARTS THEREOF, OIL AND GAS HEATERS AND PARTS THEREOF, COMBUSTION CHAMBERS AND PARTS THEREOF,SECTION SHAPES FOR COMBUSTION CHAMBERS