This 71" diameter fan impeller, weighing nearly 1 1/2 ton, is built in Ferralium® 255 (UNS S32550, Alloy 255, DIN 1.4507, ASTM F61) for an inert gas fan in a wet SO2 scrubber running at 1470 rpm. The mix of gases and corrosive products creates conditions conducive to stress corrosion, which Ferralium® 255 resists well.
Made to be worked
Ferralium® 255 can be cast, forged, rolled and welded, and this impeller shows that versatility. The boss is cast; the blades are rolled and shaped from plate, then welded to blade roots cast into the boss. The side plates are also plate, their conic-shaped segments welded together and then to the boss and blades.
In service
Built by Davidson & Co. Ltd of Belfast, the giant fan is installed in the non-ferrous smelting plant of Commonwealth Smelting Ltd at Avonmouth.
