These Ferralium® 255 forgings (UNS S32550, Alloy 255, DIN 1.4507, ASTM F61) were chosen for their high resistance to stress corrosion cracking, replacing failed sets made in ordinary ferritic stainless steel. They will run in compressors handling hot gases containing hydrogen disulphide and sulphur dioxide at an overseas petro-chemical complex.
Stress corrosion cracking is always a potential problem where high mechanical stress and severely corrosive conditions are both present. Ferralium® 255 is a good material choice here because of its higher strength and duplex microstructure.
Seen being tolerance checked between machining operations at Langley, the forgings are 24" in diameter with sections up to 5½", weigh approximately 400 lb each, and after fine balancing will operate at 15,00rpm.
