A Ferralium® 255 impeller was among the first in this super duplex stainless steel to be used in 'wet process' phosphoric acid production. When removed, it had given three years of continuous service without maintenance, handling hot acid slurries - performance that led to the alloy being adopted for all the plant's slurry pumps.
The Ferralium® 255 impeller was one of the first in this super duplex stainless steel to be used in 'wet process' phosphoric acid production. At the time of its removal, it had given three years of continuous service without maintenance, handling acid slurries of approximately 30% P2O5, 30% CaSO4 solids, 2% H2SO4, HF and H2SiF6 at 60-80°C.
Ferralium® 255 outperformed the high-nickel alloy previously used for this duty, and was adopted for all slurry pumps in the plant. Its use was then extended to evaporator circulation pumps handling acid at 45-55% P2O5, where even longer service life is expected. Such results are typical of Ferralium® 255 (UNS S32550, Alloy 255, DIN 1.4507, ASTM F61), which is now used in many 'wet process' plants at home and abroad.
These agitator blade assemblies with stabilisers, fabricated in Ferralium® 255, are destined for a phosphoric plant under construction for a large fertiliser manufacturer in Spain, where they will handle phosphoric acid slurry.
