Operating conditions in high-temperature pulp and paper production processes are among the most corrosive in industry. Super heaters and cyclone separators in Kraft recovery boilers are subjected to highly corrosive gases generated from the combustion of black liquors. Other facilities are subjected to high-temperature corrosion from process feed stocks containing sulfur-rich gases or molten salts.
HAYNES® 556® alloy combines the resistance to high-temperature corrosion required for survival in many of these hostile environments with excellent high-temperature strength - enough strength to allow for significant reduction in required section size for many types of components when compared to austenitic stainless steels or 600 or 800 alloys.
As for corrosion resistance, HAYNES® 556® is designed to resist degradation from SO2 or H2S-bearing atmospheres at temperatures as high as 1800°F. It has very good resistance to molten salt environments, and is among the best materials for chlorine-contaminated oxidizing environments up to 1650°F. It also exhibits excellent resistance to carburization.
HAYNES® 556® alloy is an iron-nickel-chromium-cobalt alloy that combines effective resistance to sulfidizing, carburizing, and chlorine-bearing environments at high temperatures with good oxidation resistance, fabricability, and excellent high-temperature strength. It has also been found to resist corrosion by molten chloride salts and molten zinc.
HAYNES® 556® alloy is highly useful for service at elevated-temperature in moderately to severely corrosive environments. Applications include tubing and structural members in waste heat recuperators, super heaters, and internals in burner buckets, air nozzles, and fluidized bed combustor heat exchangers and internals; in municipal and chemical waste incinerators; power plant burner buckets, air nozzles and fluidized bed combustor heat exchangers and internals; high-speed furnace fans, galvanizing bath hardware and brazing fixtures; and high-temperature rotary calciners and kilns. There are also additional uses in the chemical/petrochemical process and pump and paper industries.
Oxidation in Air - Excellent at 2000°F (1095°C)
Sulfidation - Second only to Co-base alloys
Molten Chloride Salts - Equal to alloy X
Chlorination - Very good to 1650°F (900°C)
Carburization - Equal to alloy 800H
Molten Zinc - Best Available