The materials history of two VGO desulfurization plants will be reviewed . Changes in materials have been made to mitigate high temperature H2 Attack, ammonium bisulfide corrosion, HIC, amine , polythionic and chloride stress corrosion cracking. The use of alloy materials, including bimetallic piping and aluminized furnace tubes will be described.
Keywords: SoIar water corrosion, HDS plants, Polythionic SCC, Bimetallic pipe, H2 attack.