The T-8-20 Task Group conducted a survey of plant practices and of the performance of materials of constrution in HF Alkylation Units. A Primary goal of the survey was to expand the limited body of the information on alternative ally performance in HF Alkylation units and to better define the susceptibility of steel to hydrogen induced cracking.
Carbon steel is the main construction material in HYDROFLUORIC ACID (HF) alkylation units. Carbon Steel has good corrosion resistance to anhydrous HF (AHF) below 160 degrees fahrenheit (71 C). The corrosion resistance is due to the formation of an inorganic iron fluoride scale on the carbon steel surface that protects the steel from futher corrosion. The presence of an adherent and continuous scale is essential in keeping the corrosion rate at a minimum.