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Question 32

Which of the following materials is not susceptible to high temperature hydrogen attack?

    Correct Answer: A

    300 Series Stainless Steels (300 Series SS) are generally known for their excellent high-temperature properties and corrosion resistance, which includes resistance to hydrogen attack up to certain conditions. On the other hand, Cr-Mo steels like 5 Cr-1Mo and 9Cr-1Mo are specifically designed for improved resistance to hydrogen attack but can still be susceptible under certain high-temperature and pressure conditions. Therefore, 300 Series SS is the material least susceptible to high-temperature hydrogen attack among the given options.

Discussion
ahmadmmOption: D

Materials affected by High-temperature Hydrogen Attack 300 series SS, as well as 5Cr, 9Cr, and 12Cr alloys, are not susceptible to HTHA at conditions normally seen in refinery units.