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Question 77

Which of the following materials are generally not suitable for HF service?

    Correct Answer: D

    Both 300 Series SS and 400 Series SS are generally not suitable for HF service. HF (Hydrofluoric acid) is highly corrosive and can dissolve the protective chromium oxide layer on the surface of stainless steels, leading to severe corrosion and cracking of both the 300 and 400 series stainless steels. This makes option D, which includes both A and C, the correct choice.

Discussion
ahmadmmOption: D

300 and 400 series stainless steels are also susceptible to cracking in HF environments. This is because HF acid can dissolve the protective chromium oxide layer on the surface of the stainless steel, exposing the underlying metal to corrosion. The resulting corrosion can lead to the formation of cracks in the metal.