In several steps of the ammonia production process, especially in the synthesis section, the pressure shells of reaction vessels as well as the connecting pipes are in contact with hydrogen at elevated pressure and temperature with a potential risk of material deterioration. One the possible risks is Chemical and physical hydrogen attack that can be summarized in the below points:

Chemical Hydrogen Attack.

Under certain conditions chemical hydrogen attack can occur. Hydrogen diffuses into the steel and reacts with the carbon that is responsible for the strength of the material to form methane, which on account of its higher molecular volume cannot escape.

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