Ammonia stress corrosion cracking
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According to GB/T30579-2014, for ammonia stress corrosion to occur, the following three conditions must be met: (1) The medium is liquid ammonia with a water content of less than or equal to 0.2%； (2) The operating temperature of the equipment is above -5℃ ； (3) The medium is contaminated by air, and the oxygen and carbon dioxide in the air accelerate the corrosion of ammonia on carbon steel. May I ask everyone, to what extent do the actual cases encountered correspond to this? Does gaseous ammonia really not suffer from stress corrosion cracking? Or even less than -5℃ won’t work either? Thank you!
If it is gaseous ammonia, or the temperature is below -5 degrees, the pressure is generally very low, so the stress is likely to be low as well
Dry ammonia has very weak corrosivity