Stress-Corrosion Cracking of Steels In Agricultural Ammonia^⋆

Stress-corrosion cracking has been determined as the cause of failure of carbon steel tanks in agricultural ammonia service. Effects of ammonia contaminants, such as air, water, carbon dioxide, oil, etc. on failure rates were studied. In general, air contamination increased stress-corrosion cracking and water in small amounts inhibited the attack.

For prevention of such failures, it was recommended that high residual stresses in ammonia vessels be avoided by the use of stress relieving treatments, that air be eliminated from agricultural ammonia systems and that the ammonia should have a minimum water content of 0.20 percent.

3.5.8