Definition - What does Urea mean?
Urea is a nitrogen containing organic chemical compound with the chemical formula CO(NH2)2 in which two -NH2 groups join with a carbonyl (C=O) functional group.
Urea is commonly used for fertilizers and feed supplements. It is also a starting material for the production of plastics and drugs. Urea can cause corrosion to steel and agricultural equipment.
Urea is also called carbamide.
Corrosionpedia explains Urea
Urea is a nitrogenous organic compound containing a carbonyl group and two amine groups. It is a crystalline substance that melts at 132.7 °C (271 °F) and decomposes before boiling. Besides fertilizers and feed supplements, urea is also used to manufacture plastics, glues, toilet cleaners, detergents, pesticides and fungicides. Urea is also increasingly used as an additive to diesel fuel for NOx control.
Synthetic urea is produced by a two-step reaction consisting of carbamate formation and urea conversion. During urea synthesis, parts of the process contain significant concentrations of ammonium carbamate. At production temperature, approximately 160 °C (320 °F) and higher, this carbamate is notorious for corroding most materials. Ammonium carbamate’s aggressive corrosiveness even corrodes the graded stainless steel that has been specifically designed for these purposes.
In a urea plant, stainless steel requires an injection of passivation air into the process stream to maintain a passive corrosion resistant layer. This layer will not completely prevent corrosion. Therefore a good alternative to stainless steel is zirconium, which does not require any passivation air to remain resistant to corrosion even in the high process temperatures found in a urea plant.