Urea is an important nitrogen-containing chemical fertilizer, synthesized from carbon dioxide and ammonia under high pressure (140-250 atmospheres) and temperature (180-210 degrees Celsius). During urea production, some highly corrosive intermediate products are generated, such as ammonium carbamate and ammonium cyanate, which can damage urea production equipment (such as the lining of the synthesis tower, stripping tower, and ammonium carbamate condenser). Stainless steel is a metallic material with excellent corrosion resistance, oxidation resistance, wear resistance, and aesthetics. It can be used to manufacture urea production equipment, improving its service life and safety. However, not all stainless steel is suitable for urea production equipment. Ordinary stainless steel, such as 316L, is severely corroded by intermediate products like ammonium carbamate under high temperature and pressure, failing to meet its corrosion resistance requirements. Therefore, a special type of stainless steel called urea-grade stainless steel has been developed specifically for urea production equipment. Urea-grade stainless steel is an austenitic stainless steel. By adjusting its chemical composition and controlling its microstructure, it suppresses the formation of ferrite, enhances the stability of austenite, and improves the steel’s corrosion resistance. The main varieties of urea-grade stainless steel are 316UG and 00Cr25Ni22Mo2N (2RE69). Both contain high levels of chromium, nickel, and molybdenum, which help form a uniform and dense passivation film to resist corrosion from intermediate products such as ammonium carbamate. Urea-grade stainless steel also requires rigorous testing and inspection, such as the Hugh test and selective corrosion test, to ensure it meets the requirements for use in urea production equipment.
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Post time: Jan-16-2026