[ Fertiliser Production ]
[ Fertiliser Production ]
including catalyst handling and precision instrumentation- require highly skilled personnel, while strict regulatory limits on emissions demand consistently high equipment integrity and maintenance standards.
Corrosive process media Fertiliser production involves the handling of highly corrosive substances, including nitric and sulphuric acids, ammonium nitrate, and ammonium carbamate solutions. In such environments, stainless steels provide essential protection through the formation of a stable, self-healing chromium oxide passive layer, which acts as a barrier against chemical attack and significantly reduces the risk of leaks and safety hazards. Many fertiliser processes, notably ammonia synthesis and nitric acid production, operate under extreme temperatures and pressures. Austenitic stainless steels such as 310 / 310S, with high chromium( 22 – 24 %) and nickel( 19 – 22 %) contents and low carbon levels, retain mechanical strength and structural integrity under these demanding conditions, ensuring safe and reliable operation. Compared with conventional materials, the superior resistance of stainless steels to chemical attack results in substantially longer service life, reduced maintenance requirements, and lower unplanned downtime. Although the initial capital cost is higher, the overall life-cycle cost is typically lower.
Fertiliser drum mixers are typically manufactured in 304 or 316L stainless steel. Photo: Dreamstime.
Cleaning & sanitation Stainless steel’ s smooth, non-porous surface also facilitates cleaning and sanitation, minimising product contamination and the accumulation of chemical residues. This is critical for maintaining consistent fertiliser quality and meeting safety and regulatory requirements. Resistance to stress corrosion cracking is a further advantage, particularly in aggressive service conditions. In high-chloride or specialised chemical environments, duplex stainless steels offer enhanced protection, combining high strength with excellent resistance to stress corrosion cracking. The corrosion resistance of stainless steel is underpinned by its passive chromium oxide film. When damaged, this film rapidly reforms as exposed chromium reacts with oxygen, restoring protection provided sufficient oxygen is present. This self-healing behaviour is fundamental to the long-term durability of stainless steel equipment in fertiliser plant service.
Corrosion and erosion mitigation strategies Fertiliser producers adopt a multipronged approach to mitigate corrosion and erosion, combining appropriate material selection, sound equipment design, effective maintenance practices, environmental control, and the targeted use of protective coatings and corrosion inhibitors. These measures are essential to maintaining equipment integrity, minimising downtime, and ensuring compliance with increasingly stringent safety and environmental regulations.
High nutrient concentration, formulation flexibility, fast response, and logistical efficiency have made inorganic fertilisers indispensable to commercial agriculture. Photo Dreamstime.
Material selection Material selection remains the most critical factor in aggressive service conditions. High-alloy stainless steels, such as 316L urea grade, are widely used in areas exposed to hot, concentrated and corrosive process media. In less severe environments, materials such as galvanised steel or aluminium may be employed, although their suitability is limited in acidic or chloride-rich conditions. Protective coatings and linings- including epoxy systems, specialised paints, and chlorinated rubber linings- are commonly applied to metal and concrete surfaces to provide an additional barrier against chemical attack. Chemical inhibitors are also
34 Stainless Steel World June 2026 www. stainless-steel-world. net