1.What are the core risks?
Highly reactive surfaces: After cold rolling, cold-rolled coils have clean, highly reactive surfaces. Even with a slight rust-preventive oil film, their corrosion resistance remains relatively weak.
Chemical corrosion: Many chemicals (such as acids, alkalis, salts, and oxidants) react directly with steel, destroying the passivation or oil film on the surface, leading to rapid rusting and surface damage.
Electrochemical corrosion: When humid air contains chemical contaminants (such as salts and sulfides), an electrolyte solution forms on the steel surface, accelerating the electrochemical corrosion process. This corrosion rate is much faster than that caused by water vapor alone.
2.What are the specific sources of chemical hazards?
Acids and acid mists: Examples include hydrochloric acid, sulfuric acid, and nitric acid. Even the volatile acid mists can condense on steel surfaces, causing severe pitting or uniform corrosion.
Alkalis: Examples include sodium hydroxide (caustic soda). While their short-term corrosion of steel is relatively weak, they can damage the protective oil film and promote corrosion in humid environments.
Salts: Examples include sodium chloride (table salt) and ammonium chloride. This is the most insidious and common hazard. Salts are highly hygroscopic, forming a liquid film on the steel surface and acting as a strong electrolyte, triggering severe electrochemical corrosion. Packaging materials (such as wood or sacks that have come into contact with seafood) or residual de-icing salt can also cause salt contamination.
Oxidizing substances: Examples include certain bleaching agents and chemical raw materials.
Other chemicals: Organic solvents can dissolve surface rust-preventive oils, rendering them ineffective.
3.Does the warehouse need to be divided into zones and segregated?
Establish a separate "clean and dry steel storage area."
This area must be kept at a safe distance from warehouses storing acids, alkalis, salts, fertilizers, dyes, pesticides, chemical reagents, or any other chemicals (ideally in separate buildings or enclosed areas).
Even within the same large warehouse, physical partitions (such as walls or barriers) should be used for separation, and independent ventilation systems should be ensured.
4.How to control the storage environment?
Keep dry: Relative humidity should ideally be below 50%, and should not exceed 60%. Use dehumidifiers or ventilation equipment.
Keep clean: Warehouse floors and walls should be clean and dust-free, free of chemical residue. Activities that may generate chemical pollution are prohibited within the warehouse area.
Maintain intact packaging: Keep the original packaging of the cold-rolled coils intact (such as rust-proof paper, plastic film, or sheet metal packaging). Damaged areas should be repaired promptly.
5.What are the management and operational procedures?
Transportation and loading/unloading equipment (such as trucks and forklifts) should be clean and free of chemical residues.
Bringing any chemicals or their empty containers into the steel storage area is strictly prohibited.
Regularly inspect the warehouse environment and the surface condition of the steel, promptly identifying and addressing any signs of contamination or rust.