1.How to control the storage environment?
Control temperature and humidity.
Storage warehouses must be kept dry, with relative humidity not exceeding 60% (a dehumidifier or humidity alarm can be installed). Avoid open-air storage (rainy and foggy weather can easily cause condensation on the panels).
Avoid extreme temperature fluctuations in the warehouse (e.g., a difference between day and night greater than 10°C). Sudden temperature fluctuations can cause moisture in the air to condense on the panels, causing "dew corrosion."
Maintain a clean environment.
Corrosive substances such as acids, bases, and salts (such as fertilizers, pesticides, and chemical raw materials) must not be stored in the warehouse to prevent their volatile gases from reacting with the zinc coating.
Regularly clean dust and oil from the warehouse floor to prevent rainwater from forming corrosive solutions that contact the panels.
Ensure good ventilation.
Warehouses should have ventilation holes or exhaust fans installed to increase air circulation and reduce the amount of time moisture remains on the panels (especially during the rainy season or in areas with high humidity).
2.How to perform protective treatment before storage?
Preserve or Replenish the Anti-Rust Coating
Galvanized steel sheets are typically factory-coated with an anti-rust oil (such as volatile anti-rust oil). Before storage, inspect the integrity of the oil film. If any areas are flaking, reapply with a dedicated anti-rust oil (avoid using non-dedicated oils such as motor oil, as this may affect subsequent processing).
Electrogalvanized steel sheets can be sprayed with an additional passivation film (such as chromate passivation or chromium-free passivation) to further enhance corrosion resistance. (The passivation film must dry before storage.)
Avoid Surface Damage
Before storage, inspect the sheet for scratches, bends, and other damage. If the substrate is exposed, repair with zinc powder paint or anti-rust paint to prevent the spread of rust.
When transporting, use dedicated lifting equipment (such as a hook with a rubber pad) to avoid direct contact between the wire rope and the sheet, which could cause scratches.
3.How to standardize stacking and isolation measures?
Overhead Moisture-Proofing
Slabs should be placed on racks or pallets at least 30cm above the ground (preferably wood or plastic, avoiding direct contact with metal racks to prevent electrochemical corrosion) to isolate them from ground moisture.
Waterproof membranes or plastic sheeting can be laid on the floor to prevent rainwater from penetrating the stacking area.
Classified and Separate Stacking
Galvanized sheets of different specifications and batches should be stacked separately to prevent squeezing and deformation. If stacking is necessary, hard rubber mats or wooden separators (≥ 5mm thick) should be placed between layers to prevent direct friction and the loss of anti-rust oil or scratches.
Staying together with other metals (such as ungalvanized steel or copper) is prohibited to prevent the formation of "galvanic cells" (zinc acts as an anode, causing corrosion). If storage is necessary, plastic film should be used to completely separate them.
Special Treatment of Coils and Flat Sheets
Galvanized coils should be stored upright (axially perpendicular to the ground) and secured with dedicated racks to prevent rolling and collision. When stored for extended periods, the coils should be rotated regularly (every two weeks) to prevent prolonged pressure on contact points, which can lead to loss of anti-rust oil. Flat panels must be stacked horizontally with a stacking height not exceeding 1.5m (to prevent the bottom panel from being compressed and deformed), and the top layer must be covered with waterproof canvas or plastic film (but ventilation gaps must be reserved to avoid internal condensation).
4.How to perform regular inspection and maintenance?
Periodic Inspections
Check the warehouse humidity and board surface condition weekly, focusing on the ends of coils and corners (where water easily accumulates) for white rust or water droplets. Address any issues immediately.
Perform monthly spot checks on the integrity of the anti-rust oil film. If the surface appears dark or dry, reapply anti-rust oil.
Emergency Measures
If a small amount of white rust is found, wipe it with a dry cloth and reapply anti-rust oil. If the rust is severe (the zinc layer has peeled), isolate the board and use it as soon as possible to prevent the spread of rust.
In the event of heavy rain or a warehouse leak, move the board to a dry area immediately, blow dry the surface with compressed air, and reapply the protective film.
5.Are there any special considerations for long-term storage?
The recommended storage period is no more than six months (especially in humid areas). After this period, the surface condition should be re-inspected and, if necessary, re-passivated or re-oiled.
Galvanized sheets for export or cross-border transport must be sealed (lined with moisture-proof paper and wrapped with stretch film) and contain a desiccant (such as silica gel) to prevent the effects of high humidity during sea or long-distance transportation.