1.What are the main risks of storing cold-rolled coils in the summer?
High temperatures accelerate corrosion-for every 10°C increase in temperature, the electrochemical corrosion rate typically increases by 1 to 2 times; high temperatures also accelerate the volatilization of light components in rust-preventive oils, leading to a thinner oil film and reduced protective ability.
High humidity and condensation-in summer, relative humidity often reaches over 80%, and condensation easily forms on the surface of steel coils after diurnal temperature variations or thunderstorms, allowing moisture to penetrate between layers and cause rust.
Strong ultraviolet aging-when stored outdoors or semi-outdoors, ultraviolet radiation accelerates the oxidation and deterioration of rust-preventive oils and the embrittlement of plastic films, reducing protective effectiveness.
Heavy rain and water accumulation-sudden heavy rain may cause water to enter the packaging or accumulate in the warehouse, increasing the risk of the bottom of the steel coils being submerged.
Microbial growth-in high-temperature and high-humidity environments, water-based rust-preventive solutions or contaminated packaging materials may breed mold, leading to localized corrosion.
2.What are the special requirements for the selection and application of rust-preventive oil in summer?
Selection Requirements – Prioritize displacement-type rust inhibitors with high flash points (≥120℃) and low volatility to prevent rapid thinning of the oil film under high summer temperatures; the oil should also have resistance to damp heat (verified through ASTM D1748 damp heat chamber test).
Oil Application Adjustment – In summer, the oil application can be increased by 15%–20% to compensate for evaporation losses, but care must be taken to avoid excessive accumulation at the edges to prevent dripping under high temperatures.
Application Timing – Apply oil when the steel coil temperature is below 35℃ and the surface is dry. Avoid applying oil after exposure to sunlight when the steel coil surface temperature is too high, otherwise the oil may evaporate too quickly and the film may form unevenly.
Oxidation Resistance – If the steel coil needs to be stored outdoors for a long time, rust inhibitors with added UV stabilizers should be selected to delay oil film aging.
3.How should packaging materials and usage methods be adjusted for summer?
Packaging Material Selection-
Plastic Film: Use UV-resistant PE film or aluminized film to prevent ordinary plastic film from becoming brittle quickly under direct sunlight;
Moisture-proof Paper: Use high-strength moisture-proof paper to prevent moisture absorption and deformation under high temperature and humidity conditions;
Vapor Phase Rust Inhibitor: In summer, corrosion inhibitors evaporate faster. Reduce the amount used per application but increase the replacement frequency to prevent excessive evaporation and ineffectiveness;
Air Permeability Balance-In summer, the temperature inside sealed packaging rises, easily generating "thermal expansion" pressure. Complete sealing may cause the packaging to bulge or even break. It is recommended to use a vent valve design or leave appropriate vents, while ensuring the vapor phase corrosion inhibitor in the rust-preventive oil can play a protective role;
Reflective Heat Insulation-When storing outdoors, add an aluminum foil reflector or use white reflective film on the outer layer of the packaging to reduce the surface temperature of the steel coil and slow down oil film evaporation;
Bottom Moisture Protection-The bottom of the steel coil must be covered with a waterproof plastic pad or raised wooden blocks (≥20cm off the ground) to prevent ground water or moisture from seeping into the packaging.
4.How should the warehouse environment be managed in summer?
Temperature and Humidity Control – For indoor warehouses, it is recommended to maintain relative humidity below 60%. If it exceeds 70%, a dehumidifier or air conditioner should be activated. When the warehouse temperature exceeds 40℃, ventilation should be strengthened or shading and cooling measures should be taken.
Shading and Heat Insulation – Steel coils should avoid direct sunlight. Shading nets or heat insulation layers can be installed in indoor warehouses. Outdoor storage must be covered with UV-protective shading cloth, ensuring a ventilation gap between the covering and the steel coils.
Rain and Flood Prevention – Before the rainy season, check the sealing of the warehouse roof, doors, and windows, and clear drainage ditches. During heavy rain, patrols should be strengthened, and any accumulated water should be drained immediately. Water barriers should be set up in the steel coil storage area to prevent rainwater backflow.
Ventilation Strategy – In summer, ventilation is best carried out in the early morning or at night when the temperature is lower and the humidity is relatively low. Doors and windows should be closed before and after thunderstorms to prevent a large influx of moisture.
Heat Source Isolation – Steel coils should be kept at least 2 meters away from heat sources (such as steam pipes or walls exposed to direct sunlight) to avoid localized high temperatures accelerating the evaporation of anti-rust oil.
5.What are the key points for inspection and maintenance during the summer storage period?
Packaging Bulges and Damage – Inspect the plastic film for bulging due to heat expansion and for cracks at the overlaps. If severe damage or bulging is found, reseal the packaging in the early morning or late evening when temperatures are lower.
Oil Film Condition – Wipe the ends and edges of the steel coil with a white cloth to check for a continuous oil film, and for any signs of drying or dripping. If the oil film is noticeably thinner, apply additional rust-preventive oil.
Condensation and Corrosion – Pay close attention to whether there is condensation inside the packaging in the early morning. Inspect the ends, edges, and bottom of the steel coil for yellow rust or white corrosion products (white rust). Treat any early-stage rust immediately. ;
Internal Packaging Temperature – Randomly check the temperature of the steel coil end face. If it is significantly higher than the ambient temperature and does not decrease, there may be internal heating (such as heat release from steel plate oxidation), requiring unpacking and inspection;
Pests and Mold – Pests and mold are prone to occur in summer. Check for mold spots on the moisture-proof paper and vapor phase rust-preventive paper, and for insect intrusion inside the packaging. If found, replace the packaging materials promptly and strengthen warehouse hygiene management;
Special Inspection After Heavy Rain – A comprehensive inspection must be conducted after each heavy rain to check for water ingress into the packaging, soaking of the bottom, and leakage in the warehouse. Address any problems immediately.