1.Why is it necessary to provide shade?
Coating Performance Impairment (Major Risk):
High Temperature Accelerated Aging: Under sustained high temperatures (such as temperatures exceeding 70°C inside a freight car), the polymer chain structure of the organic coating (polyester, PVDF, etc.) of the precast steel sheet ages more rapidly, affecting its future weather resistance and service life.
Heat Accumulation Leading to Yellowing or Loss of Gloss: Prolonged, localized exposure to sunlight can cause minor but irreversible changes in color and gloss.
Physical Damage: Inter-coil Adhesion ("Sticking"):
This is the most direct and common transportation accident. At high temperatures, the coating (especially the back side) softens, and the immense pressure of winding the coil can cause adjacent steel sheet layers to stick together.
During unloading and unwinding, sticking can cause the coating to tear and peel off, resulting in catastrophic appearance and corrosion defects, potentially rendering the entire roll unusable. Sticking is more likely to occur in PE (polyester) coatings than in PVDF coatings.
Temperature differences between the inside and outside cause condensation:
If the roll is only tightly wrapped in an airtight tarpaulin during transportation, after being exposed to the sun during the day, the temperature drops at night, causing condensation to easily form in the gaps inside the roll. This moisture cannot evaporate and can lead to internal corrosion (even if the outside is dry).
2.What are the correct protective measures for transportation?
Preferred: Use dedicated transport vehicles or install sunshades.
The transport vehicle should have a complete sunshade covering the cargo compartment. The tarpaulin should be light-colored or silver to reflect sunlight.
Avoid using dark-colored tarpaulins, as they absorb heat and exacerbate the increase in internal temperature.
Key: Ensure good ventilation.
Never wrap the pre-coated coils completely airtight. While providing sun protection, ensure there is space for airflow in the cargo compartment or under the tarpaulin to dissipate heat. This is crucial to prevent condensation and reduce overall temperature.
Standard packaging is essential:
Regular pre-coated coils are packaged in multiple layers at the factory: rust-proof paper (or rust-proof film) + waterproof woven fabric + steel protective plates, secured with steel straps. This packaging provides a certain degree of insulation and protection against physical scratches and must not be removed during transport.
3.How to load, unload, and stack?
Use specialized lifting tools (such as C-hooks) to avoid direct contact between the wire rope and the sheet material, which could damage it.
During transportation, the sheet material should be placed vertically along its axis and secured to prevent rolling and collisions.
4.How should we protect ourselves during short-distance/cloudy weather transportation?
It is also essential to use the original packaging, and it is recommended to cover it with a tarpaulin in case of sudden weather changes.
5.How to protect yourself during long-distance/hot weather transportation?
Awnings must be used, and good ventilation must be ensured. This is a necessary clause in the transport contract and should be explicitly required of the carrier.