Why Aluminum Coil and Plate Are Easily Damaged in Transit
Aluminum coil and aluminum plate leave the mill in a soft, high-value condition, and almost every claim raised after delivery can be traced to three causes: scratches, impact bruises, and wet oxidation. Unreasonable loading is the single largest contributor. Because aluminum forms no thick protective scale during rolling, a dragged strap or a rubbing edge is enough to create a visible defect that cannot be polished out during downstream forming.
Scratches from sliding coils across a bare deck, dragging interleaving paper, or allowing packaging staples to rub on the surface.
Bruises and edge dents from dropped coils, other cargo striking the bundle, or fork tines pushing into the pack.
Oxidation and water staining from rain, snow, road spray, and condensation forming under plastic wrap as the temperature changes.
Loading Rules for Coils and Flat Plate
Load placement decides whether the shipment arrives in saleable condition. The rules below apply to coils loaded eye to sky or eye to wall, and to cut-to-length plate bundles.
Keep the load low and stable. Never place aluminum on top of other cargo. Put it directly on the floor of the carriage or on a level timber bed above the trailer frame.
Separate dissimilar cargo. Steel sections, castings, and machinery must never be loaded against aluminum plate, because their edges concentrate load and cut through packaging.
Use timber dunnage. Place softwood bearers at regular intervals so the pack is supported evenly and no part of the bundle bridges an unsupported span.
Fit edge protectors. Cardboard, plastic angle, or timber corner boards protect coil edges and plate corners wherever slings and straps bear down.
Chock every coil. A coil can roll even on a nearly level deck, so wedges and nailed chocks are required in both directions.
Bundle before loading. Strapping the pack as a rigid unit at the yard is far easier than securing loose sheets inside the vehicle.
Stacking Limits and Load Distribution
Layering is permitted, but the height must be controlled so that the bottom pack is not crushed and the top pack cannot shift. The table below summarises normal practice for road and container shipments.
| Product form | Practical stacking limit | Key control point |
|---|---|---|
| Plate bundle | 3-4 layers maximum | Dry timber between layers, no metal-to-metal contact |
| Cold rolled coil | 2 layers, or 1 layer on uneven floors | Eye vertical on chocks, or horizontal in cradles |
| Light gauge coil | 1-2 layers | Reduce height to protect thin edges from dents |
| Flat bar crate | 2 layers on full-length bearers | Bundle strapped as one rigid unit |
Heavier packs always go to the bottom, and the centre of gravity should sit as low as the axle load allows. Keep the total weight below the rated payload, and spread it along the full length of the vehicle instead of concentrating it over one axle group.
Weather Protection and Moisture Control
Rain, snow, and condensation are the usual causes of white water stains, which appear as oxide marks on the surface after a long transit. Weather protection has two parts: an outer rain barrier and an inner path for moisture to escape.
Cover the finished stack with a waterproof tarpaulin or a lined container liner, and tension it so that water cannot pool on the top surface.
Use vapour-phase or moisture-absorbing film where the route passes through humid or tropical regions, and allow the wrap to vent at the ends rather than sealing it hermetically.
Lift the load clear of the deck by 50-100 mm of dry dunnage so that deck water never wicks into the pack.
Never load wet coils or wet plate. Surface moisture trapped under film will stain the metal within a few days.
Securing, Handling and Arrival Inspection
Strapping is strong enough to damage the material it holds, so tension must be applied over protectors and released slowly on arrival. Ropes and webbing that cross the top of the stack should pass over timber or rubber pads, and no single strap should be tightened until the bundle begins to deform.
Handling equipment should carry clean, flat forks and lift the pack squarely without dragging. Lifting slings must run through spreader beams so that side pressure never squeezes a coil or bundle out of shape.
Before the vehicle leaves the site, check the condition of the outer wrap, tarpaulin, and seals; look for water ingress or white staining; inspect coil edges and plate corners for dents; and confirm that strapping is still aligned. Photographs taken at the moment of unloading are the most effective evidence if a claim is raised later. Where material is supplied with mill test certificates to EN 10204 3.1, cross-check the certificate against the coil or bundle identification marks before the goods enter storage.
Store the material indoors on dry bearers away from condensation drip points, and keep it in the original packaging until it reaches the production line. That way the surface that left the mill is the same surface that enters the press or the forming line.
Frequently Asked Questions
Q: What is the most common cause of damage to aluminum coil and aluminum plate shipments?
Unreasonable or unstable loading is the main cause. Coils that are not chocked, plate bundles placed on top of other cargo, and straps tensioned directly on bare metal account for most scratches, edge dents, and bruise claims reported after unloading.
Q: How many layers of aluminum plate may be stacked during transport?
Three to four layers is the practical limit for plate bundles. Each layer must be separated by dry timber and the tallest stack should never exceed the height at which the bottom bundle begins to deform.
Q: Should a coil travel eye to sky or eye to wall?
Both are accepted. Eye to sky suits coils loaded on a flat deck with wedges and chocks, while eye to wall suits coils carried in cradles or in a container where the coil is strapped against the side wall. What matters is that the coil cannot roll in either direction and that nothing presses on the bore.
Q: Why does aluminum turn white or stained during shipping?
White surface marks are oxide films formed by moisture. Rain entering through a torn tarpaulin, deck water wicking up through dunnage, or condensation trapped under sealed plastic wrap during temperature changes all produce the same staining.
Q: Can aluminum be shipped in the same container as steel products?
It can share a container, but never share a stack. Steel sections, castings, and machinery must be separated from aluminum by timber or a rigid partition, because their edges concentrate load and can cut through packaging and into the metal surface.
Q: How should lifting slings and straps be positioned?
Use spreader beams so that slings lift vertically rather than squeezing the coil or bundle, and run straps over corner protectors or rubber pads. Tension should be released slowly at the destination so that stored energy does not snap the band against the surface.