A Complete Guide to Steel Coil Packaging and Sea Freight Safety

1. Main Requirements of Steel Coil Packs: The First Line of Defense Against Ship-Going Hazards

The physical barrier provided by steel coil packaging is essential for preventing corrosion, physical damage, and displacement. The material, dimensions, shipping history, and destination environment of the coil must be integrated to create layered protective systems. This prevents “naive wrapping” or “perfunctory bundling.” Following standardized packaging procedures reduces the maritime transportation loss rate of steel coils from 8.7% to 0.9%. Incorrect packaging not only leads to damaged goods but also results in rejections and claims for failing maritime standards.

The packaging process must strictly adhere to four core principles: material compatibility, layered protection, tight and reliable fixation, and clear marking.

1.1 Pre-Packaging Preparations: Checks and Pre-Treatment

Pre-treatment ensures that vulnerabilities are addressed before the packaging is even applied. This involves two distinct processes: the treatment of the steel coils and the selection of packaging materials.

Coil Pre-treatment:

• Clean off surface oil spots, rust, dust, and impurities. The surface must be completely dry. Moisture trapped inside will cause rapid rusting at sea, while sharp protrusions can puncture the packaging.
• For cold-rolled and galvanized coils, apply anti-rust oil (minimum 15μm thickness) or wrap with vapor-phase anti-rust paper (applied smoothly without wrinkles).
• Verify that the steel coil specifications (diameter, width, weight) perfectly match the packaging plan to prevent loose bundling.

Material Selection (Must be seawater, tear, and stretch resistant):

• Rust-proof layer: Cold-rolled, galvanized, and stainless steel coils require vapor barrier paper (12-month shipping validity). Hot-rolled and regular carbon steel can use rust-proof oil (6-month validity). High-value silicon or nuclear power coils need aluminum foil sealing plus desiccants (24-month validity).
• Moisture-proof layer: Polyethylene waterproof film (≥0.12mm thickness) with excellent sealing performance.
• Buffer layer: Pearl cotton, foam boards, or hardwood padding applied to the edges and surfaces to absorb impact.
• Binding materials: High-strength steel strips (tensile strength ≥ 6000N) or steel wire ropes (≥7.7mm diameter) with a minimum 10-ton pull force. Never use ordinary iron wires. Always use anti-abrasion sleeves to prevent the bindings from cutting into the coils.

1.2 Packaging Specifications by Material Variation

Different materials require a specific “three-layer defense system” consisting of inner rust defense, middle moisture protection, and outer buffering/fastening.

1.2.1 Normal Hot-Rolled Steel Coils (Ordinary Coils)

Because the surface is covered with iron oxide scale (providing basic corrosion resistance), the focus is on physical damage prevention and mild moisture protection.

1. Inner layer: Apply rust-proof oil or normal rust-proof paper.
2. Middle layer: Wrap tightly with polyethylene waterproof film (overlap ≥50%) and seal ends with tape.
3. Outer layer: Add hardwood or foam corner guards to the edges. Bind with strong steel straps (spacing ≤30cm), adding additional bindings across the center and ends for absolute solidity.
4. Bottom: Mount on dry, insect-free wood pallets (cross-section ≥10cm × 10cm). The pallet’s bearing capacity must be ≥1.2 times the coil’s weight, keeping the coil completely off the container floor.

1.2.2 Cold-Rolled and Galvanized Steel Coils

These coils have smooth surfaces, no iron oxide scale, and are highly prone to rust and scratches. Protection must be absolute.

1. Inner Layer: Wrap tightly with vapor-phase rust-inhibiting paper (overlap of 5-10cm at the ends). Seal entirely with rust-inhibiting tape to block all air and moisture exposure.
2. Middle Layer: Seal in pearl cotton (≥5mm thickness), covering all surfaces and edges to absorb impact.
3. Outer Layer: Wrap in a waterproof polyethylene barrier (overlap ≥50%) and seal with watertight tape.
4. Bundles: Secure with high-strength steel straps (spacing ≤25cm). Use anti-abrasion sleeves at all contact points between the straps and the coil.
5. Bottom: Install a non-slip wooden pallet with a moisture-proof mat. Secure the coil to the pallet to prevent sliding during transit.

1.3 Packaging Audits: Preventing Unqualified Shipments

Packages are only cleared for sea transport after a strict inspection. Any packaging failing this audit must be immediately repacked.

• Protective Layer: Check for unblemished seals, proper desiccant placement, and humidity indicator cards.
• Strapping Check: Ensure tension is tight, no broken strands exist, and wear sleeves are properly positioned.
• Labeling & Dimensions: Confirm that stickers are clear and that the packaged weight/size matches the shipping manifest and pallet capacity.

2. Safe Loading of Steel Coils at Sea: Preventing Displacement Hazards

Steel coils have immense density and high centers of gravity. Mismanagement during loading causes displacement, compression, and vessel hazards. Standardized loading is mandatory.

2.1 Expected Loading Performance and Inspection

• Vessel Checks: Container age must be under 7 years, with undeformed bodies and floor load capacities ≥1.2 times the coil weight. Bulk carriers require strict checks of hatch cover watertightness and sump valves.
• Equipment: Cranes must be rated for ≥1.5 times the coil weight. Forklifts must use anti-slip fork sleeves.
• Cargo Verification: Separate different materials (e.g., keep stainless away from ordinary steel) and plan heavy-to-light layering.

2.2 Shipping Loading Standards for Containers

Container shipping is ideal for high-value and brittle coils (cold-rolled, stainless) due to high security and low loss rates.

• Placement Principle: The coil’s center of gravity must align perfectly with the container’s center of gravity.
• Single Coils: Horizontal placement (axis parallel to the container length) is preferred. Keep at least 10cm clearance from sidewalls. If vertical placement is necessary, the bottom must be tightly fitted and heavily reinforced against tipping.
• Multiple Coils: Arrange from heaviest to lightest, placing the smallest coil at the front of the container. Separate adjacent coils with foam padding. If a single coil weighs ≤7 tons, the total stack weight must not exceed 8 tons.

2.3 Bulk Carrier Loading Specifications

Bulk carriers handle large-volume hot-rolled coils but carry higher risks of displacement and seawater damage.

• Hold Pre-treatment: Clean holds, lay moisture-proof rubber mats, and verify watertight seals.
• Layered Loading: Use heavy hardwood padding between layers. Do not exceed 80% of the cargo hold height to allow for ventilation (preventing sweat corrosion).
• Overall Lashing: Use lateral steel straps to connect rows, and longitudinal wire ropes to anchor the stack to the bulkhead. Space lashings ≤40cm apart.
• Top Layer Protection: Cover the top layer tightly with waterproof tarpaulins and secure ballast (sandbags) on top to prevent bouncing during ship pitching.

2.4 Loading Operation Prohibitions

• DO NOT load unpackaged/damaged coils or allow direct contact with seawater.
• DO NOT stack heavy coils on top of light ones or omit padding.
• DO NOT move cranes too fast, drag coils on the floor, or roll them manually.
• DO NOT mix ordinary iron wire with high-strength straps.
• DO NOT mix distinct steel types (like chlorine-packaged steel with stainless, which causes pitting).

3. Safety of Unloading and Delivery

The final handover must be meticulous to prevent last-minute damage and clarify liability in case of disputes.

3.1 Unloading Protocols

• Lift smoothly without swinging. Never use raw wire ropes directly on the coil packaging.
• Move forklifts slowly into containers to prevent wall collisions.
• Stack unloaded coils a maximum of two layers high (one layer for extreme heavyweights) on proper wooden pallets.
• Remove all wooden blocking from inside containers to avoid maintenance claims from the shipping line.

3.2 Pre-Delivery Inspection & Dispute Resolution

The consignor, consignee, and carrier must conduct a joint inspection. Check packaging integrity, material specifications, and quantities against the bill of lading. Take detailed photographs of any rust or deformation. If damage is found, trace the cause immediately to assign liability (consignor for poor packing, carrier for transit mishandling). A final signed delivery confirmation form is required to close the shipment or initiate a claim.