Horizontal Eye-to-Sky Packing

Standardized Process Requirements for Horizontal Eye-to-Sky Packing: Wrapping Layers, Edge Protector Coverage, and Strapping Patterns

Zhejiang Aoguan Thin Steel Technology Co., Ltd. specializes in the production and export of color-coated steel coils (PPGI and PPGL) to customers across Southeast Asia, Africa, the Middle East, and South America. As an integrated manufacturer with factories in Zhejiang, Jiangsu, and Anhui, we recognize that proper packaging is essential to protect product quality during storage and transportation. Horizontal Eye-to-Sky Packing remains one of the most widely used packaging methods in the steel industry, particularly for indoor storage, short-haul transport, and customer facilities equipped with overhead cranes. This article details the standardized process requirements for VCI paper wrapping layers, edge protector coverage methods, and steel strapping patterns when implementing Horizontal Eye-to-Sky Packing.

1. VCI Rust Preventive Paper Wrapping Layers

The inner wrapping layer provides the primary barrier against moisture and corrosion. The number of wrapping layers and the application method are critical to ensuring effective protection throughout the supply chain.

• Minimum Wrapping Layers: A minimum of two complete spiral wraps of VCI (Volatile Corrosion Inhibitor) paper is required for standard export shipments. Each wrap must overlap the previous by at least 50% of the paper width to ensure complete coverage without gaps.
• Recommended Wrapping Layers: For long-distance ocean freight or high-humidity destinations (e.g., Southeast Asian coastal areas), three full layers of VCI paper are recommended. The additional layer provides enhanced protection against condensation and salt spray ingress.
• VCI Paper Extension Beyond Coil Edges: The VCI paper must extend beyond both the inner and outer edges of the coil by a minimum of 50-80 mm. This overlap creates a protective envelope that prevents moisture from directly contacting the steel edge, which is the most corrosion-prone area.
• VCI Paper Grade and Basis Weight: The paper must have a minimum basis weight of 80 g/m² for standard applications and 100 g/m² for premium corrosion protection. The VCI formulation should be specifically designed for zinc-coated and color-coated steel surfaces (PPGI/PPGL) to avoid any chemical reaction that could affect the coating.
• Outer PE Film Layer: After the VCI paper wrapping, a layer of PE (polyethylene) film with a minimum thickness of 0.12 mm is applied as an additional moisture barrier. The PE film must cover the entire circumference and overlap at the top face, secured with moisture-resistant tape.

2. Edge Protector (Corner Guard) Coverage Method

Edge protectors serve two essential functions in Horizontal Eye-to-Sky Packing: protecting the coil edges from mechanical damage and preventing the steel straps from cutting into the coil surface under tension. The coverage method must ensure full circumferential protection.

• Inner Diameter Edge Protectors: For Horizontal Eye-to-Sky Packing, the inner diameter (ID) edge protectors must fully cover the entire inner circumference of the coil. The standard solution is a pre-formed, split-type fiberboard ring (6-8 mm thickness) that wraps completely around the ID. The two ends of the split ring should overlap by 100-150 mm and be secured with moisture-resistant tape.
• Outer Diameter Edge Protectors: The outer diameter (OD) edge protectors must similarly cover the entire outer circumference. These are typically supplied as flexible strips that can be bent around the coil circumference. For coils with outer diameters above 1,200 mm, the edge protector is applied in two half-circle sections with overlapping ends. A minimum overlap of 150 mm is required at each joint, secured with tape or metal clips.
• Thickness Requirements: The minimum thickness for fiberboard edge protectors is 6 mm for coils weighing less than 5 tons, and 8-10 mm for coils weighing 5-15 tons. For coils exceeding 15 tons, reinforced edge protectors with a thickness of 12 mm or metal-reinforced corner guards are recommended.
• Positioning Accuracy: Edge protectors must be positioned with the centerline aligned with the coil edge, allowing for a tolerance of ±5 mm. Misalignment can lead to unprotected edge exposure or interference with the steel strapping.
• Strapping Grooves: For Horizontal Eye-to-Sky Packing, the edge protectors at the top face of the coil (the upward-facing side) should be pre-fitted with grooved indentations at the planned strapping positions. This guides the steel straps into the correct alignment and prevents lateral movement during tensioning.

3. Steel Strapping (Banding) Patterns and Specifications

Horizontal Eye-to-Sky Packing uses circumferential strapping around the coil's outer diameter. Unlike vertical packing methods, horizontal eye-to-sky does not typically require cross strapping through the eye, as the coil's weight rests on the pallet base, providing inherent stability against vertical displacement.

• Number of Straps: The standard requires a minimum of four circumferential steel straps for coils with an outer diameter up to 1,500 mm. For coils with an outer diameter exceeding 1,500 mm, five to six straps are recommended to ensure uniform compression of the packaging layers.
• Strap Spacing: Straps should be evenly distributed across the coil width. The spacing between adjacent straps must not exceed 300 mm. For example, a coil with a 1,200 mm width requires four straps spaced approximately 300 mm apart, with the first and last straps positioned 150-200 mm from each end.
• Strap Material and Dimensions: High-tensile steel strapping with a minimum tensile strength of 800 N/mm² is required. The standard strap width is 32 mm (1.25 inches) with a thickness of 0.8 mm. For heavier coils (over 10 tons) or rough handling conditions, 40 mm wide straps with 1.0 mm thickness are recommended.
• Strap Tension Control: The applied tension should be controlled to 70-80% of the strap's rated breaking strength. Typical tension settings range from 250-400 kg per strap, depending on strap width and thickness. Tension must be verified using a calibrated tension meter on the first strap of each package.
• Strap Sealing Method: Steel straps must be sealed using either crimp seals (overlap joints) or friction welds (sealless joints). Crimp seals require a minimum of two crimps per joint. Friction-welded joints must pass a shear strength test of at least 70% of the strap's tensile strength.
• Protection Under Straps: To prevent indentation and coating damage (especially critical for PPGI and PPGL color-coated products), a protective layer of 0.5 mm thick PE foam strip or cardboard must be placed between the steel strap and the coil surface. This protective material must extend 10-15 mm beyond the strap width on each side.

4. Additional Packaging Components and Their Standardized Requirements

Beyond the primary packaging elements, additional components ensure comprehensive protection for steel coils in Horizontal Eye-to-Sky configuration.

• Pallet Base (Wooden Skid): A wooden base platform is required to provide stability and allow for forklift handling. The base must be constructed from heat-treated lumber complying with ISPM 15 standards and must be at least 80 mm thick. The base dimensions must exceed the coil outer diameter by at least 100 mm on all sides.
• Bottom Support Cradles: Two V-shaped or contoured wooden cradles are positioned on the pallet base to cradle the coil's outer diameter. These cradles must match the coil's curvature to distribute weight evenly and prevent deformation. The cradle material should be hardwood or high-density plywood with a minimum thickness of 100 mm.
• Top Cover Sheet: A protective sheet (heavy-duty PE film or kraft paper) is placed over the top face of the coil (the upward-facing side) to prevent dust and moisture accumulation. This cover must extend beyond the coil diameter by at least 150 mm on all sides and be secured with tape or elastic bands.
• Protective Side Wraps: For enhanced mechanical protection, optional side wraps of corrugated cardboard or 0.5 mm galvanized steel sheet can be applied around the coil circumference, between the inner packaging and the steel straps.

5. Standardized Process Parameters Summary Table

The following table summarizes the recommended and required process parameters for Horizontal Eye-to-Sky Packing of steel coils, based on industry standards and best practices:

At Zhejiang Aoguan Thin Steel Technology Co., Ltd., we strictly follow these standardized process requirements for every Horizontal Eye-to-Sky Packing application. Our packaging specifications are tailored to the unique requirements of color-coated steel coils (PPGI and PPGL), where surface integrity is paramount. Our experienced packaging teams at our Zhejiang, Jiangsu, and Anhui facilities undergo regular training on these standards to ensure consistent quality for our international customers.

6. Quality Assurance and Inspection Procedures

Zhejiang Aoguan Thin Steel Technology Co., Ltd. implements a comprehensive quality control system to verify that all Horizontal Eye-to-Sky Packing processes conform to the required standards.

• Material Incoming Inspection: All packaging materials (VCI paper, PE film, edge protectors, steel straps, and pallets) are inspected upon receipt. VCI paper is tested for effective corrosion inhibition using coupon testing according to ASTM D1748 or equivalent standards.
• In-Process Monitoring: During the packaging operation, the following checks are performed: VCI paper wrap count and overlap verification; edge protector position and joint integrity inspection; steel strap tension measurement on the first strap and at random intervals; and under-strap padding placement confirmation.
• Final Package Inspection: Before release for shipment, the complete package is inspected for: all straps intact and properly sealed; no movement of edge protectors or packaging materials; moisture barrier integrity; and proper pallet base assembly with support cradles correctly positioned.
• Drop Test and Vibration Simulation: For new packaging designs or when required by specific customer requests, sample packages undergo drop tests from 1.2 meters and vibration simulation testing to validate packaging integrity under simulated transport conditions.

Frequently Asked Questions (FAQ)

FAQ 1: Can the number of VCI paper wrapping layers be reduced for short-distance domestic shipments?

For short-distance domestic shipments (under 500 km) with delivery expected within 24 hours, it is technically acceptable to use a single layer of VCI paper combined with a full PE film wrap. However, this should only be considered for indoor-stored products that will not be exposed to rain or condensation. The minimum acceptable configuration is one layer of VCI paper (80 g/m²) plus one layer of 0.15 mm PE film, with the VCI paper extending beyond the coil edges by at least 50 mm. This reduction is not recommended for export shipments or for high-value color-coated products (PPGI/PPGL) where surface quality is critical. Even for domestic shipments, Zhejiang Aoguan Thin Steel Technology Co., Ltd. typically applies two layers of VCI paper as our standard practice to ensure consistent quality across all orders.

Zhejiang Aoguan Thin Steel Technology Co., Ltd. is a dedicated manufacturer and supplier of high-quality PPGI and PPGL products. Our headquarters in Chuansha, Shanghai, coordinates with our three production facilities to ensure that every coil is packaged according to rigorous standards. Whether shipping to Southeast Asia, Africa, the Middle East, or South America, our packaging meets international requirements for corrosion protection and handling safety.

FAQ 2: What is the recommended steel strapping pattern for a coil with an outer diameter of 1,800 mm and width of 1,250 mm?

For a coil with an outer diameter of 1,800 mm and width of 1,250 mm, the recommended pattern is six circumferential steel straps. The spacing calculation is as follows: total width 1,250 mm minus the end margins (approximately 150 mm from each edge) leaves 950 mm for five equal spacing intervals, giving approximately 190 mm between each strap. This ensures even compression across the entire coil width. The six straps should be distributed as follows: two straps near each edge (at approximately 150 mm and 350 mm from the edge) and two straps evenly positioned in the central section. All straps should be applied with a tension of 300-350 kg (for 32 mm x 0.8 mm straps) and with PE foam padding under each strap to prevent marking of the PPGI coating.

Zhejiang Aoguan Thin Steel Technology Co., Ltd. provides customized packaging solutions for coils of all dimensions. Our technical team uses engineering calculations to determine the optimal strapping pattern for each specific order. With our integrated manufacturing and packaging capabilities, we ensure that every Horizontal Eye-to-Sky Packing application meets both the customer's specifications and international safety standards.

FAQ 3: How do I verify that the steel strap tension is correctly applied without specialized equipment?

While a calibrated tension meter provides the most accurate measurement, there are practical field methods for verification. First, after tensioning, the strap should have a consistent, flat contact with the packaging surface with no visible rippling or gaps. Second, the strap should be tight enough that it cannot be rotated or slipped side to side by hand pressure. Third, using a manual method: after sealing, the strap should deflect no more than 2-3 mm when moderate thumb pressure is applied at the midpoint between two adjacent straps. Additionally, the applied tension should leave a slight but not excessive indentation (maximum 10% of the edge protector thickness) in the fiberboard edge protector. For color-coated steel coils, any indentation exceeding the edge protector thickness indicates overtensioning that could damage the coating. If you observe visible marks on the coil surface or deformation of the edge protectors, the tension should be reduced. For best results, we recommend using a simple tension meter, which is an inexpensive tool that provides reliable measurement.

Zhejiang Aoguan Thin Steel Technology Co., Ltd. ensures that our packaging team uses calibrated tension meters for every packaging operation. As a responsible manufacturer serving customers across Southeast Asia, Africa, the Middle East, and South America, we incorporate quality checks at every stage of the packaging process. Our commitment to excellence ensures that your steel coils arrive at their destination in perfect condition, maintaining the stunning appearance and exceptional quality of our color-coated products.