Having Passed all SGS Tests, Our PPGI Coils Stand Up to Scrutiny

In the international steel trade, issues such as dimensional deviations, marine corrosion, and coating peeling have always been major concerns for buyers. Wanzhi Steel lets SGS’s actual test data speak for itself! From warehousing and packaging to dimensional and weight measurements, as well as performance tests including bending, adhesion, and zinc coating thickness, our steel products have passed every inspection.

This article provides a detailed overview of SGS’s pre-shipment inspections for pre-painted galvanized steel coils and galvanized steel coils/sheets.

Storage Environment and Marine Packaging Inspection

Upon arriving at the factory, the first step for SGS inspectors is not to sample the steel coils themselves, but to verify the storage environment. This is because if the substrate becomes damp before shipment, even the most superior coating will be ineffective.

Moisture-Free Storage

All steel coils must be stored in enclosed indoor warehouses with dry, clean, hardened concrete floors, strictly avoiding outdoor stacking or exposure to rain and moisture. This fundamentally prevents “white rust” (a typical sign of early corrosion in the galvanized coating).

Export-Grade “Premium Packaging” System

To withstand up to two months of rough seas and salt fog corrosion, our packaging far exceeds standard international trade requirements.

• Inner Layer: A layer of dense PE plastic film + a layer of high-barrier waterproof paper, completely blocking moisture and air.
• Outer Layer: Fully wrapped in sturdy galvanized sheet metal, supplemented with high-strength steel sleeves to prevent mechanical impact during loading, unloading, and stacking.
• Reinforcement: At least four heavy-duty steel straps applied radially and circumferentially to ensure the steel coils remain secure and do not shift, even under severe sea conditions.

SGS On-Site Inspection Conclusion: Packaging and warehousing comply with ISO 9001 and export maritime shipping regulations, meeting “Sea-worthy” standards.

Random Physical Verification

Quantity, dimensions, and weight are verified with absolute precision. “Cutting corners” most commonly manifests as short counts, excessive negative tolerances in thickness, and misrepresented weights. To address this, SGS employs a combination of random sampling and precision measurement for inspection.

• 100% Quantity Verification: Inspectors verify the total number of items piece by piece in the warehouse and cross-check them against the packing list to ensure zero discrepancies.
• Actual Thickness and Width Measurement: Samples are randomly selected from packaged steel coils, and professional micrometers and calipers are used to measure the actual thickness and width. Our tolerance control has consistently exceeded industry stZinc Coating Weight Testandards (e.g., thickness tolerance within ±0.02 mm), fully meeting contractual requirements.
• Actual Weight Verification: Several coils are randomly lifted and weighed using calibrated floor scales or crane scales to determine the Actual Net Weight, which is then compared to the Declared Net Weight. Deviations are strictly controlled within a minimal range—meaning every penny paid by the buyer corresponds to tangible steel.

Physical Property Testing

T-Bend Test

This is the “ultimate test” of color-coated sheet processing performance. Test method: The coated sheet is tightly bent 180° along its own axis so that the inner and outer surfaces at the bend are in complete contact, and then the coating is inspected for cracks.

Our products show no cracks or peeling in the coating under 0T conditions, proving that the paint film will not crack even after deep drawing or complex forming. This is direct evidence of zero risk in subsequent processing.

Cross-Cut Adhesion Test

A 100-grid cutter is used to score 100 small squares on the coated surface, which is then peeled off using specialized adhesive tape. Test results: The cut edges are completely smooth, with not a single square peeling off—this indicates an exceptionally strong bond between the topcoat, primer, and galvanized substrate, remaining secure even under exposure to sun, rain, and temperature fluctuations.

Zinc Coating Weight Test

The zinc coating weight per unit area is precisely calculated using the chemical dissolution method (difference in weight before and after dissolution). Our GI/PPGI substrates feature a uniform and dense zinc coating, providing a solid foundation for corrosion resistance.

Double-Sided Coating Thickness Measurement

The thickness of the topcoat and backcoat directly affects UV resistance and salt spray resistance. SGS uses a magnetic thickness gauge for multi-point measurements, with data precisely meeting design targets—ensuring both color durability on the front and rust resistance on the back.

Tensile Strength Testing

Measured tensile strength values range from 330 to 355 MPa, fully meeting the requirements for structural design and standard cold-forming and stamping processes, thereby eliminating the risk of cracking during fabrication.

SGS Inspection Results for This Order: All tested items passed on the first attempt. From warehousing, packaging, and physical measurement to 0T bending, coating adhesion, zinc coating, and mechanical properties, there were no non-conformities.

All SGS Test Results for Wanzhi Steel

“Actions speak louder than words”—we have passed all SGS tests requested by our customers. All authentic SGS test reports have been compiled and displayed on our official dedicated page → https://wanzhi-steel.com/sgs-test-report-showcase/, ← please click to view.

It is worth noting that we have our own inspection center, and we conduct rigorous testing on customer products prior to shipment. If you require third-party testing for verification, we fully support this (as we have complete confidence in our products); however, the costs associated with third-party testing must be borne by you.

Examples of SGS Test Results

Why do global buyers choose to source steel through us?

In international trade, “trust” is not just an emotional slogan, but is built upon a series of verifiable facts. As a professional Chinese steel export service provider, we offer not only standard, high-quality products, but also a complete, end-to-end transparent supply chain management system:

1. Pre-sales: We welcome factory inspections by clients or third-party organizations to verify our production lines, quality control systems, and warehousing conditions on-site.
2. During Sales: We operate our own testing center and welcome on-site inspections by renowned third-party agencies such as SGS and BV (customers are responsible for third-party testing fees).
3. Pre-Shipment: We strictly enforce pre-shipment inspections, and goods are only released after passing these checks.
4. After-Sales: We provide complete test reports and material certificates, and assist with customs clearance and acceptance at the destination port.

Specific Product Examples:

We understand that every actual thickness measurement, every 0T bending video, and every micrograph of adhesion testing lays the foundation for long-term cooperation.

In the future, Wanzhi Steel will deepen cooperation with global clients by leveraging stable product quality, standardized packaging and transportation, and authoritative testing and certification. Choosing us means choosing a transparent, reliable, and trustworthy steel supplier.

Wanzhi Steel – Quality You Can See, A Partner You Can Trust