Overview
The 220*80*8 rectangular hollow section is a cold-formed structural steel tube with exterior dimensions of 220mm (height) × 80mm (width) and a uniform 8mm wall thickness. As a standardized profile under Chinese GB/T 6728 specifications, it offers superior load-bearing capacity compared to lighter gauge tubes while maintaining manageable weight for construction applications. These sections are typically manufactured from carbon steel grades Q235 or Q355 through high-frequency welding (HFW) or cold-forming processes. The designation '220*80*8' follows the industry convention of listing height × width × wall thickness in millimeters, providing immediate dimensional clarity for engineers and procurement specialists.
Structure and Working Principle
The rectangular hollow section derives its structural efficiency from the closed-box geometry, which provides excellent torsional resistance and uniform stress distribution. The 8mm wall thickness ensures sufficient rigidity for medium-to-heavy load applications without excessive material usage. In structural applications, these sections function primarily in axial compression or bending. The flat surfaces facilitate easy connection to other members through bolting or welding, while the hollow interior allows for utility routing in some architectural designs. The 220mm height dimension makes it particularly suitable for vertical load-bearing columns in industrial buildings.
Key Features
This profile offers several technical advantages for industrial buyers. The dimensional ratio (height to width) of approximately 2.75:1 provides optimized bending resistance in the stronger axis while maintaining stability. The 8mm thickness balances strength requirements with material economy. Manufacturing standards ensure consistent mechanical properties including yield strength (≥235 MPa for Q235 grade) and elongation (≥26%). Hot-dip galvanized versions are available for corrosion protection, adding approximately 50-100μm zinc coating. The sections typically exhibit dimensional tolerances of ±1.0% on height/width and ±10% on wall thickness as per GB/T 6728 Class I specifications.
Application Areas
Primary applications include structural frameworks for warehouses and factories, where the 220mm height efficiently supports roof loads. The profile serves as columns in mezzanine flooring systems and as horizontal beams in crane runways with appropriate reinforcement. Beyond construction, these sections are used in heavy-duty shelving systems, conveyor support structures, and agricultural machinery frames. In infrastructure projects, they appear as bridge guardrail supports and signboard foundations. The dimensions make them suitable for modular building systems where standardized connections are required.
Maintenance and Precautions
Regular inspection for corrosion is essential, particularly in humid or industrial environments. Uncoated sections require protective painting every 3-5 years, while galvanized versions typically last 15-25 years before significant maintenance. During installation, avoid notching or drilling near stress concentration points without engineering approval. For welded connections, preheating to 100-150°C is recommended when ambient temperatures are below 5°C. Storage should be on leveled surfaces with wooden spacers to prevent distortion, particularly for lengths exceeding 6 meters.
B2B Procurement Guide
Industrial buyers should specify material grade (Q235B or Q355B), surface treatment (black, painted, or galvanized), and length (standard 6m or 12m, custom cuts available). Mill certificates verifying chemical composition and mechanical properties should be required. Order lead times typically range from 2-4 weeks for standard stock items. For large projects, staggered deliveries can be negotiated to optimize storage space. Price fluctuations track domestic steel billet markets - consider forward contracts when prices are low. Always verify edge condition (deburred) and internal cleanliness (free of scale) upon delivery.
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