Black Steel Hollow Section Rectangle /Square Carbon Steel Welded Pipe

Black Steel Hollow Sections (Rectangular/Square) and Carbon Steel Welded Pipes are core structural and fluid-transmission components in construction, industrial machinery, and infrastructure projects. They leverage the advantages of carbon steel (strength, cost-effectiveness) and tailored structures (hollow/rectangular/square/welded) to meet diverse application needs. Their key features are detailed by product type below:

Black Steel Hollow Section (Rectangle/Square)

a. High Structural Efficiency & Load-Bearing Capacity

• Hollow Design Advantage: The hollow structure balances strength and weight—reducing material consumption by 30%–50% compared to solid carbon steel bars of the same size, while maintaining excellent bending, torsional, and compressive performance. For example:

• A 50x50mm square hollow section (wall thickness 3mm) has a bending stiffness of 120 N·m², comparable to a 20mm solid carbon steel bar but weighing 60% less.

• Rectangular sections (e.g., 40x80mm) offer asymmetric load resistance—higher stiffness in the longer axis, making them ideal for components with directional stress (e.g., building curtain wall keels, billboard frames).

• Carbon Steel Material Strength: Made of low-carbon (Q235B) or medium-carbon (Q345B) steel, with tensile strength ranging from 345MPa to 510MPa and yield strength ≥235MPa. This enables the sections to withstand medium-to-heavy loads (e.g., 50x100mm rectangular sections support up to 80kN axial compression) for structural uses like building columns or industrial machine frames.

b. Versatile Shape Adaptability for Diverse Scenarios

• Rectangle vs. Square Applications:

• Square sections (e.g., 30x30mm, 100x100mm): Even stress distribution across all sides, suitable for symmetric load-bearing (e.g., shelf uprights, outdoor pergola supports, furniture legs).

• Rectangular sections (e.g., 20x40mm, 60x120mm): Optimized for narrow spaces or directional load needs (e.g., bridge side rails, conveyor frames, automotive chassis beams) where width/height asymmetry improves structural fit.

• Customizable Sizes: Available in a wide range of dimensions (side lengths 10mm–300mm, wall thickness 1.2mm–10mm) to match specific project requirements—from small decorative frames to large industrial structures.

c. Good Workability & On-Site Adaptability

• Easy Secondary Processing: The black steel surface (free of coatings) allows seamless cutting (plasma/angle grinder), drilling, welding (MIG/TIG/arc welding), and cold bending (for sections ≤50mm side length). Welded joints retain 80%–90% of the base material’s strength, facilitating on-site assembly of complex structures.

• Surface Treatment Compatibility: The uncoated black oxide surface serves as an excellent base for post-processing (e.g., painting, galvanization, powder coating) to enhance corrosion resistance. This flexibility makes the sections suitable for both indoor (uncoated, cost-saving) and outdoor (coated, weather-resistant) applications.

d. Cost-Effective & High Production Efficiency

• Low Material & Manufacturing Costs: Hollow design reduces raw material usage, while mass production via ERW (Electric Resistance Welding) ensures high output (up to 60m/min for small sections) and low unit costs—30%–40% cheaper than seamless hollow sections of the same size.

• Minimal Waste: Standardized dimensions and automated production minimize material scrap (scrap rate ≤5%), further lowering project costs for large-volume orders (e.g., residential construction, warehouse framing).

Structural engineering (buildings, bridges, towers)

Machinery manufacturing

Steel frameworks and fabrication

Transportation equipment

Furniture and architectural projects

Fencing, gates, and support columns