Steel Hollow Section Specifications：

Our square and rectangular steel pipes are primarily manufactured from cold-rolled steel coils (strips) , with hot-rolled coils used for large-diameter and heavy-wall sizes. Cold-rolled base material offers superior surface finish and high dimensional accuracy, making it particularly suitable for small-diameter thin-wall square and rectangular tubes.

The production process begins with uncoiling, leveling, and slitting the cold-rolled steel strip to the required width (which determines the final pipe circumference). The strip then passes through a cold roll forming mill, progressively shaped through multiple passes into a round tubular form. High-frequency electric resistance welding (ERW) fuses the two edges, creating a continuous, strong weld seam.

The weld seam is squeezed, annealed (in-line heat treated) to relieve internal stress and refine grain structure. The round pipe then undergoes sizing and straightening to achieve precise outer diameter and straightness. It then enters the round-to-square forming stage: the round pipe passes through multiple sets of specially designed forming rolls, each applying controlled pressure at specific angles, gradually transforming the circular cross-section through transitional shapes into the final square or rectangular profile, typically requiring 4 to 8 passes. This cold forming process maintains the material's mechanical properties without additional heat treatment.

The finished pipe is sized, straightened, and cut to customer-specified lengths (typically 6m or 12m) by a flying saw. Each batch undergoes rigorous quality inspections including dimensional checks and hydrostatic testing. Passed pipes are then oiled for rust prevention, bundled, and packed for shipment.

Before packaging, our square and rectangular steel pipes are first surface-oiled with a uniform layer of rust-preventive oil to protect against corrosion during storage and ocean shipping. Additional surface treatments such as painting or galvanizing are also available upon request. The pipes are then sorted by size and bundled with high-strength galvanized steel strapping, with each bundle typically weighing 2-3 tons for easy forklift handling and container loading. Wooden strips or rubber pads can be placed between pipes to prevent surface damage caused by friction during transit. Plastic caps or end protectors are fitted to protect pipe ends and threads (if applicable).

After bundling, the packages are wrapped with waterproof cloth or moisture-proof paper to create a protective barrier, then loaded into standard 20-foot or 40-foot shipping containers, or shipped by bulk vessel. For large-size square and rectangular pipes, we also offer frame fixing or wooden crates for secure long-distance transport. All packaging materials comply with international export standards (ISPM 15), and each package is clearly labeled with product specifications, weight, and handling instructions.

Due to its excellent structural strength, aesthetic appearance, and ease of fabrication, square and rectangular steel pipe is widely used in various construction and industrial applications, particularly where structural support and visual appeal are required. Unlike circular pipes, square and rectangular sections are primarily used as structural components rather than for fluid transmission, as the sharp corners create stress concentration points and uneven flow dynamics that are unsuitable for pressurized liquid or gas conveyance.

1.Building and Construction Structures – Square and rectangular steel pipes are extensively used as load-bearing columns, beams, and support frames in industrial workshops, warehouses, high-rise buildings, and steel-structured buildings. Their uniform cross-section provides high strength-to-weight ratios and excellent resistance to bending and torsion.

2.Steel Frames and Trusses – Used in roof trusses, portal frames, and space frames for large-span structures such as stadiums, exhibition halls, and aircraft hangars. The closed section offers better torsional rigidity compared to open sections like I-beams or channels.

3.Welded Gates and Doors – Square and rectangular tubes are ideal for manufacturing heavy-duty industrial gates, sliding gates, security doors, and entrance frames. The flat surfaces allow easy attachment of hinges, locks, and infill panels, while the clean lines provide a modern appearance.

4.Fencing, Railings, and Barriers – Widely used for perimeter fencing, handrails, guardrails, and crash barriers in residential, commercial, and industrial projects. The rectangular profile is easy to install, provides strong impact resistance, and offers a neat, professional finish.

5.Agricultural and Greenhouse Structures – Used as framework supports for greenhouses, livestock shelters, and storage sheds. The corrosion-resistant surface and high durability make them suitable for outdoor agricultural environments.

6.Furniture and Display Racks – Employed in manufacturing steel furniture, shelving systems, display racks, workbenches, and storage solutions. The smooth, flat surfaces allow for easy cleaning and a sleek, modern aesthetic.

7.Solar Panel Mounting Structures – As the renewable energy sector grows, square and rectangular steel pipes are increasingly used for solar panel mounting frames and tracking systems, offering stability and weather resistance.