Square tubes are categorized by production process: Hot-rolled Seamless Square Tubes, Cold Drawn Seamless Square Tubes, Extruded Seamless Square Tubes, Welded Square Tubes.

By material: Carbon steel square tube, low-alloy square tube. Carbon steel includes: Q195, Q215, Q235, SS400, 20# steel, 45# steel, etc.; low-alloy steel includes: Q345, 16Mn, Q390, ST52-3, etc.

Categorized by cross-sectional shape: (1) Simple cross-section square tubes - Square tubes, rectangular tubes (2) Complex cross-section square tubes - Flower-shaped tubes, open-ended tubes, corrugated tubes, special-shaped tubes

As per surface treatment: Hot-Dip Galvanized Square Tubing, Electro-Galvanized Square Tubing, Oiled Square Tubing, Pickled Square Tubing

Categorized by Application - Decorative Square Tubes, Machining Equipment Square Tubes, Mechanical Industry Square Tubes, Chemical Industry Square Tubes, Steel Structure Square Tubes, Shipbuilding Square Tubes, Automotive Square Tubes, Steel Beam Columns Square Tubes, Special Purpose Square Tubes

Categorized by wall thickness - Extra-thick wall square tubes, thick wall square tubes, and thin wall square tubes

Rectangular tube applications:

Square tubes are extensively used in construction, machinery manufacturing, steel construction projects, shipbuilding, solar energy support structures, steel structure engineering, electrical engineering, power plants, agricultural and chemical machinery, glass curtain walls, automotive undercarriages, airports, boiler construction, highway guardrails, building construction, pressure vessels, oil storage tanks, bridges, power station equipment, lifting and transportation machinery, and other welded structural components with high loads.