Thin Wall Rectangular and Square Steel Tube

Thin Wall Rectangular and Square Steel Tubes refer to square and rectangular hollow cold-formed steel sections with relatively thin walls. In the industry, the ratio of wall thickness to the side length of the section is typically no more than 1/20. This product uses hot-rolled and cold-rolled strip steel as raw materials, processed through cold bending and high-frequency welding, ensuring stable quality. The tubes are lightweight, rigid, easy to process, and cost-effective, widely used in light steel structures, curtain wall framing, machinery manufacturing, automotive industry, and decoration engineering.

- Square tube: Specifications 20×20 mm — 500×500 mm, wall thickness 1.0–3.0 mm

- Rectangular tube: Specifications 20×30 mm — 400×600 mm, wall thickness 1.2–3.0 mm

- Standard length: 6 meters, customizable 6–12 meters

- Standards: GB/T 6728-2017, ASTM A500

Materials and Core Performance

1. Mainstream Materials

- Q235B: Yield strength ≥ 235 MPa, elongation ≥ 26%, economical and practical, suitable for lightweight structures and decorative applications.

- Q355B: Yield strength ≥ 355 MPa, excellent strength, mostly used in load-bearing and seismic engineering projects.

2. Mechanical Performance Advantages

- Excellent Rigidity: For the same cross-sectional area, thin wall rectangular and square steel tubes have 1.5–2 times the bending resistance of round tubes and excellent torsional resistance.

- Lightweight: 30%–40% lighter than solid steel; for example, a 40×40×3 mm square tube weighs only one-quarter of a solid steel tube of the same specification.

- Easy Processing: Can be cut, welded, bent, and drilled, increasing on-site assembly efficiency by approximately 25%.

Production Process

1. Raw Material Selection: Q235B and Q355B hot-rolled/cold-rolled strip steel are used.

2. Cold Bending Forming: The strip steel is bent into square and rectangular tube blanks using multiple sets of rollers.

3. High-Frequency Welding: High-frequency fusion welding is performed at the butt joints, with weld strength not less than 80% of the base material.

4. Sizing and Straightening: Strict control over product dimensional accuracy and straightness.

5. Surface Treatment: Divided into three categories: black pipe (no anti-corrosion treatment), hot-dip galvanized pipe (zinc layer thickness ≥ 65 microns), and painted/plastic-coated pipe.

Product Features

1. Corrosion and Durability: The galvanized layer of the Thin Wall Rectangular and Square Steel Tube isolates moisture corrosion, providing an outdoor service life of over 20 years and low maintenance costs.

2. Economical and Environmentally Friendly: Lightweight design effectively reduces transportation and installation costs; the steel is recyclable and environmentally friendly.

3. Strong Appearance Adaptability: Smooth surface, can be directly used as decorative components or for secondary coating; right-angle structure allows for simple splicing.

Application Areas

1. Construction: Light steel villas, factory frames, curtain wall keels, greenhouses

2. Machinery: Equipment racks, equipment bases, conveyor line supports, agricultural machinery structural components

3. Transportation: Automobile chassis, guardrails, streetlight poles, bus stops

4. Decoration: Display racks, furniture, partitions, handrails, billboard frames

Real-world Application Case

In 2025, Zhongtian supplied 120 tons of 40×60×2.0 mm Q355B Thin Wall Rectangular and Square Steel Tubes for a light steel villa project in Jiangsu Province, mainly used for floor keels and wall frames. The theoretical weight of this pipe is 3.47 kg per meter. Its lightweight characteristics reduced on-site construction labor costs by 30%, while its excellent rigidity fully met the building's seismic resistance requirements. After project acceptance, all product indicators met the standards, and the two parties established a long-term cooperative relationship.

FAQ

Q1: How is the "thin wall" standard for pipes defined?

A: The industry standard is a wall thickness ≤ 3 mm. A wall thickness less than 1.0 mm is defined as ultra-thin wall. All products comply with the national standard GB/T 6728-2017.

Q2: What is the difference between square tubes and rectangular tubes?

A: The difference lies in their cross-sectional shape: square tubes have four equal sides (e.g., 20×20 mm), while rectangular tubes have two sets of unequal opposite sides (e.g., 40×60 mm). However, their materials, manufacturing processes, and applicable standards are completely identical.

Q3: How to choose the appropriate material based on the working conditions?

A: For light loads, decorative projects, or scenarios with limited budgets, Q235B material is recommended; for load-bearing structures, seismic engineering, and other scenarios requiring high strength, Q355B material is preferred. Material testing reports can be requested from the factory for verification during purchase.