Common sizes and standards for rectangular tubes

Rectangular tubes, as an important structural material, are widely used in numerous fields such as construction, mechanical manufacturing, the automotive industry, and furniture production. With their excellent mechanical properties, high load-bearing capacity, and flexible specification adaptability, they have been widely applied. Whether it is for building frameworks, manufacturing the shells of mechanical equipment, or making the supporting structures of furniture, rectangular tubes play a crucial role. This article will introduce the dimensions of rectangular tubes and commonly used standards, providing a reference for the dazzling colors of rectangular tubes.

Common size specifications of rectangular tubes

The dimensions of rectangular tubes are mainly defined by three core parameters: the long side (width, B), the short side (height, H), and the wall thickness (t), with the unit being millimeters (mm). Among them, the ratio of the long side to the short side (B:H) is usually controlled between 1:1.2 and 1:2.5. If the ratio exceeds this range (such as a large difference in length and width), square tubes (B=H) or flat tubes (H≪B) are generally selected as substitutes to meet the structural stability requirements.

Side length range
Short side (B) : The common size is 20mm to 500mm. For small structures (such as furniture and doors and Windows), a small side length of 20mm to 100mm is often adopted, while for medium-sized and larger structures (such as building frames and mechanical skeletons), a side length of 100mm to 500mm is mostly chosen. Long side (H) : Common sizes range from 30mm to 800mm. It needs to form a reasonable proportion with the short side (such as 100×50, 150×100, 300×200, etc.) to prevent the pipe from bending or deforming due to an overly large length-to-width ratio.

Wall thickness range
Rectangular tubes for common structures: The wall thickness is generally 1.0mm to 16mm, suitable for light to medium load scenarios (such as furniture frames, interior decoration, and small mechanical supports).
Rectangular tubes for heavy-duty structures: The wall thickness can reach 16mm to 40mm, or even thicker (such as 60mm). They are mainly used in high-rise buildings, large Bridges, heavy machinery (such as excavator booms), and other applications that require high load-bearing capacity.

Typical specifications
Small-sized thin-walled tubes: Suitable for light structures or decorative scenarios, such as 20×30×1.5mm (furniture legs), 40×60×2.0mm (door and window frames), 50×80×3.0mm (indoor partitions).
Medium size: The most commonly used dimensions in the construction and mechanical fields, such as 100×150×4.0mm (building keel), 120×200×6.0mm (mechanical frame), 150×250×8.0mm (bridge support frame).
Large-sized thick-walled pipes: used in heavy engineering, such as 200×300×10mm (high-rise building frames), 300×400×12mm (large bridge beams), 400×600×20mm (heavy machinery bases).
The commonly used range in construction: The most demanded specifications in the construction industry are 50×100mm to 200×400mm, with wall thicknesses concentrated between 3mm and 12mm, which can balance structural strength and material costs.

The execution standard for rectangular tubes

1. Chinese National Standard
GB/T 6728-2017 "Cold-formed Hollow Steel Sections for Structural Purposes" : A general standard for cold-formed rectangular tubes, covering dimensions, shapes, weights, materials (such as Q235B, Q345B), processes (high-frequency welding, cold-bending forming), and performance requirements. It is applicable to most rectangular tubes used in construction and machinery.
JG/T 178-2005 "Cold-formed Rectangular Steel Tubes for Building Structures" : Standards specifically for building structure design stipulate the cross-sectional size range of rectangular tubes used in construction (such as 120×80×4mm to 500×480×22mm), mechanical properties (tensile strength ≥370MPa, yield strength ≥235MPa), and anti-corrosion treatment requirements (such as hot-dip galvanizing).
GB/T 13773-2016 "Straight Seam Welded Rectangular Steel Tubes" : It is applicable to straight seam welded rectangular tubes for general structures, clearly specifying requirements for dimensional deviations (such as width ±1.5mm, thickness ±0.15mm), welding quality (no cracks or slag inclusions in the weld seam), and surface quality (no oxide scale or rust).
GB/T 3094-2015 "Rectangular Steel Tubes for Low-Pressure Fluid Conveyance" : A standard for rectangular tubes used in the conveyance of low-pressure fluids (such as water, gas, and air), emphasizing the pressure resistance (test pressure ≥1.5 times the working pressure) and sealing performance (no leakage) of the tubes.

2. European standards
EN 10219-1 "European Standard cold-formed Hollow sections" : The standard for European standard rectangular tubes stipulates cross-sectional dimensions (such as 100×50×3mm to 400×200×12mm), materials (such as S235JR, S355J2 carbon steel), process requirements (no cracks after cold bending forming), and inspection rules. It is applicable to steel structure projects in the European and international markets.
EN 10210-1 "Hollow sections of non-alloy and fine-grained steel for hot forming structures" : It specifies the technical requirements for thermoformed hollow profiles with circular, square, rectangular and elliptical cross-sections. It covers material (such as S235JR, S355J2 carbon steel), mechanical properties (yield strength ≥235MPa, tensile strength ≥360-510MPa), impact toughness (such as JR grade, room-temperature impact ≥27J) and chemical composition (carbon content ≤0.25%, sulfur and phosphorus ≤0.05%) It is complementary to the cold-bending standard forming process of EN 10219-1.

3. American standard
ASTM A500 "Cold-Formed Welded and Seamless Carbon Steel Structural Tubing" ASTM A500 is the most commonly used standard for rectangular tubes formulated by the American Society for Testing and Materials (ASTM). It mainly specifies the dimensions, materials and performance requirements of cold-formed welded or seamless carbon steel structural tubes, and is applicable to general structural uses such as Bridges, buildings and machinery. This standard classifies rectangular tubes into three categories: A, B, and C, with the core differences lying in mechanical properties and heat treatment requirements.
ASTM A513 "Mechanical Tubing" : ASTM A513 is a standard formulated for rectangular tubes used in machinery, emphasizing the consistency of dimensional accuracy and mechanical properties of the tubes. It is applicable to scenarios such as hydraulic cylinders, pneumatic cylinders, and mechanical frames that require high-precision fits.

Key points for selection: The selection of rectangular tubes should take into account mechanical properties, environmental adaptability, processing technology and cost control. By clarifying the application scenarios, verifying standard parameters and verifying the qualifications of suppliers, a balance between safety and economy can be ultimately achieved.

Read mroe : What is a rectangular tube? or What is a carbon steel rectangular tube?