Rectangular Steel Pipe

Specification of Rectangular Pipe

Rectangular Pipe sizes

Standard of Rectangular Pipe

Standard Corner Radius of Rectangular Pipe(Structural Sizes:)

Max. 3 x Nominal Wall Thickness of Rectangular Pipe 

Straightness of Rectangular Pipe
Mechanical Sizes: Max. 1/16″ in 3 feet
Structural Sizes: Max. 1/8″ x Number of feet of total length divided by 5

Wall Thickness of Rectangular Pipe

Mechanical & Structural Sizes: ± 10% of Nominal Wall Thickness

Squareness of Sides
Mechanical Sizes: Max: ± b = c x 0.006″
b = Tolerance for out-of-square
c = Largest external dimension across flats
Structural Sizes: Adjacent sides may deviate from 90 ° by ± 2 °

Maximum Twist of Rectangular Pipe (Mechanical & Structural Sizes)

Convexity & Concavity of Rectangular Pipe(Mechanical & Structural Sizes)

Structural Tubing A 500 Requirements of Rectangular Pipe

Manufacturing Process

Rectangular steel pipes are typically produced using either hot-forming or cold-forming processes, depending on application requirements.

Hot-Formed Process

Steel strip or coil is heated and formed into a round tube, then shaped into a rectangular profile before welding. This process is suitable for heavy-duty structural applications requiring high strength and thick wall sections.

Cold-Formed Process

Cold-formed rectangular pipes are manufactured at room temperature from hot-rolled or cold-rolled steel coils. This method ensures tighter dimensional tolerances, smoother surface finish, and improved appearance quality.

Welding Methods

Depending on specification requirements, the pipes may be produced using:

High-frequency electric resistance welding (ERW)

Submerged arc welding (SAW) for heavy wall sections

Each production line is controlled to ensure stable weld integrity and consistent mechanical properties.

Painting & Coating of Rectangular Pipe

Bare, Black Painting, Lightly Oiled

Packing

Plastic plugs in both ends, Hexagonal bundles of max. 2,000kg with several steel strips, two tags on each bundle, wrapped in waterproof paper, PVC sleeve, and sackcloth with several steel strips

Q: We need rectangular steel tubes for a building framework. Which international standards can you supply?

A: We manufacture rectangular steel pipes in strict compliance with major international structural standards to meet diverse project requirements:

• For Structural Applications: ASTM A500 (USA), EN 10219 (Europe), JIS G 3466 (Japan), and KS D 3568 (Korea) are the most commonly specified standards.

• For Low-Pressure Fluid Transport: ASTM A53 and BS 1387 are applicable depending on the grade.

• Material Grades: Common grades include Q195, Q235, and Q345, which are equivalent to S235/S355 (European) or A500 Grade A/B (American). For example, Q235 is typically equivalent to ASTM A500 Grade A.

Q: What size range and wall thickness options do you offer for rectangular pipes?

A: We offer a comprehensive range of sizes to meet various project needs:

• Size Range: Typically from 20mm x 10mm up to 400mm x 300mm (or equivalent imperial sizes such as 1" x 0.5" up to 16" x 12").

• Wall Thickness: Generally ranges from 1.0mm to 25mm, depending on the dimensions.

• Lengths: Standard lengths are 5.8m, 6m, 11.8m, and 12m. We can also supply custom cut-to-length products.

• Corner Radius: Standard corner radius (r) is typically 1.5 to 2.5 times the wall thickness, but custom radii are available upon request.

Q: What is the difference between rectangular and square steel pipes, and when should I use one over the other?

A: The main difference lies in the cross-sectional profile, which affects load-bearing characteristics:

• Square Pipes (equal sides) are more efficient for uniform axial compression loads. They provide equal strength in all directions and are preferred for columns in building frames and balanced structural grids.

• Rectangular Pipes (unequal sides) offer higher bending resistance and stiffness in the direction of the longer dimension, making them particularly suitable for beams, lintels, and horizontal structural members where loads are concentrated in one plane. The larger moment of inertia allows for lighter structures with the same load capacity.

Selection Guide:

• Choose Square Pipes for columns, pillars, and structures with multi-directional loads.

• Choose Rectangular Pipes for beams, floor joists, frames, and applications where strength is needed in one primary direction (e.g., supporting floors or roof loads).

Q: What surface treatments do you offer to prevent corrosion?

A: We provide multiple surface treatment options tailored to different environments:

• Black Iron (Oiled): The most economical option, with a light oil coating for short-term protection during inland transport. Susceptible to rust in high-humidity or sea freight conditions.

• Pre-Galvanized: The steel coil is galvanized before forming, offering good corrosion resistance at a moderate cost. This is commonly used for structural and fencing applications.

• Hot-Dip Galvanized (HDG): Pipes are dipped in molten zinc after forming, providing the highest level of protection. HDG typically adds $0.08–0.15 per kilogram to the base cost but is essential for outdoor, marine, or highly corrosive environments.

• Painted: Anti-corrosion paint (e.g., epoxy or polyurethane) is applied for specific color requirements or aesthetic purposes, saving on-site painting costs.

Q: How long does it take from order confirmation to shipment?

A: Typical lead times are as follows:

• Production: 15–30 days after deposit confirmation for standard sizes and grades.

• Expedited Production: As fast as 10 days may be possible for common grades (Q235/A500) in stock sizes.

• Ocean Transit: 15–30 days depending on the destination port (e.g., 18 days to the US West Coast, 28–35 days to Europe).