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Square Steel Pipe

  • Keywords(pipe type) : carbon steel pipe,Seamless Steel Pipe, Seamless Stainless Steel Pipe, Steel Piping;Hollow Section;Square Pipe
  • OD: 20*20~1200*1200mm
  • Tickness: 2,3,4,5,6,8,10,12,14,16,18,20mm
  • Length: 5m or Customized
  • Standard & Grade: ASTM A500, ASTM A53, EN 10210, EN 10219, JIS G 3466, BS 1387, BS 6323
  • Marterial: S235JR, S355JR, S275JR, C350LO, C250LO, G250, G350（C450LO）
  • Delivery: Within 30 days and Depends on your order quantity
  • Payment: TT, LC , OA , D/P
  • Packing: Waterproof Paper Wrapped, Steel Strips Bundled, Two Tags on Each Bundle
  • Usage: In Industrial Construction, Machinery/Rack/Container manufacturing
Availability:
Get A Quote

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Description of Square Pipe


Square steel pipe, also known as square hollow section (SHS) or rectangular hollow section (RHS), is a widely used structural steel product designed for load-bearing, framing, and engineering applications. With excellent mechanical strength, uniform geometry, and versatile fabrication performance, it plays a critical role in modern construction and industrial systems. Unlike open-section steel, square steel tubing offers balanced strength in multiple directions, making it a preferred choice for structural stability, aesthetic design, and efficient material usage.


What Is Square Steel Pipe?

A square steel pipe is a hollow structural steel section formed by hot rolling or cold forming steel into a square or rectangular shape, followed by welding or seamless processing depending on specifications. It is typically manufactured in two main types:

(1) Seamless square steel pipe

(2) Welded square steel pipe (ERW/HFW)

The selection depends on strength requirements, dimensional accuracy, and application environment.


Shape:

Hollow Sections: Square, Rectangular, Round, Triangular, Hexagonal, Elliptical Hollow sections



Key Structural Features of Square Steel Pipe

1. Hollow Section Design: The closed square geometry provides excellent torsional resistance and uniform load distribution. Compared with I-beams or channels, square steel pipes perform better under multi-directional stress conditions.

2. High Strength-to-Weight Ratio: Square hollow sections deliver strong structural capacity while reducing overall steel consumption. This improves cost efficiency in large-scale construction and infrastructure projects.

3. Excellent Weldability and Fabrication Performance: Square steel pipes can be easily cut, drilled, welded, and formed into complex structures. This makes them suitable for prefabricated steel structures and modular construction systems.

4. Precise Dimensional Control: 

Modern production processes ensure tight tolerance control:

(1) Side length tolerance: typically ±0.5 mm to ±1.5 mm depending on size

(2) Wall thickness tolerance: typically ±5%–10%

This consistency is critical for structural alignment and assembly efficiency.


Surface Treatment Options

To enhance durability and corrosion resistance, various surface treatments are available:

(1) Black steel (mill finish)

(2) Hot-dip galvanized coating

(3) Anti-corrosion painting (epoxy, zinc-rich coatings)

(4) 3PE / FBE coating for industrial pipelines

Hot-dip galvanizing is widely used in outdoor and structural applications due to its long-term corrosion protection.


Advantages of Square Steel Pipe

(1) High structural stability under load

(2) Efficient material usage compared to solid steel sections

(3) Easy installation and prefabrication capability

(4) Strong adaptability to welding and machining

(5) Wide range of sizes and grades for different engineering needs

These advantages make square steel pipes a core material in modern steel structure engineering.

Specification of Square Pipe


Square tubes sizes

Size (mm)

Wall Thickness (mm)

Size (mm)

Wall Thickness (mm)

20*20

1.2

70*70

60*80

100*40

1.8

1.3

2

1.4-1.5

2.2

1.7

2.3

1.8

2.5-4.0

2

4.5-5.0

2.2

5.5-5.75

2.3

75*75

60*90

100*50

1.8

2.5-2.75

2

25*25

20*30

1.2

2.2

1.3

2.3

1.5

2.5-4.0

1.7

4.5-5.0

1.8

5.5-5.75

2

80*80

100*60

100*80

120*60

2

2.3-2.3

2.2

2.5-3.0

2.3

30*30

30*40

25*40

20*40

1

2.5-4.0

1.2

4.5-5.0

1.3

5.5-5.75

1.5

7.5-7.75

1.7

100*100

120*80

2

1.8

2.2

2

2.3

2.2

2.5-5.0

2.3

5.5-5.75

2.5*2.75

7.5-7.75

3

120*120

140*80

150*100

160*80

2.5

40*40

30*50

25*50

1.2

2.75

1.3

3

1.4-1.5

3.25-5.0

1.7

5.5-7.0

1.8

7.5-7.75

2

140*140

150*150

200*100

3.5-4.0

2.2-2.3

4.5-5.0

2.5-4.0

5.25-7.0

50*50

60*40

30*60

40*50

1.5

7.5-7.75

1.7

160*160

180*180


3

1.8

3.5

2

3.75

2.2

4.0-5.0

2.3

5.25-5.75

2.5*-4.0

7.5-7.75

4.25-5.0

60*60

40*80

75*75

50*70

50*80

2.3

60*60

40*80

75*45

50*70

50*80

1.5

2.5-4.0

1.7

4.25-5.0

1.8

5.5-5.75

2

/

2.2-2.3

/





Standard of Square Pipe

Available Quality Standards of Square Pipe

ASTM A500 Cold Formed Welded and Seamless Carbon Steel Structural Tubing in Rounds and Shapes

EN 10210 Hot finished structural hollow sections of non-alloy and fine grain structural steels

EN 10219 Cold formed welded structural hollow sections of non-alloy and fine grain steels

ASTM A53 used as structural steel or for low-pressure plumbing

Standard Corner Radius(Structural Sizes:)
Max. 3 x Nominal Wall Thickness of Square Pipe

Mechanical Sizes

Structural Sizes

Largest Nominal Outside Dimension

Outside Tolerance at all Sides at Corners

Largest Nominal Outside Dimension

Outside Tolerance at all Sides at Corners

3/16 to 5/8

± 0.004

2 1/2 and under

± 0.020

over 5/8 to 1 1/8

± 0.005

over 2 1/2 to 3 1/2

± 0.020

over 1 1/8 to 1 1/2

± 0.006

over 3 1/2 to 5 1/2

± 0.030

over 1 1/2 to 2

± 0.008

over 5 1/2

± 1%

over 2 to 3

± 0.010



over 3 to 4

± 0.020



over 4 to 6

± 0.020



over 6 to 8

± 0.025



Straightness
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 Square 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 (Mechanical & Structural Sizes) of Square Pipe

Largest Dimension, inches

Max. Twist*, inches

over 1/2 to 1 1/2

0.050

over 1 1/2 to 2 1/2

0.062

over 2 1/2 to 4

0.075

over 4 to 6

0.087

over 4 to 8

0.100


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

Largest Nominal O.D., Inches

Tolerance ± Inches

2 1/2 and under

± 0.010

over 2 1/2 to 4

± 0.015

over 4 to 8

± 0.025


Structural Tubing A 500 Requirements of Square Pipe

Grades

Chemical

Physical

C Max. %

Mn Max. %

P Max. %

S Max. %

Cu Max. %

Tensile strength, min. psi

Yield strength, min. psi

Elongation in 2 in.

Grade B

0.26

/

0.04

0.05

0.20

58,000

46,000

23

Grade C

0.23

1.35

0.04

0.05

0.20

62,000

50,000

21



Painting & Coating of Square Pipe

Bright Annealed, Black Annealed


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.

Inspection: Chemical Component Analysis, Mechanical Properties

Square-Steel-Pipe-Packing


Q: We need square steel pipes for a structural project. Which international standards can you supply, and how do we choose the right grade?

A: We manufacture square steel pipes in strict compliance with major international structural standards:

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

  • For Low-Pressure Fluid Transport: ASTM A53, BS 1387, and API 5L are also applicable depending on the grade.

  • Material Grades: Common materials include Q195, Q235, and Q345 (Chinese equivalents to S195/S235/S355 or A53/A500 grades). For example, Q235 is typically equivalent to ASTM A53 Grade B or A500 Grade A.



Q: What is the typical manufacturing process for square steel pipes? Are they seamless or welded?

A: Most square steel pipes are manufactured using the ERW (Electric Resistance Welded) process. The process involves cold-forming a steel coil into a square or rectangular shape and welding the longitudinal seam. While seamless round pipes are common, seamless square pipes are extremely rare and cost-prohibitive. ERW square pipes offer an excellent balance of strength, dimensional accuracy, and cost-effectiveness for structural and low-pressure applications.



Q: What size and thickness options do you offer for square steel pipes?

A: We offer a wide range of standard and custom sizes:

  • Size Range: Typically from 15mm x 15mm up to 500mm x 500mm (or equivalent imperial sizes such as 2" x 2" up to 10" x 10").

  • Wall Thickness: Generally ranges from 1.0mm to 30mm, depending on the size.

  • Lengths: Standard lengths are 5.8m, 6m, 11.8m, and 12m, but we can also supply cut-to-length products according to your requirements.



Q: What surface treatments do you offer to protect against corrosion?

A: We provide multiple surface treatment options to suit different environments and budgets:

  • Black Iron (Oiled): The most economical option, with a light oil coating for short-term protection during transit. Prone to rust if exposed to moisture.

  • Pre-Galvanized: The steel coil is galvanized before forming, offering good corrosion resistance at a moderate cost.

  • Hot-Dip Galvanized: Pipes are dipped in molten zinc after forming, providing the highest level of corrosion protection, ideal for outdoor or marine applications.

  • Painted: An anti-corrosion paint coating is applied, saving on-site labor costs for certain applications.



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 orders.

  • Expedited Production: 10 days may be possible for common grades.

  • Ocean Transit: 15–30 days depending on the destination port.






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