Square tubes (SHS steel) are widely used in structural engineering, manufacturing, machinery, and architectural applications. Among all their specifications, wall thickness is one of the most critical parameters, directly influencing strength, stability, weight, cost, and long-term performance.
What Is Square Tube Wall Thickness?
Wall thickness refers to the thickness of the metal between the inner and outer surfaces of the tube, typically measured in millimeters (mm).
Accurate wall thickness selection is vital because it determines:
Load-bearing capacity — thicker walls withstand higher stresses.
Weight — increased thickness raises the tube’s weight.
Cost — thicker material means higher production and transportation costs.
Application suitability — lighter tubes suit weight-sensitive uses; thicker tubes suit high-strength environments.
For instance, with the same outer dimensions, a tube with greater wall thickness supports heavier loads but weighs more, while a thinner tube is lighter but may offer lower structural resistance.
Common Ways to Express Wall Thickness
1. Metric Expression (mm)
The most widely used system globally.
Example:
A tube sized 20 × 20 mm with a 2.0 mm wall thickness is written as 20 × 20 × 2.0.
2. Imperial (Inch) Expression
Used in regions familiar with inch-based measurements.
When converting from millimeters:
20 mm = 0.7874 inches
Example:
A tube of 2 × 2 inches with a 20 mm (0.7874 in) wall thickness is written as 2 × 2 × 0.7874.
3. Weight per Meter (Section Weight)
This method reflects wall thickness through the tube’s weight per meter, commonly used for budgeting, logistics, and weight-based calculations.
The weight is determined using the tube’s cross-sectional area × material density.
Example:
A 50 × 50 mm tube with a 4.5 mm wall thickness can have its weight per meter calculated using the corresponding formula for steel density.
Square Tube Dimensions
|
Outer Diameter (OD)
|
Wall Thickness (WT)
|
Approx. Weight (kg/m)
|
Common Applications
|
|
10 × 10 mm
|
0.8 – 1.5 mm
|
0.28 – 0.55
|
Furniture, lightweight structures
|
|
20 × 20 mm
|
1.0 – 2.0 mm
|
0.56 – 1.10
|
Handrails, frames, displays
|
|
25 × 25 mm
|
1.2 – 3.0 mm
|
0.90 – 2.15
|
Equipment frames, small supports
|
|
30 × 30 mm
|
1.5 – 3.5 mm
|
1.25 – 2.70
|
Machinery frames, doors, windows
|
|
40 × 40 mm
|
1.8 – 4.0 mm
|
1.90 – 3.85
|
Structural parts, racks
|
|
50 × 50 mm
|
2.0 – 5.0 mm
|
2.60 – 5.80
|
Building columns, gates
|
|
60 × 60 mm
|
2.5 – 6.0 mm
|
3.50 – 7.20
|
Industrial frameworks
|
|
80 × 80 mm
|
3.0 – 8.0 mm
|
5.20 – 10.80
|
Construction beams, platforms
|
|
100 × 100 mm
|
4.0 – 10.0 mm
|
7.85 – 19.60
|
Heavy structures, bridges
|
|
120 × 120 mm
|
5.0 – 12.0 mm
|
11.50 – 27.00
|
Building columns, cranes
|
|
150 × 150 mm
|
6.0 – 16.0 mm
|
17.60 – 45.10
|
Industrial buildings
|
|
200 × 200 mm
|
8.0 – 20.0 mm
|
31.40 – 78.50
|
Large-scale construction
|
Wall Thickness Range by Square Tube Size
1. Small Square Tubes (13–50 mm)
Typical Wall Thickness: 0.8–3.0 mm
Applications: Furniture, shelving systems, light decorative frameworks.
2. Medium Square Tubes (50–100 mm)
Typical Wall Thickness: 2.0–6.0 mm
Applications: Building railings, machinery frames, general structural support.
3. Large Square Tubes (100–200 mm)
Typical Wall Thickness: 4.0–20 mm
Applications: Columns, heavy-duty structures, equipment support systems.
Wall Thickness Range by Manufacturing Process
1. Hot-Dip Galvanized Square Tubes
Wall thickness typically ranges from 0.8–6.0 mm.
Common examples include 20 × 20 × 0.8 mm, 40 × 40 × 1.5 mm, etc.
2. Welded Square Tubes
Offer the widest range, generally from 0.6–20 mm.
With strong load-bearing performance and good weldability, they are widely used in construction, bridge engineering, and structural fabrication.
3. Seamless Square Tubes
Usually produced with 1.0–12 mm wall thickness.
Known for high dimensional precision and superior mechanical properties, they are commonly applied in precision machinery, hydraulic systems, and high-pressure applications.
Square Tube Wall Thickness in mm
|
Size
(mm)
|
Wall thickness (mm)
|
|
1.6
|
2.0
|
2.5
|
3.0
|
3.5
|
4.0
|
4.5
|
5.0
|
6.0
|
|
13×13
|
0.56
|
|
|
|
|
|
|
|
|
|
16×16
|
0.68
|
|
|
|
|
|
|
|
|
|
19×19
|
0.94
|
1.15
|
|
|
|
|
|
|
|
|
25×25
|
1.19
|
1.47
|
1.80
|
2.13
|
|
|
|
|
|
|
32×32
|
1.52
|
1.88
|
2.31
|
2.74
|
|
|
|
|
|
|
38×38
|
1.85
|
2.29
|
2.83
|
3.36
|
3.86
|
4.37
|
|
|
|
|
50×50
|
2.44
|
3.03
|
3.76
|
4.48
|
5.18
|
5.87
|
6.55
|
|
|
|
60×60
|
2.94
|
3.66
|
4.55
|
5.42
|
6.28
|
7.12
|
7.96
|
|
|
|
63×63
|
3.09
|
3.85
|
4.78
|
5.70
|
6.60
|
7.50
|
8.38
|
|
|
|
75×75
|
3.69
|
4.59
|
5.70
|
6.81
|
7.90
|
8.98
|
10.04
|
11.10
|
|
|
80×80
|
3.95
|
4.91
|
6.11
|
7.30
|
8.47
|
9.63
|
10.78
|
11.91
|
|
|
90×90
|
4.45
|
5.54
|
6.89
|
8.24
|
9.57
|
10.88
|
12.19
|
13.48
|
16.03
|
|
100×100
|
|
6.17
|
7.68
|
9.18
|
10.66
|
12.14
|
13.60
|
15.05
|
17.91
|
|
120×120
|
|
|
|
11.06
|
12.85
|
14.64
|
16.41
|
18.18
|
21.67
|
|
152×152
|
|
|
|
|
16.42
|
|
21.00
|
|
27.78
|
Comparison of Square Tube Wall Thickness with Other Tube Types
1. Square Tube vs. Round Tube (CHS Steel)
Square tubes offer greater flexibility in wall thickness optimization due to their geometric shape.
Round tubes have uniformly distributed wall thickness, but achieving equivalent bending or torsional performance may require thicker walls, resulting in increased cost and material consumption.
In structural applications, adjusting the wall thickness of square tubes can enhance stability without adding unnecessary weight.
2. Square Tube vs. Rectangular Tube (RHS Steel)
Square tubes feature a more standardized wall thickness due to their equal-sided design.
Rectangular tubes may experience variation in wall thickness uniformity because of their aspect ratio.
The symmetrical shape of square tubes allows for easier manufacturing control and better consistency in mass production.
How Wall Thickness Affects Square Tube Performance
1. Bending Strength
Thicker walls significantly improve bending resistance.
Applications: Equipment frames, bridges, heavy-duty load-bearing structures.
2. Compressive Strength
Thick-walled tubes resist buckling more effectively.
Applications: Columns, purlins, floor supports.
3. Torsional Strength
Square tubes inherently resist twisting due to their symmetrical cross-section.
Increasing wall thickness further boosts torsional stability.
4. Corrosion Resistance
Thin-walled tubes are more vulnerable to corrosion.
Recommendation: Opt for thicker walls and choose galvanized or coated steel when needed.
Key Factors Influencing Wall Thickness Selection
1. Operating Environment
Corrosive or heavy-load conditions require thicker walls for safety and durability.
2. Manufacturing Process
Hot-rolled square tubes generally feature thicker walls, while cold-rolled tubes offer finer tolerances but thinner specifications.
3. Tube Size
As the tube’s outer dimensions increase, wall thickness must also increase to maintain structural rigidity.
How to Choose the Right Wall Thickness
1. Load Requirements
High-load applications demand thicker walls for adequate strength.
2. Environmental Conditions
For outdoor, humid, or corrosive settings, thicker or galvanized tubes are recommended.
3. Economic Considerations
Select the minimum safe wall thickness to balance performance and cost efficiency.
FAQ
1. Is thicker wall thickness always better?
No.
While thicker walls improve strength, they also increase weight and cost. Optimal wall thickness should match actual load and design requirements.
2. Are thin-walled square tubes easy to deform?
Yes.
Thin-walled tubes (≤1.5 mm) deform more easily during welding, bending, or handling. They are suitable for light-duty or decorative uses, but not for high-load situations.
Summary
Wall thickness is a crucial parameter that governs the structural performance, durability, and cost-effectiveness of square tubes. When selected correctly, square tubes offer excellent adaptability and standardization, making them a preferred choice over many other tubular materials.
Read more: Square and rectangular tubes thickness selection
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