| Material | Q235B / Q355B |
| Standard | ASTM A500 / A513,EN 10210 |
| Tolerance | ±1% |
| Surface Treatment | black or galvanized |
| Alloy Or Not | Is Alloy |
| Surface Finish | black, galvanized Surface can be customized |
| Out diameter ： | 30*30mm-200*400mm, can be customized |
| Length | 1-12m, can be customized |
| Thickness | 1.5mm-12mm, can be customized |
| Application | Structure Pipe, Construction, Steel structure engineering, Curtain wall construction etc. |
Product Overview
Seamless square steel tubes are distinguished by their weld-free, one-piece construction, formed through hot rolling or cold drawing processes that eliminate joint weaknesses. This seamless design ensures uniform strength across all four corners and walls, enhancing load-bearing capacity and resistance to torsional stress. Unlike welded square tubes, they avoid potential corrosion or fracture points at weld seams, making them ideal for structural applications where stability and durability are critical. The consistent wall thickness (typically 1mm to 12mm) further reinforces their reliability under pressure or heavy loads.
Core mechanical properties
| Materials | Yield Strengthσs(≥MPa) | Tensile Strengthσb(MPa) | elongationδ5(≥%) |
| Q235 | 235 | 375-500 | 26 |
| Q355 | 355 | 470-630 | 21 |
Materials and Chemical Compsition
|
Materials |
C |
Si |
Mn |
P |
|---|---|---|---|---|
|
Q235 |
0.22 |
0.35 |
1.40 |
0.045 |
|
Q345/Q355 |
0.20 |
0.55 |
1.70 |
0.040 |
Why Choose Our Seamless Steel Square Tubing?
- 100% Seamless Structure
No welds, no weak points, higher pressure resistance and structural stability.
- Precision Cold Drawn Technology
Tight tolerance, uniform wall thickness, straightness and excellent surface finish.
- Superior Mechanical Properties
High strength, good toughness, anti-deformation, long service life.
- Wide Material Range
Available in Q235B, Q355B, 20#, 45#, ASTM A500, S355JR and other grades.
- Customized Solutions
Custom sizes, lengths and special processing to meet your project demands.
- Full Quality Certification
Complete MTC, ultrasonic and eddy current testing for every batch.
Seamless Steel Square Tubing Applications
Construction & Steel Structure - Building frames, columns, bridges, industrial buildings, curtain walls.
Machinery & Equipment- Machine frames, bases, transmission parts, hydraulic systems.
Automotive & Transportation- Truck chassis, trailer frames, engineering vehicles.
Energy & Engineering- High-pressure pipelines, offshore structures, power facilities.
Furniture & Shelving- High-strength furniture, storage racks, guardrails.
Packing and Delivery
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