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Q355B SHS Square Hollow Section Steel Tube GB/T 6728-2017 Heavy-Duty Structural Steel Tube 40×40-400×400mm
Q355B SHS Square Hollow Section Steel Tube
Q355B square hollow section (SHS) is a high‑strength structural steel tube produced to GB/T 6728‑2017 standards.
When stacked up against regular Q235B structural steel, Q355B delivers higher minimum yield strength, which makes it a solid choice for structures that need enhanced load‑bearing performance.
Our Q355B SHS covers dimension ranges from 40×40 mm to 400×400 mm, with wall thickness spanning 2.5 mm‑16 mm. 6 m and 12 m are our standard mill lengths, and we can also provide bespoke lengths up to 21 m to match individual project needs.
This square hollow section fits perfectly for industrial building columns, heavy‑duty trusses, structural frames and other high‑demand steel construction scenarios.
| Item | Specification |
| Product | Q355B SHS Square Hollow Section |
| Steel Grade | Q355B |
| Standard | GB/T 6728-2017 |
| Shape | Square |
| Size Range | 40×40–400×400mm |
| Wall Thickness | 2.5–16mm |
| Minimum Yield Strength | ≥355 MPa |
| Tensile Strength | ≥470 MPa |
| Standard Length | 6m, 12m |
| Maximum Length | Up to 21m |
| Surface | Black / Customized |
| Typical Applications | Industrial building columns, heavy-load trusses |
Q355B is a high‑strength structural steel grade frequently specified for heavy‑duty steel construction work.
It achieves a minimum yield strength of 355 MPa and tensile strength of 470 MPa. Outperforming common lower‑grade structural steels, Q355B fits well for projects subject to heavy structural loads.
Minimum Yield Strength: ≥355 MPa
Tensile Strength: ≥470 MPa
For full chemical composition and complete mechanical property data, please check against GB/T 6728‑2017 and the product mill test certificate.
We offer Q355B square hollow sections across an extensive selection of square sizes.
Overall dimension: 40×40mm up to 400×400mm
Wall thickness: 2.5‑16mm
Frequently ordered sizes cover:
40×40mm, 50×50mm, 60×60mm, 80×80mm, 100×100mm,
120×120mm, 150×150mm, 200×200mm, 250×250mm,
300×300mm, 350×350mm, 400×400mm.
We can deliver particular dimensions and wall thicknesses based on your project drawings and purchase requirements.
Standard mill lengths for Q355B SHS are 6 m and 12 m.
For large‑scale structural projects, custom lengths up to 21 m are achievable, subject to production capability and transport limitations.
We can also arrange value‑added services including cutting, drilling and fabrication in line with customer drawings.
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Multiple surface treatment options are available for Q355B SHS to suit different service conditions:
Black mill finish
Hot‑dip galvanized
Painted finish
Primer coated
Custom‑made coating
For outdoor installations or corrosive working surroundings, hot‑dip galvanizing or other protective coatings deliver extra anti‑corrosion performance.
Industrial Building Columns
Q355B SHS works well for columns and vertical structural components within industrial facilities, where superior strength and load‑carrying capacity are essential.
Heavy‑Load Trusses
This square hollow profile fits heavy‑load truss systems widely seen in industrial buildings, workshops and other large‑scale structural projects.
Heavy‑Duty Steel Frames
Q355B square hollow sections can be processed and fabricated to build structural frames that demand high‑strength steel parts.
Industrial Structures
Typical application scenarios cover:
Factory constructions, workshop facilities, warehouse frameworks, equipment support structures, steel platforms, heavy‑duty frames and large‑size structural assemblies.
Superior Structural Strength
Featuring minimum 355 MPa yield strength, Q355B performs reliably under high‑stress structural conditions.
Closed Square Hollow Profile
Its closed‑form square geometry delivers solid structural stability, while easing fabrication and joint connection design work.
Comprehensive Size Range
Available dimensions span 40×40 mm to 400×400 mm, catering to diverse structural design needs.
Flexible Wall Thickness Options
Wall thickness ranging from 2.5 mm to 16 mm lets engineers and purchasers pick proper sections according to actual load conditions.
Custom‑Cut Length Options
Besides standard 6 m and 12 m mill lengths, custom lengths up to 21 m can be offered for eligible projects.
Ideal for Heavy‑Duty Construction
Q355B SHS is an excellent choice for industrial building columns and heavy‑load truss systems.
Our quality inspection scope includes the following items:
Chemical composition
Yield strength
Tensile strength
Elongation property
Outer dimensional check
Wall thickness
Product length
Straightness
Surface finish condition
Weld quality (for welded sections)
Mill Test Certificates (MTC) will be issued in compliance with agreed product standards and purchase specifications.
Upon request, we can also coordinate third‑party inspections carried out by authorised inspection bodies.
High‑Strength Steel Supply
Q355B square hollow sections fit well for industrial‑grade and heavy‑load structural projects.
Extensive Size Portfolio
We supply sizes ranging from 40×40mm to 400×400mm, with wall thickness between 2.5 mm and 16 mm.
Custom Fabrication Services
Cutting, drilling and other fabrication work can be completed to match your project specifications.
Complete Quality Documentation
We furnish MTC, Certificate of Origin, packing list, commercial invoice and inspection records as required by each order.
Full‑Package Export Solution
We offer end‑to‑end professional support spanning production, quality checks, packaging and global shipping.
For export shipments, Q355B SHS is typically bundled and fastened with steel straps. This reduces shifting during loading, unloading and transit.
Our export‑grade packaging covers the following options:
Steel strapping
Waterproof shielding
Protective wrapping
Bundle marking
Shipping marks
Size & quantity labels
Transport solutions can be arranged via container, bulk carrier or other suitable shipping modes, based on product dimensions, order volume and final destination.
1. What is Q355B SHS?
Q355B SHS refers to Q355B grade square hollow section steel tubes, manufactured in strict accordance with the national standard GB/T 6728-2017 for structural steel applications.
2. What is the yield strength of Q355B SHS?
This steel tube features a minimum yield strength of 355 MPa, meeting high-standard structural load requirements.
3.What is the tensile strength?
Its minimum tensile strength is rated at 470 MPa, delivering stable and reliable mechanical performance.
4. What sizes are available?
We offer a full range of Q355B square hollow sections, with outer dimensions ranging from 40×40mm to 400×400mm and wall thicknesses covering 2.5mm to 16mm.
5. What lengths are available?
Our standard stock lengths are 6 meters and 12 meters. For specific project needs, custom lengths up to 21 meters are available, subject to production feasibility and transportation conditions.
6. What are the main applications?
This high-strength hollow section is widely applied in industrial construction, mainly for building columns, heavy-load trusses, robust steel frames and various large-scale industrial structural projects.
7. Can Q355B SHS be galvanized?
Absolutely. We provide hot-dip galvanized treatment for Q355B SHS, which effectively boosts corrosion resistance, making it ideal for outdoor and corrosive working environments.
8. Can you provide an MTC?
Yes, we can supply official Mill Test Certificates (MTC) that fully comply with industry standards and customized order specifications for every batch of products.
ROYAL GROUP
Address
Kangsheng development industry zone,
Wuqing district, Tianjin city, China.
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