Description
Factory-direct Q355 S355 square hollow structural section — every batch shipped with original mill test certificates and dimensional reports verified before container sealing.
Technical Specifications + Markdown 表格
| Parameter | Value |
|---|---|
| Designation | Q355/S355 Square Hollow Structural Section |
| Product Type | Square / Rectangular Steel Tube (Hollow Section, SHS/RHS) |
| Steel Grade | Q355, S355, Gr.B, S235, S275, STK400 |
| Standard | ASTM A500, ASTM A53, GB/T 3091 |
| Section Shape | Square |
| Size Range | 19mm×19mm – 800mm×800mm |
| Wall Thickness | 1 – 30 mm |
| Length | 5.8 m / 6 m / 11.8 m / 12 m / Random Length |
| Technique | Welded (ERW) or Seamless |
| Surface Treatment | Black Painting / Galvanized / Varnish / Bare |
| Tolerance | ±10% |
| Ends | Plain |
| Application | Construction structures, Building frames, Curtain wall structures, Support columns, Structural frameworks, Machinery frames |
| MOQ | 5 Tons |
| Origin | China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Steel Fabricators | Structural frames, equipment support bases, welded column assemblies |
| Construction Companies | High-rise building columns, curtain wall skeletons, bridge support piers |
| Machinery Manufacturers | Crane boom sections, conveyor frame structures, heavy equipment bases |
What Wall-Thickness Tolerance Costs on a Structural Frame Order
A Q355 S355 square hollow structural section that fails thickness inspection at site means the entire column batch gets rejected — not just the individual pieces.
Buyers ordering structural square tubes for load-bearing frames routinely discover that the wall thickness delivered does not match the purchase order. Negative tolerance beyond acceptable limits reduces actual load capacity, triggers third-party inspection failures, and forces costly re-procurement mid-project. When grade equivalence between Q355, S355JR, and ASTM A500 Gr.C is not properly documented, customs clearance stalls and engineers cannot sign off on material substitution. [NEED_CITE: steel grade equivalence between EN and ASTM standards]
How This Q355 S355 Square Hollow Structural Section Matches Structural Frame Requirements
Structural frames demand square hollow sections that maintain dimensional consistency across every piece — side length, wall thickness, and straightness must hold within tolerance so that welded connections align without forced fitting. The Q355 S355 square hollow structural section range from 19×19 mm to 800×800 mm covers everything from light gauge curtain wall supports to heavy-load column sections for multi-story buildings. ERW welded process delivers cost efficiency for standard structural specs, while seamless options serve applications requiring higher pressure integrity or critical structural performance.
Engineering Compliance and Certification Requirements for SHS/RHS
Load-bearing structural members must conform to recognized engineering standards — EN 1993 for European projects, AISC for North American specifications, and GB 50017 for Chinese-designed structures. The Q355 S355 square hollow structural section meets ASTM A500 and GB/T 3091 requirements, with chemical composition and mechanical properties documented on original mill test certificates. For projects in corrosive environments, hot-dip galvanized surface treatment provides long-term protection without field coating maintenance. CE certification and ISO 9001:2015 quality management ensure production traceability from steelmaking to final inspection. [NEED_CITE: EN 10219 cold-formed hollow section requirements]
Steel Grade Selection and Manufacturing Process Explained
Q355 and S355 represent equivalent yield strength grades across Chinese GB and European EN systems — both deliver higher load capacity than S235 or S275 for the same cross-section dimensions. The Q355 S355 square hollow structural section is available in both ERW welded and seamless manufacturing processes. ERW welded tubes offer economical pricing for standard structural applications where internal weld seam integrity meets specification requirements. Seamless tubes eliminate the weld seam entirely, serving applications with higher pressure demands or where ultrasonic inspection of the weld zone is impractical. Wall thickness from 1 mm to 30 mm with ±10% tolerance covers light structural framing through heavy column sections. Surface treatment selection depends on service environment — black painted for indoor structural work, hot-dip galvanized for outdoor exposure or corrosive atmospheres, bare for applications requiring field welding without coating removal. [NEED_CITE: difference between ERW welded and seamless steel tube manufacturing]
Hidden Costs of Procuring Non-Conforming Square Hollow Sections
Purchasing structural square tubes without verified mill test certificates creates downstream risks that far exceed initial material cost savings. Thickness deviation beyond tolerance limits reduces actual section modulus, forcing engineers to either reject the shipment or redesign the structure — both options carry significant cost and schedule impact. Grade misidentification between Q355, S355, and ASTM A500 equivalents leads to customs holds, third-party inspection failures, and potential structural safety concerns if lower-grade material is installed in higher-load applications. [NEED_CITE: consequences of negative tolerance in structural steel procurement]
Why Source Your Q355 S355 Square Hollow Structural Section From XJY Plate
Every Q355 S355 square hollow structural section leaves our facility with original mill test certificates documenting heat number, chemical composition, and mechanical properties — no exceptions. Our dimensional inspection report verifies side length, wall thickness, and straightness before container sealing, addressing the tolerance concerns that cause site rejections. We maintain ready stock across the full 19×19 mm to 800×800 mm range in both ERW welded and seamless processes, enabling single-source procurement for mixed-specification projects. Custom cutting-to-length service eliminates field cutting waste and ensures precise member lengths for fabricated assemblies. Professional heavy cargo loading experience prevents container overweight penalties and damage during ocean transit. SGS and BV third-party inspection available for projects requiring independent verification.
Documentation & Compliance
- Mill test certificate documenting Q355/S355 chemical composition and mechanical properties per ASTM A500 or GB/T 3091, with heat number traceability
- CE certificate confirming compliance with EN 10219 for cold-formed structural hollow sections where required by project specification
- ISO 9001:2015 quality management certificate covering production processes and inspection procedures
- SGS or BV third-party inspection report available for projects requiring independent material verification
- Material traceability documentation linking each piece to specific heat number and production batch
- Complete customs documentation including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Q355/S355 square hollow sections bundled with steel strips and edge protectors to prevent surface damage during handling and transit
- Galvanized tubes packed with protective separators to preserve zinc coating integrity throughout ocean shipping
- Container loading optimized for 5.8 m and 6 m lengths to maximize payload while staying within weight limits for 20ft and 40ft containers
- Custom cutting-to-length service available for 11.8 m and 12 m requirements, with pieces bundled and marked by specification
- Each bundle labeled with heat number, steel grade, dimensions, and piece count for site identification
- FOB, CIF, and DDP shipping terms available with professional flatbed and open-top container loading experience
Start Your Q355 S355 Square Hollow Structural Section Inquiry
Submit your specification requirements including steel grade, dimensions, wall thickness, length, quantity, and destination port to receive detailed pricing with mill test certificate documentation. Our technical team responds within 12 hours with material availability, processing options, and shipping terms tailored to your project timeline.
Request Pricing and Mill Test Certificates
Contact XJY Plate for Q355 S355 square hollow structural section quotations with complete documentation.
Company: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.xjyplate.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjyplate.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
