Description
Factory-Direct Q355 S355 Square Hollow Sections — Every Q355 S355 square hollow section seamless welded steel tube supplier order ships with in-house lab-tested mill certificates and Lloyd’s CE documentation for EU clearance.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q355/S355 SHS Seamless and Welded Square Steel Tube |
| Product Type | Square Steel Tube / Square Hollow Section (SHS) |
| Steel Grade | Q355B, S355JR, S355J2H, S235JR, S275JR, STK400, Gr.B |
| Standard | ASTM A500, ASTM A53, GB/T 3091, EN 10219, EN 10210, JIS G3466 |
| 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 | Seamless / ERW Welded |
| Surface Treatment | Black Painted / Galvanized / Varnish / Bare |
| Tolerance | ±5% / ±10% / ±15% (varies by dimension) |
| Ends | Plain |
| Application | Steel structures / Construction frames / Curtain wall & facades / Support tubes / Machinery frames / Building structures |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & EPC | Building column frames, roof truss bracing, foundation pile sleeves |
| Facade & Curtain Wall | Glass facade mullions, architectural sharp-corner framing, exposed structural aesthetics |
| Steel Structure Fabrication | Portal frame members, mezzanine floor beams, industrial platform supports |
| Machinery Manufacturing | Equipment base frames, conveyor support structures, crane boom sections |
| Infrastructure | Bridge handrail posts, sound barrier supports, solar panel mounting structures |
What Wall-Thickness Tolerance Costs on a Q355 S355 Square Hollow Section Seamless Welded Steel Tube Order
Tolerance drift on heavy-wall SHS turns a structural calculation into a liability.
Procurement teams ordering Q355 S355 square hollow section seamless welded steel tube for load-bearing frames often discover—after customs clearance and partial fabrication—that wall thickness falls below the engineered minimum. The root cause is inconsistent mill practices where negative tolerance exceeds the allowable band, reducing actual section modulus and compromising structural integrity [NEED_CITE: EN 10219 cold-formed structural hollow section dimensional tolerance requirements]. Beyond rework, this triggers third-party inspection failures, project delays, and in regulated markets, outright rejection of delivered material.
Matching SHS Dimensions to Structural Frame Requirements
When engineers specify Q355 S355 square hollow section seamless welded steel tube for moment-resisting frames or facade mullions, the 19mm×19mm to 800mm×800mm range with wall thickness up to 30 mm covers everything from light-gauge curtain wall infill to heavy column sections. Seamless process serves high-precision machinery frames where concentricity matters, while ERW welded delivers cost-efficient structural members for buildings and bridges. Our 2,800+ specification coverage means non-standard dimensions—such as 450×450×25 mm for a Middle East high-rise core wall—enter production without waiting for alternative sourcing.
Engineering Compliance and Certification Pathways
Structural hollow sections destined for EU markets must carry CE marking under EN 10210 (seamless) or EN 10219 (welded), with Factory Production Control certified by a notified body such as Lloyd’s Register [NEED_CITE: CE marking requirements for structural steel hollow sections under CPR]. For North American projects, ASTM A500 Gr.B and Gr.C remain the default specification, while JIS G3466 STK400 serves Southeast Asian and Japanese-standard infrastructure. Our in-house physical and chemical laboratory tests every heat for dimensional accuracy, mechanical properties, and chemical composition before release, ensuring the Q355 S355 square hollow section seamless welded steel tube you receive matches the grade on your purchase order.
Steel Grade Selection Across GB, EN, ASTM, and JIS Systems
Q355B (GB), S355JR/J2H (EN), and ASTM A500 Gr.C occupy overlapping yield strength tiers, but their impact energy requirements and elongation specifications differ—S355J2H demands 27J impact at −20°C, making it the correct call for cold-climate structural work [NEED_CITE: steel grade equivalence between EN 10219 and ASTM A500]. S235JR and S275JR serve lighter-duty applications where weight optimization outweighs peak load capacity. The ERW welded process suits structural framing at competitive pricing, while seamless SHS is specified for precision machinery and higher-pressure environments. Surface treatment selection follows exposure conditions: hot-dip galvanized for outdoor or coastal sites, black painted for indoor structural use, and bare for applications where field coating or fireproofing will be applied post-fabrication.
Hidden Costs of Procuring Unverified SHS
Material substitution—receiving S235JR when S355JR was specified—passes visual inspection but fails mechanical testing at the project lab, triggering full-batch rejection and schedule collapse. Missing CE documentation blocks EU customs regardless of physical quality, while negative tolerance beyond ±10% on heavy-wall sections reduces load capacity below engineered thresholds [NEED_CITE: structural hollow section tolerance and weight calculation standards]. These failures share a common origin: sourcing from traders who cannot provide traceable mill test certificates or third-party inspection before loading.
Why Engineers Source Q355 S355 SHS from SD XJY Pipe
Every Q355 S355 square hollow section seamless welded steel tube we produce is tested in our own physical and chemical laboratory—no outsourced certificates, no generic templates. Our 41 invention patents include China’s original sharp-corner rectangular tube technology, filling the gap between rounded-corner standard SHS and the architectural demand for clean 90-degree edges on curtain wall framing. With 2,800+ specifications in production, off-standard sizes that other mills decline become routine orders here. Lloyd’s CE certification under EN 10210 and EN 10219, Singapore FPC, and ISO 9001:2015 ensure that every shipment clears regulated-market customs with complete documentation. We supply to construction firms, steel structure fabricators, and machinery builders across 50+ countries, with professional container loading that prevents bending and surface damage during ocean transit.
Documentation & Compliance
- Mill test certificate documenting Q355B or S355JR chemical composition and mechanical properties per EN 10219 or ASTM A500, traceable by heat number
- Lloyd’s CE certificate under EN 10210 (seamless) and EN 10219 (welded) for EU market customs clearance
- ISO 9001:2015 quality management certificate covering full production and testing process
- SGS or BV third-party inspection report available upon request before container loading
- Material traceability linking each Q355 S355 square hollow section seamless welded steel tube bundle to its 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 section seamless welded steel tube bundled with steel strips and edge protectors to preserve galvanized coating and prevent surface scratching during ocean transit
- 6 m and 12 m standard lengths loaded with anti-sag supports inside 20ft and 40ft containers; random lengths nested for optimal cube utilization
- Heat number and steel grade stenciled on each bundle for site identification and traceability verification
- Black painted SHS wrapped with waterproof paper; bare tubes coated with rust-preventive oil for humid-climate shipping
- FOB Jinan/Qingdao, CIF destination port, or DDP door-to-door delivery arranged with full container tracking
Initiating Your Q355 S355 SHS Procurement
Submit your specification sheet—including side dimensions, wall thickness, steel grade, surface treatment, quantity, and destination port—and receive a detailed quotation with unit pricing, production lead time, and shipping terms within 12 hours. For non-standard dimensions or sharp-corner architectural requirements, our engineering team provides custom sizing solutions with low MOQ flexibility.
Request Your Q355 S355 SHS Quotation with Mill Test Certificates
Send your dimensions, grade, and quantity to receive pricing and certification documentation.
Tel: +86 531 8573 6315 | Mobile/WhatsApp/WeChat: +86 188 5315 7756 | Email: admin@sdxjypipe.com
Frequently Asked Questions
Q: How do Q355B, S355JR, and ASTM A500 Gr.B compare in terms of grade equivalence?
A: Q355B (GB/T 1591) and S355JR (EN 10025) occupy similar yield strength ranges, while ASTM A500 Gr.B serves as the North American structural SHS standard. We provide cross-reference documentation for each order to ensure correct grade substitution across standards.
Q: Do your Q355 S355 square hollow section seamless welded steel tubes carry CE marking for EU import?
A: Yes. Our welded SHS carries Lloyd’s CE certification under EN 10219, and seamless SHS under EN 10210, with Factory Production Control audited for EU Construction Products Regulation compliance.
Q: Can you produce non-standard SHS dimensions with a low minimum order?
A: We cover 2,800+ specifications including off-standard sizes. Custom dimensions enter production with a 5-ton MOQ, and our engineering team reviews non-standard requests for feasibility before quoting.
Q: When should I specify galvanized versus black painted versus bare surface treatment?
A: Hot-dip galvanized SHS suits outdoor, coastal, or high-humidity environments requiring long-term corrosion resistance. Black painted serves indoor structural applications. Bare tubes are specified when field-applied fireproofing or custom coating systems will be used after fabrication.
Q: How do you prevent bending and surface damage during container shipment?
A: We use anti-sag supports for long-length tubes, edge protectors for galvanized coatings, waterproof wrapping for painted surfaces, and professional stowage plans optimized for container dimensions to eliminate movement during ocean transit.
Get Your Q355 S355 SHS Quote Today
Share your specification, grade, and destination to receive pricing with full mill test certificates within 12 hours.
Tel: +86 531 8573 6315 | Mobile/WhatsApp/WeChat: +86 188 5315 7756 | Email: admin@sdxjypipe.com
