Description
Factory-Direct Welded Square Tubes — In-house production of S355 / SS400 / Q235B welded square steel hollow section tubes with cold rolled finish, backed by ISO 9001 and Lloyd’s CE certification for EU and global project procurement.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S355 / SS400 / Q235B Welded Square Steel Tube |
| Product Type | Welded Square Steel Tube (Square Hollow Section / SHS) |
| Steel Grade | S235JR, S355, SS400, Q235B, A36 |
| Standard | BS, EN, GB, AISI, ASTM, DIN, JIS |
| Section Shape | Square |
| Outer Diameter / Side Length | 40×40 mm; customized sizes available |
| Wall Thickness | Customized |
| Length | Customized |
| Technique | Welded (Cold Rolled forming) |
| Surface Treatment | Cold Rolled |
| Tolerance | ±1% |
| Processing Services | Welding, Punching, Cutting, Bending, Decoiling |
| Invoicing | By Theoretical Weight |
| Alloy | Non-Alloy |
| Oiled or Non-oiled | Non-oiled |
| Application | Building structures, Machinery manufacturing, Home decor, Steel structures, General structural applications |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Steel Structure Fabrication | Column frames, truss members, and bracing systems for industrial warehouses and commercial buildings |
| Machinery Manufacturing | Equipment bases, conveyor supports, and robotic arm frames requiring dimensional precision |
| Architectural Facade | Curtain wall sub-frames and exposed structural elements demanding clean angular aesthetics |
| Infrastructure & EPC | Bridge handrails, solar panel mounting structures, and utility support frameworks |
Where Dimensional Tolerance Decides Structural Alignment on Site
±1% tolerance on cold rolled welded square steel hollow section tubes ensures bolt-hole alignment and welded joint fit-up without on-site rework.
When square tubes arrive with inconsistent side lengths or wall thickness variation beyond acceptable limits, fabricators face cumulative errors across multi-member assemblies. A 40×40 SHS ordered for a precision machinery frame that measures 39.2mm on one side and 40.8mm on the other forces welders to shim every connection — adding labor hours and introducing stress concentrations. [NEED_CITE: EN 10219 dimensional tolerance requirements for cold-formed structural hollow sections]
Beyond geometry, steel grade substitution without proper documentation creates certification gaps. A project specifying S355 per EN 10219 cannot accept Q235B without engineering approval, even if mechanical properties appear comparable. Missing mill test certificates or incorrect standard references trigger customs holds in regulated markets, delaying entire construction schedules.
Precision Fit-Up for Machinery Frames and Architectural Sub-Structures
The 40×40 mm welded square steel hollow section tube in S355 or SS400 grade serves as a load-bearing node in machinery bases where welding precision directly affects equipment calibration. Cold rolled surface finish provides consistent texture for coating adhesion, while the ±1% dimensional tolerance ensures that pre-drilled connection plates align without forcing. For architectural curtain wall contractors, the clean 90-degree corners of cold formed SHS eliminate the rounded transitions typical of hot rolled sections, delivering the sharp linear aesthetics that modern facade designs demand.
Engineering Compliance Across EN, ASTM, and JIS Frameworks
Structural hollow sections in S355 grade must conform to EN 10219 for cold formed welded products when used in European construction, requiring documented chemical composition and mechanical properties traceable to heat numbers. [NEED_CITE: EN 10219 cold-formed welded structural hollow sections specification] Projects in North America referencing ASTM A500 Grade B or C need equivalent yield strength verification, while JIS G3466 STKR400 applies to Japanese-standard structural applications. The welded square steel hollow section tube in S355 / SS400 / Q235B grades covers these frameworks through proper grade equivalence mapping, supported by mill test certificates that specify the exact standard under which the product was manufactured and tested.
Steel Grade Selection and Cold Rolled Welding Process Fundamentals
S355 offers higher yield strength than S235JR, making it suitable for load-bearing columns and beams where weight optimization matters. SS400 and Q235B serve general structural applications where extreme strength is not critical but cost efficiency drives specification. A36 aligns with ASTM standards for North American projects. The welded manufacturing process using cold rolled forming produces square hollow sections with tighter dimensional control than hot rolled alternatives, achieving the ±1% tolerance specified for this product. Cold rolled surface treatment leaves a mill-scale-free finish that accepts paint and powder coating without additional surface preparation, reducing downstream fabrication costs.
Hidden Costs of Grade Substitution and Tolerance Drift
Specifying S355 and receiving Q235B without engineering approval voids structural calculations, forcing costly redesign or complete material replacement. [NEED_CITE: steel grade equivalence between EN 10219 and ASTM A500 standards] Wall thickness running at negative tolerance beyond acceptable limits reduces load capacity, triggering rejection during third-party inspection. Missing CE marks or incorrect EN standard references on documentation block EU customs clearance, stranding containers at port while project timelines collapse. The welded square steel hollow section tube must arrive with full traceability from heat number to final dimension, or the entire shipment becomes scrap.
Why Procurement Teams Specify Our Welded Square Tubes
In-house physical and chemical laboratories test every heat for composition and mechanical properties before release, generating mill test certificates that satisfy SGS and BV third-party inspectors without delay. Production covers 2,800+ specifications across square, rectangular, and round profiles, meaning a single purchase order for 40×40 SHS can include matching H-beams and channels without splitting shipments across multiple suppliers. Lloyd’s CE certification under EN 10210 and EN 10219, combined with Singapore FPC and ISO 9001:2015 registration, provides the documentation chain that regulated markets require. Custom non-standard sizes and lengths enter production with typical lead times, while professional container loading with anti-damage measures prevents the bending and surface scratches that trigger rejection at destination. Exports to 50+ countries demonstrate proven logistics capability across EU, North America, Middle East, and Southeast Asian ports.
Documentation & Compliance
- Mill test certificate documenting S355 / SS400 / Q235B chemical composition and mechanical properties per EN 10219 or ASTM A500 as specified
- CE certificate under EN 10210 and EN 10219 for cold formed welded structural hollow sections exported to EU markets
- ISO 9001:2015 quality management certificate covering production processes and inspection protocols
- SGS or BV third-party inspection report available upon request before shipment, verifying dimensions and surface quality
- Material traceability by heat number linking each welded square steel hollow section tube to its original mill test certificate
- Customs documentation including packing list, bill of lading, and certificate of origin for destination country clearance
Packaging, Loading & Delivery
- Cold rolled welded square steel tubes bundled with steel strips and edge protectors to preserve surface finish during ocean transit
- 40×40 mm SHS loaded in containers with wooden spacers preventing tube-to-tube contact that causes cold rolled surface damage
- Custom length cutting available before shipment, reducing on-site waste and handling for construction projects
- Heat number and steel grade markings stenciled on each bundle for site identification and traceability verification
- FOB, CIF, and DDP shipping terms available with professional loading plans optimizing container capacity for 40×40 and other sizes
- Full export documentation provided including packing list, bill of lading, and certificate of origin for customs clearance
Request Quotation with Mill Test Certificate
Submit your specification including steel grade (S355, SS400, Q235B), dimensions, quantity, and destination port to receive a detailed quotation with unit pricing, typical production lead times, and shipping terms. We provide mill test certificates and arrange third-party inspection upon request, confirming compliance before the welded square steel hollow section tube leaves our facility.
Frequently Asked Questions
Q: Can you provide mill test certificates for S355 welded square tubes?
A: Yes, every shipment includes a mill test certificate documenting chemical composition and mechanical properties per EN 10219 or the standard specified in your order. The certificate traces each welded square steel hollow section tube back to its heat number for full material verification.
Q: What is the difference between S355, SS400, and Q235B grades?
A: S355 is a European standard grade with higher yield strength suitable for structural applications. SS400 is the Japanese equivalent for general structural use. Q235B is the Chinese standard grade. All three are available as welded square steel hollow section tubes with cold rolled finish.
Q: Do you offer custom sizes beyond 40×40 mm?
A: Yes, we produce welded square steel tubes in customized sizes across our 2,800+ specification range. Non-standard dimensions and wall thicknesses are available with typical production lead times for custom orders.
Q: Can you arrange third-party inspection before shipment?
A: Yes, we arrange SGS or BV third-party inspection upon request. The inspection verifies dimensions, surface quality, and documentation compliance before the welded square steel hollow section tube is loaded for shipment.
Q: How do you prevent damage during container shipping?
A: Cold rolled welded square tubes are bundled with edge protectors and loaded with wooden spacers preventing tube contact. Professional loading plans optimize container capacity while preserving the cold rolled surface finish during ocean transit.
Get Your Welded Square Steel Tube Quotation
Send your specification for S355 / SS400 / Q235B welded square steel hollow section tubes including dimensions, quantity, and destination to receive pricing and mill test certificate samples.
Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxjypipe.com
