Description
Factory-direct Q345B ERW welded square steel tube supplier — raw steel production and SHS fabrication under one roof eliminates material traceability gaps and middleman markups on every 110×110mm order.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q345B ERW Welded Square Steel Tube |
| Product Type | Welded Square Steel Tube (SHS) |
| Steel Grade | Q345B, Q235B, S235JR, S355JR, SS400, A36 |
| Standard | BS, EN, GB, AISI, ASTM, DIN, JIS, ASTM A500, EN10219, EN10210, JIS G3466, GB/T 6728 |
| Section Shape | Square |
| Size Range | 110×110mm (2×2 inch) |
| Wall Thickness | Customizable |
| Length | Custom (e.g., 24ft / 6m standard) |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Cold Rolled |
| Tolerance | ±1% |
| Ends | Plain |
| Application | Building structures, machinery manufacturing, infrastructure construction, furniture and home decor |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Steel Structure Fabrication | Industrial building frames, warehouse columns and beams, truss systems |
| Machinery Manufacturing | Equipment frames, conveyor supports, automation line structures |
| Infrastructure Construction | Bridge auxiliary structures, greenhouse frames, utility support posts |
| Commercial Construction | Handrails, storage racks, mezzanine platforms, furniture frameworks |
What Wall-Thickness Tolerance Costs on a Structural Frame Order
±1% dimensional control separates accepted shipments from rejected containers.
When overseas fabricators source Q345B ERW welded square steel tube from multiple mills without centralized quality oversight, wall thickness drifts toward negative tolerance limits. A batch labeled 110×110×5.0mm arrives at site with actual measurements below specification, triggering dimensional rejection during structural assembly. The cost compounds: return freight, replacement production, project schedule delays, and strained contractor relationships. [NEED_CITE: dimensional tolerance requirements for cold-formed structural hollow sections]
How 110×110mm SHS Matches Industrial Frame Requirements
The 110×110mm square section delivers balanced torsional resistance for machinery frames and conveyor structures where bidirectional loading occurs. Cold rolled surface treatment provides smooth finish suitable for visible architectural applications or direct painting without additional surface preparation. Q345B ERW welded square steel tube in this profile connects to gusset plates and base assemblies using standard welding procedures, with the flat face geometry ensuring full contact area for moment-resisting connections. Our integrated production from raw steel plate to finished SHS means each heat number traces back to mill chemistry reports, eliminating the material certification gaps that plague multi-source procurement.
Engineering Compliance and Certification Pathways
Structural applications demand compliance with EN10219 for cold-formed welded hollow sections in European markets, while ASTM A500 governs North American construction projects. Q345B correlates to S355JR in yield strength classification, though chemical composition limits differ between GB and EN standards — proper material substitution requires engineering approval rather than assumption. [NEED_CITE: steel grade equivalence between Chinese GB and European EN standards] Third-party inspection through SGS or BV validates dimensional accuracy and weld integrity before container loading, providing independent verification that satisfies EPC contractor audit requirements. CE marking under EN10219 enables customs clearance across EU member states without additional testing delays at port of entry.
Steel Grade Selection and ERW Welding Mechanics
Q345B offers higher yield strength than Q235B, making it suitable for load-bearing structural frames where weight optimization matters. The S-series European grades (S235JR, S355JR) provide equivalent mechanical performance with different chemical composition limits, while ASTM A36 and A500 serve North American specification requirements. ERW welding creates the longitudinal seam through electrical resistance heating without filler metal, producing a weld zone with properties matching the base material when properly controlled. Cold rolled surface treatment follows forming operations, removing mill scale and achieving uniform surface finish that accepts coatings without extensive preparation. Wall thickness tolerance of ±1% ensures theoretical weight calculations match actual delivered quantities, preventing the cost overruns that occur when negative tolerance accumulation reduces section modulus below design requirements.
Hidden Costs of Unverified Material Sources
Purchasing Q345B ERW welded square steel tube from trading companies without mill-direct traceability creates risk: material test certificates may not correspond to delivered batches, chemical composition remains unverified, and weld seam quality lacks independent inspection. When dimensional tolerance exceeds ±1% limits, structural engineers must recalculate load capacity or reject entire shipments. [NEED_CITE: consequences of material certification gaps in structural steel procurement] Customs authorities in EU markets increasingly require CE EN10219 documentation for structural hollow sections — missing certificates trigger inspection holds and demurrage charges that exceed the original price difference between verified and unverified suppliers.
Why Direct Mill-to-Fabrication Sourcing Matters
Our Shandong facility operates three production lines for raw steel plate and maintains over 2,800 specification combinations in inventory, enabling same-week shipment for standard Q345B 110×110mm profiles while custom lengths undergo cutting and preparation within typical production lead times. Vertically integrated control from steelmaking through ERW welding and cold rolling means each Q345B ERW welded square steel tube carries heat-number traceability to original slab chemistry. Certified welding procedures under AWS and EN standards, combined with qualified welder credentials, ensure seam integrity meets international structural codes. Complete quality documentation packages include WPS, PQR, dimensional inspection reports, and coating certificates — the paperwork that prevents customs delays and satisfies EPC contractor audit requirements. Professional loading plans optimize container utilization for 6m and 12m lengths, reducing per-piece freight costs on overseas shipments.
Documentation & Compliance
- Mill test certificate documenting Q345B chemical composition and mechanical properties per GB/T 6728, with heat number traceability to original steelmaking batch
- CE certificate confirming EN10219 compliance for cold-formed welded structural hollow sections, enabling EU market access without additional testing
- ISO 9001 quality management system certification covering entire production process from raw material inspection through final dimensional verification
- SGS or BV third-party inspection report available upon request, providing independent validation of wall thickness, weld seam quality, and surface finish
- Material traceability documentation linking each bundle to specific heat numbers, chemical composition reports, and mechanical test results
- Complete customs documentation package including packing list, bill of lading, and certificate of origin formatted for destination country requirements
Packaging, Loading & Delivery
- Q345B cold rolled square tubes bundled with steel strips and edge protectors to preserve surface finish during ocean transit and prevent coating damage
- Plain end tubes packed in seaworthy bundles with waterproof wrapping for containers, with bundle weight optimized for 20ft and 40ft standard shipping containers
- Custom length cutting to 6m, 12m, or project-specific dimensions reduces on-site waste and optimizes container loading density for 110×110mm profiles
- Heat number stenciled on each tube end alongside steel grade identification, enabling site verification against mill test certificates during receiving inspection
- FOB, CIF, and DDP delivery terms available with professional export documentation and container tracking through final destination port
- Oversized cargo loading plans for non-standard lengths or mixed-size shipments maximize container utilization and reduce per-piece freight costs
Initiating Your Procurement Process
Submit project specifications including 110×110mm profile requirements, wall thickness, steel grade preference (Q345B or equivalent S355JR/ASTM A500), total quantity, and destination port to receive detailed quotation with production timeline. Our engineering team reviews shop drawings and confirms dimensional tolerance capabilities before contract execution, ensuring Q345B ERW welded square steel tube meets your structural requirements. Mill test certificates and third-party inspection arrangements are confirmed at order placement, eliminating documentation surprises during customs clearance.
Request Quotation with Material Certification
Send your technical specifications and quantity requirements to receive pricing, production schedule, and mill test certificate samples within 24 hours.
Contact:
Email: admin@xjystructure.com
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Website: www.xjystructure.com
