Description
Factory-direct ERW welded square steel tube supply — No middlemen, full mill test certificates for S355JR and Q235B grades shipped to 50+ countries.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S355JR ERW Welded Square Steel Tube |
| Product Type | Welded Square Steel Tube |
| Steel Grade | S235JR, A36, S355, SS400, Q235B |
| Standard | BS, EN, GB, AISI, ASTM, DIN, JIS |
| Section Shape | Square |
| Outer Diameter or Side Length | 40×60 mm (4×6 inch) |
| Length | Customized |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Cold Rolled |
| Tolerance | ±1% |
| Ends | Plain |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Oiled or Non-oiled | Non-oiled |
| Application | Curtain wall structures, Building structures, Machinery, Home decor, Steel structures, Construction frames |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Curtain Wall & Facade | Vertical and horizontal mullion frames, window sub-frames, cladding support grids |
| Commercial Construction | Interior partition frames, mezzanine structures, column casings |
| Machinery Manufacturing | Equipment base frames, conveyor support structures, robotic arm housings |
| Steel Fabrication | Bracing members, truss chords, portal frame purlins |
| Home & Interior Decor | Furniture frames, display rack structures, decorative screen supports |
Dimensional Tolerance Decides Whether Your Curtain Wall Frames Align on Site
±1% tolerance on 40×60 mm ERW welded square steel tube prevents cumulative alignment errors across facade runs.
When procurement teams source ERW welded square steel tube from fragmented suppliers, each batch arrives with slightly different outer dimensions. On a curtain wall project spanning hundreds of meters of mullion framing, a 0.5 mm deviation per tube compounds into visible misalignment at connection nodes. Worse, if the weld seam sits proud of the flat face, fabricators waste hours grinding before they can bolt adjacent members together. We have seen entire facade batches rejected at site because the supplier’s tolerance claim existed only on paper, not in the mill test certificate. [NEED_CITE: EN 10219 cold-formed welded structural hollow section dimensional tolerances]
Precision Framing for Curtain Wall and Structural Connections
The 40×60 mm profile with cold-rolled surface finish delivers clean, flat faces that accept direct bolted or welded connections without secondary machining. For curtain wall systems, this means mullion-to-transom joints sit flush, reducing silicone sealant gaps and improving weather-tightness. Our ERW welded square steel tube production holds ±1% tolerance across customized lengths, so fabricators receive material ready for cutting and assembly rather than spending shift time correcting dimensional drift. The cold-rolled surface also provides a uniform base for powder coating or anodized aluminum attachment brackets common in facade engineering.
Engineering Compliance and Grade Selection for Structural Frames
Structural engineers specifying S355JR or Q235B grades for building frames require traceable compliance with EN 10219 or GB/T 6728 respectively. The ERW welding process produces a longitudinal seam that, when properly controlled, matches the base metal’s mechanical performance — but only if the manufacturer maintains weld-line quality through inline ultrasonic testing. For projects targeting European markets, CE certification under EN 10210/10219 is non-negotiable for customs clearance and structural approval. [NEED_CITE: CE marking requirements for structural steel hollow sections under EN 10210] Customized lengths with end-cutting and punching services reduce on-site waste and accelerate erection schedules, particularly for repetitive portal frame or bracing configurations.
Understanding S355JR, Q235B, and A36 Grade Selection
S355JR belongs to the European EN 10025 non-alloy structural steel series, offering higher yield strength than S235JR and suitable for moderately loaded structural members. Q235B follows the Chinese GB standard system, widely specified across Belt & Road infrastructure projects and equivalent in application scope to ASTM A36 in North American practice. SS400, the Japanese JIS G3101 general structural grade, overlaps with both S235JR and A36 in typical building frame applications. The ERW welding technique joins the strip edges through electrical resistance heating without filler metal, producing a clean internal seam suitable for non-oiled delivery and subsequent painting or galvanizing. Cold-rolled surface treatment provides dimensional accuracy and surface smoothness that hot-rolled alternatives cannot match for architectural-exposed applications. [NEED_CITE: steel grade equivalence mapping between EN 10025, ASTM A36, and JIS G3101]
The Hidden Cost of Unverified Tolerance and Missing Mill Certificates
Ordering ERW welded square steel tube based on price alone, without verified mill test certificates, exposes projects to material substitution risk. A batch labeled S355JR that actually contains off-grade S235JR material will pass visual inspection but fail structural load testing during commissioning. Similarly, tolerance claims of ±1% mean nothing if the supplier cannot produce original mill test certificates showing actual measured dimensions per heat number. Customs authorities in the EU and Middle East increasingly demand CE documentation and third-party inspection reports; shipments without these documents face port holds, demurrage charges, and potential rejection. [NEED_CITE: customs documentation requirements for structural steel imports into EU and GCC markets]
Why Procurement Teams Source ERW Welded Square Steel Tube From Us
Our Jinan facility operates three dedicated production lines running simultaneously, delivering monthly capacity exceeding 20,000 tons across all major steel product categories. Every ERW welded square steel tube batch undergoes three-stage in-house inspection covering dimensional verification, weld seam integrity, and surface quality before release. Original mill test certificates accompany every shipment, documenting chemical composition and mechanical properties per the specified steel grade and standard. We maintain ready stock across 2,800+ specifications, enabling urgent dispatch for standard sizes while custom lengths and processing services — cutting, punching, bending — ship within typical production lead times. Third-party SGS or BV inspection is available on request for projects requiring independent verification. Professional export documentation handling covers customs clearance requirements for 50+ destination countries, with container loading optimization maximizing payload per shipment.
Documentation & Compliance
- Mill test certificate documenting S355JR or Q235B chemical composition and mechanical properties per EN 10219 or GB/T 6728, traceable by heat number
- CE certificate confirming EN 10210/EN 10219 compliance for structural hollow sections exported to European markets
- ISO 9001:2015 quality management certificate covering the full production and inspection process
- SGS or BV third-party inspection report available upon request for independent dimensional and material verification
- Material traceability documentation linking each bundle to its heat number, production date, and test results
- Complete customs document package including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Cold-rolled ERW welded square steel tubes bundled with steel strips and edge protectors to preserve surface finish during ocean transit
- Non-oiled surface condition requires moisture-barrier wrapping for container shipping to prevent condensation-related staining
- 40×60 mm profile dimensions optimized for nested container loading, maximizing payload per 20ft or 40ft unit
- Customized lengths cut to order and labeled with heat number, steel grade, and purchase order reference on each bundle
- Professional container loading plans balancing weight distribution across axles for road transport at destination
- FOB, CIF, and door-to-door delivery options with real-time shipment tracking
Start Your Procurement With Verified Specifications
Submit your ERW welded square steel tube requirements — including steel grade, 40×60 mm or other dimensions, customized lengths, quantity, and destination port — to receive competitive factory-direct pricing with volume discount consideration. Our team responds within hours with a detailed quotation, available mill test certificate samples, and confirmed production lead times. For projects requiring third-party inspection or non-standard processing, we provide complete documentation and technical support from inquiry through delivery.
Frequently Asked Questions
Q: What is the difference between S355JR, Q235B, and A36 for structural applications?
A: S355JR follows the European EN 10025 standard and offers higher yield strength than S235JR, making it suitable for primary structural members. Q235B follows the Chinese GB standard and is widely used across infrastructure projects in Asia and Africa. A36 follows ASTM standards for North American markets. All three grades are available in our ERW welded square steel tube production, and we provide mill test certificates confirming compliance with the specified standard.
Q: How do you ensure dimensional accuracy and weld quality for 40×60 mm ERW square tubes?
A: Our production maintains ±1% tolerance through inline dimensional monitoring and three-stage in-house inspection covering outer dimensions, wall thickness, and weld seam quality. Original mill test certificates document actual measured values per heat number. Third-party SGS or BV inspection is available for independent verification.
Q: Can you provide customized lengths and processing services like cutting and punching?
A: Yes, we offer customized lengths to your project specifications along with processing services including cutting, punching, bending, and welding. This reduces on-site fabrication time and material waste for curtain wall and structural frame applications.
Q: What certifications and mill test documents do you provide for customs clearance?
A: Every shipment includes original mill test certificates, and we hold CE certification under EN 10210/10219 for European markets plus ISO 9001:2015 quality certification. Complete customs documentation including packing list, bill of lading, and certificate of origin is provided. SGS or BV third-party inspection reports are available on request.
Q: What is your typical delivery time for bulk orders?
A: Standard specifications are available from ready stock for urgent dispatch. Custom orders with specific lengths or processing services ship within typical production lead times. Volume discount programs apply for long-term partners with recurring procurement needs.
Request Your Factory-Direct Quote for S355JR ERW Welded Square Steel Tube
Send your specifications — steel grade, dimensions, lengths, quantity, and destination — to receive pricing with mill test certificate confirmation. Our team provides complete export documentation and technical support for curtain wall and structural frame projects worldwide.
Contact: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.sdxinjiyuan.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxinjiyuan.com
