Description
Factory-Direct ERW Square Tubes — Every S355JR and Q235B section rolls off our own lines with in-house lab verification before shipment.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S355JR / Q235B / SS400 ERW Square Steel Tube |
| Product Type | Welded Square Steel Tube (ERW) |
| Steel Grade | S235JR, A36, S355, SS400, Q235B |
| Standard | ASTM A500, EN 10219, EN 10210, JIS G3466, GB/T 6728 |
| Section Shape | Square |
| Outer Diameter or Side Length | Customized |
| Wall Thickness | Customized |
| Length | 6m / 8m / 12m / Customized |
| Technique | ERW (Electric Resistance Welded) / Cold Rolled |
| Surface Treatment | Cold Rolled / Galvanized (optional) |
| Tolerance | ±1% |
| Ends | Plain |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors | Steel structure frames for industrial buildings and stadiums |
| Machinery Manufacturers | Precision frames for automation equipment and conveyors |
| Construction Companies | Scaffolding, bridge auxiliary structures, and infrastructure projects |
| Infrastructure Developers | Greenhouse frames and trailer chassis |
What Wall-Thickness Tolerance Costs on a Structural Frame Order
A ±1% tolerance on a S355JR ERW square steel tube supplier shipment keeps theoretical weight aligned with actual load-bearing capacity.
When wall thickness drifts into negative tolerance beyond acceptable limits, the structural engineer’s load calculations no longer match the delivered material. I have seen entire container loads of square tubes held at destination ports because the third-party inspector measured wall thickness below the specified minimum. The S355JR ERW square steel tube supplier must guarantee that every heat number on the mill test certificate corresponds to physical measurements taken in the laboratory, not just catalog specifications. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]
Matching S355JR and Q235B Sections to Structural Load Requirements
The S355JR ERW square steel tube supplier delivers closed square sections that resist torsion more effectively than open profiles, making them suitable for column and beam applications where bending moments act in multiple directions. Our cold-rolled ERW process produces smooth internal and external surfaces that facilitate welding connections without excessive preparation. For projects spanning European and Asian markets simultaneously, we supply both S355JR per EN 10219 and Q235B per GB/T 6728 from the same production run, ensuring consistent mechanical behavior across mixed-specification orders.
Engineering Compliance and Certification Pathways
Structural applications demand conformity with recognized standards: EN 10219 for cold-formed welded hollow sections in European projects, ASTM A500 for North American construction, and JIS G3466 for Japanese-specification structures. [NEED_CITE: steel grade equivalence between EN 10219 and ASTM A500 standards] The S355JR ERW square steel tube supplier provides Lloyd’s Register EU CE certification under EN 10210 and EN 10219, which satisfies customs requirements across European Union member states. Wall thickness up to 40mm covers heavy-duty structural applications, while custom non-standard sizes address specialized machinery frames where off-the-shelf dimensions create fabrication delays.
Steel Grade Selection and ERW Process Fundamentals
The S-series grades (S235JR, S355JR) follow European EN standards where the number indicates minimum yield strength in MPa, making S355JR suitable for higher-load structural members compared to S235JR. Q235B follows the Chinese GB system and remains widely specified across Southeast Asian and African infrastructure projects due to its balance of formability and strength. SS400, the Japanese industrial standard grade, offers comparable general structural performance. The ERW (Electric Resistance Welded) process forms the square section from cold-rolled coil through progressive forming rolls, then welds the seam using electrical resistance heating without filler metal — this produces a consistent weld zone with mechanical properties matching the parent material when properly controlled. [NEED_CITE: ERW welded tube manufacturing process and weld zone properties] Optional galvanizing adds zinc coating for corrosion resistance in outdoor or humid environments, while cold-rolled black finish suits indoor applications or projects where painting follows fabrication.
Hidden Costs of Unverified Material Procurement
Purchasing square tubes without verified mill test certificates creates risk across multiple dimensions: customs authorities in the EU and North America increasingly demand EN 10219 or ASTM A500 compliance documentation, and missing certificates cause shipment holds that delay project timelines. [NEED_CITE: customs documentation requirements for structural steel imports] Material that fails to meet specified steel grade requirements forces costly rework or complete replacement after delivery, while excessive negative tolerance reduces actual load capacity below engineering design assumptions. The S355JR ERW square steel tube supplier eliminates these risks by providing original mill test certificates with every shipment, documenting chemical composition and mechanical properties for each heat number.
Why Procurement Teams Choose Our Production Lines
Our factory operates three dedicated ERW production lines with in-house physical and chemical laboratories that test every heat before release — no material ships without verified test data matching the mill test certificate. We hold 41 invention patents including proprietary sharp-corner rectangular tube technology that addresses fit-up challenges in welded connections. The S355JR ERW square steel tube supplier maintains over 2,800 specifications in current production, covering wall thickness up to 40mm and custom non-standard dimensions that eliminate the need for multiple suppliers. Lloyd’s Register EU CE certification under EN 10210 and EN 10219, ISO 9001:2015 quality management, and third-party verification by SGS and BV provide the documentation package that satisfies project owners and customs authorities across 50+ export markets. Professional loading plans optimize container utilization for 6m, 8m, and 12m lengths, reducing freight cost per ton.
Documentation & Compliance
- Mill test certificate documenting S355JR chemical composition and yield strength per EN 10219 for each heat number
- Lloyd’s Register EU CE certificate under EN 10210 and EN 10219 for European customs clearance
- ISO 9001:2015 quality management system certificate covering full production and testing processes
- SGS or BV third-party inspection report available for projects requiring independent verification
- Material traceability linking each tube to heat number, production date, and test results
- Complete customs document package including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- ERW square tubes bundled with steel strips and edge protectors to prevent surface damage during ocean transit
- Galvanized S355JR sections wrapped with waterproof paper to preserve zinc coating integrity
- Custom-length tubes (6m, 8m, 12m) loaded with professional stowage plans maximizing container capacity
- Heat number and steel grade marked on each bundle for site identification and traceability
- FOB, CIF, and DDP shipping terms available with door-to-door logistics to 50+ countries
- Cutting and punching services completed before shipment to reduce on-site fabrication labor
Submit Specifications for Quotation and Mill Test Certificates
Engineering procurement teams specify steel grade, section dimensions, wall thickness, length, quantity, and destination port to receive detailed pricing with delivery timeline and applicable certification documentation. Our technical team reviews requirements for compliance with EN 10219, ASTM A500, or other specified standards and confirms non-standard dimension feasibility within typical production lead times.
Request Your S355JR ERW Square Steel Tube Quote
Send specifications via email or WhatsApp to receive pricing, mill test certificate samples, and certification documentation within 12 hours.
Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.sdxjysteel.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxjysteel.com
Frequently Asked Questions
Q: What is the difference between S355JR, Q235B, and ASTM A500 Grade B for square tube applications?
A: S355JR follows European EN 10219 standard with higher yield strength suitable for heavy structural applications. Q235B follows Chinese GB/T 6728 standard and offers good formability for general construction. ASTM A500 Grade B is the North American specification. We supply all three grades from the same production facility with full certification for each standard.
Q: How do you guarantee material traceability and provide mill test certificates?
A: Every production heat receives unique identification numbers tracked through our in-house physical and chemical laboratory. The mill test certificate documents chemical composition and mechanical properties for each heat number, ensuring full traceability from raw material to finished tube. Third-party inspection by SGS or BV is available for additional verification.
Q: Can you produce non-standard square tube sizes with custom wall thickness?
A: Yes, we maintain over 2,800 specifications including custom non-standard dimensions. Wall thickness ranges up to 40mm covers heavy structural requirements. Our dedicated production lines handle specialized sizes that standard catalogs cannot accommodate, with typical production lead times confirmed upon order.
Q: What surface treatment options are available for corrosion protection?
A: We offer cold-rolled black finish for indoor applications or projects requiring painting after fabrication. Hot-dip galvanizing provides zinc coating for outdoor exposure, humid environments, or corrosive conditions. Surface treatment selection depends on project environment and expected service life.
Q: What certifications do you provide for EU customs and project compliance?
A: We hold Lloyd’s Register EU CE certification under EN 10210 and EN 10219, which satisfies European Union customs requirements for structural steel. ISO 9001:2015 quality management certification covers full production processes. Additional third-party verification by SGS or BV is available for projects requiring independent inspection.
Get Factory-Direct Pricing with Full Certification
Submit your S355JR or Q235B square tube specifications to receive competitive pricing, mill test certificates, and complete export documentation.
