Description
Factory-Direct ERW Square Tube Supply — Raw coil to finished S235JR welded square steel tube under one roof, eliminating trading company markups and material certification gaps.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S235JR ERW Welded Square Steel Tube |
| Product Type | Welded Square and Rectangular Steel Tube |
| Steel Grade | S235JR, A36, S355, SS400, Q235B |
| Standard | BS, EN, GB, AISI, ASTM, DIN, JIS |
| Section Shape | Square / Rectangular |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Cold Rolled |
| Tolerance | ±1% |
| Oiled or Non-oiled | Non-oiled |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Delivery Time | 31–45 days |
| Invoicing | By Theoretical Weight |
| Place of Origin | Jiangsu, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Commercial Construction | Building frames, column and beam assemblies, curtain wall support structures |
| Industrial Warehousing | Warehouse roof trusses, mezzanine platforms, racking uprights |
| Machinery Manufacturing | Machine frames, equipment bases, conveyor support structures |
| Scaffolding & Access | Scaffolding uprights and ledgers, temporary access towers |
| Architectural & Decorative | Decorative screen frames, facade elements, interior structural features |
What Dimensional Tolerance Costs on a Structural Frame Order
±1% tolerance on cold-rolled ERW square tubes prevents cumulative fit-up errors across multi-story steel frames.
Overseas buyers sourcing welded hollow sections from trading companies frequently encounter wall thickness variations that exceed acceptable limits. When negative tolerance runs too deep, theoretical weight invoicing masks actual material shortfall — the beam arrives lighter than spec, the connection plate doesn’t align, and the site crew spends days grinding and re-fitting. On a S235JR ERW welded square steel tube order for a warehouse frame, even minor deviations in outer dimension compound across dozens of bolted connections, turning a straightforward erection into a costly rework cycle. [NEED_CITE: EN 10219 dimensional tolerance requirements for cold-formed welded hollow sections]
How Cold-Rolled ERW Process Matches Precision Structural Assembly
The cold-rolled ERW process starts from hot-rolled coil that is slit, formed, and welded into square or rectangular profile, then cold-rolled to final dimension. This produces a clean surface with tight dimensional control — critical when the S235JR ERW welded square steel tube goes directly into welded connections or bolted end-plates without secondary machining. The non-oiled surface arrives ready for galvanizing or painting per project specification, avoiding the degreasing step that oiled tubes require before coating adhesion can be verified.
Structural Compliance and Certification Requirements for EPC Projects
European EPC projects require CE marking under EN 10219 for cold-formed welded structural hollow sections, with full mill test certificates documenting chemical composition and mechanical properties per heat number. Middle East and Southeast Asian projects often accept ASTM A500 or GB/T 6728 equivalents, but customs authorities increasingly demand third-party inspection reports from SGS or BV before release. The S235JR grade, conforming to EN 10025-2, serves as the baseline structural steel across these markets — its 235 MPa minimum yield strength covers the majority of non-heavy-load building frames, while S355 steps in for longer spans or higher point loads. [NEED_CITE: steel grade equivalence mapping between EN 10025 and ASTM standards]
Understanding S235JR, A36, and Q235B Grade Selection
S235JR, A36, and Q235B occupy roughly equivalent positions in their respective standard systems — EN, ASTM, and GB — with similar carbon content and yield strength ranges. The key difference lies in impact testing requirements: S235JR mandates Charpy impact testing at 20°C, while A36 does not require impact values unless specified by the purchaser. For projects in colder climates or dynamic loading conditions, specifying S235JR or stepping up to S355J2 ensures verified toughness. The ERW welding process used here produces a weld seam that is normalized during manufacturing, eliminating the as-welded microstructure weakness that can appear in poorly controlled SSAW production.
Cold-rolled surface finish on these square tubes delivers tighter dimensional tolerance compared to hot-rolled alternatives. The ±1% tolerance applies across outer dimensions and wall thickness, meaning a 100×100×5 square tube will hold within 99–101mm on the flat sides. This matters for bolted connections where hole alignment depends on predictable geometry, and for welded assemblies where gap consistency affects weld quality.
The Hidden Cost of Negative Tolerance and Missing Mill Certificates
Purchasing welded square tubes based on theoretical weight invoicing without verified tolerance control creates a systematic material shortfall. A trading company quoting below-market prices often sources from mills running maximum negative tolerance — the tubes pass visual inspection but weigh less per meter than declared. When the structural engineer calculates load capacity based on nominal wall thickness, the actual section modulus falls short, creating a safety margin gap that only surfaces during third-party inspection or, worse, under service load. [NEED_CITE: structural hollow section tolerance standards and weight verification procedures]
Why Source S235JR ERW Welded Square Steel Tube from an Integrated Mill-Fabricator
Our facility operates three production lines for raw steel and maintains over 2,800 specifications in inventory, covering the full range from small-bore structural tubes to large rectangular hollow sections. The vertically integrated model — own steel mill feeding directly into the fabrication workshop — means every S235JR ERW welded square steel tube ships with full material traceability from coil heat number to finished bundle. We hold CE certification under EN 10210 and EN 10219, ISO 9001 quality management, and routinely arrange SGS or BV third-party inspection for overseas buyers who require independent verification before shipment.
Documentation & Compliance
- Mill Test Certificate documenting S235JR chemical composition (C, Mn, Si, P, S) and mechanical properties (yield strength, tensile strength, elongation) per EN 10025-2, issued per heat number
- CE certificate of conformity for cold-formed welded structural hollow sections under EN 10219, required for European market customs clearance
- ISO 9001 quality management system certificate covering the entire production chain from raw coil procurement through ERW welding and cold-rolling
- SGS or BV third-party inspection report available upon request, verifying dimensional tolerance, surface quality, and weld integrity before container loading
- Material traceability documentation linking each bundle to its coil heat number, with chemical and mechanical test results traceable to the original steelmaking batch
- Export customs documents including packing list, bill of lading, and certificate of origin formatted for destination country requirements
Packaging, Loading & Delivery
- Non-oiled cold-rolled S235JR square tubes bundled with steel strips and edge protectors to prevent surface scratching during ocean transit, with each bundle tagged by heat number and dimension
- Cut-to-length service available for 6m or 12m standard lengths, or custom lengths per project drawing to minimize on-site cutting waste
- Container loading optimized for square and rectangular profile nesting, maximizing weight per 20ft or 40ft container while maintaining bundle integrity
- Each bundle labeled with steel grade (S235JR / S355 / A36), outer dimension, wall thickness, heat number, and bundle weight for site identification
- FOB, CIF, and DDP shipping terms available from Jiangsu production base to major ports worldwide, with typical production lead times of 31–45 days depending on order volume and specification
Ready to Source Your Next S235JR ERW Welded Square Steel Tube Order
Submit your project specifications — steel grade, outer dimension, wall thickness, quantity, and destination port — to receive a detailed quotation including material cost, fabrication services, and mill test certificate documentation. Our engineering team reviews shop drawings for material optimization and confirms tolerance compliance before production begins.
Request Quotation and Mill Test Certificate
Send your specifications to admin@xjystructure.com or contact us via WhatsApp at +86 188 5315 7756. Our team responds within 24 hours with pricing, lead time, and available certification documentation for your S235JR ERW welded square steel tube inquiry.
Frequently Asked Questions
Q: What is the difference between S235JR, A36, and Q235B for structural applications?
A: These three grades occupy equivalent positions in EN, ASTM, and GB standard systems respectively, with similar carbon content and yield strength ranges. S235JR requires Charpy impact testing at 20°C per EN 10025-2, making it the preferred specification for European projects or applications in moderate climate zones. A36 and Q235B serve similar structural functions but may not include mandatory impact testing unless specifically ordered.
Q: How does XJY Structure guarantee material traceability from coil to finished tube?
A: Our vertically integrated facility produces raw steel and fabricates finished tubes under one quality management system. Each S235JR ERW welded square steel tube bundle carries a heat number tag linking it to the original coil, with mill test certificates documenting chemical composition and mechanical properties from steelmaking through final cold-rolling.
Q: Can you provide custom cut-to-length and pre-punched square tubes to reduce site labor?
A: Yes. Our processing services include cutting to project-specified lengths, punching bolt holes per shop drawings, and bending for curved structural elements. Pre-fabricated components ship with full dimensional inspection reports, reducing on-site cutting and drilling time for EPC projects.
Q: What documentation package is included for EU and Middle East customs clearance?
A: Each shipment includes mill test certificates per EN 10204 3.1, CE certificate of conformity under EN 10219 for European destinations, packing list, bill of lading, and certificate of origin. Third-party inspection reports from SGS or BV are available upon request for projects requiring independent verification.
Q: How is invoicing handled — theoretical weight or actual weight?
A: All S235JR ERW welded square steel tube orders are invoiced by theoretical weight calculated from nominal outer dimension and wall thickness per standard formulas. Our cold-rolled process maintains ±1% dimensional tolerance, ensuring the actual weight per meter stays within acceptable variance from theoretical calculation.
Get Your S235JR ERW Welded Square Steel Tube Quote Today
Email your project drawings and specifications to admin@xjystructure.com or message +86 188 5315 7756 on WhatsApp. We respond within 24 hours with pricing, mill test certificate samples, and production lead time for your S235JR ERW welded square steel tube order.
