Description
Direct Mill Supply, No Middlemen — S275JR and S355JR sharp corner square and rectangular steel tubes produced in-house from raw slab to finished section, with full material traceability by heat number.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S275JR S355JR Sharp Corner Square / Rectangular Steel Tube |
| Product Type | Sharp Corner Square / Rectangular Steel Tube (SHS / RHS) |
| Steel Grade | S235JR, S275JR, S355JR, S355J2H, S355J0, Q460, A36, SS400, ASTM A53 GR.B |
| Standard | EN 10210, EN 10219 |
| Section Shape | Square / Rectangular (Sharp Corner 90 Degree) |
| Size Range | 15×15 mm – 1000×1000 mm (Square) / 20×30 mm – 600×800 mm (Rectangular) |
| Wall Thickness | 0.5 mm – 50 mm |
| Length | 5.8 m – 14 m (or custom cut-to-length) |
| Technique | ERW / Hot Rolled Welded |
| Surface Treatment | Bare / Oiled / Painted / Galvanized / 3PE / Varnish |
| Ends | Plain / Cut / Beveled / Flanged |
| Tolerance | ±1% (dimensional) |
| Application | Steel structures / Construction frames / Machinery structures / Scaffolding / Greenhouse / Furniture / Building materials / Low-pressure fluid transport |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC & General Contracting | Building frames, column-beam assemblies, platform structures for industrial warehouses and commercial facilities |
| Machinery Manufacturing | Equipment support frames, conveyor structures, crane booms requiring precise 90° corner geometry for bolted connections |
| Infrastructure & Scaffolding | Scaffolding systems, bridge handrails, signage gantries across Middle East, Southeast Asia, and African markets |
| Agricultural & Light Industrial | Greenhouse frames, storage rack systems, workshop mezzanine structures |
Why Corner Radius Tolerance Decides Site Assembly Speed on Structural Frame Orders
Sharp corner 90° geometry eliminates connection plate misalignment and field re-cutting.
When overseas buyers receive conventional cold-formed RHS with oversized corner radii, gusset plates and connection brackets fail to sit flush against the tube face. This forces on-site re-cutting, welding repositioning, and schedule delays — costs that compound quickly on EPC projects with tight erection windows. A S355JR sharp corner square steel tube supplier producing via hot-rolled ERW process maintains tight ±1% dimensional tolerance and true 90° corner formation, ensuring bolt holes align and weld prep proceeds without deviation. Material traceability gaps from third-party sourcing further complicate acceptance, as missing heat number documentation triggers inspection hold points [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements].
How Sharp Corner Geometry Matches Structural Connection Requirements
The 90° sharp corner profile of S275JR and S355JR sharp corner square steel tube sections provides flat bearing surfaces for gusset plates, end caps, and bolted flange connections. Unlike rounded-corner cold-formed tubes where contact occurs only at the tangent point, sharp corners distribute load across the full plate width, reducing stress concentration at weld toes. This geometry is critical for machinery frames and scaffolding couplers where repeated assembly-disassembly cycles demand consistent fit-up. Our hot-rolled ERW forming process controls corner radius within ±0.5 mm across the full 15×15 mm to 1000×1000 mm size range, verified by in-house dimensional inspection before shipment.
Structural Code Compliance and Surface Protection Selection
Engineering specifications for steel frames in EU markets require EN 10210 or EN 10219 certification with CE marking for customs clearance and site acceptance. S355JR and S355J2H grades meet EN 1993-1-1 design assumptions for structural hollow sections, while S275JR serves lighter-load applications where weight optimization is secondary to cost control. For projects in coastal or high-humidity environments — common across West African and Southeast Asian job sites — galvanized or 3PE surface treatment extends service life without field painting. Wall thickness selection from 0.5 mm to 50 mm allows designers to balance load capacity against self-weight, with ±1% tolerance ensuring theoretical weight calculations match delivered material [NEED_CITE: EN 10210-1 hot finished structural hollow sections certification requirements].
Steel Grade Selection and ERW Welding Process Fundamentals
The S-series steel grades (S235JR, S275JR, S355JR, S355J2H) follow EN 10025 designation where the number indicates minimum yield strength in MPa — S355JR delivers higher load capacity than S275JR for the same cross-section, allowing section size reduction in heavily loaded columns. Q460 serves Chinese-spec projects requiring higher strength-to-weight ratios, while A36 and SS400 cover ASTM and JIS project specifications respectively. The ERW (Electric Resistance Welding) process used for these sharp corner tubes produces a longitudinal weld seam with mechanical properties matching the parent metal after heat treatment, offering cost advantages over seamless pipe for non-pressure structural applications. Surface treatment selection depends on end-use: bare or oiled tubes suit indoor fabrication shops, galvanized coatings protect outdoor scaffolding and signage structures, while 3PE or painted finishes serve industrial environments with chemical exposure risk.
Hidden Costs of Non-Conforming Material and Missing Certification
Procuring S355JR sharp corner square steel tube from suppliers without verified EN 10210 certification creates downstream risks: customs authorities in EU markets reject shipments lacking CE documentation, forcing return or destruction at buyer’s expense. Material test certificates without heat number traceability fail inspector approval, halting erection until replacement material arrives. Negative tolerance abuse — where actual wall thickness falls below specified minimum — reduces load capacity and triggers structural recalculation, potentially requiring section upgrades that invalidate original connection designs. These costs remain invisible until site acceptance, long after the initial price advantage of non-conforming material has disappeared [NEED_CITE: steel grade equivalence and certification requirements for EN versus ASTM standards].
Integrated Mill-to-Tube Supply Chain and Quality Verification
Our vertically integrated production eliminates material sourcing gaps — raw steel slab from our own mill flows directly to tube forming lines, ensuring chemical composition consistency from heat to finished S275JR or S355JR sharp corner square steel tube. In-house理化实验室 performs chemical analysis and mechanical testing per EN 10204 3.1 requirements, issuing mill test certificates with full traceability. Third-party inspection by SGS, BV, or TÜV is available prior to shipment for projects requiring independent verification. With 2,800+ specifications in stock and custom cut-to-length capability from 5.8 m to 14 m, we consolidate multi-size orders into single shipments, reducing logistics complexity for EPC projects sourcing from China. Professional loading plans optimize container utilization for oversized rectangular sections up to 600×800 mm, with door-to-door delivery coordination to final site destination.
Documentation & Compliance
- Mill test certificate documenting S275JR and S355JR chemical composition and yield strength per EN 10219, with heat number traceability from slab to finished tube
- CE certificate confirming EN 10210 and EN 10219 compliance for EU market customs clearance and structural code acceptance
- ISO 9001 quality management system certificate covering forming, welding, and dimensional inspection processes
- SGS or BV third-party inspection report available upon request for projects requiring independent material verification
- Material traceability documentation linking each bundle to specific heat number, chemical composition, and mechanical test results
- Export customs documents including packing list, bill of lading, and certificate of origin for import clearance
Packaging, Loading & Delivery
- S275JR and S355JR sharp corner tubes bundled with steel strips and edge protectors to preserve 90° corner geometry during ocean transit
- Galvanized surface treatment protected by plastic wrapping and separation layers to prevent zinc coating damage from bundle contact
- Container loading optimized for rectangular sections up to 600×800 mm, with nested arrangements maximizing 20ft and 40ft GP utilization
- Custom cut-to-length service available for 5.8 m to 14 m requirements, reducing on-site cutting waste and handling time
- Heat number and steel grade stenciled on each bundle for site identification and inspection traceability
- FOB, CIF, and DDP delivery terms with professional loading supervision and tracking until site delivery
Getting Your Quote and Material Documentation Ready
Submit your project drawings with specified steel grade (S275JR, S355JR, or S355J2H), section dimensions, wall thickness, quantity, and destination port. We respond within 24 hours with pricing, mill test certificate sample, production timeline, and loading plan. For non-standard sizes or custom cut-to-length requirements, share your specification list and we confirm feasibility against our 2,800+ specification inventory.
Request Pricing and Mill Test Certificate
Send your S275JR or S355JR sharp corner square steel tube requirements to admin@xjystructure.com or contact us via WhatsApp at +86 188 5315 7756 with section size, wall thickness, length, quantity, and destination port for quotation and material documentation.
