Description
Factory-direct welded SHS with full material traceability — Every S235JR S355 square steel tube we ship carries a heat-number-linked Mill Test Certificate from our own steel mill, eliminating third-party sourcing gaps.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S235JR / S355 / SS400 Square Steel Tube |
| Product Type | Welded Square Steel Tube |
| Steel Grade | S235JR, A36, S355, SS400, Q235B |
| Standard | ASTM A500, EN 10219, EN 10210, JIS G3466, GB/T 6728 |
| Section Shape | Square |
| Outer Diameter / Side Length | Customized |
| Wall Thickness | Customized |
| Length | Customized |
| Technique | Welded (ERW) |
| Surface Treatment | Cold Rolled / Galvanized |
| Tolerance | ±1% |
| Ends | Plain / Customized |
| Application | Building structures, machinery manufacturing, infrastructure, vehicle manufacturing, furniture frames |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC & Industrial Construction | Factory frame structures, warehouse columns and beams, platform supports |
| Commercial Building | Stadium trusses, shopping center structural frames, logistics center portals |
| Infrastructure | Bridge auxiliary structures, stage truss systems, greenhouse framing |
| Vehicle Manufacturing | Trailer chassis frames, RV structural skeletons |
| Machinery & Equipment | Machine tool bases, conveyor support structures, automation equipment frames |
What Negative Tolerance Costs When You Bend a Square Tube on Site
A -12% wall thickness deviation turns a clean bend into a cracked corner — and two containers of air-freighted replacements.
When overseas contractors receive welded square tubes with wall thickness running below the ordered specification, the first sign of trouble often appears during on-site bending or welding. Corners crack. Weld penetration fails. Dimensional checks come back outside tolerance. By then, the steel is already at the job site, the crane is booked, and the schedule is burning. The root cause is rarely the fabricator’s skill — it is the material supplier’s tolerance control and the missing traceability chain between the mill and the fabrication floor. For any S235JR S355 square steel tube supplier operating across borders, the gap between a paper certificate and actual product consistency is where project budgets die. [NEED_CITE: EN 10219 dimensional tolerance requirements for cold-formed hollow sections]
How ERW Welded SHS Matches Structural Frame Demands
Square hollow sections fabricated by ERW welding deliver consistent corner geometry and uniform wall distribution that make them ideal for moment-resisting frames and truss chords. The S235JR S355 square steel tube in welded form provides predictable load paths for column-to-beam connections, while the flat internal surfaces simplify gusset plate welding and bolted node design. Our vertically integrated production — from raw steel coil to finished welded SHS — means the same quality system governs both the base material and the forming process, so weld seam integrity and dimensional accuracy stay within ±1% tolerance across every length.
Engineering Compliance Across International Standards
Structural engineers specifying these tubes for EU projects need EN 10219 compliance for cold-formed welded hollow sections, while North American projects typically call for ASTM A500 Grade B or C. The S235JR S355 square steel tube we produce meets EN 10219 and ASTM A500 requirements, with CE marking available for European customs clearance. For corrosive environments — coastal warehouses, chemical plant galleries, agricultural buildings — galvanized surface treatment extends service life without field coating. Custom cut-to-length and pre-punched sections reduce on-site secondary work, which matters when labor costs dominate project budgets in Southeast Asia and the Middle East. [NEED_CITE: ASTM A500 structural tubing specification requirements]
Steel Grade Selection and ERW Welding Fundamentals
S235JR, S355, and SS400 represent different yield strength tiers across European and Japanese standard systems. S235JR suits general structural framing where moderate load capacity is required, while S355 provides higher yield strength for heavily loaded columns and long-span trusses. SS400, common in Japanese-spec projects across Southeast Asia, offers comparable performance to S235JR with different chemical composition limits. The ERW welding process forms the tube from rolled steel strip, creating a longitudinal weld seam that — when properly controlled — delivers strength consistent with the parent material. Cold rolled finish provides a clean surface for painting, while hot-dip galvanizing adds zinc coating for corrosion protection in exposed applications. Wall thickness tolerance directly affects both theoretical weight calculations and actual structural capacity — a tube running thin on wall thickness may pass visual inspection but fail under design load. [NEED_CITE: steel grade equivalence between EN 10219 and ASTM A500 standards]
The Hidden Cost of Unverified Material Certification
Ordering welded square tubes without verified mill test certificates creates downstream risk at every project stage. Customs authorities in the EU require CE documentation for structural steel components — missing paperwork means container holds and demurrage charges. On-site, material that does not match the specified grade fails third-party inspection, forcing either rejection or costly engineering reassessment. Welding procedures qualified for S355 cannot be applied to unverified material of unknown chemistry. The engineering firm signs off on calculations assuming certified properties; when those assumptions prove wrong, liability follows the procurement trail. [NEED_CITE: EN 1090 structural steel fabrication execution class requirements]
Why Project Procurement Teams Source From Us
Our steel mill produces the raw coil; our fabrication workshop forms, welds, and finishes the tube. This vertical integration means every S235JR S355 square steel tube carries a heat number traceable from the ladle to the finished bundle — no third-party material sourcing, no certificate gaps. Our in-house laboratory issues Mill Test Certificates covering chemical composition and mechanical properties per the ordered standard. We hold CE certification for EN 10219 and EN 10210, ISO 9001 quality management, and accept SGS or BV third-party inspection at any production stage. With over 2,800 specifications in our rolling schedule, non-standard dimensions and custom lengths do not require separate supplier qualification. Our loading team plans container stowage for oversized structural sections, maximizing payload while protecting surface finish during ocean transit.
Documentation & Compliance
- Mill Test Certificate documenting S235JR or S355 chemical composition and mechanical properties per EN 10219 or ASTM A500, linked to heat number
- CE certificate confirming EN 10219 compliance for structural hollow sections destined for EU member states
- ISO 9001 quality management system certificate covering the full production chain from steelmaking to finished tube
- SGS or BV third-party inspection report available for wall thickness, dimensional accuracy, and weld seam quality verification
- Full material traceability by heat number from raw steel coil through ERW forming and welding
- Export customs documentation including packing list, bill of lading, and certificate of origin for destination-country clearance
Packaging, Loading & Delivery
- Welded square tubes bundled with steel strips and edge protectors to maintain ±1% dimensional tolerance and prevent surface damage during handling
- Galvanized S235JR S355 square steel tube bundles wrapped with waterproof paper and plastic film to preserve zinc coating integrity during ocean shipment
- Custom-length tubes cut to project specification and marked with heat number, steel grade, and dimension at both ends for on-site identification
- Container loading plans optimized for square hollow section geometry, maximizing weight utilization while securing bundles against transit shift
- FOB, CIF, and DDP delivery terms available with professional export documentation and tracking through final site delivery
Ready to Move From Drawing to Mill Test Certificate
Share your project specifications — steel grade, section dimensions, wall thickness, total quantity, and destination port — and we respond within 24 hours with a detailed quotation including material cost, fabrication charges, surface treatment, and shipping. Our engineering team reviews your drawings for shop drawing preparation before production begins, ensuring dimensional accuracy and weld procedure compliance.
Request Your Quotation and Material Certification Package
Submit your technical specifications to receive pricing, production schedule, and Mill Test Certificate preview.
Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.xjystructure.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjystructure.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
