Description
Mill-direct ERW tube supply — 2,800+ specifications in stock from own steel mill, eliminating third-party sourcing gaps for Q235 and S235 structural orders.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 / S235 / SS400 ERW Square and Rectangular Steel Tube |
| Product Type | Welded Square and Rectangular Steel Tube (ERW) |
| Steel Grade | Q195, Q215, Q235, Q345, S235, SS400, ASTM |
| Standard | ASTM, API, CE, JIS, ISO9001, SGS |
| Section Shape | Square / Rectangular |
| Size Range | 20×20 mm – 200×200 mm |
| Wall Thickness | 1.5 – 30 mm |
| Length | 1 – 12 m (6 m / 6.4 m / 12 m standard; custom upon request) |
| Technique | ERW (Electric Resistance Welded) / Hot Rolled |
| Surface Treatment | Black (Hot Rolled) / Slightly Oiled / Galvanized Coated |
| Tolerance | ±5% |
| Ends | Plain |
| Application | Steel structures / Construction frames / Machinery / Scaffolding / Furniture / Fluid transport / Bridge / Car manufacturing / Electrical installation / Mining |
| MOQ | 25 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Steel Structure & Construction | Building frames, column-to-beam connections, portal frame warehouses |
| Infrastructure & Bridge | Bridge support piers, highway sign gantries, culvert reinforcement |
| Industrial & Machinery | Machine bases, conveyor support structures, platform handrails |
| Scaffolding & Access | Scaffolding uprights, cross braces, ladder stringers |
| Mining & Heavy Industry | Conveyor frames, equipment guardrails, ventilation duct supports |
What Negative Tolerance Surprises Cost on a 20-Ton ERW Square Tube Order
A ±5% wall-thickness tolerance sounds acceptable on paper — until the theoretical weight invoice meets the actual weight at destination port.
When buyers order Q235 ERW square and rectangular steel tubes by theoretical weight but receive goods at the lower end of tolerance, the gap between invoiced tonnage and physical mass can exceed a full container’s worth of value. Third-party inspectors at discharge ports routinely flag wall-thickness deviations beyond contractual limits, triggering cargo rejection or costly renegotiation. [NEED_CITE: EN 10219 dimensional tolerance requirements for cold-formed hollow sections] For EPC firms managing fixed-price contracts, these discrepancies translate directly into margin erosion and schedule delays.
How ERW Square and Rectangular Tubes Match Structural Frame Requirements
The 20×20 to 200×200 mm dimension range covers the majority of light-to-medium structural framing used in warehouse construction, industrial platforms, and scaffolding systems. Q235 and S235 grades provide adequate yield strength for non-seismic zones, while Q345 serves higher-load applications such as crane runway beams and mezzanine floors. The ERW process produces a continuous longitudinal weld seam that, when properly controlled, delivers consistent mechanical properties across the full cross-section — critical for moment-resisting connections in portal frame structures.
Engineering Compliance and Certification Pathways for ERW Tube Procurement
European projects require CE marking under EN 10219 for cold-formed welded structural hollow sections, meaning the ERW square and rectangular steel tube must carry factory production control certification and declaration of performance documentation. [NEED_CITE: CE marking requirements for structural steel hollow sections under EN 10219] North American specifications typically reference ASTM A500 Grade B or C, which differs in chemical composition limits and tensile requirements from both the Chinese Q-series and European S-series. Buyers sourcing for Middle East and African infrastructure projects often accept either standard, but customs authorities at destination may demand specific test certificates matching the declared standard — making mill test documentation alignment essential before shipment.
Steel Grade Selection and ERW Process Fundamentals for Structural Tubes
The Q-series (Q195, Q215, Q235, Q345) follows Chinese GB/T 700 and GB/T 1591 standards, where the number indicates minimum yield strength in MPa. S235 corresponds roughly to Q235 in yield class but follows EN 10025 for impact testing requirements at specified temperatures. SS400, per JIS G3101, sits between Q235 and Q345 in tensile range. The ERW process forms the tube from hot-rolled coil through continuous roll-forming and resistance welding without filler metal — producing a clean internal surface suitable for fluid transport while maintaining dimensional accuracy of ±5% on wall thickness. Surface treatment options include hot-rolled black finish for indoor structural use, oiled surface for temporary corrosion protection during transit, and galvanized coating for outdoor or humid environments.
Hidden Costs of Procuring ERW Tubes Without Verified Material Traceability
Ordering Q235 or S235 ERW square and rectangular steel tubes without full heat-number traceability creates downstream risk: if third-party inspection at destination reveals chemical composition outside specification, the entire batch faces rejection or downgrading. [NEED_CITE: material traceability requirements for structural steel under EN 10204] Missing or inconsistent mill test certificates delay customs clearance in strict-markets like the EU and Australia, where import authorities cross-reference declared standards against submitted documentation. Welding procedure qualification records become void if base material cannot be positively identified, forcing costly re-qualification or component replacement on active job sites.
Why Source Your ERW Square and Rectangular Steel Tube From an Integrated Mill-Fabricator
XJY Structure operates its own steel production facility with three rolling lines, maintaining 2,800+ specifications of raw material in stock — this vertical integration means every ERW square and rectangular steel tube ships with complete material traceability from slab to finished section. Our in-house laboratory performs chemical analysis and mechanical testing per ISO 9001 protocols, generating mill test certificates that document actual heat chemistry and test results rather than generic compliance statements. We hold CE certification under EN 10210 and EN 10219 for European market access, and routinely arrange SGS, BV, or TÜV third-party inspections before shipment for clients requiring independent verification. Custom cutting, punching, bending, and welding services allow buyers to receive fabrication-ready components rather than raw tubes, reducing on-site labor and waste.
Documentation & Compliance
- Mill test certificate documenting Q235 chemical composition and mechanical properties per GB/T 700, with heat number traceability
- CE certificate covering EN 10219 cold-formed welded structural hollow sections for European project compliance
- ISO 9001 quality management system certificate covering the full production process from coil reception to finished tube
- SGS or BV third-party inspection report verifying dimensional accuracy, wall thickness, and surface quality before shipment
- Material traceability report linking each bundle to specific heat numbers and rolling schedules
- Export documentation including packing list, bill of lading, and certificate of origin for customs clearance
Packaging, Loading & Delivery
- Q235 and S235 ERW square tubes bundled with steel strips in seaworthy packaging, with edge protectors for galvanized surfaces to prevent zinc coating damage during ocean transit
- Hot-rolled black finish tubes lightly oiled before bundling to prevent surface rust during storage and shipping
- Standard 6 m and 12 m lengths optimized for 20-foot and 40-foot container loading, maximizing payload within weight restrictions
- Custom cut-to-length service available for 1–12 m requirements, with cut ends deburred and protected
- Each bundle marked with heat number, steel grade, size specification, and purchase order number for site identification
- FOB, CIF, and DDP shipping terms available, with professional loading plans for oversized rectangular sections
How to Request a Fabrication-Ready Quote for Your ERW Tube Project
Submit your project drawings or specification list indicating steel grade (Q235, S235, SS400, or ASTM equivalent), section dimensions, wall thickness, quantity, and destination port. Our engineering team responds within 24 hours with pricing, mill test certificate format confirmation, and production lead time. For non-standard sizes or custom fabrication requirements including cutting, drilling, or welding, share your shop drawings for detailed assessment.
Start Your ERW Square and Rectangular Steel Tube Inquiry Today
Send your specifications and required standards to receive a detailed quotation with full material documentation.
Contact XJY Structure
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
