Description
Factory-Direct ERW Hollow Sections — 2,800+ specifications produced on 3 dedicated lines with wall thickness up to 25 mm, shipped to 50+ countries without middleman markups.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 Carbon Steel Square / Rectangular Tube |
| Product Type | Square / Rectangular Steel Tube (SHS / RHS) |
| Steel Grade | Q195, Q215, Q235, Q345, 10#, 20#, S235, S355JR, A53 Grade A, A53 Grade B, A500 Grade A, A500 Grade B, A500 Grade C, SS400, STK400, ST42.2 |
| Standard | ASTM A500, ASTM A53, EN 10219, EN 10210, GB/T 6728, GB/T 3091, JIS G3466 |
| Section Shape | Square / Rectangular |
| Size Range (OD) | 10×10 mm – 500×500 mm |
| Wall Thickness | 0.9 – 25 mm |
| Length | 6 m / 9 m / 12 m (or customized) |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Cold Rolled / Customized (Galvanized, Oiled, Black, Painted available) |
| Tolerance | ±1% |
| Ends | Plain / Beveled (as required) |
| Processing Service | Welding, Cutting, Bending, Punching, Decoiling |
| Application | Steel structures / Construction frames / Machinery frames / Scaffolding / Electric power transmission towers / Municipal projects / Water & oil pipeline engineering / Piling / Furniture |
| MOQ | 500 KG |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors & Construction | Building frames, scaffolding systems, transmission tower structures, piling supports |
| Machinery Manufacturers | Equipment frames, conveyor structures, precision-machined tube components |
| Infrastructure & Municipal | Water and oil pipeline supports, bridge auxiliary structures, road facility frames |
| Steel Distributors | Full-range SHS/RHS stock for regional resale and project supply |
Tolerance Drift on Thin-Wall ERW Tubes Can Collapse a Scaffolding Budget
±1% dimensional tolerance verified at incoming, in-process, and final inspection stages eliminates the wall-thickness variance that triggers on-site rework.
When Q235 carbon steel square rectangular tube orders arrive at port with wall thickness drifting below the specified 0.9 mm on thin-wall sections, scaffolding contractors face rejected inspection reports and replacement costs that dwarf the original material savings. Fragmented sourcing from multiple vendors compounds the problem — tubes from one mill, plates from another, fabrication from a third — each with mismatched certificates and incompatible tolerances. A single qualified Q235 carbon steel square rectangular tube manufacturer that controls the entire production chain from raw coil to finished component removes this coordination risk entirely [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements].
How ERW Square and Rectangular Tubes Match Structural Frame Requirements
The 10×10 mm to 500×500 mm size range with wall thickness from 0.9 to 25 mm covers everything from light-gauge furniture frames to heavy-load piling and transmission tower structures. ERW welding produces a clean internal seam suitable for bolted and welded connections in steel frame construction, while the ±1% tolerance ensures consistent fit-up on scaffold couplers and beam-to-column joints. Our in-house physical and chemical laboratory tests every heat for tensile strength, yield behavior, elongation, and chemical composition before release — so the Q235 carbon steel square rectangular tube you receive matches the mill test certificate heat number printed on each bundle [NEED_CITE: structural hollow section compliance under EN 10210 and ASTM A500].
Engineering Compliance Across EU, North American, and Asian Standards
Q235 and Q345 grades map directly to S235JR and S355JR under EN 10219 for European structural work, while ASTM A500 Grade B and C cover North American construction frames under AISC guidelines. JIS G3466 STK400 and SS400 serve Japanese-spec infrastructure projects across Southeast Asia. CE certification under EN 10210 and EN 10219 is mandatory for structural hollow sections entering the EU market — missing this mark means customs holds and project compliance failures that no amount of expediting can fix [NEED_CITE: CE marking requirements for structural steel under EN 10210 and EN 10219]. For corrosion-prone environments, hot-dip galvanized or painted surface treatments extend service life without requiring field coating after delivery.
Steel Grade Selection and ERW Process Fundamentals
The Q-series (Q195 through Q345) follows the Chinese yield-strength naming convention, where the number indicates minimum yield strength in MPa — Q235 delivers higher load-bearing capacity than Q195 for the same cross-section. S-series grades (S235, S355JR) align with European EN standards, while ASTM A500 Grades A, B, and C serve the North American market with progressively higher strength requirements. ERW electric resistance welding fuses the coil edges under heat and pressure without filler metal, producing a uniform seam that suits structural applications at lower cost than seamless alternatives for non-pressure use. Wall thickness tolerance directly affects theoretical weight calculations — a 1.5 mm specified wall arriving at 1.35 mm reduces load capacity and triggers structural engineer rejection on certified projects.
The Hidden Cost of Accepting Unverified Mill Certificates
Material that fails to match its declared steel grade creates cascading failures: structural engineers reject the batch, customs authorities hold the shipment without valid CE documentation, and project timelines slip while replacement material is sourced and shipped. Negative tolerance abuse — where actual wall thickness falls below the lower limit — compromises load-bearing capacity and voids structural insurance claims. Third-party inspection by SGS or BV before loading catches these discrepancies at the mill, not at the destination port where return costs become prohibitive [NEED_CITE: steel grade equivalence verification between EN 10219 and ASTM A500 standards].
Why Engineering Procurement Teams Source From Our Mill
Three dedicated production lines cover 2,800+ specifications in square and rectangular sections with wall thickness up to 25 mm — eliminating the need to coordinate tubes, plates, and fabrication across separate vendors. Our in-house physical and chemical laboratory conducts incoming, in-process, and final inspections on every heat, producing original mill test certificates with full traceability. CE certification under EN 10210 and EN 10219, ISO 9001:2015 quality management, and SGS/BV third-party verification satisfy EU, North American, and Middle Eastern customs requirements. Professional loading plans with inner bracing for thin-wall and异形 sections prevent the deformation and edge damage that triggered a USD 20,000 rework on a previous Monte Rey shipment — every container is optimized before departure.
Documentation & Compliance
- Mill test certificate documenting Q235 chemical composition and mechanical properties per GB/T 6728 with heat number traceability on every bundle
- CE certificate under EN 10210 and EN 10219 for structural hollow sections entering EU member states
- ISO 9001:2015 quality management system certificate covering the full ERW production process
- SGS or BV third-party inspection report available upon request before container sealing
- Material traceability by heat number linking each bundle to incoming coil test data and in-process inspection records
- Complete customs document package including packing list, bill of lading, and certificate of origin for the destination country
Packaging, Loading & Delivery
- Q235 ERW square and rectangular tubes bundled with steel strips and edge protectors to preserve surface finish during ocean transit
- Thin-wall sections (0.9–2.0 mm) receive inner bracing and wooden cradle support to prevent deformation on 40-day sea voyages
- Galvanized tubes packed with waterproof interleave and zinc-preserving separators to maintain coating integrity
- Custom cut-to-length service available for 6 m, 9 m, and 12 m standard lengths or project-specific dimensions
- Heat number and steel grade stenciled on each bundle for on-site identification and inspection traceability
- FOB, CIF, and DDP shipping options with professional container loading plans optimized for 20ft and 40ft equipment
Start Your Procurement With Verified Specifications
Submit your required dimensions, steel grade, quantity, and destination port to receive a detailed quotation including unit pricing, production lead time, applicable certifications, and mill test certificate availability. Our engineering team responds within 12 hours with a complete technical and commercial proposal for your Q235 carbon steel square rectangular tube requirement.
Request Your Quotation and Mill Test Certificate Today
Send your specifications via email or WhatsApp to receive pricing, certification details, and loading plans within 12 hours.
Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxjysteel.com
Website: www.sdxjysteel.com
Frequently Asked Questions
Q: How do Q235 and Q345 map to S235JR/S355JR and ASTM A500 grades?
A: Q235 corresponds to S235JR under EN 10219 and offers comparable yield behavior to ASTM A53 Grade B. Q345 aligns with S355JR under EN 10219 and matches ASTM A500 Grade B in structural applications. We provide cross-reference documentation with every inquiry to confirm grade equivalence for your project standard.
Q: What documentation is provided, and can SGS or BV inspect before loading?
A: Every shipment includes original mill test certificates with heat number traceability, packing list, bill of lading, and certificate of origin. CE certificates under EN 10210/EN 10219 are provided for EU-bound orders. SGS and BV third-party inspections are available at our facility before container sealing at the buyer’s request.
Q: Can you produce non-standard dimensions, and what is the minimum order quantity?
A: Beyond the standard 10×10 mm to 500×500 mm range with 0.9–25 mm wall thickness, we produce custom non-standard sizes across 2,800+ specifications on our dedicated production lines. The minimum order quantity is 500 KG, suitable for both project-specific procurement and distributor restocking.
Q: What surface treatment options are available for outdoor structural use?
A: Standard options include black (as-welded), oiled for short-term rust prevention, hot-dip galvanized for long-term corrosion protection in outdoor and marine environments, and painted finishes for architectural or color-matched applications. Surface treatment selection depends on the service environment and project design life.
Q: Are your products CE marked, and will this avoid customs delays in Europe?
A: Yes, our structural hollow sections carry CE certification under EN 10210 for hot-finished and EN 10219 for cold-formed applications. This certification is mandatory for structural steel entering EU member states and prevents customs holds and project compliance failures at the destination port.
