Description
Q235 Q345 ERW Square Rectangular Tube Factory Direct Supplier
Mill-direct ERW hollow sections — XJY Structure rolls, welds, and finishes Q235 and Q345 ERW square rectangular tube in-house, eliminating broker markups and material-traceability gaps.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 Q345 ERW Square Rectangular Tube |
| Product Type | Cold-formed welded structural hollow sections (square & rectangular) |
| Steel Grade | Q235B, Q345B (also available in S235JR, S275JR, S355JR per EN 10219) |
| Standard | GB/T 6728, EN 10219, ASTM A500 Grade B/C |
| Section Shape | Square and rectangular |
| Size Range | 20×20 mm to 500×500 mm (square); 30×20 mm to 600×400 mm (rectangular) |
| Wall Thickness | 1.5 mm – 25 mm |
| Length | 6 m, 12 m, or cut-to-length per drawing |
| Technique | ERW (electric resistance welding), cold-formed |
| Surface Treatment | Black, galvanized (hot-dip or pre-galvanized), or painted |
| Ends | Plain ends, beveled, or threaded |
| Application | Building frames, industrial platforms, scaffolding, machinery structures |
| MOQ | 5 tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Architecture | Column and beam frames, portal structures, mezzanine floors, curtain-wall supports |
| Industrial & Manufacturing | Conveyor frames, machine bases, equipment support platforms, crane runways |
| Infrastructure & Civil Works | Bridge handrails, signage gantries, solar mounting structures, pipe racks |
| Warehousing & Logistics | Racking uprights, warehouse portal frames, loading-dock canopies |
| EPC & Energy Projects | Pipe support structures, cable tray frames, substation frameworks |
What Wall-Thickness Tolerance Costs on a Structural Frame Order
Tight tolerance on Q235 Q345 ERW square rectangular tube prevents on-site rework and customs rejection.
When cold-formed welded hollow sections arrive at an African or Middle-East job site with wall thickness drifting beyond the negative limit allowed by EN 10219-2, the third-party inspector flags the entire batch. The contractor faces a choice: air-freight replacement sections at many times the original freight cost, or submit an engineering concession that delays the structural steel erection schedule by weeks. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements] Buyers who source through brokers rather than integrated mills often discover that the mill test certificate does not match the physical product — a gap that only surfaces after the container has been stripped at destination.
How ERW Square Rectangular Tube Fits Structural Frame Connections
Q235 Q345 ERW square rectangular tube produced under EN 10219 or GB/T 6728 delivers flat bearing surfaces on all four faces, which means moment connections and base plates seat without additional machining. The cold-forming process produces corners with a controlled outer radius, allowing gusset plates and connection brackets to sit flush — a detail that matters when an EPC contractor is assembling portal frames for a warehouse in Lagos or a solar mounting structure in Riyadh. Because XJY Structure operates both the steel production line and the fabrication workshop, the same heat number on the mill test certificate carries through to the shop drawings and the final shipping list, closing the traceability loop that overseas inspectors increasingly demand. [NEED_CITE: cold-formed hollow section connection design guidance]
Engineering Compliance and Certification Pathways
Structural engineers specifying Q235 Q345 ERW square rectangular tube for load-bearing frames typically require compliance with EN 10219 for European and African markets, or ASTM A500 for North American projects. The steel grade selection — Q235B for general construction, Q345B where higher yield strength reduces section size — directly affects the member design capacity under EN 1993-1-1 or AISC 360. For corrosive environments such as coastal warehouses or chemical plant pipe racks, hot-dip galvanized coating extends service life without altering the structural calculation, provided the additional coating thickness is accounted for in connection detailing. CE marking under EN 10219 is mandatory for structural hollow sections entering the EU and many African countries that adopt European norms, and missing this certificate can hold a shipment at the port of discharge. [NEED_CITE: CE marking requirements for structural steel hollow sections under EN 10219]
Steel Grade Logic and ERW Process Characteristics
Q235B and Q345B belong to the Chinese GB/T 1591 series; Q235B offers a minimum yield strength suitable for secondary structures and light frames, while Q345B provides roughly 50 percent higher yield, allowing engineers to reduce wall thickness or section size in primary load-bearing members. In international procurement, Q235B maps closely to S235JR under EN 10219 and ASTM A36 under ASTM standards, while Q345B corresponds to S355JR and ASTM A572 Grade 50 — though exact equivalence depends on the specific chemical composition and impact testing requirements of the destination standard. [NEED_CITE: steel grade equivalence between GB, EN, and ASTM standards] The ERW process forms the tube by cold-rolling steel coil into a hollow shape and welding the seam through electric resistance, producing a consistent wall thickness and smooth internal surface at lower cost than seamless alternatives. For structural applications where internal pressure is not a factor, ERW square rectangular tube offers a favorable strength-to-weight ratio and predictable behavior under bending and compression.
Hidden Costs of Sourcing the Wrong Hollow Section
Procuring Q235 Q345 ERW square rectangular tube from a supplier who cannot demonstrate full material traceability from slab to finished tube creates risk at three points. First, the mill test certificate may reference a different heat or a different grade entirely, causing the structural engineer to reject the material and halt erection. Second, wall thickness that drifts into excessive negative tolerance reduces the load-carrying capacity below the design assumption, creating a latent safety concern that only emerges under extreme loading or during a post-incident forensic review. Third, shipments lacking CE certification or proper certificate of origin face customs detention in EU-aligned markets, turning a six-week delivery into a three-month delay with demurrage charges accumulating daily. [NEED_CITE: consequences of non-compliant structural steel in international construction projects]
Why Procurement Teams Source Q235 Q345 ERW Square Rectangular Tube from XJY Structure
XJY Structure operates as the fabrication division of a Shandong-based steel producer with three rolling lines and over 2,800 stock specifications, meaning the Q235 Q345 ERW square rectangular tube you order is rolled, welded, and inspected under one quality system rather than sourced from a third-party mill and resold. The in-house理化 laboratory issues mill test certificates that record the actual chemical composition and mechanical test results for each heat, and these reports travel with the shipment — not as a photocopy, but as the original document tied to the heat number stenciled on every bundle. For projects requiring EN 10219 compliance, the factory holds CE certification and can arrange SGS or BV third-party inspection before loading. The fabrication workshop downstream handles CNC cutting, drilling, welding, and shot blasting, so a contractor ordering portal frame components can receive fabricated assemblies rather than bare tubes, reducing on-site labor and welding qualification requirements. Professional loading teams plan container stowage for square and rectangular sections to maximize weight utilization and prevent transit damage, a detail that matters when a 40-foot open-top container carries 12-meter lengths to West Africa.
Documentation & Compliance
- Mill test certificate recording Q235B or Q345B chemical composition and mechanical properties per GB/T 1591, with heat number traceability to the original slab
- CE certificate confirming EN 10219 compliance for structural hollow sections destined for EU and African markets
- ISO 9001 quality management certificate covering the integrated steel production and fabrication process
- SGS or BV third-party inspection report verifying dimensional tolerance, surface coating thickness, and visual weld quality before shipment
- Material traceability sheet linking each bundle to its heat number, size, length, and purchase order line item
- Full customs documentation package including packing list, bill of lading, certificate of origin, and commercial invoice formatted for the destination port
Packaging, Loading & Delivery
- Q235 Q345 ERW square rectangular tube bundled with high-tensile steel strips at intervals matched to the section size, with edge protectors on galvanized finishes to preserve the zinc coating during ocean transit
- Black finish tubes coated with anti-rust oil on inner and outer surfaces before bundling, preventing surface oxidation during storage and shipping in humid climates
- Container loading plans optimized for 6-meter and 12-meter lengths to maximize weight per 20-foot or 40-foot container, reducing per-ton freight cost for West African and Southeast Asian destinations
- Cut-to-length service available for sections under 6 meters, with saw-cut ends deburred and marked with heat number, steel grade, and size for easy site identification
-唛头 stenciled on each bundle showing steel grade (Q235B or Q345B), section dimensions, wall thickness, length, heat number, and purchase order reference
- Delivery terms available as FOB Qingdao, CIF destination port, or DDP to project site, with full export documentation and container tracking provided from loading to discharge
Getting a Firm Quote for Your Structural Steel Package
Submit your project drawings or a specification list showing section sizes, wall thickness, steel grade, surface treatment, and total tonnage, and the XJY Structure engineering team returns a detailed quotation within 24 hours, including the mill test certificate format, production lead time, and container loading plan. For non-standard sizes or fabricated assemblies requiring cutting, drilling, or welding, share the shop drawings and the team confirms feasibility and pricing in the same response.
Request Your Quotation and Mill Test Certificate
Send your specification list or project drawings to receive a detailed quotation with full material documentation and a container loading plan.
Company: 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
