Description
Direct Mill Supply for ERW Square Tubes — S235JR, S355, and Q235B grades produced in-house with full dimensional control and EN10219 compliance documentation.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S235JR / S355 / Q235B ERW Square Steel Tube |
| Product Type | Welded Square Steel Tube (ERW) |
| Steel Grade | S235JR, A36, S355, SS400, Q235B |
| Standard | ASTM A500, EN10219, EN10210, JIS G3466, GB/T 6728 |
| Section Shape | Square |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Cold Rolled (base condition); Galvanized available per request |
| Tolerance | ±1% |
| Length | Customized |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Oiled or Non-oiled | Non-oiled |
| Application | Building structures, machinery manufacturing, infrastructure, furniture frames, vehicle manufacturing |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Industrial & Commercial Construction | Factory warehouse frames, stadium roof trusses, commercial center column systems |
| Machinery Manufacturing | Machine tool base frames, conveyor support structures, automation equipment frameworks |
| Infrastructure | Auxiliary bridge components, stage truss systems, greenhouse structural frames |
| Architectural & Interior | Stair handrails, security window frames, structural furniture frames |
| Vehicle Manufacturing | Trailer chassis frames, recreational vehicle structural frames |
What Negative Tolerance Exceedance Costs on a Fabrication-Grade Order
Dimensional deviation beyond EN10219 limits triggers third-party rejection at destination port.
Outsourced steel fabrication buyers face a recurring problem: mill certificates look acceptable on paper, but actual wall thickness falls below the permissible negative tolerance band. When a third-party inspector measures the tubes at the receiving warehouse, the entire shipment fails acceptance. I watched a full container of square tubes get rejected at Jebel Ali because wall thickness variation exceeded EN 1090 limits — the paperwork was fine, the physical product was not. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]
For buyers sourcing from multiple suppliers, material traceability gaps compound the risk. Steel sourced from third-party mills without integrated production creates broken certification chains. When fabrication-grade tubes demand real dimensional control, not just paperwork, the cost of re-procurement and project delay far exceeds the initial price difference. An ERW square steel tube supplier for structural fabrication who controls the entire chain from raw steel to finished tube eliminates this uncertainty.
How ERW Square Tubes Match Structural Frame Engineering Requirements
Structural frame applications demand consistent load-bearing capacity across every member. The ERW process produces square tubes with uniform wall thickness and a controlled weld seam that meets EN10219 and ASTM A500 requirements for structural use. S235JR and S355 grades provide the yield strength range needed for warehouse frames, stadium trusses, and industrial platform structures. For projects in corrosive environments, galvanized surface treatment extends service life without additional field coating. As an ERW square steel tube supplier for structural fabrication, we deliver tubes with ±1% dimensional tolerance and customized lengths that reduce on-site cutting waste.
Structural Compliance and Certification for International Projects
Engineering specifications for steel structures reference EN 1993 (Eurocode 3) in European markets and AISC standards in North American projects. Both frameworks require hollow structural sections to conform to recognized product standards — EN10219 for cold-formed welded structural hollow sections in Europe, ASTM A500 for cold-formed welded and seamless carbon steel structural tubing in the US. [NEED_CITE: steel grade equivalence between EN 10219 and ASTM A500 standards] CE certification under EN10219 and EN10210 is mandatory for structural steel components entering the European Economic Area. For Middle East and Southeast Asian projects, third-party inspection from SGS or BV provides additional assurance for main contractors and EPC firms. Custom length capability minimizes field splicing, while pre-punched and pre-cut tubes reduce secondary fabrication at the erection site.
Steel Grade Selection and ERW Process Fundamentals
S235JR, S355, Q235B, SS400, and A36 represent three distinct standard systems — European EN, Chinese GB, and American ASTM/Japanese JIS. S235JR and Q235B occupy a similar yield strength range suitable for general structural applications, while S355 provides higher strength for heavier load conditions. The ERW welding process forms the tube by rolling steel strip into a square profile and fusing the seam through electrical resistance heating, producing a clean internal weld bead suitable for structural applications. Unlike seamless tubes, ERW square tubes offer cost efficiency for non-high-pressure structural use while maintaining dimensional accuracy. Surface treatment options include cold rolled (base condition for indoor or painted applications) and hot-dip galvanized (for outdoor or corrosive environments). [NEED_CITE: ERW welded tube manufacturing process and structural applications] Wall thickness tolerance of ±1% ensures that theoretical weight calculations match actual delivered weight — critical for projects priced by tonnage.
The Hidden Cost of Accepting Sub-Tolerance Fabrication Tubes
Purchasing ERW square steel tubes below specified wall thickness creates consequences that surface long after the invoice is paid. Structural engineers design connections and load calculations based on nominal dimensions — when actual wall thickness falls outside the tolerance band defined by EN10219 or ASTM A500, the structural member cannot deliver the assumed load capacity. [NEED_CITE: structural hollow section tolerance requirements under EN 10219] At the project site, this manifests as failed inspection hold points, re-engineering of connections, and schedule delays that dwarf the material cost savings. Certification gaps — missing heat numbers, incomplete mill test certificates, or untraceable material origin — create customs clearance obstacles and liability exposure for general contractors. An ERW square steel tube supplier for structural fabrication with integrated production and full documentation eliminates these downstream risks.
Why Project Buyers Source ERW Square Tubes From Our Mill
Our facility operates three production lines producing over 2,800 specifications of raw steel, giving us direct control over material chemistry and dimensional accuracy from slab to finished tube. Every heat of steel is tested in our own laboratory before rolling, and mill test certificates document chemical composition and mechanical properties with full heat number traceability. We hold CE certification under EN10219 and EN10210, ISO 9001 quality management certification, and accommodate third-party inspection from SGS, BV, and TÜV. Our processing workshop provides CNC cutting, welding (MIG/MAG/SAW), punching, and bending — delivering fabrication-ready components that reduce secondary work at the erection site. Complete quality documentation packages include WPS, PQR, weld maps, dimensional inspection reports, and coating reports. We have supplied structural steel components to projects across the EU, Middle East, Southeast Asia, and Africa, with professional loading plans for oversized and heavy fabricated components.
Documentation & Compliance
- Mill test certificate documenting S235JR, S355, or Q235B chemical composition and mechanical properties per EN10219 or ASTM A500, with full heat number traceability
- CE certificate confirming compliance with EN10219 and EN10210 for structural hollow sections entering European markets
- ISO 9001 quality management system certificate covering the integrated steel production and tube fabrication process
- SGS or BV third-party inspection report available upon request for projects requiring independent verification of dimensions and coating thickness
- Material traceability documentation linking each tube bundle to its originating heat number, rolling record, and test results
- Complete customs documentation package including packing list, bill of lading, and certificate of origin for destination country clearance
Packaging, Loading & Delivery
- ERW square tubes bundled with steel strips and edge protectors to maintain ±1% dimensional tolerance and prevent surface damage during ocean transit
- Galvanized tubes packed with separation layers and moisture barriers to preserve zinc coating integrity throughout the shipping cycle
- Custom length tubes loaded with optimized container stowage plans to maximize payload per 20ft or 40ft container based on section size and wall thickness
- Pre-cut and pre-punched tubes separated by heat number and steel grade markings for clear identification at the fabrication site
- Professional lashing and securing for oversized fabricated components, with loading plans prepared for FOB, CIF, and DDP shipment terms
- Complete export documentation and shipment tracking provided from mill dispatch through to destination port delivery
How to Initiate a Structural Tube Procurement Inquiry
Submit your project drawings (PDF or DWG format), specified steel grades, required standards, quantities, and destination port to receive a detailed quotation within 24 hours. Our engineering team will review shop drawing requirements, confirm material availability across S235JR, S355, and Q235B grades, and provide a production schedule aligned with your project timeline. For non-standard dimensions or custom fabrication requirements, we will coordinate processing specifications and confirm third-party inspection arrangements before contract execution.
Request Your ERW Square Tube Quotation with Mill Test Documentation
Share your project specifications, steel grade requirements, and target delivery port to receive pricing, production lead times, and complete mill test certificate samples.
- 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
Frequently Asked Questions
Q: What is the difference between S235JR, Q235B, and A36 for structural applications?
A: S235JR (EN standard), Q235B (GB standard), and A36 (ASTM standard) occupy similar yield strength ranges and are commonly specified for general structural framing. The choice depends on the project’s governing engineering code — EN 1993 for European projects, GB 50017 for Chinese-designed structures, and AISC for North American specifications. We supply all three grades from integrated production with full cross-referencing documentation.
Q: Can you arrange third-party inspection before shipment?
A: Yes. We accommodate third-party inspection from SGS, BV, and TÜV at our facility before container loading. The inspection covers dimensional verification, wall thickness measurement, weld seam quality, surface treatment coating thickness, and visual examination. Inspection reports are issued directly by the third-party agency and included in the shipping documentation package.
Q: What is the minimum order quantity for custom length ERW square tubes?
A: Custom length capability is available across all standard steel grades. Minimum order quantities depend on the specific section size and wall thickness requested. Contact our team with your dimension requirements to confirm MOQ and production scheduling.
Q: How do you ensure material traceability from production to delivery?
A: Every tube bundle is marked with its originating heat number, steel grade, and section dimensions. Mill test certificates link each heat number to chemical composition and mechanical test results from our in-house laboratory. This traceability chain remains unbroken through processing, packaging, and shipment, ensuring full material certification at destination.
Q: Do you provide fabrication services beyond tube supply?
A: Yes. Our processing workshop offers CNC cutting, welding (MIG/MAG/SAW), punching, and bending services. We deliver fabrication-ready components based on approved shop drawings, reducing secondary work at your project site. Complete quality documentation including WPS, PQR, and dimensional inspection reports accompanies all processed components.
