Description
Factory-direct ERW welded square steel tube supplier — integrated mill production ensures full material traceability from billet to finished 40x40x3mm S355JR and Q235B hollow sections.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S355JR / Q235B ERW Welded Square Steel Tube |
| Product Type | Welded Square Steel Tube (ERW Hollow Section) |
| Steel Grade | S235JR, S355JR, Q235B, SS400, A36 |
| Standard | ASTM A500, EN 10219, EN 10210, JIS G3466, GB/T 6728 |
| Section Shape | Square |
| Size Range | 40×40 mm (4×4 inch) |
| Wall Thickness | 3 mm (12 Gauge) |
| Length | Customized |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Galvanized / Black (as per customer requirement) |
| Tolerance | ±1% |
| Ends | Plain |
| Application | Steel structures / Construction frames / Machinery manufacturing / Infrastructure construction / Furniture and decoration |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC & Industrial Construction | Warehouse portal frames, equipment support columns, mezzanine beam grids |
| Machinery Manufacturing | Conveyor frame structures, automation line supports, crane runway beams |
| Infrastructure | Scaffolding uprights, bridge railing posts, cable tray support systems |
| Commercial Building | Curtain wall sub-frames, canopy structures, partition steel framing |
What Dimensional Tolerance Costs on a 40mm ERW Welded Square Steel Tube Order
±1% tolerance on a 40×40×3mm section means less than 0.4mm deviation per side — but that margin decides whether site crews can bolt connections without reaming holes.
When overseas buyers source ERW welded square steel tube from fragmented suppliers, wall thickness inconsistencies compound across hundreds of pieces. A batch that measures 2.8mm on one side and 3.2mm on another passes theoretical weight checks but fails dimensional inspection at the project site. The result: field rework, rejected connection plates, and schedule delays that no mill test certificate can fix. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]
Matching 40×40 Square Hollow Sections to Structural Frame Requirements
A 40×40×3mm ERW welded square steel tube sits at the intersection of light structural framing and heavy-duty machinery support. The square profile provides equal moment resistance on both axes, making it suitable for column applications where bidirectional loading exists. For warehouse purlin bracing or conveyor support legs, the flat surfaces allow direct bolt-through connections without gusset plates. Our integrated production line runs S355JR and Q235B grades through the same ERW welding station with certified WPS procedures, so whether your drawing calls for European or Chinese standard material, the weld seam quality remains consistent across every bundle.
Engineering Compliance and Surface Treatment Selection for Overseas Projects
Structural frames destined for EU markets require EN 10219 compliance with CE marking, while North American projects specify ASTM A500 Grade B or C. The 40×40×3mm ERW welded square steel tube we produce meets both standard families, but the documentation package differs — EN 10219 demands factory production control certificates and weld seam traceability, whereas ASTM A500 requires chemical composition reports per heat number. For coastal or industrial environments, hot-dip galvanizing to 80 microns minimum extends service life significantly over black finish. [NEED_CITE: steel grade equivalence between EN 10219 and ASTM A500 standards]
Understanding ERW Welding Process and Grade Selection for Square Tubes
ERW (Electric Resistance Welded) forming heats the steel strip edges through electrical resistance and fuses them under pressure — no filler metal, no flux. This process suits square and rectangular hollow sections in the 40mm to 400mm range where wall thickness stays below 12mm. S355JR offers higher yield strength than Q235B, allowing thinner walls for the same load capacity, but requires stricter welding parameter control to avoid seam brittleness. The ±1% tolerance we hold on 40×40×3mm sections means the out-to-out measurement stays between 39.6mm and 40.4mm — tight enough for pre-fabricated connection plates designed to European tolerances. Galvanized finish adds 50-70 microns of zinc coating on all surfaces including the weld seam, providing sacrificial corrosion protection without field painting.
Hidden Costs of Non-Compliant Square Tube Procurement
Ordering ERW welded square steel tube without verified mill test certificates creates downstream risks that surface only during installation. Material supplied under Q235B designation but actually containing lower manganese content will fail impact testing at sub-zero temperatures — a problem invisible until structural connections crack under wind load. Similarly, galvanizing thickness below specification (45 microns instead of 80) accelerates corrosion in tropical climates, forcing complete re-coating at multiples of the original galvanizing cost. [NEED_CITE: structural steel quality verification requirements for imported hollow sections]
Why Source Your ERW Welded Square Steel Tube From Our Integrated Mill
We operate our own steel production facility with dedicated ERW tube mills, eliminating the gap between raw material supplier and fabricator. Every 40×40×3mm S355JR or Q235B square tube we ship carries full traceability from steelmaking heat number through final dimensional inspection. Our in-house laboratory performs chemical analysis, tensile testing, and weld seam flattening tests per EN 10219 before any bundle leaves the warehouse. Third-party inspection through SGS or BV is available at our facility, not at a distant port — meaning defects get caught before containers are sealed. We maintain 2,800+ specifications in stock, so mixed-size orders for warehouse projects ship in single containers without waiting for partial production runs.
Documentation & Compliance
- Mill test certificate documenting S355JR chemical composition and yield strength per EN 10219, with heat number traceability to original steelmaking batch
- CE certificate confirming EN 10219 compliance for structural hollow sections destined for European Union markets
- ISO 9001 quality management certificate covering the full production process from strip slitting through ERW welding and final inspection
- SGS or BV third-party inspection report verifying dimensional tolerance, coating thickness, and weld seam quality before shipment
- Material traceability sheet linking each bundle to specific heat numbers, production dates, and test results
- Complete customs documentation including packing list, bill of lading, and certificate of origin for destination country clearance
Packaging, Loading & Delivery
- Galvanized 40×40×3mm ERW welded square steel tubes bundled with steel strips and edge protectors to preserve zinc coating during ocean transit
- Black finish tubes coated with anti-rust oil and wrapped in waterproof paper before bundling for container loading
- Custom length cutting available from 6m to 12m, with bundles optimized for 20ft or 40ft container payload based on section weight
- Each bundle tagged with heat number, steel grade (S355JR/Q235B), size designation, and production date for site identification
- FOB Qingdao port standard, with CIF and DDP terms available to major construction ports across Africa, Southeast Asia, and Middle East
- Professional loading plans provided for mixed-size orders to maximize container utilization and prevent transit damage
Getting Your ERW Welded Square Steel Tube Quote Started
Send your project drawings or specification list with required steel grade, surface treatment preference, and total tonnage. We return a detailed quotation including material cost, fabrication if needed, coating charges, and shipping terms within 24 hours — along with sample mill test certificates from recent production runs for your engineer’s review.
Request Your ERW Welded Square Steel Tube Quotation
Submit your 40×40×3mm square tube requirements with steel grade and surface treatment preference to receive pricing and mill test certificate samples.
Contact:
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
