Description
Mill-Direct ERW Square Tubes — Vertically integrated from raw steel slab to finished Q235B and Q345B welded hollow sections, eliminating third-party material gaps.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B/Q345B ERW Welded Square Steel Tube |
| Product Type | Welded ERW Square Steel Tube (Hollow Section) |
| Steel Grade | Q195, Q215, Q235, Q345, GR.A, GR.B, S235, S355 |
| Standard | ASTM |
| Section Shape | Square |
| Size Range | 10×10 mm – 600×600 mm |
| Wall Thickness | 0.8 – 30 mm |
| Length | 5.7 m / 6 m (standard) |
| Technique | Welded ERW |
| Surface Treatment | Pre-galvanized / Hot-dipped galvanized / Bare / Oiled |
| Tolerance | ±1% |
| Ends | Plain |
| Application | Steel structures / Construction frames / Machinery / Scaffolding / Furniture / Fluid transport / Pipeline |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Steel Structure & Construction | Building frames, warehouse columns, portal rafters, mezzanine beams |
| Machinery & Equipment | Conveyor support structures, crane booms, equipment bases |
| Scaffolding & Access | Scaffold uprights, cross braces, walkway handrails |
| Infrastructure | Pipeline supports, cable tray frames, signpost structures |
| Furniture & Interior | Display racks, shelving uprights, decorative structural elements |
Wall-Thickness Tolerance Determines Structural Acceptance on Site
A ±1% tolerance on 600×600×20 square tubes means the difference between passing inspector sign-off and full container rejection.
When overseas buyers source an ERW welded square steel tube supplier from China, the most common dispute is not price — it is dimensional accuracy. Negative tolerance beyond acceptable limits triggers third-party inspection failures at destination ports, forcing rework or scrap. Our own steel mill controls slab thickness and rolling reduction directly, so every heat number on the mill test certificate matches the physical product leaving the warehouse. [NEED_CITE: EN 10219 dimensional tolerance requirements for cold-formed hollow sections]
Matching Load-Bearing Requirements Across Structural Frame Applications
An ERW welded square steel tube supplier serving EPC contractors must deliver consistent section properties across the full 10×10 to 600×600 mm range. For warehouse portal frames, Q345B provides higher yield capacity than Q235B in the same cross-section, reducing steel tonnage per project. For scaffolding and light machinery frames, Q195 or Q215 offers adequate strength at lower cost. We supply both grades from the same production line with full heat-number traceability, so procurement teams can consolidate orders without splitting shipments across multiple vendors.
Compliance Pathways for EU, Middle East, and Domestic Projects
Structural hollow sections exported to European markets must conform to EN 10219, which governs cold-formed welded structural hollow sections of non-alloy and fine-grain steels. Middle East specifiers often reference ASTM A500 for cold-formed welded and seamless carbon steel structural tubing. Our Q-series grades (Q235B, Q345B) map directly to S235 and S355 under EN standards, and we provide cross-reference documentation for customs and engineer approval. [NEED_CITE: steel grade equivalence between Chinese GB, European EN, and American ASTM standards] Pre-galvanized finish meets corrosion protection requirements for coastal and industrial environments, while hot-dipped galvanizing extends service life in aggressive atmospheric conditions.
ERW Process, Grade Selection, and Surface Treatment Trade-Offs
ERW (Electric Resistance Welding) produces a longitudinal seam with consistent weld quality suitable for structural and low-pressure fluid applications. Compared to seamless pipe, ERW square tubes offer tighter dimensional tolerance and lower cost per ton — critical for high-volume frame projects. Q235B remains the default structural grade across Asia and Africa for its balance of weldability and strength. Q345B serves heavier load paths where reduced section weight matters. S235 and S355 equivalents are supplied for European-spec projects requiring CE marking. Surface options include bare (oiled for transit protection), pre-galvanized (zinc coating applied before forming), and hot-dipped galvanized (full immersion after fabrication), each selected based on project corrosion category and budget.
Hidden Costs of Sourcing Without Verified Material Certification
Purchasing an ERW welded square steel tube supplier offering prices significantly below market typically means negative tolerance abuse or unverified mill test certificates. The consequences are not theoretical: customs holds due to missing CE documentation, structural inspection failures requiring component replacement, and project delays measured in weeks rather than days. [NEED_CITE: consequences of non-compliant structural steel in international construction projects] An ERW welded square steel tube supplier controlling raw material production eliminates the certification gap between mill and end user.
Why Procurement Teams Consolidate Square Tube Orders With Us
Our fabrication division operates under the same roof as the steel mill producing the raw coil and plate. This means every ERW welded square steel tube we ship carries a mill test certificate generated from our own laboratory, not a third-party trader’s reprint. We hold 2800+ specifications in stock across Q195 through Q345 and S-series equivalents, so custom cut-to-length requests below standard 6 m can be fulfilled without waiting for rolling campaigns. CE certification under EN 10219 and ISO 9001 quality management are standard, with SGS or BV third-party inspection available per shipment. Professional loading plans maximize container utilization for 6 m lengths, and we provide full export documentation including certificate of origin for preferential tariff treatment.
Documentation & Compliance
- Mill test certificate documenting Q235B or Q345B chemical composition and mechanical properties per heat number, issued from our in-house laboratory
- CE certificate confirming EN 10219 compliance for structural hollow sections exported to European Union markets
- ISO 9001 quality management system certificate covering the full production chain from slab to finished square tube
- SGS or BV third-party inspection report available upon request, covering dimensional checks, visual weld inspection, and coating thickness measurement
- Material traceability linking each bundle to its heat number, rolling record, and test results
- Customs documentation package including packing list, bill of lading, and certificate of origin for destination-country tariff claims
Packaging, Loading & Delivery
- Bare Q235B and Q345B square tubes bundled with high-tensile steel strips, ends protected by plastic caps to prevent edge damage during transit
- Pre-galvanized and hot-dipped galvanized tubes packed with edge protectors and separated by rubber spacers to preserve zinc coating integrity
- Standard 5.7 m and 6 m lengths loaded in 20ft and 40ft containers with optimized stowage plans minimizing void space and shifting risk
- Cut-to-length square tubes below 6 m available per drawing, bundled separately with clear length marking on each piece
- Heat number and steel grade stenciled on each bundle tag, matching mill test certificate for site verification
- FOB, CIF, and DDP terms supported, with door-to-door logistics coordination to project sites across the Middle East, Southeast Asia, and Africa
Getting Your Quotation and Material Certification Started
Send your project drawings or specification list including square tube dimensions, wall thickness, steel grade, surface treatment, and total tonnage. We return a detailed quotation with material cost, fabrication charges if applicable, coating options, and estimated production lead time within 24 hours. Mill test certificates and CE documentation are confirmed at quotation stage, not after order placement.
Request Your ERW Square Tube Quotation With Full Mill Documentation
Submit your size schedule, steel grade, and destination port to receive pricing and material certification details.
Contact: admin@xjystructure.com | WhatsApp: +86 188 5315 7756
