Description
Mill-Direct ERW Square Tube Supply — XJY Structure operates its own steel production lines alongside the fabrication workshop, so every S355JR ERW square steel tube shipped carries full heat-number traceability back to our mill without third-party sourcing gaps.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Carbon Steel Square Steel Tube |
| Product Type | Welded Square Steel Tube (ERW) |
| Steel Grade | Gr.B, S235, S275, S355, STK400, Q235B, Q345B |
| Standard | ASTM A500, ASTM A53, GB/T 3091, EN 10219 |
| Section Shape | Square |
| Size Range | 19mm×19mm – 800mm×800mm |
| Wall Thickness | 1 – 30 mm |
| Length | 5.8m / 6m / 11.8m / 12m / Random Length |
| Technique | ERW (Welded) |
| Surface Treatment | Black Painting / Galvanized / Varnish / Bare |
| Tolerance | ±1% |
| Ends | Plain |
| Application | Construction structures / Building frames / Curtain wall supports / Machinery / Scaffolding / Industrial platforms |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Commercial & Industrial Construction | Steel frame structures, building columns, warehouse portal frames for EPC and general contractor projects |
| Facade & Curtain Wall Engineering | Curtain wall support systems, mullion tubes, scaffolding structures for high-rise buildings |
| Machinery & Equipment Manufacturing | Machinery bases, industrial platform structures, conveyor frame supports requiring dimensional accuracy |
| Infrastructure & Civil Engineering | Bridge walkway supports, utility platform frames, renewable energy mounting structures |
When Wall-Thickness Tolerance Decides Whether the Whole Shipment Clears Customs
A ±1% tolerance on a 30mm-wall S355JR ERW square steel tube means the difference between structural acceptance and port rejection.
Overseas buyers outsourcing square tube procurement often discover material traceability breaks at the mill-to-fabricator handoff. When a third-party fabricator sources raw material from an unverified mill, heat numbers disappear, and EN 10219 compliance documentation becomes impossible to reconstruct. [NEED_CITE: EN 10219 cold-formed welded structural hollow sections certification requirements] Negative tolerance abuse — where wall thickness sits permanently at the lower limit — reduces load-bearing capacity below design calculations, triggering rejection during third-party inspection at destination ports. For EPC firms managing multi-million-dollar infrastructure projects, a single container of non-conforming tubes can delay an entire erection schedule by weeks.
How 1–30mm Wall Thickness Covers Both Light Framing and Heavy-Load Columns
From 19×19mm light-gauge tubes used in curtain wall supports to 800×800mm heavy sections forming primary building columns, the S355JR ERW square steel tube range spans structural requirements across commercial, industrial, and infrastructure projects. The ERW welding process delivers consistent seam quality across the full 1–30mm wall thickness range, while ±1% dimensional tolerance ensures connection plates and bolt-hole patterns match shop drawings without on-site rework. XJY Structure’s vertically integrated supply chain — raw steel production through to finished fabricated components — means every heat number traces back to our own mill, eliminating the material certification gaps that plague broker-sourced procurement.
Structural Compliance Across EN, ASTM, and GB Specification Frameworks
European projects specifying EN 10219 require CE-marked hollow sections with full chemical and mechanical test documentation, while North American tenders reference ASTM A500 Grade B or Grade C with corresponding mill test certificates. [NEED_CITE: steel grade equivalence mapping between EN 10219 and ASTM A500 standards] The S-series grades (S235, S275, S355) map directly to increasing yield strength levels suitable for progressively heavier structural applications, while Q235B and Q345B serve domestic-standard projects across Southeast Asia and Africa. STK400 meets JIS requirements for Japanese-specification infrastructure contracts. Surface treatment selection — hot-dip galvanized for coastal or industrial corrosion environments, black painted for interior dry conditions, or bare for projects applying site-applied coating systems — must align with the project’s corrosion-protection specification before fabrication begins.
Understanding ERW Welding, Steel Grade Selection, and Surface Protection Trade-Offs
The ERW (Electric Resistance Welding) process forms square tubes by cold-forming steel strip into shape and welding the seam through electrical resistance heat — delivering dimensional accuracy and cost efficiency for structural applications where seamless tubes are not required. Unlike SSAW (spiral submerged arc welding), ERW produces straight seams with minimal heat-affected zones, making it suitable for the precise dimensional tolerances demanded by bolted and welded structural connections. Steel grade selection directly governs load-bearing capacity: S235 serves light structural framing, S275 covers medium-duty industrial platforms, while S355 provides the higher yield strength required for primary building columns and heavy-load transfer beams. [NEED_CITE: structural steel grade yield strength hierarchy in EN 10025 and EN 10219] Wall thickness tolerance matters critically — a 10mm nominal wall measured at 9.5mm due to negative tolerance abuse carries approximately 10% less load capacity than calculated, a discrepancy that only surfaces during structural loading tests or third-party inspection. Hot-dip galvanizing provides 50–80μm zinc coating for long-term corrosion protection in outdoor or humid environments, while black painting suits interior applications where appearance and moderate rust prevention suffice.
The Hidden Cost of Buying Square Tubes Without Verified Material Traceability
Correct steel grade selection and verified mill test certificates cost marginally more upfront than broker-sourced alternatives — but material substitution, missing certification, or tolerance abuse creates exponential downstream costs. [NEED_CITE: consequences of non-conforming structural steel in international construction projects] Engineering inspectors rejecting weld connections due to untraceable material, customs authorities holding containers lacking EN 10204 3.2 certificates, or structural engineers discovering actual wall thickness falls below design minimums — each scenario triggers rework, schedule delays, and contractual penalties that dwarf the original procurement savings. For S355JR ERW square steel tube orders destined for EU markets, CE marking compliance with EN 10219 is not optional documentation — it determines whether the shipment enters the country or sits at port awaiting return.
Why Vertically Integrated Production Eliminates the Procurement Gaps That Cause Project Delays
XJY Structure operates both steel production lines and fabrication workshops under one roof, controlling material from raw slab to finished S355JR ERW square steel tube — this integration eliminates the handoff gaps where material certificates get lost between independent mills and fabricators. Our in-house理化实验室 issues Mill Test Certificates with full heat-number traceability, while third-party inspection through SGS, BV, or TUV remains available at every production stage for clients requiring independent verification. The 2,800+ specification range covers every standard size from 19×19mm to 800×800mm, while custom cut-to-length service at 5.8m, 6m, 11.8m, or 12m reduces on-site waste and welding joints. CE marking to EN 10219, ISO 9001 certification, and complete export documentation packages ensure smooth customs clearance across EU, Middle East, Southeast Asian, and African markets. Professional container loading plans maximize payload for 11.8m and 12m lengths while protecting surface treatment through edge protectors and seaworthy bundling.
Documentation & Compliance
- Mill Test Certificate documenting S355JR chemical composition and yield strength per EN 10219, with heat-number traceability to XJY Structure’s own steel production lines
- CE Certificate confirming EN 10219 compliance for European market projects requiring Factory Production Control certification
- ISO 9001 Quality Management System certificate covering the full production process from raw material incoming inspection through final dimensional and coating verification
- SGS / BV / TUV Third-Party Inspection Report available at pre-production, in-process, and pre-shipment stages for clients requiring independent quality verification
- Material Traceability Documentation linking every S235, S275, S355, or Q345B tube to its original heat number, chemical composition report, and mechanical test results
- Customs Clearance Package including packing list, bill of lading, certificate of origin, and commercial invoice formatted for destination-country import requirements
Packaging, Loading & Delivery
- S355JR and S235 square tubes bundled with high-tensile steel strips at minimum three points per bundle, preventing shift during ocean transit and crane handling
- Galvanized square tubes packed with edge protectors and plastic end caps to preserve zinc coating integrity and prevent white rust formation during container shipping
- 11.8m and 12m lengths loaded in 20ft and 40ft containers using optimized stowage plans maximizing payload while maintaining weight distribution within port handling limits
- Custom cut-to-length service at 5.8m, 6m, 11.8m, or 12m reduces on-site cutting waste and eliminates field welding joints for scaffolding and curtain wall applications
- Every bundle marked with heat number, steel grade (S355JR / S235 / Q345B), size specification, and XJY Structure identification for site traceability and inspection verification
- FOB, CIF, and DDP shipping terms available with professional export documentation and door-to-door logistics coordination for project sites across EU, Middle East, and Southeast Asia
Getting Your S355JR ERW Square Steel Tube Quote Started
Submit your project drawings, steel grade requirements, size specifications, and destination port — XJY Structure responds within 24 hours with preliminary pricing, shop drawing timeline, and Mill Test Certificate sample. For non-standard sizes or custom cut-to-length requirements, our engineering team reviews feasibility and provides fabrication sequencing recommendations before contract signing.
Request Pricing and Material Certification
Send your specifications, steel grade, quantity, and destination port to receive a detailed quotation including material, fabrication, coating, packing, and shipping costs with full Mill Test Certificate documentation.
Contact XJY Structure
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
