Description
Factory-Direct Welded Square Steel Tube — Direct mill supply of Q235/Q345/S235/S355 welded square steel tubes with full EN 10219 compliance and in-house dimensional testing before every shipment.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235/Q345/S235/S355 Welded Square Steel Tube |
| Product Type | Welded Square Steel Tube (RHS/SHS) |
| Steel Grade | Q195, Q215, Q235, Q345, GR.A, GR.B, S235, S355 |
| Standard | EN 10219, ASTM A500, GB/T 6728 |
| Section Shape | Square |
| Size Range | 10×10 mm – 600×600 mm |
| Wall Thickness | 0.8 – 30 mm |
| Length | 5.7 m / 6 m |
| Technique | Welded ERW |
| Surface Treatment | Bare / Pre-galvanized / Hot-dipped galvanized / Oiled |
| Tolerance | ±1% |
| Ends | Plain |
| Invoicing | By Theoretical Weight |
| Application | Structure Pipe / Construction frames / Steel structures / Machinery / Scaffolding |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & EPC | Building frames, column supports, roof trusses for commercial and industrial facilities |
| Steel Structure Fabrication | Primary and secondary structural members for warehouses, workshops, and multi-story buildings |
| Scaffolding & Shoring | Vertical standards, ledger braces, and base plates for modular scaffolding systems |
| Machinery Manufacturing | Structural frames for conveyors, crane booms, and equipment bases |
| Infrastructure Projects | Bridge handrails, sound barrier supports, and solar panel mounting structures |
Where Negative Tolerance on EN Standard Welded Square Steel Tube Supplier Orders Triggers Customs Rejection
Wall thickness tolerance is the single most common reason welded square steel tubes fail SGS re-inspection at destination ports.
I once saw a container of EN 10219 RHS held at Rotterdam for three weeks because the client’s SGS re-inspection found wall thickness negative tolerance reached -12%, and the CE certificate wrongly referenced EN 10210 instead of 10219. The tubes were structurally sound, but the documentation and dimensional compliance were both wrong. That shipment taught our entire quality team one lesson: every EN standard welded square steel tube supplier order must be verified in-house before loading — not just sampled, but measured on every piece.
When procurement teams source welded square steel tubes for EU or regulated markets, the hidden risk is not the steel itself but the tolerance stack-up and certificate mismatch. Mills that invoice by theoretical weight without controlling negative tolerance deliver tubes that look correct on paper but fail on-site measurement. [NEED_CITE: EN 10219 cold-formed hollow section requirements]
How 10-600mm Square Sections Match Structural Frame and Scaffolding Load Paths
Welded square steel tubes in the 10×10 to 200×200 mm range with wall thickness 0.8–6 mm are the standard choice for scaffolding uprights and light structural frames, where self-weight and ease of handling matter more than raw load capacity. For primary building columns and heavy machinery bases, the 200×200 to 600×600 mm range with wall thickness up to 30 mm provides the section modulus needed to resist bending moments without adding excessive weight. Our ERW welded square steel tube production covers this full range in Q235, Q345, S235, and S355 grades, with in-house lab testing confirming dimensional accuracy before any container is sealed.
Engineering Compliance: EN 10219, ASTM A500, and Surface Protection Selection
Structural hollow sections for European projects must comply with EN 10219-1 for technical delivery conditions and EN 10219-2 for tolerances, dimensions, and sectional properties. [NEED_CITE: EN 10219 cold-formed hollow section requirements] For North American projects, ASTM A500 Grade B or C is typically specified, with S235JR and S355J2 serving as common EN equivalents to GR.B and GR.C respectively. Surface treatment selection depends on the service environment: bare tubes with shop primer suit indoor structural frames, pre-galvanized tubes handle moderate outdoor exposure, and hot-dipped galvanized tubes are specified for coastal or industrial corrosion zones. Mill test certificates must reference the exact standard ordered — EN 10219 for European delivery, ASTM A500 for North American — as mixing certificate references blocks customs clearance.
Steel Grade Selection: Q235 vs S235 vs ASTM GR.B in Structural Applications
Q235 and S235JR are broadly equivalent in yield strength and chemical composition, both suitable for general structural frames and scaffolding where moderate load capacity is required. Q345 and S355J2 offer higher yield strength for primary structural members, bridge components, and heavy machinery frames where deflection limits are tighter. ASTM A500 GR.B aligns closely with S235JR, while GR.C corresponds to S355J2 in most structural applications. The ERW welding process used for these welded square steel tubes produces a consistent weld seam with mechanical properties matching the parent material, making it cost-effective for structural applications up to 30 mm wall thickness. For projects requiring full traceability, each tube is marked with heat number, steel grade, and standard designation.
The Hidden Cost of Wrong Certificate References and Uncontrolled Negative Tolerance
Procuring welded square steel tubes without verifying the mill test certificate against the ordered standard creates downstream risk: a certificate referencing EN 10210 when EN 10219 was specified will be rejected by EU customs, regardless of whether the tubes themselves meet dimensional requirements. Uncontrolled negative tolerance — where actual wall thickness falls below the permitted deviation — triggers rejection at third-party re-inspection, even if the tubes passed the originating mill’s check. The cost is not just the rejected shipment but the project delay: replacement tubes must be manufactured, shipped, and re-inspected, often pushing construction schedules back by weeks. [NEED_CITE: steel grade equivalence between EN and ASTM standards]
Why SD XJY Pipe Delivers EN Standard Welded Square Steel Tube Supplier Orders with Full Compliance
Every EN standard welded square steel tube supplier order from our mill undergoes dimensional and chemical testing in our in-house physical and chemical laboratory before loading — not sampled, but verified. We hold Lloyd’s CE certification specifically referencing EN 10219 and EN 10210, Singapore FPC, and ISO 9001:2015, ensuring that the certificate you receive matches the standard you ordered. Our production lines cover 2,800+ specifications across square, rectangular, and round sections with wall thickness up to 40mm, meaning non-standard sizes and heavy-wall tubes are available without sourcing from multiple suppliers. We are the original inventor of sharp-corner rectangular steel tubes in China, holding 41 patents for this proprietary technology, which provides superior aesthetics and structural performance for glass curtain walls and architectural facades. Professional container loading with anti-damage measures ensures tubes arrive without bending or surface damage, and we export to 50+ countries with complete documentation for customs clearance.
Documentation & Compliance
- Mill test certificate documenting Q235/Q345/S235/S355 chemical composition and mechanical properties per EN 10219-1 or ASTM A500 as ordered
- Lloyd’s CE certificate referencing EN 10219 for European market delivery, with correct standard designation matching the purchase order
- ISO 9001:2015 quality management certificate covering the full production process from raw material to finished welded square steel tube
- SGS or BV third-party inspection report available upon request, covering dimensional verification, weld seam quality, and surface treatment thickness
- Material traceability by heat number stamped on each tube, linking back to the original mill test certificate
- Complete customs documentation including packing list, bill of lading, and certificate of origin for destination port clearance
Packaging, Loading & Delivery
- Bare welded square steel tubes bundled with steel strips and edge protectors to prevent surface damage during ocean transit, with oil coating applied for temporary rust prevention
- Hot-dipped galvanized tubes packed with rubber separators between layers to preserve the zinc coating, bundled in seaworthy packaging suitable for 6 m length containers
- Pre-galvanized tubes wrapped in waterproof paper and bundled with steel strips, optimized for 20ft and 40ft container loading based on side length and wall thickness
- Custom cutting to project-specific lengths available, with 5.7 m and 6 m standard lengths cut to order for scaffolding and structural frame applications
- Heat number, steel grade, and standard designation marked on each tube at 1 m intervals for on-site traceability and inspection verification
- FOB, CIF, and DDP shipping terms available, with professional container loading plans optimized for 10×10 to 600×600 mm square sections to maximize payload per container
Submit Your EN Standard Welded Square Steel Tube Supplier Inquiry for Mill Test Certificate Review
Provide your required side length, wall thickness, steel grade, surface treatment, quantity, and destination port, and we will respond within 12 hours with a detailed quotation including unit price, lead time, and shipping terms. We will also attach a sample mill test certificate for your review, confirming that the certificate standard matches your project specification before you place an order. For non-standard sizes or heavy-wall tubes outside the 10×10 to 600×600 mm range, our engineering team will provide a custom production plan with dimensional drawings.
Request Your EN Standard Welded Square Steel Tube Supplier Quotation with Full Mill Test Certificate
Submit your specifications via email at admin@sdxjypipe.com or contact us via WhatsApp at +86 188 5315 7756 to receive your quotation and sample mill test certificate within 12 hours.
