Description
Mill-Direct ERW Square Tubes — S355 and S235JR grades produced on our own rolling lines with full heat-number traceability from slab to finished 40×60 mm section.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S355 ERW Square Steel Tube |
| Product Type | Welded Square Steel Tube |
| Steel Grade | S235JR, A36, S355, SS400, Q235B |
| Standard | BS, EN, GB, AISI, ASTM, DIN, JIS |
| Section Shape | Square |
| Side Length | 40×60 mm |
| Length | Customized |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Cold Rolled |
| Tolerance | ±1% |
| Ends | Plain |
| Oiled or Non-oiled | Non-oiled |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Application | Building structures, Curtain wall systems, Machinery, Home decor, Steel frames |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Commercial Construction | Curtain wall龙骨 framing, interior partition steel frames, facade support grids |
| Industrial Infrastructure | Machinery base frames, conveyor support structures, platform handrails |
| Residential & Decorative | Furniture steel frames, interior structural columns, balustrade posts |
What Dimensional Tolerance Costs on a Curtain Wall Frame Order
Tight tolerance on 40×60 mm ERW square tubes determines whether field welds align or require costly rework.
When overseas buyers source welded steel tubes from fragmented suppliers, dimensional drift beyond ±1% forces on-site grinding, re-drilling, or even component rejection. Material traceability gaps compound the problem — without a continuous chain from steel mill to finished tube, project engineers cannot verify whether S355 grade claims match actual chemistry. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]
Matching 40×60 mm Sections to Curtain Wall and Machinery Frame Loads
The 40×60 mm rectangular profile delivers higher section modulus along the 60 mm axis compared to equal-leg squares, making it a preferred choice for curtain wall mullions and machinery base frames where bending resistance matters in one direction. Our ERW welded square steel tube production maintains ±1% tolerance across customized lengths, ensuring that site-cut pieces fit into pre-drilled connection plates without forcing. The cold rolled surface arrives non-oiled and ready for immediate painting or powder coating — no degreasing delay on the assembly line.
Engineering Compliance and Certification for Structural Frame Applications
Structural frames in EU markets require EN 10219 compliance with CE marking, while North American projects specify ASTM A500 or A36 equivalence. Our S355 and S235JR grades meet EN 10219 requirements; A36 and Q235B serve ASTM and GB-specification projects respectively. [NEED_CITE: steel grade equivalence between EN S355JR and ASTM A36] Plain ends come ready for field welding per approved WPS procedures, and our in-house processing — cutting, punching, bending — reduces secondary fabrication at the job site. Third-party inspection by SGS or BV confirms dimensional accuracy and weld seam integrity before shipment.
Understanding ERW Welding and Cold Rolled Surface for Square Tubes
Electric Resistance Welding fuses the steel strip edges through heat and pressure without filler metal, producing a clean internal bead suitable for structural applications where internal flow or corrosion is not a concern. The cold rolled surface finish on our 40×60 mm tubes provides tighter dimensional control than hot rolled alternatives, with smoother faces that accept paint and coating systems uniformly. S355 grade offers higher yield strength than S235JR, allowing thinner wall sections for equivalent load capacity — a weight and cost advantage on large-frame projects. [NEED_CITE: ERW versus seamless steel tube manufacturing process comparison]
The Hidden Cost of Unverified Steel Grade and Tolerance
Ordering S355 square tubes that arrive with S235 chemistry means the structure carries lower load capacity than engineered — a safety risk that surfaces only during final inspection or, worse, under service load. Tolerance drift beyond ±1% on 40×60 mm sections forces field modification: grinding oversized corners, re-drilling misaligned bolt holes, or scrapping pieces that no longer fit connection details. Missing mill test certificates delay customs clearance in markets requiring EN 10219 or ASTM A500 documentation. [NEED_CITE: consequences of material non-compliance in structural steel procurement]
Why Source Your ERW Welded Square Steel Tube From Our Mill
We operate our own steel production facility with three rolling lines and over 2,800 specifications in raw material inventory — meaning your 40×60 mm S355 tubes come from a single source with uninterrupted heat-number traceability from slab to finished product. Our fabrication division handles cutting, punching, bending, and welding to your shop drawings, eliminating the gap between material supplier and processor. Every batch ships with complete quality documentation: WPS, PQR, dimensional inspection reports, and coating certificates. We hold CE certification under EN 10219 and ISO 9001 quality management, with third-party inspection available through SGS or BV for projects requiring independent verification.
Documentation & Compliance
- Mill test certificate documenting S355JR chemical composition and mechanical properties per EN 10219, with heat number traceability to original slab
- CE certificate confirming EN 10219 compliance for structural hollow sections exported to EU member states
- ISO 9001 quality management certificate covering the full production chain from steelmaking to finished tube
- SGS or BV third-party inspection report verifying dimensional tolerance and ERW weld seam quality for 40×60 mm sections
- Material traceability documentation linking each bundle to its heat number, chemical analysis, and mechanical test results
- Customs documents including packing list, bill of lading, and certificate of origin for import clearance
Packaging, Loading & Delivery
- Cold rolled S355 and S235JR square tubes bundled with steel strips and edge protectors to preserve surface finish during ocean transit
- Non-oiled 40×60 mm sections wrapped in waterproof paper to prevent surface oxidation before arrival at the fabrication shop
- Custom cut lengths loaded into 20ft or 40ft containers with optimized stowage to maximize payload while preventing bundle shift
- Heat number and steel grade stenciled on each bundle for immediate site identification and traceability verification
- FOB, CIF, or DDP delivery terms available with professional loading supervision and complete export documentation
Start Your Procurement With Drawings and Specifications
Share your project drawings in PDF or DWG format along with steel grade requirements, quantity, and destination port — we respond within 24 hours with a detailed quotation including material cost, processing charges, and shipping terms. Our engineering team reviews shop drawings for material optimization and fabrication sequencing before production begins, ensuring your 40×60 mm ERW welded square steel tube order arrives with full certification and on schedule.
Frequently Asked Questions
Q: What is the difference between S355JR and A36 steel grade for square tubes?
A: S355JR is a European standard grade under EN 10219 with minimum yield strength of 355 MPa for thickness up to 16 mm, while A36 is an ASTM standard with minimum yield strength of 250 MPa. Both grades serve structural applications, but S355JR allows thinner wall sections for equivalent load capacity. We supply both grades with full mill test certificates documenting chemical composition and mechanical properties.
Q: Can you provide third-party inspection for dimensional tolerance and weld quality?
A: Yes, we arrange SGS or BV third-party inspection before shipment to verify dimensional accuracy within ±1% tolerance and ERW weld seam integrity. The inspection report accompanies your mill test certificate as part of the complete quality documentation package for project compliance.
Q: What surface treatment options are available for cold rolled square tubes?
A: Our 40×60 mm ERW welded square steel tube comes with cold rolled surface finish and non-oiled condition, ready for immediate painting, powder coating, or galvanizing. We do not offer hot dip galvanizing in-house, but the smooth cold rolled surface accepts zinc coating uniformly when processed by your local galvanizer.
Q: What is the minimum order quantity for customized lengths?
A: We accept customized length orders based on project requirements. For standard stock sizes, typical minimum order applies; for non-standard dimensions or processing services including cutting, punching, and bending, we evaluate each inquiry based on drawing complexity and production scheduling.
Q: Do you provide shop drawing review and engineering support?
A: Yes, our engineering team reviews your project drawings before fabrication begins, providing material optimization recommendations and fabrication sequencing guidance. This service helps reduce field rework and ensures your ERW welded square steel tube order fits connection details as designed.
Request Your Quotation With Full Certification Package
Submit your project specifications, steel grade requirements, and destination port to receive a detailed quotation with mill test certificate commitment within 24 hours.
Contact:
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
