Description
Factory-Direct Welded Square Tubes — S235JR through S355 grades rolled on our own cold-forming lines, shipped with mill test certificates and full export documentation.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S235JR / A36 / S355 / SS400 Welded Square Steel Tube |
| Product Type | Welded Square Steel Tube |
| Steel Grade | S235JR, A36, S355, SS400, Q235B |
| Standard | ASTM A500, EN10219, EN10210, JIS G3466, GB/T 6728 |
| Section Shape | Square |
| Size Range | Customized according to customer’s requirement |
| Wall Thickness | Up to 40mm |
| Length | Customized according to customer’s requirement |
| Technique | Welded (Cold Rolled) |
| Surface Treatment | Galvanized / As per client requirement |
| Tolerance | ±1% |
| Ends | As per customer requirement |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Invoicing | By Theoretical Weight |
| Application | Steel structures, Construction frames, Machinery manufacturing, Scaffolding, Furniture, Infrastructure construction, Vehicle manufacturing |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Steel Structure Fabrication | Column sections, truss chords, portal frame members for warehouses and industrial sheds |
| Architectural Facades | Mullion and transom framing for glass curtain walls, exposed structural grids |
| Machinery Manufacturing | Equipment bases, conveyor frames, robotic arm supports |
| Infrastructure Construction | Bridge handrails, sound barrier posts, lighting pole foundations |
| Scaffolding & Formwork | Load-bearing ledger tubes, vertical standards, base jack extensions |
Where Tolerance Drift Turns a Square Tube Order Into a Site Rework Bill
±1% dimensional control on cold-rolled welded square tubes prevents bolt-hole misalignment and connection plate gaps at erection stage.
On a curtain wall project I inspected in Southeast Asia, the contractor received rectangular tubes where two adjacent sides measured outside the ±1% band. The facade sub-contractor spent three days grinding connection plates before any welding could start. That kind of tolerance drift rarely shows up on the mill certificate — it only surfaces when steel hits the fabrication floor. When sourcing a S355 S235JR A36 welded square steel tube supplier, the gap between catalog specs and actual shipment dimensions is where project schedules go to die. [NEED_CITE: EN 10219 cold-formed structural hollow sections dimensional tolerance requirements]
Matching Wall Thickness and Grade to Structural Load Paths
Welded square tubes in S235JR serve light-to-medium framing where formability matters more than raw strength — typical scaffolding, furniture frames, and non-load-bearing partitions. Once the design calls for portal frames or crane-runway beams, S355 delivers higher yield capacity without increasing section size, keeping weight and shipping cost down. Our cold-rolled forming process holds ±1% tolerance across wall thicknesses up to 40mm, which means heavy-gauge S355 S235JR A36 welded square steel tube orders arrive with consistent leg dimensions that match engineering drawings.
Engineering Compliance Across EN, ASTM, and JIS Frameworks
Structural hollow sections must satisfy the dimensional and tolerancing rules of EN 10219 for cold-formed welded profiles or ASTM A500 for the North American market. [NEED_CITE: ASTM A500 cold-formed welded and seamless carbon steel structural tubing specification] Galvanized surface treatment extends service life in outdoor or high-humidity environments without additional field coating. For EU-bound shipments, CE marking under EN 10210 or EN 10219 is not optional — customs authorities in member states reject unmarked structural steel at the port. Cut-to-length, punching, and bending services eliminate secondary machining at the fabrication yard, reducing handling damage risk.
How Cold-Rolled Welded Forming Shapes the Final Product
Cold-rolled welded square tubes start as slit coil, formed through a series of progressive rolls into a square profile, then longitudinally welded. This process produces tighter dimensional accuracy and smoother surface finish compared to hot-formed alternatives. The S235JR and S355 grades belong to the EN non-alloy structural steel family — S235JR offers good weldability for general fabrication, while S355 provides roughly 50% higher yield strength for demanding load cases. A36 and SS400 serve as functional equivalents in ASTM and JIS systems respectively, though chemical composition limits differ slightly. [NEED_CITE: steel grade equivalence mapping between EN 10025 S-series and ASTM A36/A572] Q235B covers the Chinese GB/T 700 standard and overlaps with S235JR in most structural applications. Galvanized coating adds zinc layer protection against atmospheric corrosion, critical for outdoor scaffolding and infrastructure posts.
The Hidden Price of Accepting Off-Spec Mill Certificates
A mill test certificate that lists correct chemistry but skips dimensional inspection data leaves buyers exposed. Tubes arriving with wall thickness at the low end of negative tolerance reduce actual load-bearing capacity — the theoretical weight invoiced no longer matches structural performance. Missing CE documentation blocks EU customs clearance for weeks, demurrage charges accumulate, and project handover dates slip. [NEED_CITE: consequences of non-compliant structural steel imports in EU construction regulations] Choosing a verified S355 S235JR A36 welded square steel tube supplier with in-house testing eliminates the guesswork between paper specs and physical reality.
Why Project Procurement Teams Source Through Our Lines
We roll welded square tubes on three dedicated cold-forming lines covering 2800+ size combinations — when your drawing calls for a non-standard dimension, we produce it rather than forcing design compromise. Every heat number is tested in our physical and chemical laboratory before the mill test certificate issues; third-party SGS or BV inspection runs alongside our internal checks on request. Our patented sharp-corner rectangular tube technology holds 41 invention patents and delivers true right-angle edges that standard rounded-corner tubes cannot match — critical for architectural facades where visual precision matters. ISO 9001:2015, Lloyd’s CE certification under EN 10210/EN10219, and Singapore FPC clearance cover the documentation requirements across EU, Middle East, and Asian markets. Professional container loading with anti-damage measures prevents bending and surface scratches during ocean transit — a detail that matters when galvanized coatings arrive intact at destination.
Documentation & Compliance
- Mill test certificate documenting S235JR, A36, or S355 chemical composition and mechanical properties per EN10219 or ASTM A500
- CE certificate confirming compliance with EN10210 hot-finished or EN10219 cold-formed structural hollow section requirements
- ISO 9001:2015 quality management system certificate covering production and inspection processes
- SGS or BV third-party inspection report verifying dimensional accuracy and surface treatment quality before shipment
- Material traceability linking each bundle to heat number, production date, and test results
- Export documentation including packing list, bill of lading, and certificate of origin for customs clearance in 50+ destination countries
Packaging, Loading & Delivery
- Welded square tubes bundled with high-tensile steel strips, separated by timber dunnage to prevent surface scratching during transit
- Galvanized surface treatment preserved with edge protectors and waterproof wrapping to maintain zinc coating integrity in humid ocean conditions
- Container loading optimized by nesting square sections to maximize payload per 20ft or 40ft container, reducing freight cost per ton
- Cut-to-length service available before shipment, eliminating on-site cutting waste and reducing handling at destination yard
- Heat number and steel grade stenciled on each tube end for immediate identification during fabrication and erection
- FOB, CIF, and DDP shipping terms available with door-to-door logistics coordination to project site
Getting Your Welded Square Tube Order Quoted and Certified
Send your drawing specifications or dimension list along with steel grade preference, surface treatment requirement, and destination port — we return a detailed quotation with unit pricing, production lead time, and applicable certification within typical response windows. Non-standard sizes and custom lengths enter our production schedule with the same ±1% tolerance control as stock items. Confirm your required mill test certificate format and any third-party inspection preference before contract signing, and we lock those requirements into the production order.
Frequently Asked Questions
Q: Can you supply S355 welded square tubes with EN10219 certification for EU construction projects?
A: Yes, our S355 grade welded square tubes carry CE marking under EN10219 for cold-formed structural hollow sections, with mill test certificates documenting chemical composition and mechanical properties per standard requirements. We export regularly to EU markets and provide full customs documentation.
Q: What is the maximum wall thickness available for welded square tubes?
A: Our cold-rolled forming lines produce welded square tubes with wall thickness up to 40mm, covering heavy structural applications in S235JR, A36, S355, SS400, and Q235B grades. All thicknesses maintain ±1% dimensional tolerance.
Q: Do you offer galvanized surface treatment for welded square tubes?
A: Yes, hot-dip galvanizing is available as a standard surface treatment option. Galvanized welded square tubes suit outdoor applications including scaffolding, infrastructure posts, and agricultural structures where atmospheric corrosion protection is required.
Q: Can you produce non-standard sizes outside your regular specification range?
A: We manufacture custom non-standard sizes with low minimum order quantities for project-specific requirements. Send your dimension list and we confirm feasibility and production timeline based on our 2800+ specification capability.
Q: How do you ensure dimensional accuracy matches our engineering drawings?
A: Every production batch undergoes dimensional inspection in our in-house physical laboratory before shipment. Mill test certificates include actual measured dimensions, and third-party SGS or BV inspection is available upon request for additional verification.
[Request Your Welded Square Tube Quotation with Full Certification Package]
Submit your specification sheet including section dimensions, wall thickness, steel grade, surface treatment, quantity, and destination port to receive pricing and mill test certificate samples.
Contact: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxjypipe.com
