Description
Factory-Direct ERW Square Tube Mill — We roll, cut, and ship S235JR / S355 / Q235B ERW welded square steel tube from our own production line with full mill traceability.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S235JR / S355 / Q235B ERW Welded Square Steel Tube |
| Product Type | Welded Square Steel Tube (SHS) |
| Steel Grade | S235JR, A36, S355, SS400, Q235B |
| Standard | BS, EN, GB, AISI, ASTM, DIN, JIS |
| Section Shape | Square |
| Size Range | 40×40 mm, 40×60 mm |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Non-oiled / Cold Rolled finish |
| Tolerance | ±1% |
| Length | Customized |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Invoicing | By Theoretical Weight |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Building Construction | Curtain wall frames, structural columns, portal frames |
| Machinery Manufacturing | Equipment bases, conveyor supports, machine guards |
| Architectural Decoration | Interior structural frames, display stands, modern furniture skeletons |
| Infrastructure Projects | Sound barrier supports, signage gantries, walkway handrails |
Dimensional Tolerance Is Where Square Tube Projects Actually Fail
A ±1% tolerance on a 40×60 mm ERW welded square steel tube is the difference between a frame that bolts together on site and one that gets re-cut at the fabricator’s yard.
I still remember a 40×60 mm square tube order we shipped to the Middle East. The wall thickness ran past the negative tolerance limit, the client measured it on site with a caliper, and the whole container came back. Since then, every batch I ship gets checked against the ±1% tolerance before loading, with the original mill test certificate and a pre-loading video sent to the buyer. [NEED_CITE: EN 10219 dimensional tolerance requirements for cold formed hollow sections]
When buyers source ERW welded square steel tube from multiple suppliers, they often face inconsistent grade markings, missing heat numbers on certificates, and thickness deviations that only show up after cutting. The hidden cost is not the tube price — it is the rework, the delayed handover, and the argument over who pays for the wasted welding consumables.
How 40×60 mm ERW Square Tube Matches Structural Frame Requirements
The 40×60 mm rectangular profile gives higher moment of inertia along the 60 mm axis, making it suitable for curtain wall mullions and machinery frames where bending load is directional. ERW welded square steel tube in S235JR or S355 grade delivers clean internal corners for gusset plate fitting, while the ±1% tolerance ensures bolt-hole alignment stays within structural steel fabrication standards. For projects in marine or humid environments, buyers typically specify galvanized finish; for indoor architectural work, the cold-rolled non-oiled surface accepts powder coating directly.
Engineering Compliance Across EN, ASTM, and GB Frameworks
S235JR conforms to EN 10025 and is widely specified under EN 10219 for cold-formed structural hollow sections, while S355 serves heavier load paths in the same standard. Q235B maps to GB/T 6728 for Chinese domestic projects, and A36 / SS400 cover ASTM and JIS procurement respectively. [NEED_CITE: steel grade equivalence between EN 10025 S235JR and ASTM A36] For EU-bound shipments, CE marking under EN 10219 is required at customs; for North American EPCs, ASTM A500 Grade B documentation must accompany the mill test certificate. Custom cut-to-length service eliminates on-site sawing and reduces scrap at the fabrication shop.
Steel Grade Selection and ERW Welding Process Explained
S235JR, S355, and Q235B represent three different national grading systems but share similar carbon-manganese chemistry suitable for general structural welding. S355 offers higher yield strength than S235JR, allowing thinner wall sections for the same load — a direct weight and cost saving on large frame orders. The ERW process forms the tube from cold-rolled coil through continuous forming and resistance welding without filler metal, producing a clean internal bead suitable for fluid passage and a smooth external seam ready for coating. [NEED_CITE: ERW versus seamless hollow section manufacturing differences] Negative tolerance practices, if unchecked, reduce actual wall thickness below the design assumption — this is why we invoice by theoretical weight but guarantee the ordered thickness is met within ±1%.
The Hidden Cost of Buying the Wrong Grade or Unverified Certificates
Specifying S235JR when the structural engineer calculated for S355 means the frame passes visual inspection but fails load testing. Shipping without a verifiable mill test certificate triggers customs holds in the EU and GCC, where EN 10219 compliance must be documented per heat number. [NEED_CITE: EN 10219 CE marking requirements for structural hollow sections] Buyers who accept the lowest per-ton price without checking tolerance often discover the cost shift at the welding bay — thin walls burn through, corners distort, and the fabricator bills the extra hours back to the procurement team.
Why Procurement Teams Source ERW Welded Square Steel Tube From XJY Plate
We operate as the dedicated plate and coil division of a Shandong-based steel producer, meaning the ERW welded square steel tube you order comes from our own rolling and welding line — no trading markup, no third-party stock uncertainty. Every heat is tested in our in-house lab, and the mill test certificate lists chemical composition and mechanical properties traceable to the heat number. We stock S235JR, S355, Q235B, A36, and SS400 in 40×40 mm and 40×60 mm profiles, so mixed-grade container orders ship together without waiting for separate mill campaigns. Custom cutting, punching, and bending are done before loading, reducing your yard labor. Our loading team uses flatbed and open-top container methods proven for heavy steel cargo, with full export documentation handled in-house. Third-party inspection by SGS or BV is arranged on request, and ISO 9001:2015 plus CE certification covers the quality system behind every shipment.
Documentation & Compliance
- Mill test certificate documenting S235JR / S355 / Q235B chemical composition and mechanical properties per EN 10025 or GB/T 6728, traceable by heat number
- CE certificate confirming EN 10219 compliance for structural hollow sections shipped to EU and GCC markets
- ISO 9001:2015 quality management certificate covering the ERW welding and cold-rolling process
- SGS or BV third-party inspection report available upon request for projects requiring independent verification
- Full material traceability from coil heat number through forming, welding, cutting, and final bundling
- Export customs documents including packing list, bill of lading, and certificate of origin for the destination country
Packaging, Loading & Delivery
- ERW welded square steel tube bundled with steel strips and edge protectors to preserve the cold-rolled finish during ocean transit
- Non-oiled surface protected by waterproof wrapping for S235JR and S355 grades destined for humid climates
- 40×40 mm and 40×60 mm profiles loaded in open-top containers optimized for the customized length ordered, maximizing payload without overweight penalties
- Custom cut-to-length service completed before bundling, with each piece marked by heat number, steel grade, and size
- FOB, CIF, and DDP shipping terms available from Shandong ports to project sites worldwide
Request a Quote With Mill Test Certificate
Send your specification list — steel grade (S235JR, S355, Q235B, A36, or SS400), size (40×40 mm or 40×60 mm), wall thickness, length, quantity, and destination port — and receive a detailed quotation with material cost, processing fees, and shipping terms within 12 hours. We will attach the original mill test certificate for your quality review before shipment and confirm loading details by video.
Get Your ERW Welded Square Steel Tube Quote Today
Submit your size, grade, and quantity to receive pricing and mill test certificates.
Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.xjyplate.com
Tel: +86 531 8573 6315
Mobile / WhatsApp / WeChat: +86 188 5315 7756
Email: admin@xjyplate.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
Frequently Asked Questions
Q: What is the difference between S235JR, S355, and Q235B for ERW welded square steel tube?
A: S235JR and S355 follow the EN 10025 European standard, with S355 offering higher yield strength for heavier structural loads. Q235B follows the Chinese GB standard and is commonly specified for domestic projects in China and regions that adopt GB procurement. All three grades are available in 40×40 mm and 40×60 mm ERW square tube from our mill, with full chemical composition and mechanical property data on the mill test certificate.
Q: How can I verify the mill test certificate and request third-party inspection?
A: Every shipment of ERW welded square steel tube is accompanied by an original mill test certificate listing heat number, chemical composition, and mechanical properties. You can verify the heat number against the markings on each tube. For projects requiring independent validation, we arrange SGS or BV third-party inspection before loading at our facility.
Q: Can I order custom lengths and small quantities for ERW welded square steel tube?
A: Yes. We offer custom cut-to-length service for 40×40 mm and 40×60 mm ERW square tube in S235JR, S355, Q235B, A36, and SS400 grades. Small batch orders are accepted, and processing services including welding, punching, cutting, and bending are completed before shipment to reduce your on-site labor.
Q: How is theoretical weight invoicing different from actual weight, and what about negative tolerance?
A: We invoice ERW welded square steel tube by theoretical weight calculated from the ordered dimensions and standard steel density. Our production maintains ±1% dimensional tolerance, so the actual wall thickness matches the ordered specification without hidden negative tolerance reductions. This avoids the common issue where buyers pay for theoretical weight but receive under-thickness material.
Q: What are the delivery time and shipping options for heavy steel tube orders?
A: Typical production lead times apply once the deposit is received and stock or mill rolling schedule is confirmed. We offer FOB, CIF, and DDP shipping terms, with professional flatbed and open-top container loading handled by our heavy cargo logistics team. Full export documentation and shipment tracking are provided until arrival at your destination port.
