Description
Factory-Direct ERW Square Tubes — Every S235JR welded carbon steel square tube rolls off our own ERW lines with in-house lab verification before it leaves Jinan.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | S235JR ERW Welded Carbon Steel Square Tube |
| Product Type | Welded Square Steel Tube (SHS) |
| Steel Grade | S235JR, A36, S355, SS400, Q235B, Q345B |
| Standard | BS, EN, GB, AISI, ASTM, DIN, JIS |
| Section Shape | Square |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Cold Rolled |
| Tolerance | ±1% |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Delivery Time | 31–45 days |
| Invoicing | By Theoretical Weight |
| Oiled or Non-oiled | Non-oiled |
| Application | Steel structures, Construction frames, Machinery, Scaffolding, Furniture, Curtain wall, Machine frames, Decorative elements |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors & Construction | Structural columns, roof trusses, curtain wall support frames, scaffolding uprights |
| Machinery Manufacturers | Machine base frames, conveyor system structures, equipment support stands |
| Steel Distributors | Regional stock for building frames, infrastructure bracing, furniture manufacturing |
| System Integrators | Automation line frames, industrial platform structures, modular rack systems |
What Negative Tolerance Really Costs on a Scaffolding Order
A ±1% tolerance on cold-rolled ERW square tubes means what you ordered is what you get — on paper and on site.
I spent two months on a factory floor in Ho Chi Minh City watching a 2×4 square tube order get held up at third-party re-inspection. The wall thickness kept drifting into negative tolerance territory, and theoretical weight invoicing suddenly meant the client was paying for steel that wasn’t there. Every bundle had to be re-measured, re-weighed, and re-documented. The S235JR ERW welded carbon steel square tube you spec needs to match the mill test certificate — not just the purchase order. When fragmented suppliers ship without in-house lab verification, you end up absorbing the cost of material uncertainty. [NEED_CITE: EN 10219 dimensional tolerance requirements for cold-formed structural hollow sections]
Matching Structural Frames and Machinery Bases to Project Loads
Cold-rolled S235JR square tubes deliver consistent surface quality and dimensional accuracy for welded connections in structural frames and machine bases. The non-oiled finish accepts paint or galvanizing without additional surface prep, which matters when your curtain wall supports or conveyor structures need to go straight into fabrication. Our ERW lines produce square sections with uniform weld seam integrity across the full length, so load transfer at welded joints stays predictable. When EPC contractors source a S235JR ERW welded carbon steel square tube from us, they get sections that hold their geometry through cutting, punching, and bending — no surprise spring-back on the assembly floor.
Engineering Compliance Across EU, North American, and Asian Standards
Structural hollow sections in S235JR must comply with EN 10219 for cold-formed welded profiles entering the European market, while A36 and ASTM A500 grades serve North American structural codes. SS400 and Q235B cover Japanese and Chinese project specifications respectively. The ±1% tolerance on our cold-rolled ERW tubes keeps dimensional deviation within limits accepted by most international engineering norms, but certification paperwork is what actually clears customs. CE marking under EN 10219 is non-negotiable for EU project sites, and Singapore FPC certification opens doors across Southeast Asian infrastructure tenders. [NEED_CITE: CE marking requirements for structural steel hollow sections under EN 10219]
Steel Grade Selection and ERW Welding Fundamentals
S235JR sits at the entry point of European structural steel grades — adequate yield strength for general construction frames, scaffolding, and non-heavy machinery bases. Step up to S355 when your design calls for higher load-bearing capacity in columns or crane-support structures. Q235B and Q345B serve the same tiered logic in the Chinese standard system, while A36 and ASTM A500 cover the American market. ERW welding fuses the strip edges through high-frequency electric current, producing a weld seam that matches base metal strength without filler material — ideal for square tubes where uniform wall thickness and clean internal surfaces matter. Cold rolling after forming tightens dimensional tolerance and produces the smooth, non-oiled surface finish you see on our S235JR ERW welded carbon steel square tube, ready for downstream coating or direct assembly.
The Hidden Price of Unverified Mill Test Certificates
Ordering structural square tubes without verified chemical composition and mechanical property documentation means your project carries invisible risk. Material that fails third-party re-inspection at destination gets rejected outright — or worse, accepted and then discovered during structural audit. Missing CE certificates delay customs clearance for weeks, and inconsistent steel grades across bundles force on-site re-sorting that kills fabrication schedules. A S235JR ERW welded carbon steel square tube shipped without proper heat number traceability becomes a liability, not an asset. [NEED_CITE: material traceability requirements for structural steel in EN 10204 inspection documents]
Why Procurement Teams Source ERW Square Tubes From Xin Jiyuan
We run three dedicated ERW production lines in Jinan with physical and chemical laboratories on-site — every heat gets tested before it ships, and every S235JR ERW welded carbon steel square tube leaves with a mill test certificate tied to its heat number. Our catalog covers over 2,800 specifications across square tubes, round pipes, plates, and sections, so your structural frame order and your machinery base order ship from one factory in one container. We hold 41 invention patents including proprietary sharp-corner rectangular tube technology, CE certification under EN 10210 and EN 10219, ISO 9001:2015, Singapore FPC, and third-party verification from SGS and BV. Non-standard dimensions and custom lengths are produced on the same lines with the same lab oversight — no separate “special order” quality tier. Professional loading plans optimize container space for your specific size mix, and we handle FOB, CIF, and DDP logistics to 50+ countries.
Documentation & Compliance
- Mill test certificate documenting S235JR chemical composition and mechanical properties per EN 10219, tied to individual heat numbers
- CE certificate covering EN 10219 cold-formed structural hollow sections for EU market access
- ISO 9001:2015 quality management system certificate covering full production and inspection process
- SGS or BV third-party inspection report available for pre-shipment verification at buyer’s request
- Full customs documentation package including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Cold-rolled S235JR square tubes bundled with steel strips and edge protectors to preserve surface finish during ocean transit
- Non-oiled surface requires moisture barriers inside containers to prevent condensation staining on 6–12 meter lengths
- Container loading plans optimized for mixed-size square tube orders to maximize payload within weight limits
- Custom cutting to project-specific lengths available before shipment, reducing on-site waste and handling
- Heat number and steel grade stenciled on each bundle for traceability from warehouse to installation
- FOB Jinan/Qingdao, CIF, and DDP delivery options with real-time shipment tracking
Getting Your S235JR Square Tube Quote Started
Send your specification sheet — section dimensions, wall thickness, steel grade, quantity, and destination port — and we return a detailed quotation within 12 hours including unit price, production timeline, payment terms, and applicable certification scope. If your project requires non-standard dimensions or custom lengths outside the catalog range, we confirm feasibility and lead time before you commit. Mill test certificates and CE documentation scope are locked into the proforma invoice so there are no surprises at customs.
Frequently Asked Questions
Q: How does S235JR compare to A36 and Q235B for structural applications?
A: S235JR, A36, and Q235B all serve general structural purposes with comparable yield strength ranges. S235JR follows European EN standards, A36 follows ASTM, and Q235B follows Chinese GB standards. The choice depends on your project’s governing code and destination market certification requirements.
Q: Can you provide mill test certificates for third-party re-inspection?
A: Yes. Every shipment includes EN 10204 3.1 mill test certificates documenting chemical composition and mechanical properties by heat number. SGS or BV third-party inspection is available upon request before shipment.
Q: What is the minimum order quantity for non-standard square tube sizes?
A: We produce custom non-standard dimensions on the same ERW lines as catalog products. MOQ depends on section size and wall thickness — contact us with your drawing or specification for a confirmed minimum.
Q: Is the cold-rolled surface suitable for direct painting without additional preparation?
A: The non-oiled cold-rolled finish provides a clean, smooth surface that accepts paint and powder coating directly. For high-corrosion environments, we also supply galvanized or hot-rolled options from the same factory.
Q: What certification documents are included for EU customs clearance?
A: EU shipments include CE certificate per EN 10219, mill test certificates per EN 10204, packing list, bill of lading, and certificate of origin. Singapore FPC documentation is added for Southeast Asian destinations.
Secure Your S235JR ERW Square Tube Supply
Submit your specifications, steel grade, and destination to receive a detailed quotation with mill test certificate scope and delivery timeline within 12 hours.
Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxjysteel.com
Website: www.sdxjysteel.com
