Description
Factory-direct ERW square tubes — 2,800+ specifications from one production line with in-house lab testing before every shipment.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235/Q345 ERW Welded Square Steel Tube |
| Product Type | Welded ERW Square Steel Tube |
| Steel Grade | Q195, Q215, Q235, Q345, GR.A, GR.B, S235, S355 |
| Standard | ASTM, EN 10219, EN 10210, JIS G3466, AS1163, ISO 9001, CE, BSI, BIS, GS |
| Section Shape | Square |
| Size Range | 10×10 – 600×600 mm |
| Wall Thickness | 0.8 – 30 mm |
| Length | 5.7 m / 6 m (customizable) |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Pre-galvanized / Hot-dipped galvanized / Bare / Oiled |
| Tolerance | ±1% |
| Ends | Plain (default) |
| Application | Steel structures / Construction frames / Machinery / Fluid transport / Scaffolding / Pipeline |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors & Steel Fabricators | Structural frames for industrial buildings, conveyor system supports, equipment bases |
| Construction Companies | Scaffolding systems, high-rise building frames, bridge support columns |
| Machinery Manufacturers | Hydraulic support columns, machine bases, precision-machined structural components |
| Infrastructure Developers | Pipeline supports, utility pole structures, solar farm mounting frames |
What Negative Tolerance Costs on a Structural Frame Order
A 10% weight shortfall on paper means a 10% load-bearing gap on site.
When a warehouse contractor in Southeast Asia received a container of ERW square tubes, the third-party inspector at the port flagged the entire batch — actual weight came in over 10% lighter than theoretical. The wall thickness negative tolerance had been pushed far beyond what the purchase order specified. Air-shipping replacement pieces and eating the cost was the only option. [NEED_CITE: EN 10219 cold-formed hollow section tolerance requirements] That kind of failure does not show up in a catalog — it shows up at customs, at the inspection point, or worse, after the frame is erected.
Matching Wall Thickness and Grade to Load-Bearing Demands
A Q235 Q345 ERW welded square steel tube in the 10×10 to 200×200 mm range with 0.8–3 mm wall thickness serves light structural work — scaffolding, conveyor frames, and non-load-bearing partitions. Once you move into 200×200 to 600×600 mm with wall thickness above 6 mm, the same ERW process delivers sections capable of handling heavy-load columns and beam replacements in industrial buildings. The ±1% tolerance on wall thickness means every cut piece carries the load the engineer calculated, not a rounded-down estimate. Our in-house physical and chemical laboratory tests every heat before loading, so the mill test certificate matches what arrives on the truck.
Structural Compliance and Certification Across Markets
Engineering projects in the EU require CE certification under EN 10219 for cold-formed welded hollow sections — without it, customs holds the container and the project timeline slips. [NEED_CITE: CE marking requirements for structural steel hollow sections under EN 10219] North American EPC contractors typically specify ASTM A500, and the grade equivalence between Q345 and S355 or ASTM A500 Grade C needs to be documented clearly on the mill test certificate. Our production line covers both GB and EN grade designations from a single order, and the chemical composition and mechanical properties are tested against each standard the project demands. Custom cut-to-length in 5.7 m or 6 m lengths reduces on-site welding and secondary processing.
How ERW Welding and Steel Grade Selection Shape Performance
The ERW (Electric Resistance Welded) process forms the square section from steel coil through cold-forming and passes the weld seam through high-frequency electric current — no filler metal, no slag, and a weld zone that matches the base metal in strength when properly controlled. Q195 and Q215 sit at the lower end of the yield strength range and suit non-structural or lightly loaded frames. Q235 is the workhorse grade for general construction and scaffolding across Asia and the Middle East. Q345 delivers higher yield strength for heavy-load columns and crane runways. On the European side, S235 and S355 follow the EN 10025 designation system and map directly to Q235 and Q345 in most structural applications. [NEED_CITE: steel grade equivalence between EN 10219 and GB/T 6728 standards] The surface treatment choice — pre-galvanized for indoor or mild environments, hot-dipped galvanized for outdoor or coastal exposure, bare or oiled for projects that will be painted or coated on site — is matched to the end-use corrosion environment before the tubes leave the mill.
The Hidden Cost of Skipping Mill Test Verification
Ordering a Q235 Q345 ERW welded square steel tube without verified mill test certificates means you cannot prove the chemical composition meets the standard when the inspector arrives. A missing CE certificate on an EN 10219 order blocks EU customs clearance — the container sits at the port, demurrage charges accumulate, and the project waits. [NEED_CITE: customs clearance requirements for structural steel imports with CE certification] Wall thickness that drifts beyond ±1% tolerance changes the theoretical weight, the load calculation, and the structural safety margin — none of which are visible until a third-party inspector measures the cross-section. The cost of replacing an erected frame is always higher than the cost of testing before loading.
Why Procurement Teams Source This Grade from Xin Jiyuan
Every Q235 Q345 ERW welded square steel tube we ship is tested in our own physical and chemical laboratory — incoming raw material, in-process weld seam inspection, and final dimensional check before the container is sealed. We hold 41 invention patents, including proprietary sharp-corner rectangular tube technology, and our production line covers 2,800+ specifications from 10×10 mm to 600×600 mm with wall thickness up to 30 mm — one factory, one quality system, one point of contact. CE certification under EN 10210 and EN 10219, ISO 9001:2015 registration, and SGS or BV third-party inspection are available on every order. We export to 50+ countries across the EU, North America, the Middle East, Southeast Asia, and India, and our loading team optimizes container weight distribution for heavy-wall sections to avoid port rejection. Custom non-standard sizes and cut-to-length service eliminate on-site waste and secondary cutting cost.
Documentation & Compliance
- Mill test certificate documenting Q235/Q345 chemical composition and mechanical properties per EN 10219 or ASTM A500, traceable by heat number
- CE certificate under EN 10219 / EN 10210 for EU market customs clearance and structural compliance
- ISO 9001:2015 quality management system certificate covering full production and inspection process
- SGS or BV third-party inspection report available before shipment for project-specific verification
- Material traceability by heat number linking each bundle to incoming raw material and in-process test records
- Full customs document package: packing list, bill of lading, certificate of origin, and commercial invoice
Packaging, Loading & Delivery
- Bare Q235/Q345 ERW square tubes bundled with steel strips and edge protectors, oiled surface to prevent transit corrosion during ocean freight
- Pre-galvanized and hot-dipped galvanized tubes packed with waterproof wrapping and rubber spacers to preserve zinc coating integrity
- Container loading optimized for 6 m and 5.7 m lengths with weight distribution calculated for heavy-wall sections (above 10 mm) to meet port weight limits
- Custom cut-to-length service available for 5.7 m or 6 m定尺 or project-specific lengths, reducing on-site cutting waste
- Heat number and steel grade stenciled on each bundle for site identification and inspection traceability
- FOB, CIF, and DDP trade terms supported with door-to-door logistics to 50+ countries
Getting Your Quotation and Mill Test Package Ready
Send your specification sheet — section size, wall thickness, steel grade, quantity, and destination port — and we return a detailed quotation with unit price, delivery timeline, and applicable certification within 12 hours. If your project requires non-standard dimensions or custom cut-to-length, we provide a fabrication drawing for confirmation before production begins. Mill test certificates and CE documentation are prepared in parallel with production so there is no delay at shipment.
Request Your Q235 Q345 ERW Welded Square Steel Tube Quotation
Submit your specifications via email or WhatsApp to receive pricing, mill test certificate samples, and container loading confirmation.
Company: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.sdxjysteel.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxjysteel.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
Frequently Asked Questions
Q: How do Q235 and Q345 map to S235/S355 and ASTM A500 grades?
A: Q235 is broadly equivalent to S235 in the EN system and ASTM A500 Grade B in the US system. Q345 maps to S355 and ASTM A500 Grade C. The chemical composition and mechanical properties are comparable, but each standard has its own testing and certification requirements. We provide mill test certificates referencing the specific standard your project specifies.
Q: Can you provide third-party inspection and original mill test certificates for customs clearance?
A: Yes. Every order is supported by an original mill test certificate with full chemical composition and mechanical properties. We also accept SGS or BV third-party inspection before shipment. For EU projects, CE certification under EN 10219 / EN 10210 is provided to ensure customs clearance and structural compliance.
Q: Do you accept non-standard sizes and what is the MOQ for custom orders?
A: We produce custom non-standard sizes beyond the standard 10×10 to 600×600 mm range. The MOQ for standard specifications is 1 Ton. For custom non-standard dimensions, the MOQ depends on the section size and wall thickness — contact us with your drawing for a specific answer.
Q: When should I choose pre-galvanized vs hot-dipped galvanized vs bare?
A: Pre-galvanized tubes suit indoor or mild environments where cost is a priority. Hot-dipped galvanized provides thicker zinc coating for outdoor, coastal, or high-humidity environments with longer corrosion protection. Bare or oiled tubes are the right choice when the project will apply its own paint or coating system on site.
Q: What trade terms do you support and how do you handle heavy-wall tube shipping?
A: We support FOB, CIF, and DDP trade terms. For heavy-wall Q235 Q345 ERW welded square steel tubes (above 10 mm wall thickness), our loading team calculates container weight distribution to meet port weight limits and avoid overweight rejection. Professional loading plans maximize container utilization and reduce per-ton freight cost.
