Description
Factory-direct pricing, no middlemen — Every ERW square and rectangular steel tube we ship comes straight from our 3 production lines in Jinan, cutting agent markups from your per-ton cost.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B / S355JR ERW Square & Rectangular Steel Tube |
| Product Type | Square & Rectangular Steel Tube (ERW Welded) |
| Steel Grade | Q235, Q235B, Q355, S235JR, S355JR, S355JOH, S355J2H, STK400, SS400, C250, C350, C460, St37, St52, ASTM A500 Grade A/B/C/D |
| Standard | ASTM A500, EN 10219, EN 10210, JIS G3466, AS1163, GB/T 6728 |
| Section Shape | Square & Rectangular |
| Size Range | Square 12×12mm–800×800mm; Rectangular 10×20mm–800×1000mm |
| Wall Thickness | 0.5–25mm |
| Length | 1–12m (up to 24m per extended range) |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Bare, Oiled, Black Painting, Galvanized (zinc coating 30–550g/m²) |
| Tolerance | ±1% (diameter tolerance ≤0.12%, deflection <1/2000, ovality <1%) |
| Ends | Plain End |
| Processing Service | Cutting, Bending, Punching, Welding, Decoiling |
| Application | Steel structures, Construction frames, Scaffolding, Fencing posts, Handrails, Brackets, Shelving, Guard bars, Furniture, Greenhouse structures, Machinery frames |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building structural frames, scaffolding systems, fencing posts, guard rails for urban and industrial projects |
| Industrial & Machinery | Equipment support frames, conveyor structures, shelving racks, machinery bases for OEM factories |
| Agricultural & Commercial | Greenhouse skeleton structures, furniture frames, handrails, display brackets for wholesalers |
When Diameter Tolerance Decides Whether Your Frame Bolts Align on Site
Tight ERW tolerance means field crews spend zero time reaming or re-drilling connection holes.
Nothing kills a structural frame schedule faster than tubes that arrive with oval ends or bowed sections. When diameter tolerance drifts beyond ±0.12% and deflection exceeds 1/2000, bolt holes no longer line up, gusset plates sit at angles, and welders burn hours grinding fit-up gaps. We have seen entire container loads of cheap square tube rejected at Middle Eastern job sites because the ovality exceeded 1% — the steel passed visual inspection at origin, but the loading crew never checked with a caliper. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]
Matching Section Geometry to Load Paths in Structural Frames
An ERW square and rectangular steel tube in S355JR or Q355 grade carries bending loads efficiently in both axes, making it the default choice for portal frames, mezzanine structures, and equipment supports where bidirectional loading is expected. The flat faces simplify bolted and welded connections — no saddle cuts needed as with round pipe. For corrosive environments such as coastal greenhouses or chemical plant walkways, we supply hot-dip galvanized versions with zinc coating up to 550g/m², eliminating the need for post-fabrication painting. Our 2,800+ specification inventory means your site team can pull standard sections from ready stock while custom non-standard dimensions run on parallel production lines.
Engineering Compliance Across Destination Markets
Structural hollow sections destined for European projects must conform to EN 10219 (cold-formed welded) or EN 10210 (hot-finished welded), with CE marking mandatory for load-bearing applications. [NEED_CITE: CE marking requirements for structural steel under EN 10210 and EN 10219] North American specifiers typically call for ASTM A500 Grade B or C, while Australian infrastructure projects require AS1163 C250/C350/C460 compliance. We hold CE certification under both EN 10210 and EN 10219, and every batch ships with original mill test certificates documenting chemical composition and mechanical properties per the specified standard. For projects requiring independent verification, SGS or BV third-party inspection is arranged before container sealing.
Steel Grade Selection: Q-Series, S-Series, and ASTM Equivalents
Q235B and S235JR occupy the same yield strength tier and serve general structural applications where high load capacity is not critical. Moving to Q355 or S355JR/S355J2H increases yield strength for heavier frames, long-span structures, and seismic-zone construction — S355J2H adds Charpy impact testing at sub-zero temperatures for cold-climate projects. ASTM A500 Grade B roughly aligns with S275JR, while Grade C approaches S355 performance. The ERW welding process produces a consistent weld seam with tight dimensional control, making these tubes suitable for precision fabrication without secondary straightening. Surface treatment choice depends on environment: bare or oiled tubes work for indoor structural frames, black painting adds moderate corrosion resistance, and galvanized coating (30–550g/m²) handles outdoor exposure, marine atmospheres, and agricultural humidity.
The Hidden Cost of Tolerance Drift and Missing Documentation
Specifying S355JR per EN 10219 means nothing if the mill delivers Q235 material with a forged certificate. Customs authorities in the EU and Middle East increasingly reject structural steel shipments lacking proper CE documentation or traceable heat numbers. [NEED_CITE: steel grade equivalence and documentation requirements for international structural projects] Negative tolerance abuse — where wall thickness consistently sits at the lower limit — reduces load capacity and triggers engineering rejection during site inspection. The cost of replacing 20 tons of non-conforming tube after it arrives at destination dwarfs any per-ton savings from an unverified supplier.
Why Project Buyers Source ERW Square and Rectangular Steel Tube From Us
We operate 3 simultaneous production lines with monthly capacity exceeding 20,000 tons, running standard sections from 12×12mm to 800×800mm in ready stock for urgent dispatch. Our in-house metallurgical lab conducts three-stage inspection — raw material verification, in-process weld seam testing, and final dimensional check — before any batch leaves the facility. Every order ships with original mill test certificates tied to specific heat numbers, ensuring full traceability from slab to container. For European and international projects, our CE certification under EN 10210 and EN 10219 plus ISO 9001:2015 registration clears customs without documentation delays. We handle non-standard dimensions, custom lengths up to 24m, and multi-product container consolidation — pipes, plates, and sections loaded in one shipment to reduce your freight cost per ton. Our export team manages optimized container loading plans, professional lashing, and complete documentation packages for FOB, CIF, and DDP terms.
Documentation & Compliance
- Mill test certificate documenting Q235B or S355JR chemical composition and mechanical properties per EN 10219 or ASTM A500, with heat number traceability
- CE certificate covering EN 10210 and EN 10219 structural hollow sections for European market compliance
- ISO 9001:2015 quality management certificate covering full production and inspection process
- SGS or BV third-party inspection report available on request for independent quality verification
- Material traceability report linking each bundle to specific heat number and production batch
- Complete customs documentation package including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- ERW square and rectangular tubes bundled with steel strips and seaworthy packaging, sized for 12m or custom cut lengths
- Galvanized tubes packed with edge protectors and waterproof wrapping to preserve zinc coating during ocean transit
- Container loading optimized by our export team — mixed sections and sizes consolidated to maximize payload per 20ft or 40ft container
- Cut-to-length service available for 1–24m lengths, with plain ends deburred and marked with heat number and steel grade
- Each bundle labeled with steel grade (Q235B / S355JR), size, wall thickness, and heat number for site identification
- FOB Jinan/Qingdao, CIF destination port, or DDP door delivery with full export documentation and real-time tracking
Start Your Procurement With a Detailed Quote
Submit your specification list — section size, wall thickness, steel grade, quantity, and destination port — and receive a competitive bulk quote within 12 hours, complete with mill test certificate samples and loading plan preview. For non-standard dimensions or custom fabrication requirements, our engineering team provides technical confirmation and production timeline before you commit.
Request Factory-Direct Pricing With Mill Test Certificates
Send your inquiry via email to admin@sdxinjiyuan.com or WhatsApp at +86 188 5315 7756 with your specification list to receive a detailed quote and documentation preview.
Frequently Asked Questions
Q: How do Q235B, S235JR, and ASTM A500 Grade B compare for structural applications?
A: Q235B and S235JR occupy similar yield strength ranges and serve general structural frames, fencing, and scaffolding. ASTM A500 Grade B offers comparable performance for North American specifiers. For heavier loads or seismic zones, upgrade to Q355, S355JR, or S355J2H. We provide cross-reference documentation and mill test certificates confirming compliance with your specified standard.
Q: What documentation accompanies each shipment?
A: Every batch ships with original mill test certificates documenting chemical composition and mechanical properties, tied to specific heat numbers. CE certification under EN 10210/EN 10219 and ISO 9001:2015 certificates are provided for European and international projects. SGS or BV third-party inspection is available on request for independent verification.
Q: Can you produce non-standard sizes, and what is the minimum order quantity?
A: Yes, we manufacture custom dimensions beyond standard catalog ranges, with lengths up to 24m and wall thickness up to 25mm. Minimum order quantity is 1 ton for trial orders, with volume discounts applied for bulk procurement. Standard sizes ship from ready stock within typical production lead times.
Q: When should I specify galvanized versus bare or painted surface treatment?
A: Galvanized coating (30–550g/m² zinc) is essential for outdoor exposure, marine environments, greenhouses, and corrosive industrial atmospheres. Bare or oiled tubes suit indoor structural frames and enclosed machinery. Black painting provides moderate corrosion resistance for semi-exposed applications. We advise on optimal surface treatment based on your project environment.
Q: How do you handle container loading for mixed-size orders?
A: Our export team creates optimized loading plans that consolidate multiple section sizes and lengths into single containers, maximizing payload and reducing freight cost per ton. Professional lashing and edge protection prevent transit damage. Complete documentation including packing list, bill of lading, and certificate of origin is prepared for smooth customs clearance.
