Description
Factory-Direct Carbon RHS Supply — Q235, Q345, and S355JR rectangular hollow sections produced on our own hot-rolled lines, shipped without trading margins.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235/Q345/S355JR Carbon Rectangular Hollow Section Steel Tube |
| Product Type | Rectangular Hollow Section (RHS) / Square Steel Tube |
| Steel Grade | Q195, Q235, Q345, S235JR, S275JR, S355JR |
| Standard | ASTM / EN 10219 / EN 10210 |
| Section Shape | Rectangular / Square |
| Size Range | 25×50 mm, 40×60 mm, 40×80 mm (outer dimensions) |
| Wall Thickness | Up to 40 mm |
| Length | 6 m / 6.4 m / 12 m |
| Technique | Hot Rolled |
| Surface Treatment | Black / Oiled |
| Tolerance | ±1% |
| Ends | Plastic Pipe Cap |
| Application | Steel structures, construction frames, building frameworks, ornamental designs |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors | Portal frames for industrial warehouses, pipe rack supports, modular plant structures |
| Construction Companies | High-rise building columns, bridge handrails, scaffolding uprights |
| Machinery Manufacturers | Conveyor system frames, equipment base plates, crane boom sections |
| Steel Distributors | Regional stock of standard RHS profiles for resellers and fabricators |
| System Integrators | Automation line guards, mezzanine flooring supports, access platform structures |
Why Steel Grade Equivalence Decides Whether Your Container Clears Customs
A mill certificate that reads Q345B means nothing at a European port unless the inspector can trace it to S355JR.
Global procurement teams routinely order Chinese-grade steel for projects governed by EN or ASTM codes. When the mill test report lists Q235 or Q345 without a cross-reference table, EU customs agents flag the shipment for missing EN 10219 compliance documentation. The result is a container sitting at Hamburg or Rotterdam, accruing demurrage daily, while the buyer scrambles for a third-party equivalence letter. [NEED_CITE: steel grade equivalence between EN and ASTM standards] This is not a paperwork formality — it is a structural compliance gate that separates deliverable cargo from rejected freight.
How Q235 and Q345 RHS Match Structural Frame Requirements
For load-bearing frames in warehouses and industrial plants, the 25×50 mm and 40×80 mm rectangular hollow sections in Q345 deliver higher yield capacity than Q235 at the same cross-section, allowing engineers to reduce member weight without sacrificing span. The hot-rolled black finish with oil coating provides baseline corrosion protection during transit and fabrication, while the ±1% dimensional tolerance ensures that welded connections fit without forced alignment. Our in-house laboratory tests every heat number against the chemical and mechanical requirements before release, so the mill test certificate you receive matches the steel that arrives on site.
Engineering Compliance Across EN, ASTM, and GB Frameworks
Structural designers specifying EN 1993 (Eurocode 3) require hollow sections that conform to EN 10210 for hot-finished or EN 10219 for cold-formed profiles. Our Q345 grade maps to S355JR under the EN system and approximately to ASTM A500 Grade C, though exact equivalence depends on the project’s acceptance criteria. [NEED_CITE: EN 10219 cold-formed hollow section requirements] For projects in the Middle East or Southeast Asia, Singapore FPC certification and SGS third-party inspection reports satisfy local authority submission requirements. The 6 m and 12 m standard lengths minimize on-site splicing, while custom cut-to-length service reduces waste at the fabrication shop.
Understanding Carbon Steel Grades and Hot-Rolled Process Selection
The Q-series (Q195, Q235, Q345) follows the Chinese GB/T 1591 standard, where the number after “Q” indicates minimum yield strength in MPa. The S-series (S235JR, S275JR, S355JR) follows EN 10025, with “JR” denoting room-temperature impact toughness at 27 J. Hot-rolled rectangular hollow sections are formed from coil or plate at elevated temperatures, producing a mill scale surface that is typically oiled to prevent rust during storage. This process allows wall thicknesses up to 40 mm — far beyond what cold-forming can achieve — making hot-rolled RHS suitable for heavy structural columns and bridge components. The proprietary sharp-corner technology we developed fills a gap in the global market for rectangular tubes with tight external corner radii, improving connection fit-up for bolted and welded joints.
Hidden Costs of Procuring the Wrong Grade or Missing Certification
Ordering Q235 when the structural drawing calls for S355JR means the delivered steel fails the designer’s load calculation — not because the tube is defective, but because it was never intended for that stress level. The cost is not just the material replacement; it is the demolition of erected frames, the delay penalties from the project owner, and the reputational damage with the end client. Similarly, shipping without CE certification to an EU country triggers customs rejection, and arriving without a mill test certificate forces the buyer to pay for independent chemical analysis at the destination port. [NEED_CITE: structural steel compliance requirements for EU construction projects] These are not theoretical risks — they are recurring line items in the cost structure of buyers who prioritize unit price over documentation integrity.
Why Project Procurement Teams Source Carbon RHS From Us
We operate three dedicated production lines in Jinan, Shandong, producing over 2,800 specifications of square and rectangular hollow sections — including the 25×50 mm, 40×60 mm, and 40×80 mm sizes in this listing — with wall thicknesses reaching 40 mm. Every batch is tested in our physical and chemical laboratory before shipment; no material leaves the mill without a heat-number-traceable mill test certificate. Our 41 patented technologies include the sharp-corner rectangular tube process that delivers tighter corner radii than conventional roll-forming, reducing gaps at welded connections. We hold CE certification under EN 10210 and EN 10219, ISO 9001:2015, Singapore FPC, and third-party verification from SGS and BV, covering exports to over 50 countries across the EU, North America, the Middle East, and Southeast Asia. Custom non-standard sizes are available without prohibitive minimum order quantities, and our logistics team designs container loading plans that maximize payload for 6 m and 12 m lengths, reducing per-ton freight costs.
Documentation & Compliance
- Mill test certificate documenting Q235/Q345/S355JR chemical composition and mechanical properties per heat number
- CE certificate confirming compliance with EN 10210 (hot-finished) and EN 10219 (cold-formed) hollow section standards
- ISO 9001:2015 quality management system certificate covering production and inspection processes
- SGS or BV third-party inspection report available upon request for pre-shipment verification
- Material traceability report linking each bundle to its heat number, chemical analysis, and tensile test results
- Complete customs documentation package including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Black hot-rolled Q235 and Q345 rectangular hollow sections packed in steel-strip bundles with edge protectors to prevent surface damage during ocean transit
- Oiled surface treatment applied before bundling to inhibit rust formation during storage and shipping to humid climates
- Container loading plans optimized for 6 m and 12 m lengths, maximizing payload per 20-foot and 40-foot containers for 25×50 mm and 40×80 mm profiles
- Custom cut-to-length service available for 6.4 m and other non-standard lengths, reducing on-site cutting waste for construction frame applications
- Heat number and steel grade stenciled on each bundle for site identification and traceability verification
- FOB, CIF, and DDP shipping terms available, with door-to-door logistics coordination to project sites in the EU, Middle East, and Southeast Asia
Request a Quote With Mill Test Certificate and Loading Plan
Submit your required dimensions (25×50 mm, 40×60 mm, or 40×80 mm), steel grade (Q235, Q345, or S355JR), quantity in tons, and destination port. We respond within 12 hours with a detailed quotation including unit price, production lead time, payment terms, and a sample mill test certificate for your review. Non-standard sizes and custom lengths are available — specify your drawing requirements for a tailored production plan.
Frequently Asked Questions
Q: How do Q235 and Q345 Chinese grades correspond to S235JR and S355JR European grades?
A: Q235 approximates S235JR in yield strength, while Q345 maps closely to S355JR. However, chemical composition limits and impact toughness requirements differ between GB/T 1591 and EN 10025 standards. We provide a cross-reference table with every quotation so your engineer can verify compliance with the project specification.
Q: Can you provide mill test certificates and arrange third-party inspection before shipment?
A: Yes. Every bundle is tested in our in-house laboratory, and we issue an original mill test certificate documenting chemical composition and mechanical properties by heat number. SGS and BV third-party inspections are available for pre-shipment verification at our facility.
Q: What is the minimum order quantity for custom rectangular hollow sections outside your standard catalog?
A: We stock over 2,800 specifications, including 25×50 mm, 40×60 mm, and 40×80 mm in Q235, Q345, and S355JR grades. For non-standard sizes or custom lengths, minimum order quantities depend on the specific profile and wall thickness — contact us with your drawing for a production feasibility assessment.
Q: What is the difference between black hot-rolled, oiled, and galvanized surface finishes?
A: Black hot-rolled RHS has a mill scale surface suitable for indoor structural applications or projects where the steel will be painted after fabrication. Oiled treatment adds a thin protective layer to inhibit rust during transit and outdoor storage. Galvanized coating provides long-term corrosion resistance for exposed outdoor or marine environments.
Q: Do you handle FOB, CIF, and DDP logistics with complete customs documentation?
A: Yes. We coordinate ocean freight under FOB, CIF, or DDP terms and provide a full customs documentation package including mill test certificates, packing lists, bills of lading, and certificates of origin. Our logistics team designs container loading plans to maximize payload for 6 m and 12 m lengths.
Get Your Carbon RHS Quote With Full Documentation
Send your specifications, steel grade, and destination port to receive a detailed quotation and sample mill test certificate within 12 hours.
Contact: admin@sdxjysteel.com | WhatsApp: +86 188 5315 7756
