Description
Factory-Direct ASTM Rectangular Tubes — Hot rolled carbon steel rectangular and square hollow sections shipped directly from our Jinan mill with full mill test certificates and third-party inspection support.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235/Q345/S355JR Rectangular Hollow Section Steel Tube |
| Product Type | Rectangular Hollow Section / Square Steel Tube |
| Steel Grade | Q195, Q235, Q345, S235JR, S275JR, S355JR |
| Standard | ASTM |
| Section Shape | Rectangular / Square |
| Size Range | 20×20mm – 50×50mm (square); 40×80mm, 25×50mm, 40×60mm (rectangular) |
| Length | 6m / 6.4m / 12m |
| Technique | Hot Rolled |
| Surface Treatment | Black / Oiled (as requirement) |
| Tolerance | ±1% |
| Ends | Plastic Pipe Cap (end protector) |
| Application | Steel structures / Construction frames / Building frameworks / Ornamental and decorative designs / Indoor and outdoor structural use |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Building | Structural frames for commercial buildings, warehouse frameworks, mezzanine support systems |
| Architectural Facade | Decorative curtain wall framing, ornamental steel features, exposed structural elements |
| Infrastructure | Bridge handrail supports, pedestrian walkway structures, signage gantry frames |
| Industrial & Machinery | Equipment base frames, conveyor support structures, platform guardrails |
What Steel Grade Equivalence Costs You on an ASTM Hollow Section Order
Mismatched grade documentation delays customs clearance and triggers on-site rejections.
Procuring a carbon rectangular hollow section steel tube under ASTM standards often means navigating equivalence tables between GB, EN, and ASTM systems. Q235 maps roughly to S235JR, Q345 aligns with S355JR — but mill test certificates must explicitly confirm chemical composition and mechanical properties per the standard specified on your purchase order. When certificates reference the wrong standard or omit impact test data, EU and North American customs brokers hold the shipment [NEED_CITE: steel grade equivalence between EN and ASTM standards]. I have seen containers sit at port for weeks because the MTC listed GB/T 6728 while the PI called for ASTM A500 Gr. C. The tubes were perfectly good steel, but the paperwork did not match the spec.
How Hot Rolled Rectangular Sections Match Structural Frame Requirements
Hot rolled carbon rectangular hollow section steel tube in Q235, Q345, and S355JR grades delivers consistent corner geometry and uniform wall thickness for load-bearing frame applications. The hot rolling process produces a mill scale surface that accepts paint and coating systems without additional blast preparation, reducing fabrication time on structural projects. For 40×80mm and 40×60mm rectangular sections used in building frameworks, the ±1% dimensional tolerance ensures predictable connection details — critical when multiple fabricators are working from the same drawing set. Our 6m and 12m standard lengths align with typical container loading plans, minimizing on-site cutting waste for overseas construction projects across Southeast Asia and the Middle East.
Engineering Compliance for ASTM-Standard Hollow Sections
Structural hollow sections used in load-bearing applications must comply with project-specified design codes — whether AISC 360 for North American projects or EN 1993-1-1 for European-spec buildings. The ASTM standard referenced on your purchase order governs dimensional tolerances and testing frequency, but the steel grade determines yield strength class and weldability. Q345 and S355JR both offer higher yield strength than Q235/S235JR, making them suitable for columns and primary beams where deflection limits apply. For projects requiring CE marking, our mill holds EN 10210/10219 certification through Lloyd’s Register, ensuring factory production control documentation satisfies EU construction product regulations [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerances]. Black surface with optional oiling provides short-term corrosion protection during ocean transit; for aggressive environments, specify galvanized finish or specify post-fabrication coating.
Understanding Hot Rolled Process and Multi-Grade Coverage
Hot rolled rectangular and square hollow sections are formed from steel strip at elevated temperatures, then welded and re-heated to normalize the weld seam. This process produces a uniform microstructure across the section — important for Q345 and S355JR grades where through-thickness properties affect weld zone performance. The Q-series (Q195, Q235, Q345) follows Chinese GB standards where the number indicates minimum yield strength in MPa; S-series (S235JR, S275JR, S355JR) follows EN 10025 naming conventions. ASTM A500 Gr. A/B/C/D provides equivalent coverage for North American projects. For ornamental applications where surface appearance matters, hot rolled black finish shows a characteristic mill scale pattern that architects sometimes specify for industrial aesthetic. The ±1% tolerance on these smaller sections (20×20mm to 50×50mm square, up to 40×80mm rectangular) reflects the precision achievable in hot rolling thin-wall hollow sections — tighter than typical cold-formed alternatives for these size ranges.
Hidden Costs When Mill Test Certificates Do Not Match Purchase Orders
Ordering carbon rectangular hollow section steel tube without verifying MTC content against your project specification creates downstream risk. A certificate listing Q235 chemistry when your engineer specified S355JR means the material cannot be used in the structural calculation — even if physical dimensions are correct. Third-party inspection by SGS or BV before shipment catches grade mismatches at the mill, not at destination. Projects with strict traceability requirements — infrastructure, public buildings, industrial plants — need heat number marking on each piece to link back to the original test report. Missing traceability means the inspector cannot verify the material, and the entire batch may be rejected regardless of actual quality [NEED_CITE: material traceability requirements for structural steel in construction].
Why Procurement Teams Source ASTM Hollow Sections From Our Jinan Mill
Our mill produces hot rolled rectangular and square hollow sections across 2,800+ specifications, covering the full range from 20×20mm square tubes to heavy-wall rectangular sections for structural applications. We maintain in-house physical and chemical laboratories that test every heat for composition, yield strength, tensile strength, and elongation before issuing mill test certificates. For export orders requiring third-party verification, we coordinate SGS or BV inspection at our facility — included in the production schedule, not an afterthought. Our loading teams use detailed bracing plans for rectangular tubes to prevent transit damage; I redesigned our container loading protocol after an early shipment to Dubai arrived with bent tubes because layers lacked proper separation. Every export order now ships with plastic end caps, edge protectors, and anti-rust treatment appropriate to the surface finish specified. We hold CE certification (EN 10210/10219) through Lloyd’s Register, ISO 9001:2015, and Singapore FPC — documentation that clears customs in regulated markets without delay.
Documentation & Compliance
- Mill test certificate documenting Q235/Q345/S355JR chemical composition and mechanical properties per ASTM standard, with heat number traceability
- CE certificate (EN 10210/10219) issued by Lloyd’s Register for structural hollow sections exported to EU member states
- ISO 9001:2015 quality management certificate covering hot rolled rectangular and square hollow section production
- SGS or BV third-party inspection report available for pre-shipment verification of dimensions, surface quality, and marking
- Material traceability report linking each piece to original heat number and test certificate
- Export documentation package including packing list, bill of lading, and certificate of origin for customs clearance
Packaging, Loading & Delivery
- Hot rolled black surface rectangular tubes bundled with steel straps and plastic end caps to prevent edge damage during handling and ocean transit
- Oiled surface tubes wrapped with VCI paper to maintain corrosion protection through humid climate delivery to Southeast Asia and Middle East destinations
- 6m and 12m lengths loaded in dedicated containers with timber dunnage and cross-bracing to prevent shifting and bending during vessel movement
- Heat number and steel grade marked on each tube end for on-site identification and traceability verification by project inspectors
- FOB Qingdao or CIF destination port terms available, with DDP delivery coordination for projects requiring door-to-door logistics to site
Ready to Confirm Specifications and Receive Your Quotation
Submit your rectangular hollow section requirements — including section size, wall thickness, steel grade (Q235/Q345/S355JR), length, quantity, and destination port — to receive a detailed quotation with mill test certificate sample and estimated production timeline. For non-standard sizes or cutting requirements, our technical team will confirm feasibility and lead time within one working day.
Request Your ASTM Hollow Section Quotation
Send your specifications to admin@sdxjypipe.com or contact us via WhatsApp at +86 188 5315 7756. Our team responds within 12 hours with pricing, certification details, and loading plan confirmation.
Frequently Asked Questions
Q: Can you provide mill test certificates that match ASTM standards for Q235 and Q345 grades?
A: Yes. We issue mill test certificates documenting chemical composition and mechanical properties per the standard specified on your purchase order. For ASTM orders, we test and certify according to ASTM requirements while noting the equivalent GB grade designation.
Q: What is the minimum order quantity for 40×80mm rectangular hollow sections in S355JR?
A: MOQ depends on section size and length. For standard sizes like 40×80mm in 6m or 12m lengths, we can accommodate smaller trial orders. Contact us with your specific quantity for confirmation.
Q: Do you arrange third-party inspection before shipment?
A: Yes. We coordinate SGS or BV inspection at our Jinan facility during production or before loading. The inspection covers dimensional verification, surface quality, marking, and witness of mechanical testing if required.
Q: Can you supply rectangular tubes with custom lengths other than 6m and 12m?
A: We offer cutting services for non-standard lengths. Specify your required cut lengths when requesting quotation, and we will confirm feasibility and any additional processing charges.
Q: How do you ensure rectangular tubes arrive without bending or surface damage?
A: We use detailed container loading plans with timber dunnage, cross-bracing between layers, and edge protectors. Our loading team photographs each container before sealing to document proper bracing placement.
