Description
Factory-direct bulk supply — Q235B and Q345B hot rolled square hollow pipes rolled and dispatched from our own production lines, eliminating trader markups on every container.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B/Q345B Carbon Steel Square Hollow Pipe |
| Product Type | Square / Rectangular Steel Tube (SHS/RHS) |
| Steel Grade | Q195, Q235, Q235B, Q345, Q345B, SS400, SGC, SGHC, DC51D+Z, DC52D+Z, DC53D+Z |
| Standard | ASTM |
| Section Shape | Square / Rectangular / Round |
| Wall Thickness | 0.5–200 mm |
| Length | 12 m |
| Technique | Hot Rolled / Cold Rolled |
| Surface Treatment | Hot Rolled / Galvanized |
| Tolerance | ±1% |
| Ends | Plain |
| Application | Fluid Pipe / Boiler Pipe / Drill Pipe / Hydraulic Pipe / Gas Pipe / Steel Structures / Construction Frames / Machinery |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, scaffolding systems, column supports, bridge bracing members |
| Industrial & Energy | Hydraulic pipelines, boiler tubing, gas distribution networks, fluid conveyance |
| Machinery & Equipment | Conveyor frames, crane booms, machine base structures, equipment housings |
| Steel Structures | Portal frames, warehouse trusses, mezzanine supports, industrial shed columns |
Where Wall-Thickness Tolerance Decides Structural Acceptance on Site
A ±1% tolerance on a 12 mm wall square hollow pipe is the difference between passing监理 inspection and full-container rejection.
I watched an entire shipment of galvanized square tubes get sent back because the actual wall thickness fell below the minimum allowed by the project spec. The supplier had quoted a “standard tolerance” that turned out to mean minus-side only. When the tubes were cut and bent on site, the zinc coating cracked along the inner radius — the监理 refused to sign off. That kind of failure doesn’t show up in a catalog; it shows up when you’re standing in front of a container full of rejected steel. Sourcing a Hot Rolled Carbon Steel Square Hollow Pipe Supplier who controls tolerance at the rolling stage, not just at the inspection table, is what prevents this. [NEED_CITE: EN 10219 cold-formed hollow section tolerance requirements]
Matching Structural Load Paths in Building Frames and Scaffolding
Hot rolled Q235B and Q345B square hollow pipes carry compressive and bending loads in portal frames, scaffolding uprights, and mezzanine supports where section geometry directly governs buckling resistance. The square profile provides equal moment of inertia on both axes, simplifying connection design for bolted and welded joints. Our production lines roll these sections from 0.5 mm thin-wall up to 200 mm heavy-duty, covering both light-gauge cladding supports and primary structural columns within a single procurement package. A Hot Rolled Carbon Steel Square Hollow Pipe Supplier running three simultaneous lines can ship mixed-size containers without splitting orders across multiple vendors.
Engineering Compliance and Certification Requirements
Structural frames designed under ASTM or EN 1993 require traceable material properties — the mill test certificate must document chemical composition and mechanical behavior per heat number. For projects entering the European market, CE certification under EN 10210 (hot finished) or EN 10219 (cold formed) determines whether the shipment clears customs or sits at the port. Q235B and Q345B grades correspond broadly to S235 and S355 in the European system, but formal equivalence documentation is required for engineer approval. [NEED_CITE: steel grade equivalence between Chinese GB and European EN standards] Third-party inspection by SGS or BV provides independent verification that the delivered material matches the certified specification, closing the loop between factory output and site acceptance.
Steel Grade Selection and Rolling Process Fundamentals
The Q-series grading system — Q195 through Q345B — designates minimum yield strength in MPa, where Q235B delivers approximately 235 MPa yield and Q345B reaches 345 MPa. Higher yield grades reduce section weight for the same load capacity, but demand tighter control over welding parameters and bending radii. Hot rolling produces the grain structure needed for heavy structural sections above 6 mm wall thickness, while cold rolling achieves the dimensional precision and surface finish required for visible architectural applications. Galvanized coatings in the DC51D+Z through DC53D+Z range protect against atmospheric corrosion in outdoor scaffolding and industrial shed frames, where maintenance access is limited. Wall thickness tolerance of ±1% ensures that theoretical weight calculations match actual delivered weight — a critical factor when projects are priced per ton. [NEED_CITE: hot rolled versus cold rolled steel tube mechanical property differences]
Hidden Costs of Tolerance Drift and Missing Documentation
Ordering square hollow pipes without verified tolerance control means the delivered wall thickness may fall below the project specification — triggering re-inspection, re-work, or outright rejection at the construction site. Missing or incomplete mill test certificates delay customs clearance and force the buyer to arrange expensive retroactive testing. Steel grade substitution without formal approval voids structural warranties and exposes the contractor to liability if the frame underperforms. A Hot Rolled Carbon Steel Square Hollow Pipe Supplier providing original mill certificates per heat number, with third-party inspection available before shipment, eliminates these downstream risks. [NEED_CITE: material traceability requirements in structural steel procurement]
Why Buyers Source This Hot Rolled Carbon Steel Square Hollow Pipe Supplier from Xin Jiyuan
We operate three production lines running simultaneously, producing over 20,000 tons monthly across square, rectangular, and round sections — meaning your Q235B structural tubes and Q345B heavy columns ship from the same facility, not three different vendors. Every batch leaves the mill with original test certificates documenting chemical composition and mechanical properties per heat number, backed by ISO 9001:2015 certification and Lloyd’s CE approval for EN 10210/10219 compliance. Our inventory covers 2,800+ specifications in standard sizes, so trial orders of 5 tons and full-container bulk shipments of 300 tons both dispatch from ready stock without waiting for production slots. In-house bending, cutting, welding, and punching services eliminate the need for secondary fabrication at the job site, reducing labor costs and material waste. We handle export documentation, customs clearance, and container loading optimization — including consolidated multi-product shipments combining pipes, plates, and section steel in a single container. Volume discount programs review pricing every six months for long-term partners, ensuring procurement costs track market movements rather than staying locked at first-order rates.
Documentation & Compliance
- Mill test certificate documenting Q235B and Q345B chemical composition and mechanical properties per heat number, conforming to ASTM standards
- CE certificate under EN 10210 for hot finished structural hollow sections, required for European market customs clearance
- ISO 9001:2015 quality management system certificate covering production processes and inspection protocols
- SGS or BV third-party inspection report available upon request for independent verification of wall thickness and coating quality
- Material traceability by heat number linking each bundle to its original rolling heat and test results
- Complete customs documentation including packing list, bill of lading, and certificate of origin for destination port clearance
Packaging, Loading & Delivery
- Hot rolled Q235B and Q345B square hollow pipes bundled with steel strips and edge protectors to prevent coating damage during ocean transit
- Galvanized DC51D+Z to DC53D+Z tubes wrapped with waterproof paper and secured on wooden pallets to preserve zinc coating integrity
- 12 m standard length tubes loaded in containers using optimized stowage plans that maximize weight utilization while maintaining access for unloading
- Custom cutting to project-specified lengths available before shipment, reducing on-site waste and handling for scaffolding and frame applications
- Heat number and steel grade stenciled on each bundle for immediate site identification and traceability verification
- FOB, CIF, and DDP shipping terms available with professional export team handling port coordination and door-to-door logistics
Starting Your Procurement Process
Submit your specification sheet — including section dimensions, wall thickness, steel grade, quantity, and destination port — and receive a detailed quotation within 12 hours, complete with mill test certificate samples and container loading plans. For non-standard sizes or custom bending and cutting requirements, our engineering team provides fabrication drawings and lead time confirmation before production begins. Confirm certification requirements (CE, ASTM, SGS/BV inspection) at the inquiry stage to ensure all documentation aligns with your project compliance needs.
Request Your Quotation and Mill Test Certificate
Send your specifications via email to admin@sdxinjiyuan.com or contact us directly at +86 188 5315 7756 (WhatsApp/WeChat available) to begin your procurement process.
Frequently Asked Questions
Q: What is the difference between Q235B and Q345B steel grades for square tubes?
A: Q235B offers minimum 235 MPa yield strength suitable for general structural applications, while Q345B provides 345 MPa yield strength for heavier load-bearing members. The higher grade allows reduced section weight for the same capacity but requires adjusted welding parameters and bending procedures.
Q: Can you provide custom cutting and bending services for non-standard lengths?
A: Yes, our in-house processing facility handles cutting to project-specified lengths, bending to required radii, welding, and punching. These services are completed before shipment, reducing on-site fabrication time and material waste.
Q: What certifications are included for customs clearance and project compliance?
A: Every shipment includes original mill test certificates per heat number. We hold ISO 9001:2015 certification and Lloyd’s CE approval for EN 10210/10219. Third-party inspection by SGS or BV is available for independent verification.
Q: How do you ensure material traceability and quality consistency across bulk orders?
A: Each bundle is marked with heat number and steel grade, linking it to the original rolling heat and test results. Our in-house laboratory conducts three-stage inspection during production, and third-party inspection is available before shipment.
Q: What is the MOQ for trial orders versus full-container bulk shipments?
A: The minimum order quantity is 5 tons for trial orders. We maintain ready stock across 2,800+ specifications, supporting both small trial shipments and full-container bulk orders from the same inventory base.
Get Factory-Direct Pricing with Full Documentation
Email your specifications to admin@sdxinjiyuan.com or call +86 188 5315 7756 to receive your quotation and mill test certificate samples within 12 hours.
