Description
Factory-Direct Q235B Hollow Sections — 3 production lines running EN 10219 / ASTM A500 cold-formed welded tubes with original mill test certificates on every heat.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B Square / Rectangular Steel Tube |
| Product Type | Square and Rectangular Steel Tube (Hollow Section) |
| Steel Grade | Q195, Q215, Q235, Q345 (Q355), #20, #45; Equivalent: S195, S235JR, S355JR, A53 Grade A/B, A500 Grade A/B/C, STK400, SS400, ST42.2 |
| Standard | EN 10219, EN 10210, GB/T 6728, JIS G3466, ASTM A500, ASTM A53, ASTM A36 |
| Section Shape | Square / Rectangular |
| Size Range | Square 20×20 mm – 500×500 mm; Rectangular 20×40 mm – 300×500 mm |
| Wall Thickness | 1.2 mm – 20 mm |
| Length | 3 m – 12 m (random / cut-to-length) |
| Technique | Hot Rolled / ERW Welded |
| Surface Treatment | Pre-galvanized (40–80 g/m²), Hot-dip galvanized (200–600 g/m²), Black / Oiled |
| Tolerance | ±1% |
| Ends | Plain / Beveled (as required) |
| Application | Construction & building structures, Steel structure engineering, Solar mounting structures, Machinery manufacturing, Fence posts, Greenhouse frames, Shipbuilding, Power engineering |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & EPC | Building frames, column sections, portal frames, mezzanine structures |
| Solar & Renewable Energy | Solar mounting racking, PV support posts, inverter platforms |
| Machinery Manufacturing | Conveyor frames, equipment bases, crane booms, machine guards |
| Agriculture & Infrastructure | Greenhouse skeletons, fence posts, irrigation support structures |
| Shipbuilding & Power | Cable tray supports, platform handrails, structural bracing members |
Where Wall-Thickness Tolerance Decides Whether a Container Gets Accepted on Site
A ±1% tolerance on a 5 mm wall means the difference between passing SGS复检 and shipping the whole container back for re-rolling.
On a Lagos high-rise frame order I supervised, the supplier’s “standard” Q235B square tubes arrived with walls reading 2.5 mm instead of the specified 3.0 mm. The client’s third-party inspector flagged it within 48 hours. Three weeks of re-production, re-shipping, and idle crane time later, everyone learned that tolerance is not a catalogue footnote — it is the line between a structure that loads out and one that sits in a yard. When sourcing a Q235B square and rectangular steel tube supplier, mill test certificates must show actual measured thickness per heat, not just nominal values. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]
How Q235B Hollow Sections Match Structural Frame and Solar Mounting Loads
Q235B delivers a balanced combination of formability and weldability for load-bearing frames in both building construction and solar mounting systems. Its yield behavior aligns with S235JR under EN 10219, making it the default choice for portal frames, bracing members, and PV racking posts where extreme strength is secondary to dimensional consistency and on-site weldability. The Q235B square and rectangular steel tube supplier range from 20×20 mm up to 500×500 mm covers everything from small equipment skids to main column sections, while wall thicknesses from 1.2 mm to 20 mm let engineers tune weight versus load capacity without switching steel families mid-project.
Engineering Compliance Across EN, ASTM, and GB Frameworks
Structural designers specifying EN 1993 (Eurocode 3) or AISC 360 require traceable material properties, and the Q235B square and rectangular steel tube supplier documentation must map Q235B to its European and American equivalents — S235JR and ASTM A500 Grade B respectively — with matching chemical and mechanical data. [NEED_CITE: steel grade equivalence between EN 10219 and ASTM A500 standards] For projects entering the EU market, CE marking under EN 10210 / EN 10219 is mandatory and customs will hold shipments without FPC certificates. Hot-dip galvanized coatings (200–600 g/m²) handle outdoor corrosion exposure for solar and infrastructure applications, while pre-galvanized or black/oiled finishes suit indoor machinery frames where cost matters more than long-term weathering. Cut-to-length capability between 3 m and 12 m reduces on-site cutting waste and keeps工地 welding schedules tight.
Steel Grade Logic: Why Q235B Sits at the Center of Global Hollow Section Procurement
Q235B belongs to the Chinese GB/T 700 carbon structural steel family and sits between Q195 (light forming) and Q345/Q355 (higher strength) in the grade ladder. Its carbon equivalent stays low enough for straightforward ERW welding without pre-heat, yet its yield point carries typical portal frame and bracing loads without over-specifying material cost. The ERW cold-forming process used for these hollow sections produces a continuous longitudinal weld that, when properly controlled, delivers consistent corner mechanical properties — critical for sharp-corner rectangular tubes used in architectural exposed structures. [NEED_CITE: ERW weld quality requirements in EN 10219 cold-formed hollow sections] Wall thickness tolerance of ±1% across the 1.2–20 mm range means theoretical weight calculations stay reliable for structural analysis, and the hot-rolled or ERW welded production routes give buyers the choice between tighter surface finish (hot rolled) or higher dimensional precision (ERW).
The Hidden Cost of Buying Hollow Sections Without Verified Tolerance
Specifying Q235B on a purchase order means nothing if the delivered wall thickness falls outside the ±1% band — undersized walls reduce load capacity and trigger rejection under EN 10219 dimensional checks, while oversized walls inflate freight weight without adding structural value. Missing or forged mill test certificates create customs holds at EU and Middle Eastern ports, where authorities cross-reference heat numbers against declared standards. [NEED_CITE: customs documentation requirements for structural steel under EN 10219] A container of non-conforming tubes does not just cost the material price — it costs the crane rental, the idle labor, the re-order lead time, and the client relationship. Sourcing from a Q235B square and rectangular steel tube supplier that provides original mill test certificates with every heat and allows SGS/BV third-party inspection before loading eliminates this risk class entirely.
Why Project Buyers Choose Xin Jiyuan for Q235B Hollow Sections
Xin Jiyuan operates 3 dedicated production lines for square and rectangular hollow sections, running simultaneous orders across EN 10219, ASTM A500, and GB/T 6728 standards with monthly capacity exceeding 20,000 tons. Every heat rolls with original mill test certificates documenting chemical composition and mechanical properties, and the in-house lab conducts three-stage inspection before any batch reaches the loading bay. The factory maintains ready stock across 2,800+ standard specifications, so trial orders starting from 1 ton can ship within days while bulk project orders follow typical production lead times. CE EN 10210 / EN 10219 and FPC certifications clear European customs without delay, and the professional export team handles container loading optimization — mixing 20×20 mm small sections with 500×500 mm columns in a single 40ft container to maximize weight utilization and reduce per-ton freight cost.
Documentation & Compliance
- Mill test certificate documenting Q235B chemical composition (C, Mn, Si, S, P) and yield/tensile strength per GB/T 700 and EN 10219 equivalence mapping
- CE certificate covering EN 10210 and EN 10219 for structural hollow sections entering European Union markets
- ISO 9001:2015 quality management system certificate covering production, inspection, and traceability processes
- SGS or BV third-party inspection report available upon request, covering dimensional checks, weld quality, and coating thickness verification
- Full material traceability by heat number linking each bundle to its original slab and rolling record
- Customs document package including packing list, bill of lading, certificate of origin, and commercial invoice formatted for destination port requirements
Packaging, Loading & Delivery
- Q235B black/oiled square and rectangular tubes bundled with steel strips and edge protectors to prevent coating damage and bundle shift during ocean transit
- Pre-galvanized and hot-dip galvanized hollow sections wrapped with waterproof paper and plastic sleeves to preserve zinc coating integrity in humid container conditions
- Mixed-size container loading optimization combining 20×20 mm small sections with 300×500 mm large rectangular tubes to maximize 40ft GP weight utilization for project shipments
- Cut-to-length service available across the 3 m – 12 m range, with random length or fixed length options matching project cutting plans
- Heat number and steel grade stenciled on each bundle tag for on-site identification and traceability verification
- FOB, CIF, and DDP shipping terms available with professional export documentation handling for door-to-door delivery to project sites across 50+ countries
Getting Your Q235B Hollow Section Quote Started
Submit your specification sheet — section size, wall thickness, length, steel grade, surface treatment, quantity, and destination port — and the engineering team returns a detailed quotation with volume pricing, production lead time, and mill test certificate confirmation within 12 hours. For non-standard sizes outside the 20×20 mm to 500×500 mm range or custom cut lengths, the team provides a feasibility check and tooling timeline before order confirmation.
Request Your Q235B Hollow Section Quotation with Mill Test Certificate
Send specifications via email to admin@sdxinjiyuan.com or WhatsApp at +86 188 5315 7756 to receive pricing, availability, and certification documentation.
Frequently Asked Questions
Q: How does Q235B map to European and American steel grades for hollow sections?
A: Q235B under GB/T 700 corresponds to S235JR under EN 10219 and ASTM A53 Grade B / A500 Grade B in the American system. The Q235B square and rectangular steel tube supplier provides mill test certificates showing chemical composition and mechanical properties with equivalence mapping across all three standards, so engineers can specify in their local code while sourcing from China.
Q: Can I order non-standard sizes outside the 20×20 mm to 500×500 mm catalog range?
A: Yes. Beyond the 2,800+ standard specifications held in ready stock, custom sizes can be produced on the 3 dedicated lines with typical production lead times of 15–25 days. The MOQ for trial orders starts at 1 ton, and the engineering team reviews non-standard dimension requests for feasibility before order confirmation.
Q: What is the difference between pre-galvanized and hot-dip galvanized surface treatment for Q235B tubes?
A: Pre-galvanized coating (40–80 g/m²) suits indoor applications like machinery frames and indoor bracing where moderate corrosion protection is sufficient and cost is a priority. Hot-dip galvanized coating (200–600 g/m²) provides heavy zinc coverage for outdoor exposure in solar mounting, fencing, and infrastructure projects where long-term weathering resistance is required.
Q: How do you verify material authenticity and compliance before shipment?
A: Every batch ships with original mill test certificates documenting chemical composition and mechanical properties per heat number. Third-party inspection by SGS or BV is available on request to verify dimensional tolerance, weld quality, surface coating thickness, and marking before container loading.
Q: How do you optimize container loading for mixed-size hollow section shipments?
A: The export team designs loading plans that combine small sections (20×20 mm to 100×100 mm) with large rectangular tubes (up to 300×500 mm) in a single 40ft container, nesting smaller tubes inside larger ones where geometry allows. This maximizes weight utilization, reduces per-ton freight cost, and consolidates multi-specification orders into fewer shipments.
Start Your Q235B Hollow Section Procurement Today
Submit your project specifications — section dimensions, wall thickness, steel grade, quantity, and destination — to receive a detailed quotation with mill test certificate confirmation and production timeline within 12 hours.
Contact: admin@sdxinjiyuan.com | WhatsApp: +86 188 5315 7756
