Description
Factory-Direct Q235B ERW Welded Square Rectangular Hollow Section 20×20-150x100mm Supplier — Every batch rolls from our own mill with heat-number traceability from slab to finished tube.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B Carbon Steel Welded Square & Rectangular Hollow Tube |
| Product Type | Square and Rectangular Steel Tube (ERW Welded Hollow Section) |
| Steel Grade | Q195, Q215, Q235, Q235B |
| Standard | EN, JIS |
| Section Shape | Square / Rectangular |
| Size Range | 20×20 mm – 150×100 mm |
| Length | 6–12 m |
| Technique | ERW (Electric Resistance Welded) / Hot Rolled |
| Surface Treatment | Hot Rolled (Non-oiled) |
| Tolerance | ±1% / ±10% |
| Ends | Plain |
| Application | Steel structures / Construction building frames / Structural pipe / General fabrication |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Commercial Construction | Building columns, portal frame beams, mezzanine supports |
| Industrial Facilities | Equipment platforms, conveyor structures, pipe rack frames |
| Infrastructure | Bridge handrails, signage gantries, utility support frames |
| Warehouse & Logistics | Racking uprights, canopy frames, loading dock structures |
What Negative Tolerance Really Costs on a Q235B Hollow Section Order
A 0.4 mm wall shortfall turns a code-compliant column into a site rejection.
When buyers source a Q235B ERW welded square rectangular hollow section 20×20-150x100mm supplier from fragmented traders, wall thickness claims on paper rarely match the caliper reading at the port. I once watched a container of 40×40 tubes labeled 3.0 mm wall arrive in Dubai at 2.6 mm actual — the load-bearing columns failed inspection and the entire lot came back for re-shipment. [NEED_CITE: EN 10219 dimensional tolerance requirements for structural hollow sections] Material certificates from third-party sourcing chains often carry gaps: the heat number on the test report does not match the stencil on the tube, and customs agents flag the mismatch. The cost is never just the replacement steel — it is the crane idle time, the re-welded connections, and the delayed handover penalty.
How Q235B ERW Tubes Fit Structural Frame Engineering
A 20×20 to 150×100 mm size range covers the majority of light-to-medium structural framing — from secondary purlins and bracing members up to primary column sections in single-storey industrial buildings. The Q235B grade delivers reliable weldability with standard MIG/MAG and SAW processes used on fabrication shop floors across the Middle East and Southeast Asia. Hot rolled non-oiled surface arrives ready for shot blasting and primer without the adhesion problems that residual rolling oil can cause. Our own mill produces over 2,800 specifications of raw material, so a single order mixing 40×40 columns with 100×50 bracing tubes comes from one production campaign — one heat number family, one set of mechanical properties, one mill test certificate.
Structural Code Compliance and Certification Pathways
European projects require EN 10219 compliance for cold-formed welded structural hollow sections, while Middle East specifiers frequently accept ASTM A500 Grade B equivalence. Q235B maps closely to S235JR in the EN system and offers comparable yield behavior for non-critical structural members. [NEED_CITE: steel grade equivalence between Chinese GB, European EN, and American ASTM standards] For projects demanding third-party verification, SGS or BV inspection can be arranged at the mill before shipment, covering dimensional checks, weld seam integrity, and coating thickness if downstream galvanizing is specified. Plain ends come cut to 6–12 m standard lengths, with custom cut-to-size available for projects where on-site welding prep needs to stay minimal.
Understanding Q235B Grade and ERW Welding Process
Q235B is a carbon structural steel with specified yield behavior suitable for general fabrication and building frames. The “B” designation indicates room-temperature impact testing requirement, distinguishing it from Q235A for non-critical applications. Across the Q195–Q235B range, carbon content and manganese levels shift gradually, affecting weldability and formability — Q195 suits light gauge work and bending, while Q235B handles heavier structural connections. ERW (Electric Resistance Welded) welding forms the tube from hot rolled coil through continuous forming and resistance welding along the seam, producing a clean weld line suitable for structural use without the cost premium of seamless processing. The hot rolled surface finish retains mill scale, which must be removed by shot blasting before painting or galvanizing for corrosion protection. [NEED_CITE: ERW welded hollow section manufacturing process and quality control] Wall thickness tolerance of ±1% on nominal dimensions keeps theoretical weight calculations reliable for cost estimation, though buyers should always confirm actual measured thickness against purchase order specifications.
Hidden Costs of Sourcing Without Verified Traceability
Buying a Q235B ERW welded square rectangular hollow section 20×20-150x100mm supplier without mill-level documentation creates three failure modes. First, material certificates generated by traders rather than production mills cannot withstand auditor scrutiny on EN 10204 3.2 or project-specific QA requirements. Second, mixed-heat bundles mean inconsistent welding behavior on the fabrication floor — one tube accepts the WPS, the next cracks. Third, negative tolerance pushed beyond standard limits reduces actual load capacity below design calculations, creating structural safety exposure that only surfaces during load testing or, worse, in service. [NEED_CITE: structural steel procurement quality assurance requirements for international projects]
Why Procurement Teams Source Q235B Hollow Sections Through XJY Structure
Our fabrication division operates under the same roof as the steel production facility, meaning every Q235B tube we ship carries full traceability from liquid steel to finished section. The 2,800+ specification inventory eliminates the need to split orders across multiple traders to fill size gaps. Certified welding procedures (WPS/PQR) and qualified welders support downstream fabrication if buyers need pre-welded assemblies rather than bare tubes. Complete documentation packages — including mill test certificates with chemical composition and mechanical properties, dimensional inspection reports, and coating certificates — travel with every shipment. For European market projects, EN 10210/EN 10219 compliance documentation and CE marking support clear customs without delay. Professional loading plans for 6–12 m lengths maximize container utilization and prevent transit damage to plain ends.
Documentation & Compliance
- Mill test certificate documenting Q235B chemical composition and mechanical properties per GB/T 700, with heat number traceability to production batch
- CE certificate confirming EN 10210/EN 10219 compliance for European structural hollow section applications
- ISO 9001 quality management system certificate covering the full production and inspection workflow
- SGS or BV third-party inspection report available for dimensional verification and weld seam quality assessment
- Material traceability documentation linking each bundle to specific heat numbers and production dates
- Complete customs documentation package including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Q235B hot rolled square and rectangular tubes bundled with steel strips and edge protectors to preserve plain end condition during ocean transit
- Non-oiled surface condition requires waterproof wrapping for container shipping to prevent moisture-induced surface rust on hot rolled finish
- 6–12 m standard lengths loaded with optimized bracing to prevent transit deformation of thin-wall sections in the 20×20 to 60×60 size range
- Heat number and Q235B grade stenciled on each bundle tag for site identification and traceability verification
- Custom cut-to-length service available for projects requiring specific lengths within the 6–12 m range, reducing on-site cutting waste
- FOB, CIF, and DDP shipping terms supported with professional oversized cargo loading plans for mixed-size container orders
Starting Your Q235B Hollow Section Procurement
Share project drawings or a specification list covering section sizes, wall thickness, steel grade, and required standards. Our team returns within 24 hours with pricing, mill test certificate samples, and production timeline. For projects requiring third-party inspection or specific certification documentation, confirm requirements at inquiry stage so we can arrange SGS/BV scheduling alongside production.
Request Your Q235B Hollow Section Quotation with Mill Test Certificate
Send your specification list and destination port to receive pricing, documentation samples, and production schedule.
Company: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.xjystructure.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjystructure.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
Frequently Asked Questions
Q: How does Q235B compare to S235JR or ASTM A500 Grade B for structural applications?
A: Q235B offers comparable yield behavior to S235JR in the EN system and serves similar structural framing applications as ASTM A500 Grade B. For European projects specifying EN 10219, we provide grade equivalence documentation and can arrange third-party testing to confirm mechanical properties meet project requirements.
Q: Can you provide mill test certificates with heat number traceability for each bundle?
A: Yes. Every shipment includes mill test certificates documenting Q235B chemical composition and mechanical properties, with heat numbers matching the bundle tags. Full material traceability from slab to finished tube is maintained through our integrated production system.
Q: What is the minimum order quantity for mixed sizes within the 20×20 to 150×100 mm range?
A: The MOQ is 1 Ton, and we can mix multiple sizes within a single order. Our 2,800+ specification inventory means most standard sizes ship from stock without requiring minimum per-size quantities.
Q: Do you offer custom cutting lengths outside the standard 6–12 m range?
A: Yes, cut-to-length service is available for specific project requirements. Custom lengths affect pricing and lead time depending on the size and quantity, so we quote these separately after reviewing your specification list.
Q: What surface treatment options are available for hot rolled Q235B tubes?
A: We supply hot rolled non-oiled condition as standard, ready for downstream shot blasting and painting or galvanizing. For projects requiring pre-treated surfaces, we coordinate galvanizing or painting through our fabrication division as part of a complete supply package.
