Description
Factory-direct Q235B RHS SHS from raw slab to finished tube — Own steel mill eliminates material certification gaps between supplier and fabricator, with full traceability from heat number to mill test certificate.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B Rectangular Hollow Section |
| Product Type | Welded Square and Rectangular Steel Tube (RHS/SHS) |
| Steel Grade | Q235B, Gr.B, S235, S275, S355, STK400 |
| Standard | ASTM A500, ASTM A53, GB/T 3091 |
| Section Shape | Square and Rectangular |
| Size Range | 15mm×20mm – 700mm×800mm |
| Wall Thickness | 1 – 30 mm |
| Length | 5.8m / 6m / 11.8m / 12m / Random Length |
| Technique | ERW (Welded) |
| Surface Treatment | Black Painting / Galvanized / Varnish / Bare |
| Tolerance | ±1% |
| Ends | Plain |
| Application | Construction structures, Building frames, Curtain walls, Support tubes, Structural frameworks, Fertilizer equipment |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| General Construction | Building frames, column and beam assemblies, curtain wall support structures |
| Industrial Infrastructure | Factory warehouse portals, equipment support frames, conveyor structures |
| EPC Projects | Pipe rack supports, platform structures, infrastructure bracing systems |
| Agricultural & Fertilizer | Fertilizer equipment frames, silo support columns, irrigation structure tubes |
What Negative Tolerance Costs When a Container Reaches Jebel Ali
A 0.4mm wall deviation on a 3.0mm nominal tube turns a standard delivery into a rejected shipment.
I have watched entire containers of rectangular hollow section sit baking at port because the buyer’s third-party inspector flagged wall thickness below the acceptable band. The Q235B rectangular hollow section supplier who quoted the lowest price per ton suddenly becomes the most expensive line item when rework, demurrage, and replacement freight enter the picture. Fragmented sourcing — buying raw material from one mill and sending it to a separate fabricator — creates exactly the kind of certification gap that triggers these failures. Material traceability breaks between the heat number on the mill certificate and the weld seam on the finished tube. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]
How Q235B RHS SHS Matches Structural Frame Demands
The 15mm×20mm to 700mm×800mm size range covers everything from light gauge purlin supports to heavy column sections in warehouse portals. For general contractors assembling building frames, the ±1% dimensional tolerance on the Q235B rectangular hollow section ensures that connection plates and bolt holes align without on-site reaming. ERW welding with certified WPS procedures produces a consistent weld seam that passes ultrasonic inspection — critical when structural frameworks carry load through moment-resisting connections. Our vertically integrated facility processes raw coil from our own mill directly into finished RHS and SHS, so every tube carries traceable chemistry from slab to shipment.
Engineering Compliance Across EN, ASTM, and GB Frameworks
Structural hollow sections for EU projects must conform to EN 10219 dimensional and material requirements, while North American specifications typically call for ASTM A500 Gr.B or Gr.C. The Q235B rectangular hollow section supplier serving international EPC firms needs to provide grade equivalence documentation — Q235B maps closely to S235JR under EN standards and approaches ASTM A500 Gr.B in yield characteristics. Surface treatment selection matters for corrosion environments: hot-dip galvanized coating suits outdoor infrastructure and coastal installations, while black painting or varnish works for indoor structural frameworks where aesthetics and moderate protection suffice. [NEED_CITE: steel grade equivalence between GB Q235B and EN S235JR standards] Custom cut-to-length at 5.8m, 6m, 11.8m, or 12m reduces on-site waste and welding joints for project-specific fabrication sequences.
Understanding Q235B, S-Series, and ASTM Grade Selection
The Q235B grade belongs to the Chinese GB system and offers reliable yield performance for general structural applications — building frames, support tubes, and non-critical load-bearing members. When projects specify S235, S275, or S355 under EN standards, the递增 yield strength levels allow engineers to optimize section weight against load requirements: heavier grades permit thinner walls for the same structural capacity. The ERW welding process used for these welded square and rectangular steel tubes produces a longitudinal seam suitable for structural applications up to moderate pressure, at lower cost than seamless alternatives for non-pressure uses. Wall thickness from 1mm to 30mm across the full size range means a single Q235B rectangular hollow section supplier can serve both light-gauge curtain wall supports and heavy industrial column sections from one procurement package. Negative tolerance control at ±1% ensures that theoretical weight calculations match actual delivered weight — a detail that prevents cost disputes when invoicing runs by actual weight.
Hidden Costs of Sourcing from Disconnected Suppliers
Purchasing structural tubes from a trader who subcontracts fabrication to a separate workshop creates three failure points: the mill certificate may not match the delivered heat number, the weld seam lacks documented WPS procedures, and dimensional tolerance drifts without in-process inspection. When a customs authority requests EN 10219 compliance documentation for a CE-marked shipment and the supplier cannot produce third-party test reports, the container sits at port until re-inspection clears — or the cargo gets returned. [NEED_CITE: material traceability requirements for structural steel under EN 10204] The Q235B rectangular hollow section supplier operating an integrated mill-and-fabrication facility eliminates these gaps by controlling chemistry, rolling, welding, and finishing under one quality management system.
Why Integrated Mill and Fabrication Changes the Procurement Equation
Our own steel production facility feeds raw material directly into the fabrication workshop, meaning every Q235B rectangular hollow section carries a continuous chain of custody from liquid steel to finished tube. The 2,800+ specifications in our inventory cover the full 15×20mm to 700×800mm range without waiting for third-party mill rolling schedules. Certified welding procedures (AWS and EN qualified) and trained welders produce every ERW seam under documented WPS, with weld maps and NDT reports included in the delivery package. We handle shop drawing review, material optimization, and fabrication sequencing for projects requiring custom cuts, drilling, or bending — reducing the number of subcontractors a general contractor must coordinate. Third-party inspection through SGS or BV is available before shipment, verifying dimensional accuracy, coating thickness, and surface quality against the purchase specification. Professional loading plans for oversized and heavy tubes prevent transit damage and ensure containers arrive within weight limits for destination port handling equipment.
Documentation & Compliance
- Mill test certificate documenting Q235B chemical composition and mechanical properties per GB/T 3091, traceable to heat number
- CE certificate confirming EN 10219 compliance for structural hollow sections exported to EU markets
- ISO 9001 quality management system certificate covering the full production process from raw material to finished RHS/SHS
- SGS or BV third-party inspection report verifying dimensional tolerance, wall thickness, and surface treatment quality
- Material traceability documentation linking each bundle to its heat number, rolling record, and welding parameters
- Complete customs documentation package including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- ERW welded Q235B rectangular hollow section bundled with steel strips and edge protectors to maintain ±1% dimensional tolerance during ocean transit
- Galvanized RHS/SHS tubes packed with moisture-resistant separators to preserve zinc coating integrity across the 15×20mm to 700×800mm size range
- Container loading optimized for 5.8m and 6m lengths in 20ft units, with 11.8m and 12m sections planned for 40ft open-top or flat-rack configurations
- Plain-end tubes marked with heat number, steel grade (Q235B/S235/S355), and size identification at both ends for site traceability
- FOB, CIF, and DDP shipping terms available with professional lashing plans for heavy-wall sections up to 30mm thickness
- Custom cut-to-length service available for project-specific requirements, reducing on-site cutting waste for building frame assemblies
Getting Your Q235B RHS SHS Quotation Moving
Share your project drawings or specification list — including section sizes, wall thickness, steel grade, surface treatment, and destination port — and we respond within one working day with pricing, mill test certificate samples, and a production timeline. For non-standard dimensions or custom fabrication requirements, our engineering team reviews shop drawings and confirms feasibility before contract signing.
Request Your Q235B Rectangular Hollow Section Quote Today
Send your specification sheet and purchase quantity to receive pricing, material certification samples, and delivery 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 and ASTM A500 Gr.B for structural applications?
A: Q235B under GB/T 3091 offers similar yield characteristics to S235JR under EN standards and approaches ASTM A500 Gr.B performance. For EU projects specifying EN compliance, we provide grade equivalence documentation and can supply S235, S275, or S355 grades from the same integrated facility.
Q: Can you provide third-party inspection before shipment for international projects?
A: Yes, SGS and BV third-party inspections are available to verify dimensional accuracy, wall thickness, coating quality, and surface treatment before container sealing. Inspection reports are included in the complete documentation package alongside mill test certificates.
Q: What surface treatment options are available for different corrosion environments?
A: We offer hot-dip galvanized coating for outdoor and coastal infrastructure, black painting for indoor structural frameworks, varnish for moderate protection requirements, and bare finish for projects where site-applied coating is specified. Each option is available across the full 15×20mm to 700×800mm size range.
Q: Do you handle custom fabrication beyond standard tube supply?
A: Our fabrication division provides CNC cutting, drilling, bending, and welding services for project-specific components. We review shop drawings, optimize material usage, and deliver finished assemblies with complete quality documentation including WPS, PQR, and weld maps.
Q: How do you ensure material traceability from raw steel to finished product?
A: As a vertically integrated producer with our own steel mill, every Q235B rectangular hollow section carries traceable chemistry from heat number through rolling, welding, and finishing. Mill test certificates document chemical composition and mechanical properties for each production batch.
