Description
Factory-direct pricing, zero middlemen — ERW welded Q235 rectangular hollow sections produced and inspected in-house from raw steel coil to finished bundle.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 Rectangular Hollow Section |
| Product Type | Welded Rectangular Steel Tube (RHS) |
| Steel Grade | Q235, Gr.B, S235, S275, S355, STK400 |
| Standard | ASTM A500, ASTM A53, GB/T 3091 |
| Section Shape | 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 | Steel Structures / Construction Frames / Curtain Wall / Building Structures / Machinery / Support Frames |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Industrial Construction | Portal frame columns, roof truss chords, warehouse purlin systems |
| Commercial Building | Curtain wall mullions, facade support grids, canopy structures |
| Infrastructure | Highway sign gantry frames, sound barrier posts, bridge handrails |
| Machinery & Equipment | Conveyor support frames, crane boom sections, equipment base platforms |
| EPC Projects | Pipe rack structures, modular plant frames, support platforms for process equipment |
What Material Traceability Gaps Cost on an Overseas RHS Order
A missing heat number on a mill cert can halt customs clearance and trigger full-batch rejection at site.
When procurement teams source a Q235 rectangular hollow section supplier from fragmented traders, the chain between steelmaking heat and finished tube often breaks. Weld seams lack WPS records, zinc coating thickness varies bundle to bundle, and dimensional reports arrive unsigned. On projects governed by EN 10219 or ASTM A500, these gaps are not paperwork inconveniences — they become structural liability. [NEED_CITE: EN 10219 cold-formed hollow section compliance requirements]
How Wall-Thickness Tolerance Aligns with Structural Load Paths
A Q235 rectangular hollow section supplier controlling ±1% wall tolerance ensures that calculated section modulus matches actual load-bearing capacity on site. For portal frames carrying crane loads or mezzanine platforms with concentrated forces, even minor thickness deviation shifts stress distribution at welded connections. Our ERW process maintains consistent seam penetration across the full 1–30mm range, verified by in-process ultrasonic testing at every production shift.
Engineering Compliance Across Regional Steel Standards
Structural frames destined for EU markets require CE marking under EN 10219, while North American EPCs specify ASTM A500 Gr.B or Gr.C. The same Q235 rectangular hollow section supplier must provide equivalent chemical composition data — carbon, manganese, sulfur, phosphorus — mapped across standard systems. [NEED_CITE: steel grade equivalence between GB, EN, and ASTM standards] Wall thickness at 1–30mm covers both light gauge curtain wall mullions and heavy-load column sections, with plain ends ready for site welding or bolted connection plates.
Understanding ERW Welding and Steel Grade Selection
ERW (Electric Resistance Welding) forms the rectangular profile from coil, then fuses the seam through high-frequency current without filler metal — producing a consistent weld zone suitable for structural loads up to S355 yield class. Q235 and S235 serve general construction frames where moderate strength suffices; S275 and S355 step up for crane-runway beams or seismic-zone structures. STK400 aligns with JIS requirements for Japanese-spec projects. Surface treatment follows environment: hot-dip galvanizing for coastal or industrial corrosion zones, black painting for indoor dry conditions, bare for sites applying field coating systems. [NEED_CITE: ERW versus seamless hollow section structural applications]
The Hidden Price of Accepting Negative Tolerance Drift
Specifying Q235 rectangular hollow section without enforcing ±1% tolerance invites theoretical weight calculations that exceed actual delivered mass. When section modulus drops below design assumptions, connection welds face higher stress, and structural engineers must either reinforce or reject the batch. Certification gaps compound the problem — a mill test certificate without heat-number traceability cannot satisfy EN 10204 3.1 requirements, triggering third-party re-inspection costs and shipment delays. [NEED_CITE: EN 10204 inspection document types for steel products]
Why Project Teams Consolidate RHS Procurement Here
Vertically integrated production eliminates the gap between raw steel coil and finished fabricated section — one quality system covers melting, rolling, ERW welding, and surface treatment. Every Q235 rectangular hollow section supplier claim of “mill direct” should be tested against actual heat-number traceability on the mill test certificate. Our in-house laboratory issues EN 10204 3.1/3.2 documentation per heat, and third-party inspectors (SGS, BV) verify dimensions and coating thickness before container sealing. With 2,800+ specifications in stock and custom non-standard sizes available, project teams avoid splitting orders across multiple vendors. Professional loading plans maximize container utilization for 6m and 11.8m lengths, reducing per-ton freight costs.
Documentation & Compliance
- Mill test certificate documenting Q235 chemical composition and mechanical properties per GB/T 3091, with heat number traceability
- CE certificate confirming EN 10219 compliance for rectangular hollow sections exported to European Union markets
- ISO 9001 quality management certificate covering the full production process from coil slitting to final bundling
- SGS or BV third-party inspection report verifying wall thickness, zinc coating weight, and dimensional tolerance before shipment
- Material traceability sheet linking each bundle to its original heat number and ERW welding parameters
- Export customs documents including packing list, bill of lading, and certificate of origin for destination-country clearance
Packaging, Loading & Delivery
- ERW welded rectangular tubes bundled with galvanized steel strips at intervals preventing bundle spread during ocean transit
- Hot-dip galvanized Q235 RHS separated by rubber edge protectors to preserve zinc coating integrity at contact points
- 6m and 11.8m lengths loaded in nested configurations maximizing 20ft and 40ft container payload for 15×20mm to 300×300mm sections
- Plain-end tubes capped at both ends to prevent moisture ingress and internal corrosion during storage and shipping
- Each bundle tagged with heat number, steel grade (Q235/S235/S355), wall thickness, and length for site identification
- FOB Jinan or Qingdao port with CIF and DDP options available for project sites requiring door-to-door delivery
Starting Your RHS Procurement Process
Submit project drawings or a specification schedule listing steel grade, section dimensions, wall thickness, total tonnage, and destination port. Our engineering team responds within 24 hours with a detailed quotation including material cost, ERW fabrication, surface treatment, packing, and freight — plus a shop drawing timeline for approval before production begins.
Request Your Q235 Rectangular Hollow Section Quotation
Send your specification list and destination port to receive pricing, mill test certificate samples, and production lead time confirmation.
Contact: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjystructure.com
Website: www.xjystructure.com
Frequently Asked Questions
Q: Can Q235 steel grade be substituted for S235JR or ASTM A500 Gr.B on international projects?
A: Q235, S235JR, and ASTM A500 Gr.B share similar carbon and manganese ranges, making them functionally equivalent for general structural applications. However, destination-country engineering codes may require formal equivalence documentation. We provide cross-reference mill test certificates showing chemical composition mapped to EN and ASTM standards.
Q: What third-party inspection options are available before shipment?
A: SGS and BV inspection teams can attend our facility to verify wall thickness, outer dimensions, zinc coating weight (for galvanized RHS), and visual weld quality. Inspection reports are issued before container sealing and included in the export documentation package.
Q: Do you produce non-standard rectangular sizes outside the 15×20mm to 700×800mm range?
A: Custom section sizes are available for project-based orders meeting the 5-ton minimum. Our ERW mill can form special profiles based on customer drawings, with tooling adjustments completed within typical production lead times.
Q: How is hot-dip galvanized coating thickness verified and documented?
A: Zinc coating thickness is measured using magnetic induction gauges at multiple points per bundle, with results recorded on the mill test certificate. Coating weight typically meets or exceeds 275 g/m² (equivalent to approximately 65μm) for standard structural applications, with heavier coatings available for aggressive corrosion environments.
Q: What is the standard packing method for export shipments?
A: Rectangular hollow sections are bundled with galvanized steel strips, nested to maximize container space, and secured with dunnage to prevent movement. Galvanized tubes receive additional edge protection to preserve coating integrity. Each bundle is labeled with heat number, grade, size, and length.
