Description
Direct Mill Supply, No Broker Markup — Q235 and Q345 ERW welded rectangular steel hollow section tube produced in-house with full chemical and mechanical traceability from slab to finished bundle.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235/Q345 ERW Welded Rectangular Steel Tube |
| Product Type | Welded Rectangular Steel Tube (Hollow Section) |
| Steel Grade | Q195, Q215, Q235, Q345 |
| Standard | ASTM A213, DIN EN 10217-1 |
| Section Shape | Rectangular |
| Size Range | 20×20mm, 50×25mm, 60×40mm, 80×40mm, 50×50mm |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Hot Rolled / Slightly Oiled |
| Tolerance | ±1% |
| Length | Customer’s Request |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Application | Fluid Pipe, Boiler Pipe, Drill Pipe, Gas Pipe, Oil Pipe, Chemical Fertilizer Pipe, Structure Pipe |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, column supports, roof trusses, bridge handrails |
| Machinery Manufacturing | Conveyor structures, equipment bases, hydraulic support frames |
| Industrial Plant Piping | Gas distribution lines, chemical fertilizer transport, boiler feed systems |
| Oil & Gas | Drill pipe casings, low-pressure fluid transport, platform structural bracing |
Dimensional Tolerance Is Where Rectangular Tube Orders Either Fit or Fail on Site
A ±1% tolerance on ERW welded rectangular steel hollow section tube means the difference between a curtain wall frame that bolts together and one that gets sent back to the yard for re-cutting.
When rectangular tubes arrive with oversized outer dimensions or uneven wall distribution, fabricators waste days re-machining connection plates. Worse, if the wall thickness drifts beyond acceptable negative tolerance, the structural engineer’s load calculations no longer hold — and the inspector will reject the entire batch. Sourcing an ERW welded rectangular steel hollow section tube supplier who controls tolerance at the mill, not just at the loading dock, eliminates this risk before the container is sealed. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]
Matching Rectangular Hollow Sections to Structural and Fluid Transport Loads
Q235 and Q345 grades cover the majority of structural framing and low-pressure fluid applications across construction and industrial plants. The ERW welding process produces a continuous longitudinal seam suitable for rectangular profiles from 20×20mm up to 80×40mm, with wall thickness controlled to ±1% tolerance — critical when these ERW welded rectangular steel hollow section tubes are welded into moment frames or used as precision machine bases. Hot rolled surface with light oiling protects the steel during ocean transit without interfering with downstream painting or galvanizing.
Engineering Compliance and Certification for Cross-Border Delivery
Structural applications demand compliance with EN 10219 for cold-formed welded hollow sections or ASTM A213 for boiler and superheater tubes, depending on the end use. EU buyers require CE marking per EN 10210/10219, while North American projects reference ASTM equivalents. The ERW welded rectangular steel hollow section tube must carry a mill test certificate showing chemical composition and mechanical properties per heat number — without it, customs clearance stalls and site inspectors refuse to sign off. [NEED_CITE: steel grade equivalence between GB Q-series and EN S-series standards]
Understanding Q235 vs Q345 and ERW Welding for Rectangular Profiles
Q235 offers adequate yield strength for general structural framing, scaffolding, and non-critical fluid lines, while Q345 provides higher yield for load-bearing columns and machinery bases where deflection limits are tighter. The ERW process forms the rectangular profile from flat strip, then welds the longitudinal seam through electrical resistance — producing a clean internal bead suitable for fluid transport and a smooth external surface for architectural applications. Hot rolled finish with slight oiling prevents white rust during storage and shipping, while still allowing weld preparation without additional surface grinding. Wall thickness tolerance of ±1% ensures that theoretical weight invoicing matches actual delivered weight within acceptable commercial limits.
The Hidden Cost of Tolerance Drift and Missing Certification
Ordering rectangular tubes based on price alone often means accepting negative tolerance beyond standard limits — the steel arrives lighter than specified, the structural capacity drops, and the project faces re-engineering or outright rejection. Missing or incomplete mill test certificates trigger customs holds in regulated markets, delaying delivery by weeks. An ERW welded rectangular steel hollow section tube supplier who provides third-party inspection (SGS/BV) and full heat-number traceability prevents these failures at source. [NEED_CITE: consequences of dimensional non-compliance in structural steel procurement]
Why Procurement Teams Source ERW Welded Rectangular Tubes from Our Mill
Our in-house physical and chemical laboratory tests every heat for composition and mechanical properties before the ERW welded rectangular steel hollow section tube leaves the line — no outsourced certificates, no batch mixing. With 2,800+ specifications in stock including custom non-standard sizes, we consolidate rectangular, square, and section steel into single-container shipments, reducing logistics cost and coordination overhead. Our 41 invention patents include China’s original sharp-corner rectangular tube technology, filling the gap for architectural facades where standard rounded-corner tubes fail aesthetic requirements. Full ISO 9001:2015, Lloyd’s CE (EN 10210/10219), and Singapore FPC certifications ensure smooth customs clearance across 50+ export markets. Professional container loading with anti-damage measures prevents bending and surface scratches during ocean transit — a lesson learned from early export claims.
Documentation & Compliance
- Mill test certificate documenting Q235/Q345 chemical composition and yield strength per DIN EN 10217-1, issued per heat number
- CE certificate per EN 10210/EN 10219 for structural hollow sections exported to EU member states
- ISO 9001:2015 quality management system certificate covering ERW welding and dimensional inspection
- SGS or BV third-party inspection report available upon request for pre-shipment verification
- Material traceability by heat number linking each bundle to its original slab test results
- Full customs documentation including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Q235/Q345 ERW welded rectangular tubes bundled with steel strips and edge protectors to maintain ±1% dimensional tolerance during handling
- Hot rolled surface with slight oiling preserved by waterproof wrapping to prevent corrosion during ocean transit
- Container loading optimized for 20×20mm to 80×40mm rectangular profiles, maximizing payload within 20ft and 40ft GP containers
- Custom cutting to project-specified lengths available, with cut ends deburred and marked per bundle
- Heat number and steel grade stenciled on each bundle for site identification and traceability
- FOB, CIF, and DDP trade terms available with door-to-door logistics to 50+ countries
Start Your Procurement With Clear Specifications
Submit your required dimensions, steel grade (Q235 or Q345), quantity, and destination port — we respond within 12 hours with pricing, lead time, and mill test certificate samples. For non-standard sizes or custom cutting, our engineering team provides fabrication drawings before production begins.
Request Your ERW Welded Rectangular Tube Quote
Send your specification sheet to admin@sdxjypipe.com or contact us via WhatsApp at +86 188 5315 7756 to receive pricing, available stock sizes, and certification documents for your next project.
