Description
Factory-Direct ERW Rectangular Tubes — Vertically integrated mill and fabrication in Jinan delivering Q235 Q345 rectangular steel tube with ±1% tolerance, eliminating fragmented sourcing risks for structural projects.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235/Q345 Rectangular Steel Tube |
| Product Type | Rectangular Steel Tube (Hollow Section) |
| Steel Grade | Q195, Q215, Q235, Q345 |
| Standard | ASTM A213, DIN EN 10217-1 |
| Section Shape | Rectangular / Square |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Hot Rolled / Slightly Oiled |
| Tolerance | ±1% |
| Length | Custom length available |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Application | Structure Pipe, Fluid Pipe, Boiler Pipe, Gas Pipe, Oil Pipe, Chemical Fertilizer Pipe, Construction frames, Steel structures |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Building Construction | Steel frame columns, roof trusses, portal frames, mezzanine beams |
| Industrial Facilities | Equipment support platforms, conveyor structures, pipe rack systems |
| Infrastructure | Bridge handrails, highway sign gantries, sound barrier posts |
| Fluid & Gas Transport | Low-pressure process piping, chemical fertilizer distribution lines |
| Commercial Projects | Warehouse frameworks, logistics center structures, exhibition hall frames |
What Dimensional Tolerance Actually Costs on a Q235 Q345 Rectangular Steel Tube Order
A ±1% deviation sounds negligible on paper — until fifty columns arrive on site and none of the connection plates align.
When procurement teams source Q235 Q345 rectangular steel tube from disconnected suppliers, the material mill and the fabrication shop operate under different quality systems. The tube arrives with wall thickness drifting beyond negative tolerance, and the fabricator either reworks connections at extra cost or forces fit-up with shims that compromise structural integrity [NEED_CITE: dimensional tolerance impact on steel structure erection efficiency]. For EPC contractors managing tight schedules, these hidden mismatches translate into crane idle time, re-welding delays, and failed third-party inspections before handover.
How ERW Rectangular Hollow Sections Match Structural Frame Requirements
The Q235 and Q345 grades in this Q235 Q345 rectangular steel tube cover the full spectrum from light-duty bracing members to primary load-bearing columns. ERW welding produces a continuous longitudinal seam with consistent mechanical properties across the cross-section, while the ±1% tolerance ensures that shop drawings translate directly into field-fit connections without on-site modification. Our integrated facility handles everything from raw coil slitting through final CNC cutting and drilling, so the dimensional chain stays under one quality system from start to finish.
Engineering Compliance and Certification for Global Projects
Structural engineers specifying these rectangular hollow sections typically require compliance with EN 10219 for cold-formed welded structural tubing or ASTM A500 for North American building codes [NEED_CITE: EN 10219 cold-formed hollow section structural requirements]. The Q235 grade maps closely to S235JR under European standards, while Q345 corresponds to S355JR in yield strength classification — a critical equivalence for projects requiring CE marking or third-party certification. Hot rolled surface with slight oiling provides baseline corrosion protection during ocean transit, while the custom length capability eliminates field splicing for members up to full container length.
Steel Grade Selection and ERW Process Fundamentals
The Q-series grading system (Q195 through Q345) designates minimum yield strength in MPa, meaning Q345 delivers substantially higher load capacity than Q235 for the same cross-section — essential when structural optimization demands smaller member sizes without sacrificing safety factors. ERW welding fuses the strip edges through electrical resistance heating without filler metal, producing a weld zone with properties matching the parent material when properly controlled. This process suits rectangular and square hollow sections because the forming sequence gradually shapes the flat strip into closed profiles, maintaining consistent wall thickness at corners where bending stresses concentrate. The slight oiling applied after hot rolling prevents surface oxidation during storage and shipping, preserving weld preparation quality until fabrication begins.
The Hidden Price of Tolerance Drift and Missing Documentation
Specifying Q235 Q345 rectangular steel tube without enforcing ±1% tolerance invites negative tolerance stacking — where every batch arrives at the lower limit, reducing actual weight and load capacity below design assumptions. More critically, shipments lacking proper mill test certificates or material traceability by heat number face customs holds or outright rejection at destination ports [NEED_CITE: steel import documentation requirements for customs clearance]. For certified welders working under WPS procedures, unknown base metal chemistry means procedure qualification records become invalid, forcing costly re-testing and project delays.
Why Source Q235 Q345 Rectangular Steel Tube From Our Jinan Facility
Our vertical integration eliminates the handoff gaps that plague fragmented supply chains — the same facility that produces the raw steel coil also runs the ERW tube mill and the structural fabrication workshop, so material traceability stays intact from heat number to finished component. We maintain over 2,800 specification combinations in stock, meaning standard sizes ship immediately while custom lengths and processed components (cut, drilled, bent per shop drawings) move through production without waiting for material procurement. Every Q235 Q345 rectangular steel tube leaves our plant with complete documentation: mill test certificates showing actual chemistry and mechanical properties, dimensional inspection reports, and coating thickness measurements where applicable. Our certified welding procedures and qualified welders hold AWS and EN certifications, so fabrication work carries the same quality assurance as the base material. Professional loading teams understand how to pack rectangular hollow sections for ocean transit — nesting smaller sizes inside larger ones, using edge protectors to preserve oiled surfaces, and maximizing container payload without damaging dimensional accuracy.
Documentation & Compliance
- Mill test certificate documenting Q235 and Q345 chemical composition (C, Mn, Si, P, S) and mechanical properties (yield strength, tensile strength, elongation) per ASTM A213 and DIN EN 10217-1
- CE certificate confirming EN 10219 compliance for structural hollow sections exported to European Union markets
- ISO 9001 quality management system certificate covering the full production chain from steelmaking through tube welding and fabrication
- SGS or BV third-party inspection report available for dimensional verification, weld seam quality, and surface treatment thickness
- Material traceability documentation linking each bundle to specific heat numbers for full supply chain transparency
- Complete customs documentation package including packing list, bill of lading, and certificate of origin for smooth port clearance
Packaging, Loading & Delivery
- Q235 and Q345 rectangular tubes bundled with high-tensile steel strips at regular intervals, with edge protectors preserving the oiled hot rolled surface during handling and ocean transit
- Custom-length tubes cut to exact project specifications, eliminating field cutting waste and enabling direct-to-site delivery for construction sequences
- Container loading optimized by nesting smaller rectangular sections inside larger ones, maximizing payload for the ±1% tolerance product while protecting dimensional accuracy
- Heat number and steel grade stenciled on each bundle end, with color-coding distinguishing Q235 from Q345 to prevent grade mixing at fabrication shops
- FOB, CIF, and DDP shipping terms available from Jinan inland port through Qingdao seaport to destination ports worldwide
Getting Your Q235 Q345 Rectangular Steel Tube Quote Started
Submit your project drawings (PDF or DWG format) with specified steel grades, section dimensions, wall thickness, quantities, and required standards — our engineering team responds within 24 hours with preliminary assessment, shop drawing timeline, and detailed pricing covering material, fabrication, coating, packing, and shipping. For projects requiring third-party inspection or specific certification packages, confirm these requirements upfront so we include them in the quotation and production schedule.
Frequently Asked Questions
Q: How do Q235 and Q345 steel grades compare to European and American equivalents?
A: Q235 corresponds closely to S235JR under EN standards and A36 under ASTM, while Q345 matches S355JR and A572 Grade 50 in yield strength classification. We provide detailed equivalence documentation for your project’s specified standard.
Q: Can you produce custom lengths and processed components beyond standard stock sizes?
A: Yes, our integrated facility handles custom cutting, drilling, bending, and welding per your shop drawings. We maintain 2,800+ specification combinations and can produce non-standard lengths to match your project’s modular coordination requirements.
Q: What quality documentation do you provide for international project compliance?
A: Every shipment includes mill test certificates with actual chemical and mechanical test results, dimensional inspection reports, material traceability by heat number, and complete customs documentation. Third-party inspection by SGS or BV is available upon request.
Q: How do you ensure material traceability from raw steel to finished tube?
A: Our vertically integrated operation means the same facility produces the raw steel, runs the ERW tube mill, and performs fabrication services. Each bundle carries heat number identification linking back to the original melt chemistry and rolling records.
Q: What is the typical production lead time from order confirmation to shipment?
A: Standard sizes in stock ship within typical production lead times after deposit receipt and drawing approval. Custom processed components require additional time for CNC programming and quality inspection, which we detail in the production schedule included with your quotation.
Start Your Q235 Q345 Rectangular Steel Tube Project Today
Send your project specifications and drawings to receive detailed pricing, mill test certificate samples, and production timeline within 24 hours.
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
