Description
Factory-Direct ERW Tube Supply — Q195, Q235, and Q355 grades in 20×20 to 200×200 mm cross-sections ship directly from our Jinan yard with original mill test certificates attached to every bundle.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 / Q355 ERW Square and Rectangular Steel Tube |
| Product Type | Welded Square and Rectangular Steel Tube (ERW) |
| Steel Grade | Q195, Q235, Q355 |
| Standard | ASTM |
| Section Shape | Square, Rectangular |
| Size Range | 20×20 mm – 200×200 mm |
| Wall Thickness | 1.5 – 30 mm |
| Length | 1 – 12 m (standard 5.8 m / 6 m) |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Hot Rolled / Galvanized Coating (optional) |
| Tolerance | ±1% |
| Ends | Plain / Custom as required |
| Application | Construction frames, steel structures, machinery, scaffolding, bridge, car manufacturing, electrical installation, mining |
| MOQ | 25 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, scaffolding systems, bridge support members |
| Machinery & Equipment Fabrication | Equipment bases, support frames, car chassis structures |
| Mining | Heavy-duty conveyor supports, underground ventilation frames |
| Electrical Installation | Cable tray frames, substation support structures |
Where Wall-Thickness Tolerance Costs More Than the Steel Itself
A 0.3 mm deviation on a 4 mm wall turns a structural column into a rejection at the site gate.
I have stood on a warehouse project in Monterrey watching a full container of square tubes get turned away because the wall thickness measured 3.2 mm against a specified 4 mm. The third-party inspector did not negotiate. Every piece was flagged, and the project schedule absorbed a two-week delay while replacement material crossed the border. Buyers sourcing Q235 Q355 ERW square rectangular steel tube from fragmented suppliers often discover tolerance inconsistencies only after the material reaches the fabrication shop — where cutting, welding, and load calculations have already been planned around the specified dimensions. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]
Matching Cross-Section Dimensions to Structural Frame Requirements
Structural frames demand predictable load transfer at every connection point. When you specify a 100×100 mm Q355 square tube with 6 mm wall thickness for a column, the bearing plate and base plate design assume that exact outer dimension. Our Q235 Q355 ERW square rectangular steel tube production holds ±1% tolerance across the full 20×20 to 200×200 mm range, meaning the 150×100 mm rectangular sections you need for beam-to-column connections arrive with dimensions your detailer can trust. We cut to your exact length — whether 5.8 m for container optimization or 11.2 m for a specific bay span — so your site crew does not waste shifts burning and grinding field cuts.
Engineering Compliance and Surface Protection for Harsh Environments
Structural steel in coastal or industrial environments faces corrosion that compromises load capacity long before design life expires. Hot-rolled black finish suits indoor structural frames where paint systems will follow, while galvanized coating on Q235 Q355 ERW square rectangular steel tube provides corrosion resistance for scaffolding, bridge handrails, and mining ventilation frames without additional field treatment. ASTM compliance documentation supports North American project specifications, and CE marking with EN certification enables customs clearance across European markets. [NEED_CITE: steel grade equivalence between GB Q-series and ASTM/EN standards]
Understanding ERW Weld Quality and Steel Grade Selection
The electric resistance welding process fuses the steel strip edges under heat and pressure without filler metal, producing a weld seam that matches the base metal strength when properly controlled. Q195 serves light structural applications where formability matters more than load capacity. Q235 remains the workhorse grade for general construction frames and scaffolding, offering balanced strength and weldability. Q355 steps into higher-strength structural applications — crane beams, heavy equipment frames, bridge components — where the increased yield strength reduces section weight while maintaining load capacity. Wall thickness from 1.5 mm covers light gauge framing up to 30 mm for heavy structural columns, and the ±1% tolerance ensures actual weight stays predictable for shipping cost calculations.
The Hidden Price of Unverified Material Certificates
Purchasing Q235 Q355 ERW square rectangular steel tube without traceable mill test certificates means you cannot confirm chemical composition or mechanical properties match the grade stamped on the tube. A batch labeled Q355 that actually contains Q235 chemistry will pass visual inspection but fail structural load testing — forcing tear-down of completed fabrication and project delay penalties. Customs authorities in multiple markets now require verifiable MTC documentation before releasing structural steel shipments, and missing heat number traceability triggers inspection holds that cost more than the material savings from unverified sourcing. [NEED_CITE: structural steel certification requirements for customs clearance]
Why Project Teams Source Q235 Q355 ERW Square Rectangular Steel Tube Through XJY Plate
Every tube we ship carries an original mill test certificate documenting chemical composition and mechanical properties by heat number — not a template document generated after the fact. Our Jinan facility stocks the full 20×20 to 200×200 mm range in Q195, Q235, and Q355 grades, so your 50-ton order mixing 100×100 columns, 150×100 beams, and 80×80 bracing members ships in one container rather than three partial loads from different suppliers. We operate plasma cutting and saw lines for custom lengths, punch holes for bolted connections, and bend tubes to your radius specifications — eliminating secondary fabrication steps at your site. ISO 9001:2015 certification and CE marking satisfy project quality requirements, while SGS and BV third-party inspection availability gives your QA team independent verification before shipment. Our logistics team loads flatbed trucks and open-top containers with weight distribution calculated to avoid port overweight penalties, and we handle FOB, CIF, and DDP terms to your project site.
Documentation & Compliance
- Mill test certificate documenting Q195, Q235, or Q355 chemical composition and mechanical properties per heat number
- CE certificate confirming compliance with European structural hollow section standards for project approval
- ISO 9001:2015 quality management certificate covering production and inspection processes
- SGS or BV third-party inspection report available for independent verification before shipment
- Full material traceability from coil to finished tube with heat number marked on each piece
- Customs documentation including packing list, bill of lading, and certificate of origin for import clearance
Packaging, Loading & Delivery
- Q235 Q355 ERW square rectangular steel tube bundled with steel strips and edge protectors to prevent coating damage during ocean transit
- Galvanized tubes wrapped with waterproof paper and plastic film to preserve zinc coating integrity in humid conditions
- Container loading optimized for 5.8 m and 6 m standard lengths to maximize 20ft and 40ft container payload without overweight penalties
- Custom cut-to-length service available for 1–12 m requirements, with cut pieces bundled separately and labeled by dimension
- Heat number and steel grade stenciled on each bundle for site identification and traceability verification
- FOB, CIF, and DDP shipping terms with professional heavy cargo loading and door-to-door delivery coordination
Start Your Q235 Q355 ERW Square Rectangular Steel Tube Inquiry
Send your specification sheet with steel grade, cross-section dimensions, wall thickness, length, quantity, and destination port. We respond within 12 hours with pricing, mill test certificate samples, and shipping options — so your procurement team can compare verified material against project requirements before committing.
Request Pricing and Mill Test Certificates
Submit your Q235 Q355 ERW square rectangular steel tube specifications to receive detailed quotation with material traceability documentation.
Company: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.xjyplate.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjyplate.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
Frequently Asked Questions
Q: How do Q235 and Q355 grades compare to ASTM A36 and S355JR?
A: Q235 offers similar yield strength to ASTM A36 and S235JR for general structural applications. Q355 provides higher yield strength comparable to S355JR and ASTM A572 Grade 50 for heavy structural members. We supply mill test certificates documenting actual chemical composition and mechanical properties for grade verification.
Q: Can you provide third-party inspection before shipment?
A: Yes. SGS and BV third-party inspection is available upon request. The inspector verifies dimensions, wall thickness, surface quality, and reviews mill test certificates against your purchase order before we release the shipment.
Q: What is the minimum order quantity for mixed sizes?
A: The MOQ is 25 tons per order. You can mix cross-section dimensions, wall thicknesses, and lengths within that quantity — for example, combining 100×100 mm columns, 150×100 mm beams, and 80×80 mm bracing tubes in one 20ft container load.
Q: Do you offer custom cutting and punching services?
A: Yes. We provide cut-to-length service for 1–12 m requirements, hole punching for bolted connections, and bending to your specified radius. Processing details are confirmed before production so your material arrives ready for assembly.
Q: How do you handle wall thickness tolerance?
A: Our Q235 Q355 ERW square rectangular steel tube production maintains ±1% tolerance on wall thickness. Every bundle is measured before shipment, and mill test certificates document actual measurements for your quality records.
