Description
One-Stop SHS & RHS Sourcing — Q195 to Q345 and S235JR to S355JR grades in 1–3 mm wall thickness, shipped with original mill test certificates and CE documentation.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 / Q345 Welded Square & Rectangular Steel Tube |
| Product Type | Welded Square and Rectangular Steel Tube (SHS / RHS) |
| Steel Grade | Q195, Q215, Q235, Q235B, Q345, Q345B, S235JR, S355JR, SS400 |
| Standard | ASTM, ASTM A213, DIN EN 10217-1, JIS, GB |
| Section Shape | Square / Rectangular |
| Size Range | 30×30 mm – 50×50 mm |
| Wall Thickness | 1 mm – 3 mm |
| Length | 6 m / 6.4 m / 12 m |
| Technique | ERW (Cold Rolled / Hot Rolled) |
| Surface Treatment | Hot Rolled / Slightly Oiled / Non-oiled |
| Tolerance | ±1% |
| Ends | Plain |
| Application | Steel structures, Construction, Machinery frames, Scaffolding, Furniture, Architectural decoration |
| MOQ | 5 Tons |
| Origin | China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, scaffolding systems, bridge support structures |
| Machinery Manufacturing | Equipment frames, conveyor supports, hydraulic machinery bases |
| Architectural & Decoration | Curtain wall supports, furniture frames, interior structural elements |
| Industrial Fabrication | Storage rack systems, workshop structures, platform frameworks |
What Negative Tolerance Really Costs on a 1–3 mm Wall Order
Hidden thickness deviations turn theoretical-weight invoicing into actual-weight disputes at the port.
When buyers order Q235 welded square rectangular steel tube in 1.5 mm or 2.0 mm wall thickness, the invoice says theoretical weight — but the mill ships with minus tolerance pushing actual wall down to 1.3 mm or 1.7 mm. The container arrives, the caliper comes out, and the project engineer rejects the lot. I watched a full 20-foot container of 50×50 SHS sit in Lagos port for three weeks because the client’s监理 measured 1.2 mm on what was specified as 1.5 mm. The steel was technically within some mill’s “standard practice,” but it failed the project spec and the client’s structural calculation. [NEED_CITE: EN 10219 dimensional tolerance requirements for cold-formed hollow sections]
How 1–3 mm Wall Thickness Matches Light Structural and Decorative Loads
The 1–3 mm range sits squarely in light-to-medium structural territory. For scaffolding and furniture frames, Q235 or S235JR in 1.5 mm wall gives adequate load capacity without over-engineering. When the Q235 Q345 welded square rectangular steel tube goes into machinery frames or conveyor supports, stepping up to 2.0 mm or 2.5 mm in Q345B provides the stiffness needed for dynamic loads. The ±1% tolerance holds across this range, meaning the 30×30×1.5 tube you spec on the drawing is the tube that shows up on site — not a thinner version that forces rework or replacement.
Engineering Compliance Across GB, EN, and ASTM Frameworks
Structural engineers working to EN 1993 or AISC 360 need traceable material properties, not just a grade name on a packing list. Q235 Q345 welded square rectangular steel tube supplied under DIN EN 10217-1 or ASTM A213 carries the chemical composition and mechanical property documentation that satisfies both EU and North American inspection regimes. [NEED_CITE: steel grade equivalence mapping between GB Q-series and EN S-series] For projects requiring CE marking, the mill test certificate must show heat number traceability back to the slab — a detail that separates compliant shipments from customs holds. The 6 m and 12 m standard lengths align with typical container loading optimization, reducing on-site cutting waste.
ERW Process, Grade Selection, and Surface Finish Trade-offs
ERW welding produces a continuous longitudinal seam with minimal heat-affected zone, making it suitable for structural applications where the weld line does not face direct bending stress. Q235 and Q235B serve general construction where yield strength around 235 MPa suffices; Q345 and Q345B step into higher-load scenarios requiring approximately 345 MPa yield. The S235JR and S355JR equivalents follow EN 10025 naming, with the “JR” suffix indicating room-temperature impact toughness — critical for projects in temperate climates but less relevant for tropical deployments. Hot-rolled surface finish accepts paint or galvanizing directly; slightly oiled condition protects against transit corrosion without affecting weldability. [NEED_CITE: ERW versus seamless tube application boundaries in structural engineering]
The Real Price of Grade Confusion and Missing Documentation
Ordering Q345B when the drawing calls for S355JR — or accepting a mill certificate that lists “equivalent grade” without chemical breakdown — creates rejection risk at every inspection point. Customs authorities in the EU increasingly demand EN 10219 compliance documentation for structural hollow sections; shipments without proper CE paperwork face delays or return. [NEED_CITE: EU customs requirements for structural steel CE marking] Beyond compliance, the wrong grade means either overpayment for unnecessary strength or structural under-design that fails load testing. The cost of re-milling and re-shipping a rejected container dwarfs the price difference between proper grade selection upfront.
Why Project Procurement Teams Choose Our SHS/RHS Supply
We run the mill directly — no trading company markup, no third-party warehousing that adds handling damage risk. Every Q235 Q345 welded square rectangular steel tube ships with original mill test certificates showing heat number, chemical composition, and mechanical properties from our in-house laboratory. The ±1% tolerance is measured and documented, not assumed. For projects spanning multiple grades, we consolidate Q235, Q345, S235JR, and S355JR into single shipments, eliminating the fragmentation that forces buyers to manage five suppliers for one structural package. Our loading teams understand heavy cargo — 12 m lengths in open-top containers, weight distribution calculated to avoid port overweight penalties. SGS and BV third-party inspection is available before shipment for clients who need independent verification.
Documentation & Compliance
- Mill test certificate documenting Q235B and Q345B chemical composition and yield strength per GB/T 6728
- CE certificate confirming EN 10219 compliance for S235JR and S355JR structural hollow sections
- ISO 9001:2015 quality management certificate covering ERW welding and dimensional inspection
- SGS or BV third-party inspection report available upon request for pre-shipment verification
- Full material traceability by heat number from slab to finished tube
- Export documentation including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Q235 and Q345 SHS/RHS bundled with steel strips and edge protectors to prevent surface damage during ocean transit
- Slightly oiled surface treatment applied to hot-rolled tubes to prevent rust without affecting weldability
- 6 m and 12 m lengths optimized for 20-foot and 40-foot open-top container loading with weight distribution plans
- Custom cutting to project-specific lengths available, reducing on-site waste and cutting labor
- Heat number and steel grade stenciled on each bundle for site identification and traceability
- FOB, CIF, and DDP shipping terms with professional heavy-cargo logistics coordination
Getting Your SHS/RHS Quote and Mill Test Certificate
Send your specification sheet with steel grade, section size, wall thickness, length, and quantity — we respond within 12 hours with pricing, available mill test certificate samples, and shipping terms. For non-standard sizes or grades outside Q195–Q345 / S235JR–S355JR, we confirm feasibility and lead time before you commit. If your project requires SGS or BV inspection, we schedule it into the production timeline so certification aligns with your shipment date.
Frequently Asked Questions
Q: How do Q235 and Q345 map to S235JR and S355JR for international projects?
A: Q235 and Q235B are Chinese standard grades roughly equivalent to S235JR in yield strength; Q345 and Q345B correspond to S355JR. We provide chemical composition comparison sheets and can supply mill test certificates showing compliance with either GB or EN standards based on your project requirements.
Q: Can I verify wall thickness tolerance before shipment?
A: Yes. We provide dimensional inspection reports with actual measurements for each batch. Third-party inspection by SGS or BV is available to verify wall thickness, section dimensions, and weld quality before the container is sealed.
Q: What is the minimum order for custom-cut lengths?
A: The standard MOQ is 5 tons. For custom cutting to non-standard lengths outside 6 m / 6.4 m / 12 m, we confirm feasibility based on your total quantity and section size.
Q: Do you supply galvanized or painted finishes?
A: Our standard supply is hot-rolled with slight oiling or non-oiled condition. Galvanizing and painting are available as secondary processing — we coordinate with certified coating partners and include the finish in your mill test documentation.
Q: How do you handle grade equivalence for EU projects requiring EN 10219?
A: We supply S235JR and S355JR grades directly to EN 10219 specifications with CE certification. If your drawing calls for S355JR but you prefer Q345B for cost, we provide technical comparison and confirm acceptance with your engineer before production.
Get Your Q235 Q345 Welded Square Rectangular Steel Tube Quote with Mill Test Certificate
Submit your specification with steel grade, dimensions, quantity, and destination port — we return pricing, available MTC samples, and shipping options within one business day.
Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.xjyplate.com
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjyplate.com
