Description
Factory-direct welded SHS/RHS — Q235 and Q345 structural tubes rolled, welded, and tested in-house with original mill test certificates for every heat.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235/Q345 Welded Square & Rectangular Steel Tube |
| Product Type | Welded Square / Rectangular Steel Tube (SHS / RHS) |
| Steel Grade | Q195, Q215, Q235, Q345, GR.A, GR.B, S235, S355 |
| Standard | ASTM A213, DIN EN 10217-1 |
| Section Shape | Square / Rectangular |
| Size Range | 20 mm – 80 mm+ (customizable) |
| Wall Thickness | 0.8 – 30 mm |
| Length | 0.1 m – 11.8 m (100 mm – 11800 mm, customizable) |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Pre-galvanized / Hot-dip galvanized / Bare / Oiled / Black original steel |
| Tolerance | ±1% |
| Processing Service | Welding, Punching, Cutting, Bending, Decoiling |
| Invoicing | By Theoretical Weight |
| Application | Steel structures, Steel fences, Steel posts, Warehouse construction, Building construction |
| MOQ | 10 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Warehouse & Industrial Construction | Primary frame columns, roof truss bracing, mezzanine support beams |
| Steel Fencing & Perimeter Security | Fence posts, gate frames, bollard foundations |
| Building Construction | Load-bearing columns, curtain wall sub-frames, stair stringers |
| Infrastructure & Civil Works | Highway sign gantries, lighting pole bases, cable tray supports |
When Grade Equivalence Tables Fail at Customs
A missing or mismatched grade equivalence statement can hold a container at port for weeks — regardless of whether the steel itself passes every mechanical test.
Procurement teams ordering Q235 Q345 welded square rectangular steel tube for projects in Europe, Southeast Asia, or the Middle East frequently discover that the mill test certificate lists a Chinese GB grade while the engineering specification calls for EN or ASTM equivalents. Without a formally documented cross-reference — signed by the mill or validated by a third-party inspector — customs brokers and project supervisors cannot clear the material. [NEED_CITE: steel grade equivalence between EN, ASTM, and GB standards] The result is demurrage charges, reshipment costs, or outright rejection on site, even when the chemistry and tensile results are fully compliant.
Matching Wall Thickness to Structural Load Paths
Structural engineers specifying Q235 Q345 welded square rectangular steel tube for warehouse frames and fence post foundations need wall thickness that aligns with the actual load path — not just the lightest gauge that fits the budget. A 2 mm wall on a 60 × 60 mm SHS may carry a roof purlin in a low-wind zone, but the same section used as a gate post in a coastal industrial park will deflect under lateral wind load if the thickness drops below the design threshold. Our ERW welding process holds ±1% tolerance across the full 0.8–30 mm range, and every bundle ships with dimensional reports so site supervisors can verify gauge before welding begins.
Engineering Codes, Corrosion Environments, and Certification Paths
When Q235 Q345 welded square rectangular steel tube enters a regulated construction project, the compliance chain starts at the mill and ends at the building inspector’s sign-off. European projects require CE marking and conformity to EN 10219 for cold-formed welded hollow sections; North American tenders often reference ASTM A500 or A53. [NEED_CITE: EN 10219 cold-formed welded structural hollow section requirements] Surface treatment selection follows the corrosion environment — hot-dip galvanized for outdoor fencing and coastal infrastructure, pre-galvanized for indoor warehouse frames, and bare or oiled for sections that will be painted or fire-proofed on site. Custom cut-to-length service eliminates secondary cutting at the fabrication shop, reducing labor cost and preserving zinc coverage at cut edges.
How ERW Welding, Steel Grades, and Surface Treatment Interact
The Q-series grades — Q195, Q215, Q235, Q345 — follow the Chinese GB system where the number indicates minimum yield strength in MPa. Q235 remains the default for general structural frames, while Q345 delivers higher yield strength for load-bearing columns and bracing in multi-storey buildings. For projects requiring European standard compliance, S235 and S355 are available as direct equivalents. [NEED_CITE: equivalence mapping between GB Q-series and EN S-series structural steel grades]
ERW (Electric Resistance Welded) welding forms the tube from rolled strip, creating a longitudinal weld seam that is forge-welded under heat and pressure without filler metal. This process suits the 20–80 mm size range and 0.8–30 mm wall thickness spectrum efficiently, offering lower cost than seamless tube while maintaining structural integrity for non-high-pressure applications. Surface treatment then determines service life: hot-dip galvanizing coats both exterior and interior surfaces with a zinc layer for long-term corrosion resistance, while pre-galvanized (galvannealed) strip offers a thinner, more uniform coating suited to indoor or moderate environments. Bare and oiled finishes serve projects where the tube will receive additional coating systems or where zinc interference with welding is a concern.
The Hidden Cost of Tolerance Drift and Missing Traceability
Ordering Q235 Q345 welded square rectangular steel tube based on price alone, without verified mill test certificates and dimensional inspection reports, shifts risk downstream. Wall thickness running below theoretical specification reduces load capacity — a problem that surfaces only when the structural engineer weighs the delivered lot against calculated requirements. [NEED_CITE: consequences of negative tolerance in structural steel tube procurement] Missing heat numbers on certificates break the traceability chain, triggering rejection during building inspection or customs audit. The true cost is not the per-ton price difference — it is the crane idle time, the re-welding of rejected joints, and the reshipment of non-conforming material.
Direct Mill Supply, Verified Chemistry, and Full Documentation
Every Q235 Q345 welded square rectangular steel tube we supply comes from our own production lines in Shandong, with no trading intermediary adding markup or obscuring the material origin. Our in-house laboratory tests each heat for chemical composition and mechanical properties before the tube leaves the mill. Original mill test certificates — showing heat number, carbon equivalent, yield strength, tensile strength, and elongation — ship with every consignment. Third-party inspection through SGS or BV is available before loading for clients who require independent verification. Custom cutting, punching, and bending services reduce on-site fabrication waste, while our logistics team plans container loading for heavy structural sections to avoid overweight penalties and port delays.
Documentation & Compliance
- Mill test certificate documenting Q235/Q345 chemical composition, yield strength, and elongation per GB/T 6728, with heat number traceability to the original strip coil
- CE certificate confirming conformity to EN 10219 for cold-formed welded structural hollow sections, required for European market customs clearance
- ISO 9001:2015 quality management system certificate covering the full ERW welding, galvanizing, and inspection process
- SGS or BV third-party inspection report available upon request, verifying dimensional tolerance, surface coating thickness, and weld seam quality before shipment
- Material traceability sheet linking each bundle to its heat number, strip coil origin, and production date
- Export documentation package including commercial invoice, packing list, bill of lading, and certificate of origin formatted for destination-country customs
Packaging, Loading & Delivery
- Q235 and Q345 welded square and rectangular tubes bundled with high-tensile steel strips, separated by rubberized edge protectors to prevent surface damage during ocean transit
- Hot-dip galvanized sections wrapped in waterproof kraft paper and plastic film to preserve the zinc coating from moisture condensation inside the container
- Pre-galvanized and bare tubes coated with anti-rust oil and bundled by size and length for efficient unloading at the fabrication yard
- Container loading plans optimized for 20ft and 40ft open-top containers, with nested nesting for smaller SHS/RHS sections and flatbed-compatible crating for lengths exceeding 6 meters
- Custom cut-to-length tubes (100 mm – 11800 mm) bundled separately with clear labels showing steel grade, wall thickness, heat number, and piece count
- FOB, CIF, and DDP shipping terms available, with professional heavy-cargo logistics handling flatbed trucking, open-top container loading, and break-bulk shipping for oversized structural sections
Request a Quote with Full Mill Documentation
Submit your required steel grade, section dimensions, wall thickness, length, quantity, and destination port — we respond within 12 hours with a detailed quotation including material cost, processing fees, and shipping terms. Original mill test certificates and third-party inspection reports are confirmed in the proforma invoice before production begins.
Start Your Q235 Q345 Welded Square Rectangular Steel Tube Order
Send your specification sheet and destination details to receive a quotation with mill test certificate confirmation and estimated delivery schedule.
Contact:
Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjyplate.com
Website: www.xjyplate.com
Frequently Asked Questions
Q: How do Q235 and Q345 grades compare to European S235/S355 and ASTM standards?
A: Q235 corresponds closely to S235 in yield strength and chemical composition under EN standards, while Q345 aligns with S355. For ASTM-referenced projects, we supply GR.A and GR.B grades. Cross-reference documentation is provided with the mill test certificate to support customs clearance and engineering approval.
Q: Can you provide mill test certificates and support third-party re-inspection?
A: Yes. Every shipment includes an original mill test certificate showing heat number, chemical composition, and mechanical properties. SGS or BV third-party inspection is available before loading to verify dimensional tolerance, coating thickness, and weld quality at our facility.
Q: What is the minimum order quantity for non-standard dimensions?
A: The standard MOQ is 10 tons. For custom cut-to-length, punching, or bending services, we evaluate the specification and confirm feasibility and pricing within the quotation response.
Q: When should I specify hot-dip galvanized versus pre-galvanized or bare finish?
A: Hot-dip galvanized is recommended for outdoor, coastal, or high-humidity environments where long-term corrosion resistance is critical. Pre-galvanized suits indoor warehouse frames and moderate conditions. Bare or oiled finish is specified when the tube will receive additional paint, fire-proofing, or powder coating at the fabrication stage.
Q: How is invoicing calculated, and what about negative tolerance?
A: Invoicing is based on theoretical weight per the specified dimensions and wall thickness. Our ERW production holds ±1% tolerance, and dimensional inspection reports are provided with each shipment so you can verify actual gauge against the order specification before acceptance.
Get Certified Q235 Q345 Welded Square Rectangular Steel Tube Direct from the Mill
Send your section dimensions, steel grade, quantity, and destination port to receive a detailed quotation with mill test certificate confirmation and delivery schedule.
Contact:
Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjyplate.com
Website: www.xjyplate.com
