Description
Factory-Direct Welded Tube Supply — 2,800+ specifications in stock with wall thicknesses up to 30mm, shipped directly from our Jinan production lines to your project site.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235/Q345 Welded Square & Rectangular Steel Tube |
| Product Type | Welded Square & Rectangular Steel Tube |
| Steel Grade | Q195, Q215, Q235, Q345, GR.A, GR.B, S235, S355 |
| Standard | ASTM A500, ASTM A213, DIN EN 10217-1, EN 10219, EN 10210 |
| Section Shape | Square / Rectangular |
| Size Range | 20mm–80mm side length |
| Wall Thickness | 0.8–30mm |
| Length | 0.5m–11.8m |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Pre-galvanized / Hot-dipped galvanized / Bare / Oiled / Black original |
| Tolerance | ±1% |
| Ends | Plain / Beveled |
| Application | Steel structures, fences, posts, warehouse construction, building construction |
| MOQ | 10 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, warehouse purlins, structural columns, bridge supports |
| Architectural Facades | Glass curtain wall framing, decorative steel cladding supports |
| Industrial Manufacturing | Conveyor structures, machine bases, equipment frames |
| Agricultural & Fencing | Steel fence posts, livestock pen frames, greenhouse structures |
Where Steel Grade Equivalence Decides Customs Clearance
Q235, S235JR, and ASTM A500 Gr.B are not interchangeable on paper—mismatched documentation blocks EU and North American imports.
Procurement teams ordering Q235/Q345 welded square rectangular steel tube supplier materials for overseas projects frequently encounter grade confusion at customs. The Chinese GB system, European EN standards, and American ASTM specifications each define chemical composition and mechanical properties differently. A mill test certificate showing Q235B will not satisfy an EU inspector expecting S235JR per EN 10219, even though the materials perform similarly in most structural applications. [NEED_CITE: steel grade equivalence between EN and ASTM standards]
The cost of getting this wrong extends beyond paperwork delays. Incorrect grade declarations trigger full chemical re-testing at destination ports, storage fees while awaiting results, and in worst cases, material rejection that forces emergency air freight replacements.
How Wall Thickness Tolerance Affects Structural Frame Assembly
When ordering Q235/Q345 welded square rectangular steel tube supplier products for precision fabrication, the ±1% tolerance specification directly impacts welding fit-up and bolt-hole alignment. Our ERW production maintains consistent wall thickness across the 0.8–30mm range, ensuring that 40×40×3mm tubes arrive with actual dimensions matching mill certificates. For facade contractors assembling glass curtain wall frames, this dimensional accuracy eliminates on-site grinding and re-welding that would otherwise delay crane schedules.
Engineering Compliance Requirements for Structural Hollow Sections
Structural hollow sections must comply with design codes such as EN 1993-1-1 for European projects or AISC 360 for North American construction. Our Q235/Q345 welded square rectangular steel tube supplier materials meet EN 10219 cold-formed welded structural hollow sections requirements, providing the dimensional tolerances and mechanical properties engineers specify. For corrosive environments, pre-galvanized or hot-dipped galvanized finishes extend service life without field painting. CE certification under EN 10210/EN 10219 enables direct import into EU member states, while ASTM A500 compliance satisfies North American structural codes. [NEED_CITE: EN 10219 cold-formed hollow section requirements]
Understanding ERW Welding Process and Surface Treatment Options
Electric Resistance Welding joins the tube edges through localized heating and pressure, creating a continuous weld seam with properties matching the base metal. This process suits the 20mm–80mm size range efficiently, offering lower production costs than seamless alternatives while maintaining structural integrity for most load-bearing applications. Surface treatment selection depends on installation environment: pre-galvanized coatings provide 40–80μm zinc thickness for indoor or mild outdoor conditions, while hot-dipped galvanizing delivers 60–120μm for aggressive marine or industrial atmospheres. Bare or oiled finishes work for interior applications where painting occurs after installation.
The Q-series grades (Q195–Q345) follow Chinese GB standards with yield strength designations, while S-series grades (S235–S355) conform to European EN specifications. Both systems indicate minimum yield strength in MPa, making Q345 roughly equivalent to S355JR in structural performance. [NEED_CITE: steel grade equivalence between EN and ASTM standards]
Hidden Costs of Incorrect Grade Specification and Missing Certificates
Ordering welded tubes without verified mill test certificates creates downstream risks that dwarf initial material savings. Material substitution discovered during structural inspection forces complete disassembly and replacement, multiplying labor costs exponentially. Customs authorities in regulated markets increasingly reject shipments lacking proper CE marking or EN standard references, leaving containers stranded at port with daily demurrage charges accumulating. [NEED_CITE: customs clearance requirements for structural steel imports]
Why Project Procurement Teams Choose SD XJY Pipe
Our Jinan facility operates three dedicated production lines covering 2,800+ specifications, enabling single-source procurement for mixed-specification orders that would otherwise require multiple supplier relationships. The in-house physical and chemical laboratory tests every heat for dimensional accuracy, mechanical properties, and chemical composition before releasing material for shipment. Full international certifications including CE EN 10210/EN 10219, ISO 9001:2015, and verified SGS/BV inspection reports accompany every export order. Our patented sharp-corner rectangular tube technology fills a market gap for architectural applications requiring true right-angle aesthetics. Professional container loading with wooden pallets and steel strip bundling prevents transit damage that plagues poorly secured shipments.
Documentation & Compliance
- Mill test certificate documenting Q235/Q345 chemical composition and yield strength per EN 10219 or ASTM A500 as specified
- CE certificate confirming compliance with EN 10210/EN 10219 for EU market structural hollow sections
- ISO 9001:2015 quality management system certificate covering production and inspection processes
- SGS or BV third-party inspection report verifying dimensional tolerances and surface treatment thickness
- Material traceability documentation linking each tube to heat number and production batch records
- Complete customs documentation including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Q235/Q345 welded tubes bundled with steel strips and edge protectors to prevent surface damage during ocean transit
- Galvanized finish tubes wrapped with waterproof paper and plastic film to preserve zinc coating integrity
- Mixed-size container loading optimized for 20ft and 40ft containers with wooden pallets separating specification groups
- Custom cutting to 0.5m–11.8m lengths per project requirements, with cut ends deburred and protected
- Heat number and steel grade stenciled on each tube bundle for site identification and traceability
- FOB, CIF, and DDP shipping terms available with door-to-door logistics coordination to 50+ countries
Requesting Quotation and Technical Documentation
Submit your specification requirements including tube dimensions, wall thickness, steel grade preference, surface treatment, quantity, and destination port to receive detailed pricing within 12 hours. Our technical team provides grade equivalence guidance for international projects and confirms certification requirements before production begins. Third-party inspection arrangements through SGS or BV can be scheduled at your request prior to container loading.
Frequently Asked Questions
Q: Can you provide mill test certificates for both Q235 and S235JR grades on the same order?
A: Yes, our in-house laboratory tests each heat according to the specified standard. We issue EN 10204 3.1 format mill test certificates showing chemical composition and mechanical properties. For mixed-grade orders, each bundle receives separate documentation matching the actual material supplied.
Q: What is the minimum order quantity for custom non-standard sizes?
A: Our standard MOQ is 10 tons for stock specifications. Custom non-standard sizes outside our 2,800+ specification range require minimum 20 tons depending on dimensions and production scheduling. We accommodate special lengths up to 11.8m and non-standard wall thicknesses within our 0.8–30mm capability.
Q: How do you prevent tube damage during container loading and ocean transit?
A: We separate different specifications with wooden pallets and secure bundles with steel strips. Edge protectors prevent corner damage on rectangular tubes. For galvanized finishes, we add waterproof wrapping to preserve coating integrity. Our loading team follows procedures developed from years of export experience to eliminate transit damage claims.
Q: Do you provide CE marking and EN 10219 certificates for EU import clearance?
A: Yes, all our structural hollow sections carry CE certification under EN 10210 (seamless) and EN 10219 (welded) standards. The CE mark appears on each tube, and certificates accompany every shipment. This enables direct customs clearance in all EU member states without additional testing requirements.
Q: What surface treatment options are available for corrosion protection?
A: We offer pre-galvanized (40–80μm zinc), hot-dipped galvanized (60–120μm zinc), bare steel with anti-rust oil, and black original finish. Pre-galvanized suits indoor applications, while hot-dipped galvanizing provides superior protection for outdoor or marine environments. Custom painting can be arranged after delivery if required.
Get Your Welded Tube Quote with Full Certification Package
Send your specification sheet to admin@sdxjypipe.com or contact us via WhatsApp at +86 188 5315 7756. Include tube dimensions, steel grade, surface treatment, quantity, and destination port for pricing and lead time confirmation within 12 hours.
