Description
Factory-direct welded square steel tube supply — 3 dedicated production lines covering Q195 through Q355 and ASTM A36/Gr60 grades with wall thickness from 0.5 to 25 mm.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 Welded Square Steel Tube |
| Product Type | Welded Square and Rectangular Steel Tube |
| Steel Grade | Q195, Q235, Q345, Q355, A36, ASTM Gr60 |
| Standard | ASTM, GB/T 6728 |
| Section Shape | Square / Rectangular |
| Size Range | Customizable non-standard sizes available per inquiry |
| Wall Thickness | 0.5–25 mm |
| Length | 6–12 m (custom cut-to-length available) |
| Technique | Hot Rolled / Welded |
| Surface Treatment | Hot Rolled (Black / Oiled / Non-oiled options) |
| Tolerance | ±1% |
| Ends | Plain / Beveled (per request) |
| Application | Construction frames / Steel structures / Building material / Scaffolding / Machinery / Fluid pipe / Structure pipe |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & EPC | Building frames, column bracing, scaffolding uprights, roof trusses |
| Steel Structure Fabrication | Portal frames, mezzanine beams, welded box girders |
| Machinery Manufacturing | Conveyor structures, crane booms, equipment bases |
| Infrastructure | Bridge handrails, sound barrier posts, solar mounting frames |
Why Corner Geometry Decides Facade Acceptance on a Welded Square Steel Tube Order
Standard ERW rectangular tubes produce corner radii of R≥2t, creating visible gaps at curtain wall joints that fail architectural inspection.
On a Suzhou site years ago, I watched a full container of standard welded rectangular tubes get rejected at destination because the oversized corner radii prevented flush alignment on a Middle East glass curtain wall. Rework and port demurrage erased the entire margin. The Q235 welded square steel tube you order for facade or structural framing work needs verified corner geometry — not just a dimension sheet that ignores what happens at the weld seam. Procurement teams sourcing a Q235 welded square steel tube for architectural applications frequently discover this gap only after the material reaches site. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]
Matching Structural Load Paths and Connection Details
A Q235 welded square steel tube in Q345 or Q355 grade carries higher yield strength for primary frame members, while Q195 and Q235 serve secondary bracing and non-load-bearing infill. Wall thickness from 0.5 mm suits light gauge purlin work, whereas 25 mm sections handle heavy column loads in multi-storey steel frames. Hot rolled welded process with oiled surface provides baseline corrosion protection during transit and fabrication, while plain ends accept site welding and beveled ends prepare for butt-welded connections in pressure or structural continuity applications.
Engineering Compliance and Certification Requirements
Structural frames designed to EN 1993 or AISC 360 require documented material properties and traceable heat numbers. A Q235 welded square steel tube shipped to EU markets must carry CE marking under EN 10219 or EN 10210, with mill test certificates showing chemical composition and mechanical test results. North American projects specify ASTM A500 or A36 equivalence, and customs authorities in regulated markets reject shipments lacking proper certification documentation. [NEED_CITE: steel grade equivalence mapping between GB, EN and ASTM standards] Cut-to-length service at 6–12 m reduces site waste and welding joints, while in-house bending and punching services eliminate secondary fabrication delays.
Steel Grade Selection and Welding Process Fundamentals
The Q-series grades (Q195–Q355) follow Chinese GB standards where the number indicates minimum yield strength in MPa — Q235 delivers 235 MPa yield, suitable for general construction, while Q355 provides higher strength for heavy structures. ASTM A36 maps closely to Q235 in yield range, while Gr60 offers elevated strength for demanding applications. Hot rolled welded process forms the tube from coil through continuous forming and high-frequency welding, producing consistent wall thickness with ±1% tolerance across the 0.5–25 mm range. Surface treatment options — black (as-rolled), oiled for rust inhibition during storage, or non-oiled for immediate painting — address different fabrication sequences and environmental exposure. The patented sharp-corner rectangular tube technology fills a critical gap where standard rounded corners compromise architectural aesthetics and structural joint fit-up.
Hidden Costs of Unverified Material Sourcing
Ordering a Q235 welded square steel tube without confirmed mill test certificates risks material substitution — lower-grade steel passing as Q355, or wall thickness falling below minimum tolerance. Customs rejection at EU ports due to missing CE documentation or incorrect EN standard references creates demurrage charges that exceed the material cost. Structural engineers specifying Q355 for seismic zones cannot accept undocumented grade claims, and rework after installation proves far costlier than upfront verification. [NEED_CITE: structural steel procurement quality assurance requirements per EN 1090]
Procurement Confidence Through Verified Capability
Every Q235 welded square steel tube rolls through 3 dedicated production lines covering 2,800+ specifications, with wall thickness reaching 25 mm for heavy structural sections. In-house physical and chemical laboratories test every heat, producing mill test certificates before shipment. Full international certifications — ISO 9001:2015, Lloyd’s CE under EN 10210/10219, Singapore FPC, and SGS/BV verification — clear customs in 50+ export markets. The 41 invention patents include China’s original sharp-corner rectangular tube technology, solving the corner radius problem that causes facade rejection. Professional container loading with anti-damage measures prevents the bending and surface defects that trigger site rejection.
Documentation & Compliance
- Mill test certificate documenting Q235 chemical composition and yield strength per GB/T 6728, with heat number traceability
- CE certificate confirming EN 10219 compliance for cold-formed welded structural hollow sections exported to European markets
- ISO 9001:2015 quality management certificate covering the full production process from coil input to finished tube
- SGS or BV third-party inspection report available upon request, verifying dimensions, surface quality, and mechanical properties
- Material traceability by heat number linking each bundle to its original mill test certificate and production batch
- Complete customs documentation including packing list, bill of lading, and certificate of origin for destination clearance
Packaging, Loading & Delivery
- Hot rolled black Q235 welded square steel tubes bundled with steel strips and edge protectors, preventing surface scratches during ocean transit
- Oiled surface treatment applied to tubes destined for humid climates or extended storage, preserving mill finish before fabrication
- Cut-to-length service at 6–12 m optimizes container loading for 20ft and 40ft shipments, reducing freight cost per ton
- Heat number and steel grade stenciled on each bundle end, enabling site identification without unpacking
- FOB, CIF, and DDP shipping terms available, with professional tube loading crews preventing shifting and damage during transport
- Professional container loading with wooden chocks and steel wire lashing for heavy-wall sections, meeting international transport safety standards
Request Your Q235 Welded Square Steel Tube Quotation
Submit your specification sheet — section dimensions, wall thickness, steel grade, surface treatment, quantity, and destination port — to receive a detailed quotation within 12 hours, including mill test certificate sample and loading plan. Non-standard sizes and custom cut-to-length available with low MOQ of 5 tons.
Start Your Q235 Welded Square Steel Tube Inquiry
Send your dimensions and steel grade requirements to receive pricing, certification documents, and delivery schedule.
Company: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.sdxjypipe.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@sdxjypipe.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
Frequently Asked Questions
Q: How do Q235 and Q355 grades map to ASTM and EN equivalents?
A: Q235 corresponds closely to ASTM A36 and EN S235 in yield strength range, while Q355 aligns with ASTM A572 Gr50 and EN S355. We provide cross-reference documentation confirming grade equivalence for your project specification.
Q: What documentation accompanies each shipment of Q235 welded square steel tube?
A: Every batch includes mill test certificate showing chemical composition and mechanical properties per GB/T 6728, with heat number traceability. Third-party inspection by SGS or BV available upon request, and CE certification provided for EU market shipments under EN 10219.
Q: Can you produce non-standard dimensions outside typical size ranges?
A: Yes, our 3 production lines cover 2,800+ specifications including custom non-standard sizes. Minimum order quantity is 5 tons, and we provide cut-to-length service within the 6–12 m range to match your project requirements.
Q: What surface treatment options are available for welded square steel tubes?
A: Hot rolled black finish (as-rolled condition), oiled surface for rust protection during transit and storage, and non-oiled option for immediate painting or galvanizing. Galvanized finish also available upon request for corrosion-resistant applications.
Q: Do your products carry CE marking for European market import?
A: Yes, our welded square and rectangular tubes carry Lloyd’s CE certification under EN 10210 and EN 10219 standards, ensuring customs clearance and compliance with European construction product regulations.
