Description
Factory-direct ERW tubes, no trading markup — Q235 carbon steel square rectangular tube 10-500mm rolls from our own mill with full MTC and CE certification for EU customs clearance.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235 Carbon Steel Square & Rectangular Tube |
| Product Type | Square / Rectangular Steel Tube (SHS / RHS) |
| Steel Grade | Q195, Q215, Q235, Q345, 10#, 20# |
| Standard | GB/T 8162, GB/T 6728, ASTM A500, ASTM A53, EN 10219, EN 10210, JIS G3466 |
| Section Shape | Square / Rectangular |
| Size Range | 10×10 mm – 500×500 mm |
| Wall Thickness | 0.9 – 25 mm |
| Length | 6 m / 9 m / 12 m (customizable) |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Cold Rolled / Oiled / Customized (Galvanized available) |
| Tolerance | ±1% |
| Ends | Plain / Beveled |
| Application | Steel structures, Construction frames, Machinery manufacturing, Scaffolding, Municipal engineering, Electric power transmission towers |
| MOQ | 500 KG |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, column supports, scaffolding systems, municipal bridge structures |
| Architectural Facades | Glass curtain wall steel framing, decorative structural beams, sharp-corner visible columns |
| Machinery Manufacturing | Conveyor structures, equipment base frames, hydraulic support columns |
| Steel Structure Fabrication | Industrial warehouse frames, platform supports, transmission tower members |
When Rounded Corners Fail on a Facade Order
Standard ERW rectangular tubes produce R≥2t corners that look unfinished against glass curtain walls — architects reject them, and fabricators waste time filling gaps with weld beads.
Sourcing true sharp-corner rectangular tubes with consistent wall thickness and full certification remains a persistent headache for global buyers. Most mills only stock popular sizes; off-standard dimensions get pushed to longer lead times or rejected outright. When a São Paulo fabricator received a container of Q235 rectangular tubes with dented corners and bent walls from improper bracing, the entire batch was rejected at Santos port — a loss that could have been prevented with a proper loading plan. [NEED_CITE: cold-formed hollow section dimensional tolerance requirements per EN 10219]
Matching Structural Loads and Connection Geometry
A Q235 carbon steel square rectangular tube from 10×10 mm to 500×500 mm covers everything from light machinery frames to heavy structural columns. The ±1% wall thickness tolerance keeps load calculations reliable, while ERW welding ensures consistent seam strength across the full length. For facade contractors, our patented sharp-corner technology delivers right-angle edges that sit flush against glass panels without visible gaps — no filler welding, no grinding.
Engineering Compliance and Certification Path
Structural frames designed to EN 1993 or AISC standards require mill test certificates that trace each batch to its heat number. Q235 maps directly to S235JR under EN 10219 and ASTM A500 Gr.B under American specs, but customs authorities in the EU and Middle East demand CE marking per EN 10210/EN 10219 — not just a supplier’s word. Our in-house physical and chemical lab tests every heat before release, and third-party SGS/BV inspection is available for clients who need independent verification. [NEED_CITE: steel grade equivalence mapping between GB Q series and EN S series]
Steel Grade Selection and ERW Process Logic
Q195 through Q345 represent a yield strength progression where each step up adds roughly 20-30% load capacity — Q235 sits in the middle as the default for general structural work, while Q345 handles heavier columns and crane beams. The ERW process welds the seam through electric resistance without filler metal, producing a clean internal profile suitable for fluid conveyance at moderate pressures. Cold rolled surface finish gives a smooth appearance for visible architectural applications, while oiled treatment prevents rust during ocean transit. Wall thickness from 0.9 mm serves light decorative framing, while 25 mm covers heavy industrial columns — the same Q235 carbon steel square rectangular tube supplier handles both ends of that range without switching mills.
Hidden Costs of Unverified Material
Ordering Q235 tubes from a trader without mill test certificates might save a few dollars per ton upfront, but the risks compound fast. Material that fails chemical composition tests at destination gets rejected by customs or fails structural inspection on site. Negative tolerance beyond ±1% means you pay for steel that isn’t there — a 20 mm wall delivered at 18.5 mm reduces load capacity and voids engineering sign-off. Missing CE documentation blocks EU imports entirely, turning a 30-day delivery into a 90-day customs hold with demurrage charges. [NEED_CITE: consequences of non-compliant hollow sections in structural engineering projects]
Why Fabricators and EPCs Source From Our Mill
We hold 41 invention patents including China’s first sharp-corner rectangular tube technology, covering 2,800+ specifications with wall thickness up to 25 mm — when you need a 450×300×20 mm Q345 RHS in 11.8 m length, we produce it without forcing you into a 5-ton MOQ. Our in-house lab issues MTC for every heat, and Lloyd’s CE certification per EN 10210/EN 10219 clears EU customs without re-inspection delays. Every container gets a custom loading plan — heavy-wall sections braced separately from lighter tubes to prevent corner dents and bending during ocean transit. We export to 50+ countries with full documentation: packing list, bill of lading, certificate of origin, and heat-number traceability from mill to port.
Documentation & Compliance
- Mill test certificate documenting Q235 chemical composition (C, Mn, Si, P, S) and yield strength per GB/T 6728 and EN 10219
- CE certificate per EN 10210/EN 10219 for EU market access, issued by Lloyd’s Register
- ISO 9001:2015 quality management certificate covering production and inspection processes
- SGS or BV third-party inspection report available upon request for independent quality verification
- Material traceability by heat number linking each tube bundle to its original steel coil and test results
- Customs documents including packing list, bill of lading, and certificate of origin formatted for destination port requirements
Packaging, Loading & Delivery
- Q235 ERW tubes bundled with steel strips and edge protectors to preserve cold rolled surface finish during ocean transit
- Heavy-wall sections (15-25 mm) loaded on bottom with wooden cradles; lighter tubes (0.9-5 mm) stacked on top with anti-scratch padding to prevent corner damage
- Custom cutting to 6 m / 9 m / 12 m or site-specific lengths reduces field welding and waste at destination
- Heat number and steel grade stenciled on each bundle for traceability and site inspection verification
- Professional container loading plan designed per order dimensions maximizes payload while preventing shifting during transit
- FOB / CIF / DDP terms available with full export documentation and tracking until arrival at destination port
Getting Your Quote and Mill Test Certificate
Send your specification sheet with section dimensions, wall thickness, steel grade, quantity, and destination port — we respond within 12 hours with unit pricing, lead time, and shipping terms. For non-standard sizes outside the 10×10 to 500×500 mm range, we provide custom production options with typical lead times of 15-25 days. Request a sample bundle with MTC before committing to a full order, and confirm CE/SGS certification requirements upfront to avoid customs delays.
Frequently Asked Questions
Q: How does Q235 compare to S235JR and ASTM A500 Gr.B?
A: Q235 is the Chinese GB standard equivalent to S235JR under EN 10219 and ASTM A500 Gr.B under American specs. Chemical composition and yield strength are closely matched, but mill test certificates must reference the correct standard for your destination market.
Q: Can you provide third-party inspection reports for EU customs?
A: Yes, SGS and BV inspection is available for every shipment. Our Lloyd’s CE certificate per EN 10210/EN 10219 covers EU imports, and we provide full documentation including packing list, bill of lading, and certificate of origin.
Q: What is the MOQ for custom non-standard sizes?
A: Standard sizes ship from stock with a 500 KG minimum. Custom dimensions outside our 2,800+ specification range enter production with typical lead times of 15-25 days — contact us with your drawing for a tailored quote.
Q: How do you prevent corner damage during container loading?
A: Every container gets a custom loading plan. Heavy-wall sections are braced on the bottom with wooden cradles; lighter tubes are stacked on top with edge protectors and anti-scratch padding. This prevents the dents and bending that cause rejection at destination ports.
Q: What surface treatment options are available for Q235 tubes?
A: Cold rolled finish provides a smooth appearance for architectural applications. Oiled treatment prevents rust during transit. Hot-dip galvanized coating is available for corrosion-prone environments — specify your requirement at inquiry stage.
Request Your Q235 Tube Quote With Full Certification
Submit your dimensions, steel grade, quantity, and destination port to receive pricing, lead time, and mill test certificate samples within 12 hours.
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
