Description
Factory-direct pricing with no middlemen — Every Q345B ERW welded square steel tube rolls off our own ERW lines, inspected in-house before shipment.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q345B ERW Welded Square Steel Tube |
| Product Type | Welded Square Steel Tube |
| Steel Grade | Q345B, S235JR, S355, SS400, Q235B, A36 |
| Standard | BS, EN, GB, AISI, ASTM, DIN, JIS |
| Section Shape | Square |
| Size Range | 110×110mm (2×2 inch) |
| Wall Thickness | Customizable |
| Length | Custom (24 ft / 6m standard or as required) |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Cold Rolled |
| Tolerance | ±1% |
| Ends | Plain |
| Application | Building structures, machinery manufacturing, infrastructure construction, vehicle manufacturing |
| MOQ | Negotiable |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| EPC Contractors & Construction | Steel structure frames for factories, warehouse columns, commercial building trusses |
| Machinery Manufacturers | Machine tool frames, conveyor support structures, automation equipment frameworks |
| Infrastructure Developers | Bridge auxiliary structures, stage trusses, greenhouse frame systems |
| Vehicle Manufacturing | Trailer chassis frames, RV structural frameworks |
What Tight Wall Tolerance Means When You Order 110×110mm Square Tubes for Structural Frames
±1% tolerance on a 110×110mm ERW square tube keeps every piece dimensionally consistent across the full order.
I have seen entire container loads rejected at site because wall thickness drifted into negative tolerance beyond acceptable limits. When a batch of square tubes varies by even a fraction of a millimetre on side length, bolt holes misalign, connection plates do not sit flush, and the erector wastes days grinding and re-drilling on site. With our in-house physical and chemical laboratory checking every heat before it leaves the mill, you receive tubes that hold their specified dimensions from first piece to last. [NEED_CITE: EN 10219 dimensional tolerance requirements for cold-formed structural hollow sections]
Matching 110×110mm ERW Square Tubes to Structural and Machinery Applications
A 110×110mm square section delivers a strong moment of inertia for medium-load columns and beam connections in factory frames and conveyor structures. The cold rolled surface gives a smooth finish that accepts paint or powder coating without additional grinding, which matters when the tube stays exposed in architectural applications like stair handrails or security window frames. Our Q345B ERW welded square steel tube supplier capability covers custom lengths up to your exact cutting list, so your fabrication shop receives material ready to weld without site-side cropping.
Engineering Compliance and Certification Requirements for Structural Hollow Sections
Structural engineers specifying square hollow sections for load-bearing frames typically reference EN 1993-1-1 or AISC 360, both of which require documented material properties and traceable heat numbers. For European projects, CE marking under EN 10219 confirms the tubes meet cold-formed structural hollow section standards, while North American buyers often request ASTM A500 Grade B or C equivalence. Our production holds CE certification under EN 10210/EN 10219 and ISO 9001:2015, with mill test certificates issued per shipment showing chemical composition and mechanical test results. [NEED_CITE: steel grade equivalence mapping between GB Q345B and EN S355 / ASTM A500] Custom cut-to-length service eliminates secondary cutting on site, reducing waste and keeping dimensional accuracy within the ±1% tolerance across every piece.
Understanding Q345B, S355, and A36 Steel Grades for ERW Welded Square Tubes
Q345B belongs to the Chinese GB standard system and offers higher yield strength than Q235B, making it suitable for structural frames requiring greater load capacity. In the European EN system, S355 provides comparable performance with guaranteed impact toughness at sub-zero temperatures, while S235JR serves lighter structural applications. ASTM A36 remains the baseline structural steel grade in North American specifications. The ERW welding process uses high-frequency electric current to fuse the strip edges, producing a uniform weld seam that matches the parent metal strength when properly controlled. Cold rolled surface treatment delivers tighter dimensional accuracy and a smoother finish compared to hot rolled alternatives, which benefits applications where appearance or coating adhesion matters. [NEED_CITE: comparison of yield strength ranges across Q345B S355 and A36 steel grade standards]
Hidden Costs of Buying Square Tubes Without Verified Tolerance and Certification
Accepting a lower price on square tubes without independent mill test certificates often surfaces as expensive problems later. Material that fails to meet the specified steel grade triggers rejection during structural inspection, forcing complete replacement and project delays. Tubes with excessive negative tolerance reduce load-bearing capacity below design calculations, creating safety liability that no amount of cost savings justifies. Missing CE documentation or incomplete customs paperwork holds containers at port, generating demurrage charges that erase any initial discount. [NEED_CITE: consequences of non-compliant structural steel in construction project验收]
Why Source Your Q345B ERW Welded Square Steel Tube From Our Mill
We operate three dedicated ERW production lines covering over 2,800 specifications, meaning your 110×110mm square tubes roll from our own mill without broker markups. Every heat undergoes incoming, in-process, and final inspection in our physical and chemical laboratory before release, with full mill test certificates documenting chemical composition and mechanical properties. Our 41 patented technologies include proprietary sharp-corner rectangular tube production that fills gaps in global supply for precision architectural applications. CE certification under EN 10210/EN 10219 and verification by SGS and BV ensure your shipments clear European and international customs without documentation delays. We export to over 50 countries including EU, North America, and Southeast Asia, with professional loading plans that optimize container space for your exact length requirements. Custom non-standard sizes and cut-to-length service eliminate secondary processing at your fabrication facility.
Documentation & Compliance
- Mill test certificate documenting Q345B chemical composition and mechanical properties per GB/T 1591, issued per heat number
- CE certificate confirming compliance with EN 10219 cold-formed structural hollow sections for European market clearance
- ISO 9001:2015 quality management system certificate covering full production and inspection process
- SGS or BV third-party inspection report available for independent verification before shipment
- Material traceability by heat number linking each tube to its original slab and test results
- Complete customs documentation including packing list, bill of lading, and certificate of origin
Packaging, Loading & Delivery
- Cold rolled Q345B square tubes bundled with steel strips and edge protectors to preserve surface finish during ocean transit
- Custom length tubes loaded with optimized container stowage plans maximizing payload for 6m and 24 ft lengths
- Non-oiled surface protected with waterproof wrapping to prevent moisture damage during multi-week shipping
- Heat number and steel grade marked on each bundle for site identification and traceability verification
- FOB, CIF, and DDP shipping terms available with door-to-door logistics coordination to your project site
- Professional loading supervision ensuring weight distribution meets container safety requirements
Start Your Q345B ERW Square Tube Procurement
Send your specification sheet with dimensions, steel grade, quantity, and destination port, and receive a detailed quotation including unit price, production timeline, and applicable certifications within hours. Request mill test certificates from previous shipments to verify our material quality before committing to your order.
Request Your Quotation and Mill Test Certificate
Submit your Q345B ERW welded square steel tube requirements via email at admin@sdxjysteel.com or contact us at +86 188 5315 7756 for pricing, certification confirmation, and delivery scheduling.
Frequently Asked Questions
Q: How do Q345B, S355, and ASTM A500 compare for my structural project?
A: Q345B meets Chinese GB standards with higher yield strength than Q235B, S355 follows European EN specifications with guaranteed impact toughness, and ASTM A500 covers North American structural applications. We provide grade equivalence documentation to help you select the appropriate steel grade for your engineering specifications and local code requirements.
Q: Can you provide Mill Test Certificates and third-party inspection reports?
A: Yes, every shipment includes original mill test certificates documenting chemical composition and mechanical properties per heat number. Third-party inspection through SGS or BV is available for independent quality verification before shipment, with full inspection reports provided.
Q: What is the MOQ for custom lengths and non-standard specifications?
A: We cover over 2,800 specifications with customizable lengths and wall thicknesses. MOQ varies by specification and quantity, contact us with your exact requirements for detailed pricing and production scheduling.
Q: Do your products meet CE and EN standards for European import clearance?
A: Our Q345B ERW welded square steel tubes hold CE certification under EN 10210 and EN 10219 for cold-formed structural hollow sections, ensuring compliance with European construction product regulations and smooth customs clearance.
Q: What are your production lead times and shipping terms?
A: Typical production lead times depend on order quantity and specification complexity. We offer FOB, CIF, and DDP shipping terms with professional container loading optimization and real-time tracking throughout transit.
