Description
Factory-direct welded hollow sections — 2,800+ specifications in stock, shipped with full EN 10219 mill test certificates and Lloyd’s CE marking for EU customs clearance.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Carbon Steel Welded Square & Rectangular Hollow Tube |
| Product Type | Square / Rectangular Steel Tube (Welded Hollow Sections) |
| Steel Grade | Q195, Q215, Q235, Q235B |
| Standard | EN 10219, EN 10210, JIS G3466 |
| Section Shape | Square / Rectangular |
| Size Range | 20×20 mm – 100×150 mm |
| Length | 6–12 m |
| Technique | ERW (Electric Resistance Welded) / Hot Rolled |
| Surface Treatment | Hot Rolled (Non-oiled) |
| Tolerance | ±1%, ±10% |
| Ends | Plain |
| Application | Structural Pipe, Construction Building Material, Building Frames |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, structural columns, portal frames for warehouses |
| Facade & Curtain Wall | Architectural steel framing, exposed structural elements in commercial buildings |
| Steel Structure Fabrication | Raw material for trusses, bracing members, connection nodes |
| Machinery & Equipment | Conveyor structures, equipment support frames, industrial platforms |
What Negative Tolerance Costs on a Structural Frame Order
A 0.6mm wall deviation can reject an entire container at destination port.
When procurement teams specify Carbon Steel Welded Square Rectangular Hollow Tube for load-bearing frames, they trust the mill test certificate reflects actual wall thickness. But inconsistent cold-forming processes produce tubes where the nominal 4mm wall measures 3.4mm at the weld seam — a 15% negative tolerance that fails SGS inspection upon arrival. The result: customs holds the shipment, the project delays steel erection by weeks, and air-freight replacement costs erase the original price advantage. EN 10219 dimensional tolerance requirements exist precisely because structural engineers calculate load capacity based on published wall thickness, not optimistic mill claims [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerances].
Matching Structural Load Requirements for Building Frames
Carbon Steel Welded Square Rectangular Hollow Tube in Q235B grade delivers yield strength suitable for non-seismic building frames up to mid-rise construction. The ERW welding process produces a continuous longitudinal seam that, when properly controlled, maintains uniform strength across the cross-section. For facade contractors specifying exposed architectural elements, the hot-rolled surface provides a consistent mill finish that accepts intumescent fireproofing coatings without additional surface preparation. Our cold-forming lines maintain ±1% dimensional tolerance on side length, ensuring connection plates fit without on-site reaming — a detail that saves labor costs when assembling curtain wall support grids.
Compliance with European Structural Standards and Site Welding
Structural engineers designing to Eurocode 3 (EN 1993) require hollow sections that conform to EN 10219 for cold-formed welded profiles or EN 10210 for hot-formed seamless sections. Q235B steel grade provides approximate equivalence to S235JR under EN 10025-2, though procurement teams must verify chemical composition matches the carbon equivalent limits for site welding — higher carbon content increases cracking risk in cold conditions [NEED_CITE: steel grade equivalence between GB Q235B and EN S235JR]. The 6–12 m random length range accommodates standard container loading while allowing fabricators to nest-cut members from 12 m stock, reducing scrap. For projects requiring CE marking, our Lloyd’s certification to EN 10210/10219 satisfies EU Construction Products Regulation, preventing customs rejection at Rotterdam or Hamburg ports.
Understanding ERW Welding and Hot-Rolled Surface Finish
Electric Resistance Welding joins the formed steel strip edges through localized heating and pressure, producing a weld seam whose metallurgical structure differs from the parent metal. Properly executed ERW creates a bond strength exceeding the base metal, but inadequate fusion or inclusions along the seam become failure initiation points under cyclic loading. The hot-rolled surface finish on our Carbon Steel Welded Square Rectangular Hollow Tube retains mill scale that provides temporary corrosion resistance during storage and transit — this oxide layer must be removed by abrasive blasting before painting in aggressive environments. Wall thickness capability up to 40mm on heavier sections allows structural engineers to specify thicker walls at high-stress connection points without switching to seamless alternatives, maintaining cost efficiency across the bill of materials.
The Hidden Cost of Unverified Material Certificates
A forged mill test certificate turns compliant steel into scrap.
When buyers accept Carbon Steel Welded Square Rectangular Hollow Tube without third-party verification, they risk receiving Q195 grade substituted for Q235B — a 35% yield strength reduction that compromises structural safety factors. Customs authorities in EU member states increasingly reject shipments lacking proper CE documentation or showing discrepancies between declared and actual chemical composition [NEED_CITE: EU customs enforcement of CE marking for structural steel]. Beyond regulatory penalties, non-conforming material forces costly remediation: cutting out and replacing erected members, project delay claims from main contractors, and reputational damage with end clients who discover the substitution during their own quality audits.
Why Engineering Procurement Teams Source From SD XJY Pipe
Our 41 invention patents include China’s original sharp-corner rectangular tube technology, solving the aesthetic and structural connection problems that rounded-corner tubes create in architectural facades. The in-house physical and chemical laboratory tests every heat number for yield strength, tensile strength, elongation, and chemical composition before issuing mill test certificates — no certificate leaves the facility without backing data from our own equipment. With 2,800+ specifications covering wall thicknesses up to 40mm, we consolidate multi-size orders into single shipments, eliminating the coordination burden of sourcing from five different mills. Full international certifications — ISO 9001:2015, Lloyd’s CE to EN 10210/10219, Singapore FPC, and SGS/BV verification — satisfy the most stringent project specifications and customs requirements across 50+ export destinations. Professional container loading with anti-damage measures prevents the bending and surface scratches that plague improperly stowed tube shipments.
Documentation & Compliance
- Mill test certificate documenting Q235B chemical composition (C, Mn, Si, P, S) and mechanical properties per EN 10219 requirements
- CE certificate issued by Lloyd’s Register confirming compliance with EN 10210/10219 for EU market access
- ISO 9001:2015 quality management system certificate covering design, production, and testing of welded hollow sections
- SGS or BV third-party inspection report available upon request, verifying dimensional accuracy and surface quality before shipment
- Material traceability linking each bundle to heat number, production date, and test results from our in-house laboratory
- Complete customs documentation including packing list, bill of lading, and certificate of origin for destination port clearance
Packaging, Loading & Delivery
- Q235B welded tubes bundled with steel strips at 1.5 m intervals, with edge protectors preventing surface damage during transit
- Hot-rolled surface finish preserved by waterproof wrapping for ocean shipment, preventing rust formation that complicates site painting
- Container loading optimized for 6 m and 12 m lengths, maximizing payload while maintaining weight distribution for 20ft and 40ft units
- Custom cutting to specified lengths available, with kerf allowance calculated to minimize material waste on fabricator premises
- Heat number and steel grade stenciled on each tube end, enabling immediate identification during site inventory and erection
- FOB, CIF, and DDP shipping terms available, with door-to-door logistics coordination to project sites across EU, North America, and Southeast Asia
Requesting Quotation and Technical Documentation
Submit your specification requirements — section dimensions, wall thickness, steel grade, surface treatment, quantity, and destination port — to receive a detailed quotation within 12 hours. Our technical team provides cross-reference guidance for steel grade equivalence between GB, EN, ASTM, and JIS standards, ensuring your procurement documents match available inventory. For non-standard dimensions outside the 20×20 to 100×150 mm range, we confirm production feasibility and lead times based on our 2,800+ specification capability. Mill test certificates and CE documentation are confirmed in the proforma invoice, eliminating post-shipment compliance disputes.
Frequently Asked Questions
Q: How does Q235B compare to S235JR and ASTM A500 Gr.B?
A: Q235B provides similar yield strength to S235JR (both approximately 235 MPa minimum), though chemical composition limits differ slightly. ASTM A500 Gr.B specifies higher minimum yield strength (290 MPa for square sections), making it non-equivalent to Q235B. Our technical team provides detailed chemical composition comparison tables for your engineer’s review.
Q: Can you provide third-party inspection before shipment?
A: Yes. We arrange SGS or BV inspection at our facility at your request. The inspector verifies dimensional accuracy, surface quality, wall thickness, and reviews mill test certificates. Inspection reports are issued directly to you, independent of our quality department.
Q: What is the minimum order quantity for non-standard dimensions?
A: Our standard MOQ is 1 Ton for catalog sizes within the 20×20 to 100×150 mm range. For custom dimensions outside standard specifications, MOQ depends on production setup requirements — typically 5–10 tons for non-standard wall thicknesses or special lengths.
Q: Do your products carry CE marking for EU customs clearance?
A: Yes. Our Carbon Steel Welded Square Rectangular Hollow Tube carries Lloyd’s CE certification to EN 10210/10219 standards. The CE mark appears on our mill test certificates and product documentation, satisfying EU Construction Products Regulation requirements for structural steel imports.
Q: How do you ensure wall thickness meets EN 10219 tolerance?
A: Our in-house laboratory measures wall thickness at four points per tube end using ultrasonic gauges. Results are recorded in the mill test certificate. We maintain ±10% tolerance on wall thickness per EN 10219 requirements, with typical production holding ±5% through controlled cold-forming processes.
[Get Your EN-Standard Hollow Section Quote]
Send your specification sheet to admin@sdxjypipe.com or contact us via WhatsApp at +86 188 5315 7756. Include section dimensions, steel grade, quantity, and destination port for a complete quotation with mill test certificate and CE documentation confirmation.
