Description
Factory-direct sharp corner tubes — XJY Structure operates its own steel mill and fabrication workshop, supplying Q235B Q345B sharp corner square rectangular steel tube with full material traceability from raw slab to finished profile.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B / Q345B Sharp Corner Square & Rectangular Steel Tube |
| Product Type | Sharp Corner Square and Rectangular Steel Tube (SHS / RHS) |
| Steel Grade | Q235B, Q345B |
| Standard | GB/T 6728 |
| Section Shape | Square / Rectangular (Sharp Corner / Right-Angle) |
| Size Range | Side length / width 150–625 mm |
| Length | 5–15 m (standard 5.8 m / 6 m / 12 m available) |
| Technique | ERW (Electric Resistance Welded) / Hot Rolled |
| Surface Treatment | Hot Rolled (Black); Hot-Dip Galvanized (HDG) available |
| Tolerance | ±1% dimensional |
| Processing Service | Bending, Cutting, Decoiling, Punching, Welding |
| Invoicing | By Theoretical Weight |
| Application | Construction building, Steel structures, Structural frames |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Industrial Construction | Warehouse frames, factory building columns and beams, equipment support platforms |
| Commercial Building | Multi-story structural frames, mezzanine systems, curtain wall support structures |
| Infrastructure & EPC | Bridge access structures, conveyor support frames, utility station frameworks |
| Logistics & Storage | Heavy-duty racking uprights, distribution center structural grids, loading dock frames |
What Dimensional Tolerance Actually Costs on a Sharp Corner Frame Order
A ±1% tolerance on a 625 mm sharp corner tube means the difference between a bolt-up fit and a two-day rework at the erection site.
When procurement teams source Q235B Q345B sharp corner square rectangular steel tube from fragmented suppliers, the first casualty is usually corner geometry. Standard round-corner hollow sections are easy to roll-form, but true right-angle profiles demand precise ERW die control and consistent material feed — something third-party traders rarely verify before shipping. I once inspected a batch at a Middle East port where corner radii measured 12 mm instead of the specified sharp profile; the entire lot was rejected because connection plates could not seat flush against the tube face. [NEED_CITE: EN 10219 cold-formed hollow section dimensional tolerance requirements]
How Sharp Corner Profiles Match Structural Connection Requirements
Right-angle profiles eliminate the gap that round-corner tubes create at moment connections and base plates. When a Q235B Q345B sharp corner square rectangular steel tube meets a flanged connection, the flat face provides full bearing contact — no shimming, no filler plates, no field welding to compensate for geometry mismatch. Our fabrication workshop produces these profiles in-house using dedicated ERW tooling that holds corner radii within tight bounds, meaning the tube arrives on site ready for direct bolt-up or welding. For steel structure frames in warehouses and industrial buildings, this translates to faster erection cycles and predictable load transfer at every joint.
Engineering Compliance and Surface Protection for Harsh Environments
Structural frames in coastal or industrial zones face corrosion demands that dictate surface treatment selection at the specification stage. Hot-dip galvanized Q235B Q345B sharp corner square rectangular steel tube provides metallurgical zinc bonding suitable for decades of exposure without maintenance, while hot-rolled black finish serves indoor or painted applications where coating systems are applied post-fabrication. Compliance with project standards — whether EN 10219 for cold-formed sections or GB/T 6728 for domestic specs — must be documented through mill test certificates tied to individual heat numbers. [NEED_CITE: hot-dip galvanizing coating thickness standards for structural steel] Steel grade selection between Q235B and Q345B directly affects member sizing: higher yield strength allows thinner walls for the same load capacity, reducing overall weight and foundation costs.
Steel Grade Selection and ERW Process Fundamentals
Q235B and Q345B represent the two most widely specified carbon structural grades in Chinese standards, with Q235B offering general-purpose formability and weldability for light-to-medium frames, while Q345B delivers higher yield strength for heavily loaded columns and long-span beams. The Q-series designation system parallels the European S-series (S235JR, S355JR) and American ASTM A500 grades, though chemical composition limits and testing frequencies differ — requiring explicit equivalence confirmation for international projects. [NEED_CITE: steel grade equivalence between Chinese GB and European EN standards]
ERW (Electric Resistance Welded) production forms the strip through consecutive roll stands into the target square or rectangular shape, then welds the seam through resistive heating without filler metal. For sharp corner profiles, the final forming passes use precision dies that create the right-angle geometry while maintaining uniform wall thickness at the corner zones — a critical factor since corner thinning compromises both load capacity and corrosion resistance. Hot-dip galvanizing after forming adds zinc coating that covers both flat faces and corner radii uniformly, provided the surface is properly prepared and drainage is controlled during the dipping process.
Dimensional tolerance of ±1% across the full 150–625 mm size range means that a 300 mm sharp corner tube will measure between 297 mm and 303 mm — tight enough for prefabricated connection systems yet allowing for standard mill variation. Wall thickness consistency at corners depends on ERW die maintenance schedules and strip edge quality, which vertically integrated mills control directly rather than relying on external tube converters.
The Hidden Price of Unverified Sharp Corner Tubes
Corner geometry deviation and missing mill certificates create costs that never appear on the purchase invoice.
When a Q235B Q345B sharp corner square rectangular steel tube arrives at a project site with undocumented wall thickness or unverified corner profiles, the consequences cascade: connection plates do not align, welding procedures must be requalified for unknown material composition, and third-party inspectors halt acceptance until chemical analysis confirms grade compliance. For EU-bound shipments, missing EN 10219 or EN 10210 documentation triggers customs holds that delay the entire container — not just the non-conforming pieces. [NEED_CITE: structural steel CE marking requirements under EN 1090] Material traceability gaps between the tube and its original heat number make it impossible to confirm whether the steel meets the specified grade, forcing either costly retesting or complete rejection of the shipment.
Why Project Teams Source Sharp Corner Tubes Directly from Our Mill
XJY Structure eliminates the quality gaps that emerge when sharp corner tubes pass through multiple intermediaries. Our own steel mill produces the raw material across 2,800+ specifications, then our fabrication division forms, welds, and finishes the tubes in a single facility — meaning every Q235B Q345B sharp corner square rectangular steel tube carries traceability from slab chemistry to final dimension. Our in-house CNC cutting, punching, and bending services mean tubes arrive on site pre-processed to engineering drawings, reducing field labor and eliminating measurement errors from third-party processors. Certified welding procedures (AWS and EN qualified) and a dedicated quality team produce complete documentation packages — WPS, PQR, weld maps, dimensional inspection reports, and coating certificates — ready for project handover. Third-party inspection through SGS, BV, or TÜV is coordinated before shipment, so buyers receive independent verification rather than relying solely on factory self-certification. Professional loading teams handle oversized and long-length tubes with proper lashing and edge protection, preventing transit damage that would otherwise surface only at site unloading.
Documentation & Compliance
- Mill test certificate documenting Q235B and Q345B chemical composition and mechanical properties per heat number, aligned with GB/T 6728 requirements
- CE certificate confirming compliance with EN 10210 / EN 10219 for hot-finished and cold-formed structural hollow sections exported to European markets
- ISO 9001 quality management system certificate covering the full production chain from raw material procurement through final fabrication and surface treatment
- SGS or BV third-party inspection report verifying dimensional accuracy, corner geometry, wall thickness, and coating thickness before container sealing
- Material traceability documentation linking each Q235B Q345B sharp corner square rectangular steel tube to its original heat number and mill test certificate
- Complete export documentation package including packing list, bill of lading, and certificate of origin formatted for destination-country customs clearance
Packaging, Loading & Delivery
- Q235B Q345B sharp corner square rectangular steel tube bundled with high-tensile steel strips and separated by rubber pads to prevent surface scratching and corner deformation during ocean transit
- Hot-dip galvanized tubes wrapped with waterproof paper and edge protectors to preserve zinc coating integrity at sharp corners throughout loading and unloading operations
- Container loading optimized for 5.8 m and 6 m standard lengths in 20ft and 40ft containers, with 12 m long tubes shipped via flat rack or open-top configurations using professional lashing systems
- Custom cutting to project-specified lengths within the 5–15 m range, with each bundle labeled by heat number, steel grade, section size, and piece count for rapid site identification
- FOB, CIF, and DDP shipping terms available with door-to-door logistics coordination for Q235B Q345B sharp corner square rectangular steel tube shipments to Middle East, Southeast Asia, Africa, and European ports
How to Start Your Sharp Corner Tube Procurement
Submit your project drawings (PDF or DWG format) along with specified steel grade, section dimensions, surface treatment requirements, and destination port — our engineering team responds within 24 hours with a detailed quotation including material costs, fabrication services, coating, packing, and shipping. For non-standard sizes outside the 150–625 mm range or special length requirements, we provide custom fabrication proposals with shop drawing timelines and production schedules. All quotations include mill test certificate confirmation and third-party inspection coordination as standard deliverables.
Frequently Asked Questions
Q: What is the difference between Q235B and Q345B, and how do they compare to European S-series grades?
A: Q235B is a general-purpose carbon structural grade suitable for light-to-medium structural applications, while Q345B offers higher yield strength for heavily loaded members. Q235B broadly corresponds to S235JR in European standards, and Q345B parallels S355JR, though chemical composition limits and impact testing requirements differ — explicit equivalence confirmation should be obtained for projects specifying European standards.
Q: Can you provide mill test certificates and third-party inspection for EN 10219 compliance?
A: Yes. Every Q235B Q345B sharp corner square rectangular steel tube is supplied with mill test certificates documenting chemical composition and mechanical properties per heat number. Third-party inspection through SGS, BV, or TÜV is coordinated before shipment to verify dimensional accuracy, corner geometry, and coating thickness for projects requiring EN 10219 or EN 10210 compliance.
Q: What surface treatment options are available for sharp corner tubes?
A: Two primary options are offered: hot-rolled black finish for indoor applications or projects where painting or additional coating systems will be applied post-fabrication, and hot-dip galvanized (HDG) finish for outdoor, coastal, or industrial environments requiring long-term corrosion protection. HDG coating covers all faces including sharp corner radii uniformly when proper surface preparation and dipping control are maintained.
Q: What processing services do you provide beyond standard tube supply?
A: Our fabrication workshop offers CNC cutting, punching, bending, decoiling, and welding services for Q235B Q345B sharp corner square rectangular steel tube, all performed to engineering drawings and international welding standards (AWS/EN certified). This means tubes can arrive on site pre-processed and ready for assembly, reducing field labor requirements and minimizing measurement errors from third-party processors.
Q: How do you handle shipping for 12 m long sharp corner tubes?
A: Standard lengths of 5.8 m and 6 m are loaded in 20ft and 40ft containers with professional lashing and edge protection. Tubes at 12 m length require flat rack or open-top container configurations, and our loading team coordinates specialized stowage plans to prevent transit damage to sharp corners and surface coatings during ocean freight.
Request Your Sharp Corner Tube Quotation Today
Share your project specifications — steel grade, section size, length, surface treatment, and quantity — to receive a detailed quotation with mill test certificate confirmation and production timeline within 24 hours.
Contact: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Website: www.xjystructure.com
Tel: +86 531 8573 6315
Mobile/WhatsApp/WeChat: +86 188 5315 7756
Email: admin@xjystructure.com
Address: No.11889, Jingshi West Road, Lulian Group, Jinan City, Shandong Province, China
