Description
Direct Mill Supply, No Trading Markup — XJY Structure produces Q235B galvanized square and rectangular steel tubes on our own ERW lines with hot-dip galvanizing, covering side lengths from 10 mm to 1000 mm and wall thicknesses from 0.6 mm to 28 mm, all backed by in-house mill test certificates.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B Galvanized Square and Rectangular Steel Tube |
| Product Type | Square and Rectangular Steel Tube (SHS / RHS) |
| Steel Grade | Q195, Q215, Q235, Q235B, Q345 |
| Standard | BS, EN, GB, AISI, ASTM, DIN, JIS |
| Section Shape | Square / Rectangular |
| Size Range | Side length 10 mm – 1000 mm |
| Wall Thickness | 0.6 mm – 28 mm |
| Length | 1 m – 12 m |
| Technique | ERW (Hot Rolled / Cold Rolled) |
| Surface Treatment | Hot-Dip Galvanized (Zinc Coating 30 – 275 g/m²); also Bare, Oiled, Color Paint, 3PE, PVC |
| Tolerance | ±1% |
| Ends | Plain, Beveled, Threaded with couplings or sockets |
| Application | Steel structures, construction frames, building and industry, machinery, bridges, ships, boilers, pressure vessels, general engineering structures |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Building frames, column and beam assemblies, bridge support structures, scaffolding systems |
| Industrial Projects | Machinery frames, conveyor structures, platform supports, pressure vessel pedestals |
| EPC & General Contracting | Certified structural tube packages for warehouse, factory, and logistics center projects |
| Marine & Shipbuilding | Deck structures, hull framing, onboard piping supports |
Where Zinc Coating Thickness Determines Site Acceptance
A 38 μm reading against a Z275 contract specification means full batch rejection — and that is exactly what happens when buyers source from traders without process control.
I have seen containers of galvanized tubes arrive at a Riyadh job site only to fail third-party coating inspection because the supplier had no visibility into the galvanizing bath temperature or immersion time. The Q235B galvanized square and rectangular steel tube we produce goes through hot-dip galvanizing on our own line, where zinc coating is maintained between 30 g/m² and 275 g/m² with in-process thickness checks. When your project specification calls for Z275, you need documentation that traces every bundle back to the galvanizing batch — not a trader’s promise. Overseas buyers consistently report that dimensional accuracy and coating uniformity are the two factors most likely to trigger costly rework when fabrication is outsourced without vertical integration [NEED_CITE: hot-dip galvanized coating thickness standards for structural steel].
Matching Structural Load Paths in Frame Construction
Q235B galvanized square and rectangular steel tubes in side lengths from 10 mm to 1000 mm and wall thicknesses up to 28 mm cover the full range of load-bearing members in commercial and industrial frames. The ERW welding process produces a continuous longitudinal seam that meets EN 10219 and ASTM A500 requirements for structural hollow sections, while the ±1% dimensional tolerance ensures that beam-to-column connections fit without on-site forcing. For EPC projects requiring certified structural tubes, our mill produces shop drawings, material optimization reports, and fabrication sequencing documents alongside the tube supply — eliminating the coordination gap between material procurement and structural assembly.
Engineering Compliance Across International Standards
Structural frame design to EN 1993 or AISC 360 demands hollow sections with verified chemical composition and mechanical properties. Q235B corresponds to S235JR under EN standards and approximates ASTM A500 Grade B, but equivalence is not automatic — the mill test certificate must confirm the specific grade’s carbon, manganese, and sulfur content within the standard’s limits [NEED_CITE: steel grade equivalence between GB Q-series and EN S-series]. For European projects, CE marking under EN 10210 (hot-finished) or EN 10219 (cold-formed) is mandatory for customs clearance, and our production lines hold both certifications. The hot-dip galvanized surface at 275 g/m² provides corrosion protection suitable for C3 to C4 atmospheric environments per ISO 12944, reducing lifecycle maintenance costs for infrastructure in coastal or industrial zones.
Understanding Q235B and ERW Process Fundamentals
Q235B is a carbon structural steel with minimum yield strength at 235 MPa, widely specified in Chinese GB standards for general construction and light-to-medium structural applications. The “B” designation indicates semi-killed steel with guaranteed impact toughness at room temperature, making it suitable for welded connections in building frames. ERW (Electric Resistance Welding) forms the tube by rolling a steel strip into a circular or rectangular profile and welding the seam through electrical resistance heating — this process is cost-effective for medium-wall thicknesses and produces consistent dimensional accuracy across long production runs. Hot-dip galvanizing immerses the finished tube in a molten zinc bath, creating a metallurgical bond between the zinc and steel substrate that provides cathodic protection even if the coating is scratched. The zinc coating range of 30 g/m² to 275 g/m² allows buyers to specify based on expected service environment — indoor dry conditions may only require 30–60 g/m², while outdoor exposure in humid or coastal areas demands 200–275 g/m² for 20-year corrosion resistance.
The Hidden Cost of Unverified Coating and Tolerance
Ordering galvanized tubes without specifying coating thickness in the purchase contract invites suppliers to deliver minimum-thickness product — typically 30–60 g/m² — while invoicing at Z275 pricing. When site inspectors measure 38 μm against a 55 μm minimum requirement, the entire shipment faces rejection, triggering air-freight replacement costs that exceed the original material value. Similarly, tubes produced with excessive negative tolerance may pass dimensional inspection but fail structural load calculations, forcing redesign or member replacement after delivery. Certification gaps compound the problem: without EN 10204 3.1 or 3.2 mill test certificates, European customs will hold the shipment regardless of physical quality [NEED_CITE: EN 10204 inspection document types for steel products].
Why Vertical Integration Eliminates Supply Chain Risk
Our own steel mill produces the hot-rolled coil that feeds the ERW tube lines, which then pass directly to the galvanizing bath — one facility, one quality system, one point of accountability. This vertical integration means the Q235B galvanized square and rectangular steel tube you order carries a mill test certificate that traces chemistry and mechanical properties from the original heat of steel through every processing stage. We maintain over 2,800 specifications in stock, covering the full range of side lengths from 10 mm to 1000 mm and wall thicknesses from 0.6 mm to 28 mm, so your project does not wait for material procurement. Third-party inspection by SGS, BV, or TÜV is accepted at any production stage, and our CE certification under EN 10210 and EN 10219 ensures your European projects clear customs without delay. Professional loading plans optimize container utilization for tubes up to 12 m length, and we provide complete export documentation including packing lists, bills of lading, and certificates of origin.
Documentation & Compliance
- Mill test certificate documenting Q235B chemical composition and yield strength per GB/T 700, with heat number traceability to the original steelmaking batch
- CE certificate confirming compliance with EN 10219 for cold-formed structural hollow sections, required for EU customs clearance
- ISO 9001 quality management certificate covering the full production process from coil slitting through ERW welding and hot-dip galvanizing
- Third-party inspection report from SGS or BV verifying zinc coating thickness, dimensional tolerance, and surface quality before shipment
- Material traceability sheet linking each bundle’s heat number to the corresponding mill test certificate and galvanizing batch record
- Complete customs documentation package including packing list, bill of lading, certificate of origin, and SASO/SONCAP certificates for Middle East and Africa destinations
Packaging, Loading & Delivery
- Q235B galvanized square and rectangular steel tubes bundled with steel strips and edge protectors to preserve the zinc coating during ocean transit and prevent bundle shifting
- Hot-dip galvanized surface protected by waterproof wrapping at bundle ends to prevent white rust formation during container condensation in humid climates
- Container loading optimized for 6 m and 12 m lengths using nested stacking patterns for smaller side lengths (10–100 mm) and single-layer arrangements for larger sections (200–1000 mm)
- Custom cutting to project-specific lengths within the 1–12 m range, with cut ends deburred and touch-up galvanized to maintain coating continuity
- Bundle identification tags showing steel grade Q235B, heat number, size specification, zinc coating class, and bundle weight for site receiving inspection
- FOB, CIF, and DDP shipping terms available with door-to-door logistics coordination for project sites in the Middle East, Southeast Asia, and Africa
Starting Your Procurement Process
Submit your project drawings or specification list indicating steel grade, size requirements, coating class, and destination port — we respond within 24 hours with a detailed quotation including material, fabrication, coating, packing, and shipping costs. For non-standard dimensions or custom lengths outside the 10–1000 mm side length range, our engineering team will confirm feasibility and lead time. We provide mill test certificates, CE documentation, and third-party inspection coordination as standard with every order.
Request Quotation with Mill Test Certificate
Share your Q235B galvanized square and rectangular steel tube specifications — side length, wall thickness, length, zinc coating class, and quantity — to receive pricing and material certification within one business day.
Company: 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
