Description
Factory-Direct Galvanized Tube Supply — Backed by our own steel mill with 3 production lines and 2,800+ specifications of raw material, we deliver hot dipped galvanized square and rectangular steel tubes from molten steel to finished product under one roof.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B/Q345B Galvanized Square and Rectangular Steel Tube |
| Product Type | Welded Square and Rectangular Steel Tube (Galvanized) |
| Steel Grade | Q195, Q235, Q235B, Q345, Q345B, SS400, SS330-SS540 |
| Standard | ASTM, JIS, ISO 9001 |
| Section Shape | Square / Rectangular / Round |
| Size Range | Wall thickness 0.5–200 mm |
| Length | 6 m / 6.4 m / 12 m (Customizable) |
| Technique | Cold Rolled / Hot Rolled / Zinc Coated (Hot Dipped Galvanized) |
| Surface Treatment | Hot Dipped Galvanized / Consumer’s Requirement |
| Tolerance | ±1% |
| Ends | Plain |
| Application | Construction / Bridges / Railways / Ships / Vehicles / Machinery Manufacturing / Petrochemical Industry / Marine Development / Fluid Transport / Drilling / Hydraulic Systems |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Construction & Infrastructure | Structural frames, scaffolding systems, column supports, roof trusses |
| Industrial Facilities | Petrochemical pipe racks, machinery frames, conveyor structures |
| Marine Development | Platform supports, dock fender systems, offshore equipment frames |
| Fluid Transport | Low-pressure water pipelines, gas distribution lines, oil transport conduits |
| Bridges & Railways | Bridge railings, structural bracing, trackside support posts |
Where Zinc Coating Thickness Decides Site Acceptance
A 25-micron shortfall on hot dipped galvanized square and rectangular steel tube means the entire shipment fails third-party inspection before it ever reaches the structure.
I’ve stood on warehouse floors in the Gulf watching crews scrape zinc off tubes that should have been installed weeks ago. The spec called for a minimum coating weight, the mill certificate showed one thing, and the on-site X-ray gauge showed another. When the galvanizing bath temperature drops or the immersion time gets cut short to save energy, the zinc-iron alloy layer never fully forms. The tube looks fine to the naked eye. It fails the moment a calibrated inspector runs a magnetic thickness gauge across the surface. For projects bound by ASTM or EN corrosion protection standards, this is not a negotiation — it is a rejection. [NEED_CITE: hot dip galvanizing coating thickness requirements per ASTM A123]
Matching Structural Load Paths in Gulf Climate Conditions
Hot dipped galvanized square and rectangular steel tube in Q345B grade carries higher yield capacity than Q235B, making it the default choice for primary structural frames where column spacing exceeds standard modular dimensions. In coastal and arid-salt environments typical of Middle East infrastructure projects, the hot dipped zinc layer provides sacrificial corrosion protection that outperforms painted or electroplated alternatives by a significant margin. Our fabrication workshop handles CNC cutting, drilling, and welding of these tubes to engineering drawings, so the structural steel arrives on site ready for bolt-up or field weld — not requiring secondary modification that damages the zinc layer at cut edges.
Engineering Compliance and Certification Requirements
Structural hollow sections used in load-bearing frames must conform to recognized dimensional and mechanical standards. For projects following EN 1993 design codes, the tubes must meet cold-formed or welded hollow section requirements with full traceability to heat numbers. ASTM-specification projects in North American and Gulf markets require material test reports showing chemical composition and mechanical properties per the relevant grade designation. Third-party inspection by SGS or BV is routinely specified in EPC contracts, and the documentation package must travel with the shipment — not arrive weeks later by email. [NEED_CITE: EN 10219 cold-formed structural hollow section dimensional tolerances]
Steel Grade Selection and Galvanizing Process Fundamentals
The Q-series grades (Q195 through Q345B) follow the Chinese GB standard system where the number indicates minimum yield strength in MPa. Q235B remains the most widely specified grade for general structural work due to its balance of formability and strength. Q345B offers higher yield capacity for heavier load applications while maintaining good weldability. The SS400 and SS330-SS540 grades follow the JIS G 3101 system, commonly specified in Japanese-standard projects across Southeast Asia. Hot dipped galvanizing immerses the fabricated tube in molten zinc at approximately 450°C, creating a metallurgical bond with the steel substrate. The resulting coating consists of multiple zinc-iron alloy layers topped by a pure zinc outer layer, providing both barrier protection and cathodic sacrifice at scratches or cut edges. Wall thickness tolerance of ±1% ensures that theoretical weight calculations match actual delivered weight within acceptable commercial margins, preventing disputes over short-weight claims at destination.
Hidden Costs of Procurement Shortcuts
Ordering hot dipped galvanized square and rectangular steel tube from a trading company that subcontracts galvanizing to a separate processor creates a documentation gap: the mill test certificate covers the base steel, but who certifies the coating thickness? When the zinc layer falls below specification, the buyer faces three costs simultaneously — re-galvanizing at destination (if local facilities exist and meet the standard), air-freighting replacement tubes to recover schedule, or accepting the non-conforming material and absorbing reduced service life. Customs authorities in Gulf and EU markets increasingly require CE marking or conformity documentation for structural steel imports. Shipment without proper certification risks port hold, demurrage charges, and in worst cases, forced re-export. [NEED_CITE: structural steel import documentation requirements for GCC countries]
Why Procurement Teams Source Directly from Our Mill
We operate three dedicated production lines for welded square and rectangular tubes, backed by our own steel mill producing over 2,800 specifications of raw material. This vertical integration means the base steel, the forming, the welding, and the galvanizing all happen within one quality management system — one heat number traceable from slab to finished coated tube. Our fabrication division provides CNC cutting, drilling, and welding services per approved shop drawings, so structural components arrive on site ready for assembly. We hold ISO 9001 certification and work with SGS and BV for third-party inspection on buyer’s request. Every shipment includes a complete documentation package: mill test certificates, dimensional inspection reports, coating thickness records, and export customs documents. For projects requiring certified welding procedures, our welders hold AWS and EN qualifications with full WPS and PQR documentation available.
Documentation & Compliance
- Mill test certificate documenting Q235B/Q345B chemical composition and mechanical properties per GB/T standard, traceable to heat number
- Third-party inspection report from SGS or BV covering dimensional accuracy, coating thickness measurement, and visual examination of hot dipped galvanized square and rectangular steel tube
- ISO 9001 quality management system certificate covering the full production process from raw steel to finished galvanized product
- Material traceability records linking each bundle to its heat number, galvanizing batch, and inspection date
- Export customs documentation including packing list, bill of lading, and certificate of origin for destination-country clearance
- Welding procedure specifications (WPS) and procedure qualification records (PQR) per AWS D1.1 or EN ISO 15614 for any fabricated connections
Packaging, Loading & Delivery
- Hot dipped galvanized square and rectangular steel tube bundled with steel strips and edge protectors to preserve the zinc coating during ocean transit and prevent edge damage from bundle movement
- Seaworthy packaging with waterproof wrapping for 6 m and 12 m lengths, optimized for 20-foot and 40-foot container loading with weight distribution calculated per bundle
- Galvanized surface protected by passivation treatment to minimize white rust formation during storage and transit in humid climates
- Heat number and steel grade stenciled on each tube end for site identification and traceability verification upon arrival
- Custom length cutting available at 6 m, 6.4 m, or 12 m with tolerance held to ±1%, reducing on-site waste and cutting labor
- Delivery terms available as FOB, CIF, or DDP to major ports, with professional loading plans for oversized and heavy tube bundles
Starting Your Procurement Process
Share your project drawings, steel grade requirements, coating specifications, and destination port. We respond within 24 hours with a technical assessment, pricing covering material through galvanizing and packaging, and a production schedule. For non-standard dimensions or fabricated components requiring CNC processing, we provide shop drawing review and fabrication sequencing before contract commitment.
Frequently Asked Questions
Q: What steel grades are available for hot dipped galvanized square and rectangular steel tube?
A: We supply Q195, Q235, Q235B, Q345, Q345B, SS400, and SS330-SS540 grades. Q235B is the most common for general structural applications, while Q345B provides higher yield strength for heavier load requirements. JIS-standard SS grades serve projects following Japanese specifications.
Q: Can you provide custom lengths beyond standard 6 m and 12 m?
A: Yes. We offer customizable lengths including 6.4 m and project-specific cut-to-size options. Wall thickness ranges from 0.5 mm to 200 mm across square, rectangular, and round sections. All dimensions are held to ±1% tolerance.
Q: What documentation accompanies the shipment for customs clearance?
A: Every order includes mill test certificates with chemical and mechanical data traceable to heat number, packing list, bill of lading, and certificate of origin. Third-party inspection reports from SGS or BV are available upon request. CE certification documentation can be provided for projects requiring EN standard compliance.
Q: How do you ensure galvanizing coating thickness meets specification?
A: Each production batch undergoes coating thickness measurement using magnetic gauges per the relevant standard. Results are recorded in the quality documentation package. Our vertically integrated facility controls the entire process from base steel production through galvanizing, eliminating gaps in quality responsibility.
Q: What is the minimum order quantity for international shipments?
A: The minimum order quantity is 5 tons. For project procurement, we typically supply full container loads or bulk vessel shipments depending on total tonnage and destination port logistics.
Get Your Technical Assessment and Quotation
Send your specifications, steel grade, coating requirements, and destination port to receive pricing with mill test certificate documentation within 24 hours.
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
