Description
Direct Mill Supply for Q235B Galvanized SHS/RHS — Hot-dip galvanized square and rectangular tubes produced from our own steel mill with full heat-number traceability and zinc coating up to 275 g/m².
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235B Galvanized Square Steel Tube |
| Product Type | Galvanized Square and Rectangular Steel Tube (SHS / RHS) |
| Steel Grade | Q195, Q215, Q235, Q235B, Q345, 10#, 20#, 45#, 16Mn, A53 (A/B), St37, St42, St35.4, St52.4, ST35 |
| Standard | BS, EN, GB, AISI, ASTM, DIN, JIS |
| Section Shape | Square / Rectangular / Round |
| Size Range | 10 mm – 1000 mm (side length / outer diameter) |
| Wall Thickness | 0.6 mm – 28 mm |
| Length | 1 m – 12 m |
| Technique | ERW (Hot Rolled / Cold Rolled) |
| Surface Treatment | Galvanized (Zinc Coating 30–275 g/m²), Bare, Oiled, Color Paint, 3PE |
| Tolerance | ±1% |
| Ends | Plain, Beveled, Threaded with couplings or sockets; plastic caps and steel rings available |
| Application | General engineering structures, building and industry frames, cars, bridges, ships, boilers, pressure vessels, fluid/gas/oil transport, structural applications |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Commercial Construction | Steel frame structures, columns, beams, platform supports, stairway handrails |
| Industrial EPC Projects | Warehouse portal frames, logistics center roof trusses, process pipe racks |
| Infrastructure | Bridge railing posts, sound barrier supports, highway sign gantries |
| Machinery & Equipment | Conveyor frames, crane booms, equipment base structures |
| Scaffolding & Temporary Works | Scaffolding uprights, ledger braces, shoring towers |
What Zinc Coating Thickness Costs You at Site Acceptance
A 20-micron gap between contract spec and actual galvanizing can halt an entire project at the inspection stage.
I have seen containers of galvanized RHS arrive at a West African port only to fail third-party coating inspection — the purchase order specified 65 microns, the lab reported 45. The entire lot was held at the laydown yard while the contractor scrambled to source touch-up paint and arrange manual recoating. For a Q235B galvanized square steel tube manufacturer, controlling zinc coating within the specified 30–275 g/m² range is not a quality bonus — it is the baseline that determines whether your cargo gets accepted or rejected at the destination. [NEED_CITE: hot-dip galvanizing coating thickness measurement standards per ISO 1461]
Matching Galvanized SHS/RHS to Structural Frame Requirements
Galvanized Q235B square and rectangular tubes serve as primary load-bearing members in portal frames, mezzanine floors, and equipment support structures where both corrosion resistance and weldability matter. The ERW process produces a consistent weld seam that meets structural welding requirements, while the hot-dip galvanizing layer protects all surfaces — including the interior of closed sections — against atmospheric corrosion in coastal and industrial environments. When your project demands EN 10210 or ASTM A500 compliance, the Q235B grade maps directly to S235JR and A53 Grade B equivalents, simplifying engineering approval across jurisdictions.
Corrosion Environment, Steel Grade Selection, and Certification Path
Coastal projects in Southeast Asia and West Africa demand zinc coating at the upper end of the 30–275 g/m² range, while indoor warehouse frames in dry climates may accept lighter coatings or even bare tubes with shop primer. Steel grade selection directly affects load capacity — Q345 offers higher yield strength than Q235B, allowing thinner wall sections for the same design load, but requires adjusted welding parameters. For EU-bound shipments, CE marking under EN 10219 is mandatory for structural hollow sections, and the mill test certificate must trace every tube back to its heat number. [NEED_CITE: EN 10219 cold-formed welded structural hollow sections certification requirements]
Understanding Q235B, ERW Welding, and Galvanizing Process Interaction
Q235B is a carbon structural steel with balanced carbon and manganese content, making it compatible with both ERW welding and hot-dip galvanizing without cracking risk in the heat-affected zone. The ERW process uses high-frequency current to fuse the tube seam, producing a weld that is subsequently annealed and galvanized — the zinc metallurgically bonds to both the base metal and the weld zone. Hot-dip galvanizing at controlled bath temperature ensures uniform coating adhesion across the full 0.6–28 mm wall thickness range, including internal surfaces of SHS/RHS sections where corrosion can initiate undetected. The ±1% dimensional tolerance covers both outer dimensions and wall thickness, ensuring that connection plates and bolt-hole patterns fabricated to drawing remain within acceptable fit-up limits.
Hidden Costs of Unverified Galvanized Tube Procurement
Ordering Q235B galvanized square steel tubes without verified coating thickness and material certification creates compounding risks: dimensional tolerance beyond ±1% causes field-fit failures at bolted connections, substandard zinc coating accelerates corrosion before handover, and missing heat-number traceability blocks customs clearance in markets requiring EN or ASTM documentation. A single rejected container at the destination port costs more in demurrage, re-inspection, and replacement shipping than the original price differential between a verified Q235B galvanized square steel tube manufacturer and an unverified supplier. [NEED_CITE: structural steel procurement quality verification requirements for international projects]
Why Project Teams Source Galvanized SHS/RHS from Our Mill
Our vertically integrated facility operates its own steel production lines alongside the fabrication workshop, meaning the Q235B galvanized square steel tube you order is produced, welded, galvanized, and inspected under one quality management system — there is no gap between raw material supplier and fabricator where traceability breaks down. We maintain over 2,800 specifications in stock, covering the full 10–1000 mm size range and 0.6–28 mm wall thickness, so custom cut-to-length orders ship without waiting for third-party tube procurement. Every heat number is documented in the mill test certificate, and we accept SGS, BV, or TÜV third-party inspection at our facility before shipment. Our CE EN 10210 / EN 10219 certification covers EU market compliance, and our professional loading team plans container stowage to protect galvanized surfaces from transit damage.
Documentation & Compliance
- Mill test certificate documenting Q235B chemical composition and mechanical properties per GB/T 700, with heat number traceability for every bundled tube
- CE certificate confirming compliance with EN 10210 / EN 10219 for structural hollow sections destined for European Union markets
- ISO 9001 quality management system certificate covering the full production chain from steelmaking through galvanizing and final inspection
- SGS or BV third-party inspection report verifying zinc coating thickness within the 30–275 g/m² range and dimensional tolerance within ±1%
- Material traceability sheet linking each bundle to its heat number, production date, and galvanizing batch record
- Complete customs documentation including packing list, bill of lading, and certificate of origin formatted for destination-country clearance
Packaging, Loading & Delivery
- Galvanized Q235B SHS/RHS tubes bundled with steel strips and edge protectors to preserve the zinc coating during ocean transit, with bundles sized for 20ft or 40ft container loading
- Zinc-coated surfaces wrapped with waterproof paper and plastic film at tube ends to prevent white rust formation from condensation during container shipping
- Custom cut-to-length tubes between 1 m and 12 m loaded with timber dunnage to prevent contact damage between galvanized surfaces and container floors
- Heat number and steel grade stenciled on each bundle tag, with bundle weight and piece count matching the packing list for site receiving verification
- FOB, CIF, and DDP shipping terms available with professional stowage planning for oversized RHS sections exceeding standard container door dimensions
- Door-to-door logistics coordination covering inland transport, port handling, and ocean freight tracking until site delivery
Starting Your Galvanized Tube Procurement
Share your project drawings or specification list — including steel grade (Q235B, Q345, or international equivalent), section dimensions, wall thickness, zinc coating requirement, and destination port — and our engineering team responds within 24 hours with a detailed quotation covering material, galvanizing, packing, and shipping costs. We provide shop drawing review, mill test certificate samples, and third-party inspection coordination before you commit to a production order.
Frequently Asked Questions
Q: How does Q235B compare to S235JR and ASTM A53 Grade B?
A: Q235B is the Chinese national standard equivalent to S235JR under EN 10025 and closely matches ASTM A53 Grade B in chemical composition and mechanical properties. All three grades are suitable for general structural applications and are compatible with hot-dip galvanizing and ERW welding processes.
Q: Can you provide third-party inspection for zinc coating thickness?
A: Yes. We accept SGS, BV, or TÜV inspection at our facility before shipment. The inspector verifies zinc coating thickness within the specified 30–275 g/m² range using magnetic induction or X-ray fluorescence methods per ISO 1461 or ASTM A123 standards, and issues an independent report.
Q: What is the minimum order quantity for custom-size galvanized tubes?
A: The MOQ is 1 Ton. For non-standard dimensions outside our regular stock range, we can produce to your specified size within the 10–1000 mm side length and 0.6–28 mm wall thickness range, subject to production scheduling.
Q: How do you ensure zinc coating uniformity on the interior of closed SHS/RHS sections?
A: During hot-dip galvanizing, molten zinc flows into the open ends of square and rectangular tubes, coating all internal surfaces. We ensure proper venting and drainage holes are maintained during the dipping process so the zinc reaches all interior corners and weld seams without air pockets.
Q: What documentation do you provide for customs clearance?
A: We supply a complete document package including mill test certificate with heat number traceability, packing list, bill of lading, certificate of origin, and commercial invoice. For EU destinations, we provide CE marking documentation per EN 10210 / EN 10219. All documents are formatted to meet destination-country import requirements.
Request Your Galvanized SHS/RHS Quotation
Submit your specification sheet — steel grade, section size, wall thickness, zinc coating requirement, quantity, and destination port — to receive a detailed quotation with mill test certificate preview and production lead time.
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
