Description
Vertically Integrated Mill-to-Fabrication Supply — From raw galvanized coil to finished Q235B and S275JR square and rectangular tubes, every coating thickness and dimensional tolerance is controlled under one roof.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Galvanized Square/Rectangular Steel Tube |
| Product Type | Hot-Dipped Galvanized Square and Rectangular Steel Tube (SHS/RHS) |
| Steel Grade | Q235, Q235B, S275, S275JR, A53, ST37, SGCC, CGCC, DX51D |
| Standard | GB |
| Section Shape | Square / Round / Rectangle |
| Size Range | Square and rectangular sections, wall thickness 1.2–20 mm |
| Wall Thickness | 1.2–20 mm |
| Length | 1–12 m (or as customer request) |
| Technique | Hot Rolled Based / Welded |
| Surface Treatment | Hot-Dipped Galvanized (Z121–Z180) / Pre-Galvanized |
| Spangle Type | Zero Spangle |
| Skin Pass | Yes |
| Surface Condition | Non-oiled |
| Tolerance | ±1% |
| Hardness | Full Hard |
| Application | Steel structures / Construction frames / Fencing / Fluid pipes / Boilers / Drilling / Hydraulic systems / Making corrugated sheets / Making containers |
| MOQ | 5 Tons |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| General Contractors & EPC | Building frames, column and beam assemblies, platform structures |
| Industrial Construction | Warehouse purlins, factory support frames, conveyor structures |
| Infrastructure | Highway guardrails, fencing posts, lighting pole bases |
| Container & Modular Build | Container corner castings, modular unit frames, corrugated sheet purlins |
| Mechanical & Hydraulic | Hydraulic cylinder sleeves, drilling support structures, fluid transport lines |
Coating Weight vs. Site Corrosion: Where Z121–Z180 Decides Service Life
Hot-dipped galvanized square and rectangular steel tube with Z121–Z180 coating weight is selected based on the corrosion category of the installation environment, not on price alone.
Overseas buyers frequently specify pre-galvanized tubes for coastal or industrial zones to save cost, only to face premature rust-through within two years. The gap between coating weight and actual atmospheric corrosivity is where project warranties collapse. [NEED_CITE: ISO 12944 corrosion category mapping for galvanized coatings]
When fabricators source raw tubes from third-party mills, coating thickness certificates often show batch averages that mask edge and corner thinning. Our integrated production line measures every tube against the Z121–Z180 range before bundling, eliminating the traceability gap that causes rejection at site inspection.
How Wall Thickness Range Covers Light Structural to Heavy-Duty Frames
The 1.2–20 mm wall thickness span of this hot dipped galvanized square steel tube supplier range allows a single procurement channel to cover both light-gauge purlin systems and heavy-load column sections. Thin-wall tubes (1.2–3 mm) serve fencing, container framing, and corrugated sheet support where dead load is minimal. Mid-range walls (4–8 mm) handle warehouse portal frames and industrial platform structures. Heavy walls (10–20 mm) are specified for drilling rigs, hydraulic system supports, and boiler frames where point loads and vibration demand higher section modulus. The zero-spangle hot-dipped finish ensures uniform paint adhesion across all thickness ranges without the oily residue that causes coating delamination.
Structural Code Compliance and Certification Pathways
Engineering specifications for steel structure frames typically reference EN 1993 or AISC 360, which require documented material properties and traceable heat numbers. [NEED_CITE: EN 10219 cold-formed welded structural hollow sections compliance requirements] For EU-bound projects, CE marking per EN 10210 or EN 10219 is mandatory for customs clearance, while Middle East and African ports often require SONCAP, SASO, or PVOC certification. The Q235B and S275JR grades in this product line meet the chemical composition and tensile requirements of their respective standards, with mill test certificates documenting each heat. Non-oiled, skin-passed surface condition ensures friction coefficients remain consistent during bolted or welded connections on site.
Steel Grade Selection: Q235B vs S275JR vs A53
Q235B is the baseline structural grade for domestic Chinese projects and general fabrication where yield strength requirements are moderate. S275JR offers higher minimum yield strength for European-spec structures, making it the default choice for EN-governed warehouse and industrial builds. A53 serves North American fluid transport and low-pressure structural applications. SGCC and DX51D are commercial-quality grades optimized for cold forming into corrugated sheets and container panels rather than load-bearing frames. Selecting the correct grade equivalence between GB, EN, and ASTM systems prevents both over-specification (unnecessary cost) and under-specification (structural rejection). [NEED_CITE: steel grade equivalence tables between GB Q235B EN S275JR and ASTM A53]
The Hidden Cost of Coating Thickness Variance
Accepting a galvanized tube batch without verified coating weight documentation creates three layers of hidden cost. First, customs authorities in strict-import markets may detain shipments lacking third-party coating inspection reports, triggering demurrage and re-export fees. Second, site engineers conducting pull-off tests on corner zones will reject tubes where edge coating falls below the specified Z-value, forcing air-freight replacement at multiples of the original material cost. Third, premature corrosion at welded joints due to inadequate coating burn-off allowance leads to warranty claims that trace back to the original procurement decision. [NEED_CITE: galvanized coating thickness measurement standards for structural hollow sections]
Why Procurement Teams Choose Our Integrated Supply Chain
As a hot dipped galvanized square steel tube supplier operating our own steel mill and fabrication workshop, we control the entire chain from hot-rolled coil to finished bundled tubes. This vertical integration means coating weight is measured at the galvanizing line, not inferred from supplier certificates. Our in-house laboratory tests chemical composition and mechanical properties per heat number, producing mill test certificates that travel with every shipment. With over 2,800 specifications in raw material inventory, we fulfill mixed-size orders without forcing buyers to meet separate MOQs at multiple mills. Every bundle carries heat-number traceability markings, and third-party inspection by SGS or BV is arranged on demand before container sealing.
Documentation & Compliance
- Mill test certificate documenting Q235B or S275JR chemical composition and mechanical properties per GB standard, with heat number traceability
- CE certificate per EN 10210 / EN 10219 for EU customs clearance, covering hot-dipped galvanized square and rectangular hollow sections
- ISO 9001 quality management certificate covering the integrated galvanizing and tube fabrication process
- SGS or BV third-party inspection report verifying coating thickness (Z121–Z180) and dimensional tolerance (±1%)
- Certificate of origin and packing list formatted for destination-country customs requirements (SONCAP, SASO, PVOC, SABS as applicable)
Packaging, Loading & Delivery
- Galvanized tubes bundled with steel strips and edge protectors to preserve the zero-spangle zinc coating during ocean transit, with non-oiled surface condition preventing stain migration
- Seaworthy packaging in steel-framed bundles sized for 20ft and 40ft containers, optimized for 1–12 m lengths to maximize payload per hot dipped galvanized square steel tube supplier shipment
- Heat number and steel grade stenciled on each bundle tag, matching mill test certificate documentation for site receiving inspection
- Custom cut-to-length service available for 1–12 m range, with kerf loss and end-cap protection included in quotation
- FOB, CIF, and DDP terms supported, with professional oversized-cargo loading plans for heavy-wall (10–20 mm) shipments requiring crane handling at destination port
Start Your Quotation with Drawings and Specifications
Submit project drawings (PDF/DWG), steel grade requirements, coating weight preference (Z121–Z180), and destination port to receive a detailed quotation including material, fabrication, coating, packing, and shipping costs. Our engineering team responds within 24 hours with a preliminary assessment and shop drawing timeline. For non-standard lengths or mixed-size orders below 5 tons, share your bill of materials and we will confirm feasibility against our 2,800+ specification inventory.
Frequently Asked Questions
Q: What is the difference between hot-dipped galvanized and pre-galvanized square tubes for structural use?
A: Hot-dipped galvanizing coats the finished tube in a zinc bath, producing Z121–Z180 coating weight with full coverage at corners and weld seams. Pre-galvanized tubes are formed from already-coated coil, leaving bare steel at welded seams. For outdoor or corrosive environments, hot-dipped is the specified choice.
Q: Can Q235B be used as a substitute for S275JR in European projects?
A: Q235B and S275JR have different minimum yield strength requirements. S275JR is specified under EN 10219 for European structural work. Substitution requires engineering approval and may not pass customs or site inspection without documented equivalence.
Q: What does Z121–Z180 mean for galvanized coating thickness?
A: Z-values represent coating weight in grams per square meter (both sides combined). Z121 suits indoor or mild atmospheric conditions; Z180 is specified for industrial or coastal environments. Coating thickness is verified by magnetic gauge measurement per ISO 1460.
Q: Is it possible to order custom lengths below the 5-ton MOQ?
A: Standard MOQ is 5 tons. For trial orders or prototype quantities, share your required lengths and quantities; we will check against existing inventory of 2,800+ specifications and confirm whether a smaller batch can be fulfilled.
Q: What quality documents are included for EU or Middle East customs clearance?
A: Each shipment includes mill test certificates, CE certificate (EN 10210/EN 10219), ISO 9001 certificate, packing list, bill of lading, and certificate of origin. Destination-specific certifications (SONCAP, SASO, PVOC, SABS, TISI, KS, JIS) are arranged per order requirement.
Request a Quotation with Mill Test Certificate
Send your project specifications, steel grade, coating requirement, and destination port to receive a detailed offer with full documentation package.
Tel: +86 531 8573 6315 | Mobile/WhatsApp/WeChat: +86 188 5315 7756 | Email: admin@xjystructure.com
