Home
About Us
Galvanized square tube
Product Overview
Our Galvanized Square Steel Tubes are high-strength structural hollow sections formed by cold bending and high-frequency welding of galvanized steel strip, or by hot-dip galvanizing pre-formed black square tubes . The result is a product that combines the mechanical advantages of a square closed cross-section with the long-term corrosion protection of a zinc coating .
The zinc metallurgically bonds to the steel substrate, providing both barrier protection and sacrificial cathodic protection. This means that even if the surface is scratched or cut during fabrication, the zinc will corrode preferentially, protecting the exposed steel from rust . Available in a wide range of sizes, wall thicknesses, and galvanizing methods, our square tubes deliver consistent quality, excellent formability, and reliable performance in demanding applications.
Quick Specification Table (Typical Options)
| Item | Typical Range / Options | Buyer Notes |
| Tube type | ERW (electric resistance welded) / welded & galvanized / hot-dip galvanized after fabrication | HDG after fabrication gives best external coverage including welds; pre-galvanized cheaper but weld seams may be less protected |
| Shape & sizes (external) | Square: 10×10 mm – 300×300 mm; Rectangular: 20×10 mm – 400×200 mm | Common sizes: 20×20, 25×25, 30×30, 40×40, 50×50, 60×60, 80×80 mm etc. Specify OD precisely |
| Wall thickness (WT) | 0.8 mm – 12.5 mm (typical: 1.0–6.0 mm for light/medium duty) | Use nominal WT; state tolerance and whether exact or minimum required |
| Length | 1.0 m – 12.0 m (common: 6.0 m) | Cut-to-length services available; specify tolerance |
| End finish | Plain cut, beveled, threaded inserts (on request) | Plain ends standard; if welding OEM parts, specify beveling or factory-prepped ends |
| Coating method | Pre-galvanized (GI) / Hot-dip galvanized (HDG) after fabrication | HDG preferred when full coverage (including inside weld area) is required |
| Zinc coating mass | Z60 – Z600 g/m² (depends on spec & method) | Higher mass for corrosive environments; specify whether per side or total |
| Surface finish | Smooth / spangled (HDG) / painted (optional) | For architectural exposed applications, request specific finish or painting |
| Material grades | ASTM A500, ASTM A53 (square/rectangular made to schedule), EN 10219, GB/T 6728 | Choose grade based on structural or non-structural application |
| Tolerances & standards | Per EN 10219 / ASTM A500 / GB/T 6728 / JIS standards | Specify standard & tolerance class in purchase order |
| Packing | Bundles with steel straps, wooden pallets/crates, plastic/VCI inner wrap | Seaworthy export packing available; end caps to prevent ingress |
| Certificates & tests | MTR, coating mass report, dimensional & squareness checks, third-party inspection (SGS/BV) | State inspection/certification requirements in RFQ |
| Lead time | Stock sizes: 7–21 days; customized sizes/finishes: 14–45+ days | Rush options sometimes available; confirm when quoting |
| MOQ | Typically 1–5 MT per size; depends on mill and finish | Negotiable for framework contracts |
Buyer Priorities Covered
Fit-for-purpose performance: corrosion resistance, coating coverage (including welds), and expected service life.
Dimensional accuracy: outside dimensions, wall thickness, squareness, and length tolerances to match fabrication and connections.
Traceability & compliance: MTRs, applicable standards (ASTM, EN, JIS, GB), and third-party inspection.
Handling & installation: weight per meter, cutting/ welding behaviour, and packaging for safe arrival.
Commercial & logistics: MOQ, lead time, packaging, Incoterms and documentation for customs.
Typical Applications (buyer-centered)
Structural framing & supports: lightweight structural elements for buildings, canopies, carports and modular systems.
Fencing, gates & handrails: square tube is a standard for architectural railings and security fencing.
Furniture & equipment frames: indoor/outdoor furniture, racking, display stands and industrial frames.
Greenhouse & agricultural structures: frames, purlins and trellises where corrosion resistance extends life.
Sign posts & bollards: durable outdoor posts and protection posts with good finish options.
Automotive & trailer components: subframes, racks and supporting members where cost-efficiency and corrosion protection are needed.
Fabricated assemblies: welded boxes, enclosures and general manufacturing requiring consistent sectional properties.
FAQ — Frequently Asked Questions (for International Buyers)
Q: What is the difference between pre-galvanized square tube and hot-dip galvanized square tube?
A: Pre-galvanized square tube is made from steel strip that was galvanized before forming and welding; coating is usually thinner and weld seams may have reduced protection.
Hot-dip galvanized (HDG) tube is galvanized after fabrication, providing more uniform and thicker external coverage including weld areas and, when dipped long enough, partial internal protection.
Q: How do I specify square tube to match my weld fixtures and jigs?
A: Provide exact external dimensions (e.g., 50×50 mm), wall thickness (e.g., 2.5 mm), acceptable tolerance ranges for flatness and squareness, length tolerance, and whether ends should be beveled or prepped. Include reference to a standard (EN 10219, ASTM A500, GB/T 6728) if relevant.
Q: What zinc coating mass should I request for outdoor or coastal projects?
A: For general outdoor use Z120–Z275 g/m² is typical. In aggressive coastal or industrial environments, specify Z275+ or consider additional protective paint systems.
Confirm whether the number is per side or total; for HDG, follow standards like ASTM A123 for required mass.
Q: Can galvanized square tube be welded, cut and painted on site?
A: Yes. Galvanized tube is weldable and easily cut; however, welding produces zinc fumes—use appropriate ventilation and PPE.
After on-site cutting/welding, touch-up with zinc-rich paint or re-galvanizing is recommended for exposed bare steel. Proper surface prep and primer are required before painting.
Q: Do you supply square tube with pre-applied paint or powder coating?
A: Yes, prepainted (pre-galvanized and coil-coated) or post-fabrication painting/powder coating is available on request.
Paint systems should be specified (primer/topcoat, thickness, color, warranty) and often require additional lead time.
Q: What tolerances on squareness and straightness can I expect?
A: Tolerances depend on the manufacturing standard and mill capability.
Specify the required tolerance for squareness (corner deviation), straightness and wall thickness in the PO if your assembly or machinery is sensitive to variation.
Q: Are MTRs and third‑party inspections available?
A: Yes. Mill test reports (MTRs) are standard; buyers can arrange third‑party pre‑shipment inspections (SGS, Bureau Veritas, Intertek). Specify these requirements in your RFQ.
Q: How should I store galvanized square tube on arrival?
A: Store indoors or under cover, off the ground on dunnage, in a dry ventilated area.
Protect cut ends and inside surfaces from moisture; use end caps if possible. Avoid stacking different coating classes together to prevent contact corrosion.
Contact our sales team today for a quotation or to discuss your project requirements. We are committed to providing high-quality galvanized square tubes that meet your exact specifications and delivery deadlines.
Your trusted partner in galvanized steel solutions.For further technical information, pricing, or customization, please contact our sales team:
Tel/WA/Wechat: +86 13225105678
Email: sales01@duohessplate.com
Previous：no more
Next：no more