Tianjin Brisk Steel is one of the manufacturers of Hot Dip Galvanized Hollow Section in China. Our products are mainly exported to the Middle East, Southeast Asia, Europe, New Zealand, and other regions.If you would like to learn more about our products, feel free to contact us and send your purchase list.
Manufactory Process
- Hot-Dip Galvanizing (HDG): The component is fully immersed in molten zinc at approximately 450°C to form a metallurgically bonded zinc coating (typically around 85 μm thick, with a zinc mass of 200–275 g/m²). Its corrosion resistance is far superior to that of electro-galvanizing, making it suitable for outdoor, high-humidity, and coastal environments exposed to salt spray.
- HDG SHS = Hot Dip Galvanized Square Hollow Section
- HDG RHS = Hot Dip Galvanized Rectangular Hollow Section
- HDG CHS = Hot Dip Galvanized Circular Hollow Section
Key Features
- Long-lasting Rust Protection: Combines physical barrier protection with sacrificial anode action, ensuring decades of maintenance-free service for outdoor structures.
- Structural Advantages: Hollow sections offer a high strength-to-weight ratio with excellent bending and compressive strength; widely used for steel frameworks, bus shelter supports, guardrails, photovoltaic mounting systems, curtain wall framing, and scaffolding bases.
- Fabrication Versatility: Can be cut, drilled, and welded; the zinc coating at cut edges possesses self-healing anti-corrosion properties.
Hot Dip Galvanizing VS Pre-Galvanized
Manufacturing Process
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Pre-galvanized (PG)
The steel coil substrate is galvanized in molten zinc bath first. Afterwards, the galvanized steel strip is bent and welded into square / rectangular tubes. The zinc coating at welding seams will be burnt off by welding heat with no supplementary galvanizing treatment normally.
-
Hot Dip Galvanized (HDG)
Tubes are fabricated, welded and cut into finished products at first. After pickling & rust removal, the whole tube is immersed into high-temperature liquid zinc for overall galvanizing. Zinc alloy layers fully cover the tube body, pipe ends and welding joints.
Zinc Coating Parameters
| Items | Pre-galvanized | Hot Dip Galvanized |
|---|---|---|
| Coating Thickness | Thin: 10～30 μm | Thick: 70～90 μm (85 μm for standard) |
| Bonding Mechanism | Physical adhesion with average bonding force | Metallurgical combination of iron-zinc alloy with strong adhesion |
| Surface Appearance | Bright, smooth and uniform finish | With spangle, slight unevenness & minor zinc knobs, matte surface |
| Anti-abrasion | Coating peels easily during bending & welding | Resistant to peeling under collision and bending |
Anti-corrosion Service Life & Application Scenarios
-
Pre-galvanized
Only applicable to dry indoor conditions: indoor storage racks, simple indoor railings, light steel keels. Rust will emerge on welds and tube body within 1~3 years under humid, rainy or coastal salt-spray environment.
-
Hot Dip Galvanized
Suitable for all outdoor exposure scenarios: bus station frames, photovoltaic brackets, steel workshop structures, municipal guardrails, seaside steel structures. Normal outdoor service life reaches 15~30 years, with anti-corrosion performance 5–10 times higher than pre-galvanized tubes.
Performance during Fabrication
- Pre-galvanized: Coating is destroyed after cutting & welding. Touch-up with zinc-rich paint is mandatory to avoid rusting.
- Hot Dip Galvanized: Cut sections own sacrificial anode protection. Minor cuts can resist rust efficiently without extra treatment outdoors.
Simple Selection Principle
- Pick pre-galvanized for cost-saving indoor dry use
- Choose HDG for outdoor load-bearing projects, coastal humid environments & long-term maintenance-free demands
FAQ
Q: What types of Hot Dip Galvanized Hollow Sections are available?
A: Hot Dip Galvanized Hollow Sections are available in various shapes, including Square Hollow Sections (SHS), Rectangular Hollow Sections (RHS), and Circular Hollow Sections (CHS). Different sizes and wall thicknesses can be supplied according to project requirements.
Q: What are the advantages of Hot Dip Galvanized Hollow Section?
A: The main advantages include superior corrosion resistance, long service life, low maintenance requirements, strong structural performance, and excellent protection against moisture, rain, and harsh environmental conditions.
Q: What standards do Hot Dip Galvanized Hollow Sections comply with?
A: Hot Dip Galvanized Hollow Sections can be manufactured according to international standards such as ASTM, EN, JIS, and GB. Common structural steel grades include ASTM A500, EN S235/S355, and other grades based on customer requirements.
Q: What is the difference between galvanized hollow section and regular steel hollow section?
A: The main difference is the surface protection. Regular steel hollow sections require additional coating or painting to prevent corrosion, while hot-dip galvanized hollow sections have a bonded zinc coating that provides long-term corrosion protection.
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