Tianjin Brisk Metalwork Co., Ltd. is one of the leading manufacturers and suppliers of hot galvanized round hollow section in China. We have world-leading production equipment and strong manufacturing capabilities. Please feel free to buy bulk durable hot galvanized round hollow section from our factory.
Tianjin Brisk Steel is one of the hot galvanized round 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.
Quick spec reference
| Parameter | Typical Range |
|---|---|
| Outer diameter | 21.3 mm – 610 mm |
| Wall thickness | 2.0 mm – 20 mm |
| Length | 6 m standard, custom cut on request |
| Coating standard | EN ISO 1461, ASTM A123 |
| Base tube standard | EN 10219 (cold-formed) / EN 10210 (hot-finished) |
| Common grades | S235JRH, S275J0H, S355J2H, Q235B, Q345B |
| Typical coating thickness | 55–85 μm depending on wall thickness class |
| Typical use | Structural columns, handrails, balustrades, agricultural framing, solar mounting structures, marine and coastal steelwork |
Why a Round Hollow Section Galvanizes Differently Than an Open Profile
Hot-dip galvanizing works by submerging steel in molten zinc, and the zinc has to reach every internal and external surface for the coating to be complete. An open section like an angle or a channel has no hidden internal cavity, so the zinc flows freely across it. A round hollow section is a sealed tube - without an escape path for air and without a route for zinc to reach the inside wall, the coating fails in two specific ways: trapped air prevents zinc from entering the bore at all, and any moisture sealed inside a capped tube can flash to steam in the kettle and cause a violent expansion.
That is why every hollow section sent for galvanizing needs venting and drainage holes, positioned and sized according to the tube's diameter and length, cut before the tube goes anywhere near the kettle. Get the hole placement wrong - too few, too small, or positioned so a pocket of air still gets trapped at one end - and the result is a tube with bare, unprotected steel on the inside wall that looks fully coated from the outside. This single detail is the most common quality failure point specific to hollow-section galvanizing, and it is largely invisible until the coating starts failing from the inside out years later.
Choosing Round Hollow Section for the Job at Hand
Structural columns and framing. EN 10210 hot-finished or EN 10219 cold-formed round hollow section in S275 or S355 grade covers most building-frame and canopy column applications, with galvanizing specified for any member exposed to weather or ground contact rather than fully enclosed in conditioned space.
Handrail, balustrade, and guardrail systems. Lighter wall thicknesses in the 21.3–48.3 mm OD range are common here, where appearance and corrosion resistance both matter and the coating's smooth, uniform finish is as much a selection factor as its protective function.
Agricultural and solar mounting structures. Round hollow section galvanized to full outdoor-exposure standards is the default choice for ground-mounted solar racking and agricultural framing, where decades of unmaintained outdoor service life is the baseline expectation, not an upgrade.
Marine and coastal steelwork. Splash-zone and coastal-atmosphere exposure accelerates coating consumption, so specifications for this environment often call for the upper end of the EN ISO 1461 thickness range or a duplex system (galvanizing plus a top coat of paint) rather than galvanizing alone.
Frequently Asked Questions (FAQ)
Q: Why does galvanized hollow section sometimes have small holes drilled near the ends?
A: hose are vent and drainage holes required for the galvanizing process itself - they let trapped air escape and molten zinc flow through the tube's interior so the inside wall gets coated, and they let the tube drain fully on withdrawal from the kettle.
Q: Can round hollow section be galvanized after it's already welded into a frame?
A: Yes, and this is common for finished assemblies, but every closed cavity in the weldment needs its own vent and drain path planned before fabrication - a frame designed without this in mind can trap air pockets that prevent full coating in some sections.
Q: Does hot-dip galvanizing change the mechanical properties of the tube?
A: The galvanizing process itself does not meaningfully affect the base steel's yield or tensile strength; the main consideration is the elevated kettle temperature's effect on stress-relieved or cold-worked material, which is why the applicable standard specifies acceptable steel grades and conditions for galvanizing.
Q: Is there a minimum wall thickness for galvanizing round hollow section?
A: Very thin-walled tube can be galvanized, but extremely light gauges are more prone to warping from thermal stress during the dipping and cooling cycle, so a fabricator working near the thin end of the range should confirm the mill's practical minimum for the specific diameter.
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