What Galvanized Q235 Tube Is
Galvanized Q235 tube is welded carbon steel pipe or square tube, produced in grade Q235 to GB/T 700-2006, that receives a hot-dip zinc coating after welding. The zinc layer protects the steel against corrosion, which makes the tube suitable for outdoor structures without painting.
Manufacturing Standards
Welded round pipe for general and low-pressure service is produced to GB/T 3091, and cold-formed square and rectangular hollow sections to GB/T 6728. The zinc coating is applied by hot-dip galvanizing, with coating weight and quality following the governing standard, typically 65-85 microns on the specified thickness range. The pipe is then cut, threaded or plain-ended and bundled for delivery.
Size Range
Round pipe: nominal sizes from about 21 mm to 219 mm outside diameter, in wall thicknesses from 1.5 mm to 6 mm
Square tube: from 20 x 20 mm to 200 x 200 mm, with wall thicknesses from 1.0 mm to 8 mm
Standard lengths are 6 m, with cutting to length available.
Properties of the Zinc Coating
Hot-dip galvanizing forms a metallurgically bonded zinc-iron layer that protects the steel both as a barrier and sacrificially at cut edges and scratches. The coating withstands bending and forming within normal limits, and damaged areas are repaired with zinc-rich paint. Service life depends on the coating thickness and the environment, with decades of life typical in rural and urban atmospheres.
Fabrication and Installation
Galvanized tube is cut with a saw or abrasive wheel, drilled, and joined by welding, threaded fittings or mechanical connectors. When welding is used, the weld zone is cleaned and repaired with zinc-rich paint to restore corrosion protection. The material is easy to work with standard tools, which keeps installation fast.
Typical Applications
Fencing, gates and barriers
Handrails and guardrails
Greenhouse and agricultural frames
Scaffolding and temporary structures
Cable management and support posts
Frequently Asked Questions
Q: What is the difference between black and galvanized pipe?
Black pipe has no protective coating, while galvanized pipe carries a hot-dip zinc layer that resists corrosion, making it the choice for outdoor and wet service.
Q: Can galvanized tube be welded?
Yes, but the zinc coating burns off at the weld and must be repaired with zinc-rich paint afterwards to maintain corrosion protection.
Q: What sizes of square tube are available?
Square tube ranges from 20 x 20 mm to 200 x 200 mm with wall thicknesses from about 1.0 mm to 8 mm, in 6 m lengths.
Q: How long does the galvanized coating last?
With a typical coating thickness of 65-85 microns, the tube can last for decades in rural and urban atmospheres before maintenance is needed.
Q: Is the pipe suitable for carrying water?
Galvanized pipe to GB/T 3091 is commonly used for low-pressure water service; for potable water, check the applicable local requirements.
Q: Are mill certificates supplied?
Yes, certificates record the grade, chemistry, mechanical properties and coating information for traceability.