Galvanized Square Steel Tube
Hot-dip galvanized square steel tube (SHS) with uniform zinc coating inside and out. Sizes 10x10-500x500 mm, wall 0.8-20 mm, zinc 210-610 g/m2. ASTM A500 / EN 10219 / JIS G3466. Mill test certificate, SGS inspection, 7-15 day delivery.
Before you send an enquiry for galvanized square steel tube, you usually want two things answered: whether the zinc coating will genuinely survive a few years outdoors, and whether the mill can cut your exact list without turning a 15-day delivery into a 45-day one. Those two questions decide most of the orders we handle, so they come first here - the numbers follow after.
What buyers ask us before placing an order
"How many grams per square metre do I actually need?" For indoor racking and furniture frames, 210–275 g/m² is plenty and keeps the cost down. Once the tube goes outdoors - fence posts, greenhouse frames, solar brackets - most of our customers step up to 400–610 g/m². One thing worth watching when you compare quotations: 275 g/m² works out to roughly 38 µm per side, while 610 g/m² is nearer 85 µm. A supplier quoting "60 micron" and another quoting "275 g/m²" may be describing two very different tubes. Ask for the figure in g/m² and check that it appears on the mill certificate.
"Can you cut to my list, or do I have to take 6 m lengths?" Standard export lengths are 5.8 m and 6 m, but we cut to your sizes in the same production run. Send your cutting plan with the enquiry and the tolerance gets fixed before the tube is made, rather than bundled around afterwards.
"Will it show up rusted?" Hot-dip galvanizing covers the outside face, the inside bore and the cut ends. We check coating weight batch by batch instead of order by order, bundles stay steel-strapped and lifted off the ground, and SGS, BV or TUV inspection can be arranged before loading - not after the container has sailed.
Sizes, grades and coating we run every week
The table below is what leaves our yard most often. Treat it as a starting point rather than a limit.
| Item | Range |
|---|---|
| Standards | ASTM A500 Gr. A/B/C · EN 10219 S235/S275/S355 · JIS G3466 STK400/STK500 |
| Section Size | 10×10 mm – 500×500 mm (1/2"×1/2" – 20"×20") |
| Wall Thickness | 0.8 – 20 mm |
| Zinc Coating | 210 – 610 g/m² (approx. 30 – 85 μm), pre-galvanized or hot-dip after forming |
| Length | 5.8 m / 6 m / 12 m, or cutting to your plan |
| Steel Grade | Q195 / Q235 / Q355, S235JR, S355JR, Gr. A/B/C |
| End Finish | Plain cut ends, burr removed; threading or end caps on request |
If your sizes sit outside these ranges, say so anyway. Wall thickness and section size are the two variables we can usually work around, and asking costs you nothing.
Why fabricators keep coming back
The coating is what most people check first, and it is the part we refuse to compromise on. Zinc is applied evenly and verified per batch, so you do not open a container to find bare patches or black rust on the inner faces. Dimensions are held to EN 10219 limits - diagonal deviation and twist included - because a frame that has to be re-drilled on site costs more than the tube ever did.
After that it comes down to paperwork and timing. An EN 10204 3.1 mill test certificate travels with every shipment, common sections sit in stock for 7–15 day dispatch, and urgent orders are better handled over a phone call than an email thread. Packing is built for the sea, not the warehouse: steel-strapped bundles, seaworthy marks, and container loading planned to leave as little dead space as possible.
Where this tube ends up
A fair share of our output goes into factory floors, where it becomes machine guards, workbench frames and trolley bodies that never see rain. Another chunk goes outdoors: fence posts set into concrete, greenhouse hoops bent on site, solar panel rails bolted to rooftops, gates and railings that have to look right as well as hold up. Scaffolding and signage work takes the rest. Different jobs, same requirement - the tube has to arrive straight, coated, and on size, because nobody wants to re-cut a bundle on the customer's driveway.
Packing, loading and what lands on your desk
Bundles are tied with galvanized steel strips and can be weighed individually if your project needs it. Tube goes into 20ft or 40ft GP and HQ containers with dunnage between layers, and the loading plan is worked out from your actual metre weight so the box is not half empty. Before the doors are sealed you get loading photographs and the weight slip by email - there is nothing worse than finding a problem 30 days out at sea.
Send your size list, get a price back
Tell us the section, wall thickness, length, coating weight and destination port. Our sales engineers reply with FOB or CIF pricing and current stock availability, normally within 12 hours. If you already have a specification sheet in front of you, just send it - we will read it and come back with questions only where it matters.
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