Sino Steel supplies galvanized square and rectangular steel tube for structural fabrication, frames and project purchasing. As a galvanized box tube manufacturer and supplier, we match section size, wall thickness, galvanizing route, weld condition, factory processing, dimensional inspection and export packing to the actual order.
Start with the finished outside dimensions on the drawing. Square and rectangular hollow sections are measured and inspected differently from round pipe, so the RFQ should identify both section dimensions clearly.
Use one outside side dimension, wall thickness and finished length.
Use outside width × outside height × wall thickness × finished length.
A galvanized box tube factory can use different routes depending on the ordered structural-tube standard, coating requirement and product form. The sequence matters because coating coverage and weld-seam treatment are not identical.
Metallic-precoated sheet or strip is formed and welded into the square or rectangular tube. The original zinc coating exists before tube forming.
The structural tube is formed and welded first, then the exterior is zinc-coated in a continuous hot-dip coating line under the applicable route.
The same bright zinc appearance can hide different forming, welding and coating sequences. Put the required manufacturing / galvanizing route on the RFQ when the project specifies it.
The base structural-tube standard defines geometry and mechanical requirements. The galvanizing or precoated-feedstock route adds a separate coating requirement.
A500 describes the structural-tube product route. If zinc coating is required, the coating / galvanizing requirement must also be stated.
A clear size description reduces quotation errors and keeps drawings, inspection records and packing lists consistent.
| Product | How to Specify | Example |
|---|---|---|
| Square Tube | A × A × t × L | 80 × 80 × 3.0 × 6000 mm |
| Rectangular Tube | B × H × t × L | 100 × 50 × 3.0 × 6000 mm |
| Coating Route | State separately | Precoated-feedstock route / exterior hot-dip galvanized route |
| Processing | Add when required | Cut length / simple drilling / slot / end trimming |
If a drawing calls a section 100 × 50, the same orientation should remain on the RFQ, inspection record and packing list.
Cold-formed square and rectangular tube has real formed corner radii. If the section must fit an insert, bracket or mating component, corner geometry can matter as much as the nominal outside size.
The formed outer radius should look physically realistic and consistent with wall thickness and forming route.
The internal corner is also rounded; it should not be treated as a perfect sharp 90-degree corner.
If another part must slide inside the tube, include the actual fit requirement instead of relying only on nominal outside size.
One width measurement is not enough for a finished box section. Factory inspection should follow the actual hollow-section geometry.
Square tube is checked across both sides and diagonals; rectangular tube keeps width and height orientation consistent.
Wall thickness is reviewed together with formed corners instead of measuring an unrealistic sharp corner.
A tube can look straight from one side and still rotate along its length. Twist should be reviewed separately where it affects fabrication.
Long square and rectangular tubes need more than a single straightness check. End rotation and twist along the length can affect welding jigs, frames and assembly.
Check deviation along the tube length on suitable level supports.
Compare the section orientation from one end to the other rather than judging only one face.
For frames and welded assemblies, excessive twist can create alignment problems even when the nominal section size is correct.
Galvanized box tube is commonly welded. The manufacturer review should check seam position and geometry together with the coating condition around the welded area.
The weld seam should stay in a controlled position along the section rather than wandering around the tube.
Finished seam condition and local zinc protection depend on the manufacturing and coating route.
Relevant when fit-up, inserts, internal clearance or the project specification makes the inside seam important.
Do not describe the weld zone as automatically identical to the untouched pre-coated strip surface.
A galvanized box tube supplier should not promise identical zinc coverage everywhere unless the actual manufacturing route and order support that claim.
Visible zinc coating and local handling damage can be inspected on the finished external faces and corners.
Internal coating coverage depends on the chosen route; an exterior-galvanized structural tube should not be presented as automatically identical inside.
The seam area deserves separate coating review, especially when the tube is formed from pre-coated sheet or strip.
Newly processed edges and holes created after galvanizing are no longer identical to the original zinc-coated surface.
Factory cutting and simple drilling can reduce the buyer's next fabrication step, but later processing creates new surfaces that need separate review after the zinc-coated tube has been made.
Long sections can be cut to the confirmed fabrication or project length.
Round holes can be arranged on suitable orders when size and location are defined by the drawing.
Simple slots or openings can be reviewed where they fit the factory processing route.
Finished size, hole position, burr and the newly exposed steel edge should be checked before packing.
Closely packed flat faces and corners can trap water between galvanized box tubes. Dry factory packing and condensation control are therefore important even after zinc coating has been applied.
Do not close obvious rainwater or washing water into a tight square-tube bundle.
Flat galvanized faces can hold moisture over a long contact area when tubes are bundled tightly together.
Open tube ends can collect water before packing; internal drainage should be checked before shipment.
Temperature changes can create moisture inside wrapping even when the material left the factory dry.
Mill, manufacturer and factory records should explain how the coated feedstock or base tube became the finished galvanized square or rectangular section.
Cutting or drilling changes the finished member, but the bundle should still trace back to the original steel and coating route required by the order.
A galvanized box tube supplier should pack long square and rectangular sections with multiple support points, stable banding and realistic edge protection instead of using a single loose bundle.
Each bundle should contain one consistent section and length where practical, with different sizes physically separated.
Long tubes should rest on several level supports rather than only the two ends.
Multiple steel bands and protectors reduce local damage where the bands contact galvanized corners.
Bundle tags should stay linked to section size, grade, coating route and shipment records.
Send square or rectangular section, outside dimensions, wall thickness, length, grade, galvanizing route, quantity and destination. Add cutting, drilling, coating or tolerance requirements when they matter to fabrication.
Yes. Square and rectangular hollow sections can be quoted according to section size, wall thickness, length, grade, coating route and quantity.
Precoated-feedstock tube is formed from metallic-precoated sheet or strip, while a continuous hot-dip structural-tube route zinc-coats the exterior after the tube has been formed and welded. Weld treatment and coating coverage are therefore different.
No. ASTM A500 is a structural-tubing standard. The zinc-coating or galvanizing requirement must be specified separately.
Yes. Suitable orders can be cut to fixed length or processed with simple holes or slots. Newly cut or drilled surfaces should then be reviewed separately because they are not identical to the original galvanized surface.
Keep tubes dry before bundling, avoid trapping water between flat faces, check internal drainage, protect the package from rain and manage condensation risk during transport.
Section shape, outside size, wall thickness, length, grade, galvanizing route, quantity and destination are enough to start. Add cutting, drilling, coating, corner / tolerance or packing details when they matter to the order.
