304
General purpose
Widely used for architectural frames, handrails, equipment guards, furniture and general fabrication.
Product form hub · Square tube
Stainless Steel Square Tube
Specify stainless steel square tube by grade, outside dimension, wall thickness, finish, length and fabrication requirements. This page gives buyers a practical route from common market sizes to a quote-ready specification.
304 / 304L / 316 / 316L
ASTM A554 route
Mill, brushed or polished finish
Square hollow section · product visual
Common grades304 / 304L / 316 / 316L
Typical market size12 × 12 to 200 × 200 mm
Typical wall1.0 to 6.0 mm
Build the specification
01Choose grade
02Set side dimension
03Set wall thickness
04Choose finish
05Confirm length / fabrication
06Send RFQ
Product overview
What to define before buying stainless steel square tube
Square tube is normally purchased by outside side dimension and wall thickness. Grade, finish, corner appearance and fabrication route can be just as important as the nominal size.
Material304 / 304L
General architectural, fabrication and indoor-to-moderate corrosion service.
Material316 / 316L
Often selected where chloride exposure or a more demanding corrosion environment is expected.
GeometrySquare outside dimension
Specify side × side × wall, for example 50 × 50 × 2.0 mm.
FinishMill to decorative
Mill, satin / No.4, hairline and mirror-type finishes are common market options.
M03 · Grade selection
Choose the grade from the service environment first
Do not choose square tube only by appearance. Corrosion environment, welding, cleaning chemicals, temperature and fabrication route should drive grade selection.
304L
Weld-friendly low carbon
Common when welded fabrication is important and a low-carbon 304 route is preferred.
316
Higher corrosion resistance
Common for more demanding outdoor, coastal or chemical-service environments.
316L
Corrosion + welding route
Frequently specified when both welding and improved chloride resistance are important.
M04 · Technical data
Common stainless steel square tube size reference
The table below uses common market dimensions for stainless square tube. Treat it as a buying reference, not as a promise of current stock. Confirm exact size, wall and finish in the RFQ.
| Outside size | Common wall options | Typical grade routes | Typical finish routes | Buying note |
|---|---|---|---|---|
| 12 × 12 mm | 1.0 / 1.2 / 1.5 mm | 304 / 304L | Mill / brushed | Light fabrication and decorative work |
| 20 × 20 mm | 1.0 / 1.2 / 1.5 / 2.0 mm | 304 / 304L / 316L | Mill / No.4 / hairline | Frames, furniture and guards |
| 25 × 25 mm | 1.2 / 1.5 / 2.0 / 3.0 mm | 304 / 304L / 316L | Mill / No.4 / hairline | General fabrication size |
| 30 × 30 mm | 1.2 / 1.5 / 2.0 / 3.0 mm | 304 / 304L / 316L | Mill / No.4 / mirror-type | Architectural and equipment frames |
| 40 × 40 mm | 1.5 / 2.0 / 3.0 mm | 304 / 304L / 316 / 316L | Mill / No.4 / hairline | Common frame and railing size |
| 50 × 50 mm | 1.5 / 2.0 / 3.0 mm | 304 / 304L / 316 / 316L | Mill / No.4 / hairline | Widely used square hollow section |
| 60 × 60 mm | 2.0 / 3.0 / 4.0 mm | 304 / 304L / 316L | Mill / brushed | Heavier frames and fabrication |
| 75 × 75 mm | 2.0 / 2.5 / 3.0 / 4.0 mm | 304 / 316L | Mill / brushed | Confirm corner radius and straightness |
| 100 × 100 mm | 2.0 / 3.0 / 4.0 / 5.0 mm | 304 / 316L | Mill / brushed | Confirm structural design requirements separately |
| 120–200 mm square | 2.0–6.0 mm market range | 304 / 316L | Primarily mill / brushed | Availability becomes more supplier-specific |
Market reference range: suppliers commonly list square tube from about 12 × 12 mm up to 200 × 200 mm with wall thicknesses around 1.0–6.0 mm. ASTM A554 itself covers welded stainless mechanical tubing in square, rectangular, round and special shapes and extends to larger outside dimensions; actual commercial availability varies.
M05 · Dimensions and finish
Define the tube beyond just “square”
A usable purchase specification should state the side dimension, wall thickness, length, finish and any fabrication requirement that affects the final fit or appearance.
Dimensions
- Outside side × outside side
- Nominal wall thickness
- Length or cut length
- Corner radius if critical
- Straightness / squareness if project-critical
Surface finish
- Mill finish
- 2B-related strip finish before forming
- No.4 / satin brushed
- Hairline finish
- Mirror-type decorative finish
Fabrication details
- Cut to length
- Square or mitred cut
- Visible-weld appearance requirement
- Protective film if required
- Packaging for cosmetic surfaces
M06 · Selection guide
Match the tube specification to the actual use
Indoor decorative work304 is a common starting point. Prioritize cosmetic finish, corner consistency and scratch protection.
Welded fabrication304L or 316L may be preferred when the fabrication route and corrosion requirements justify a low-carbon grade.
Coastal / chloride exposure316 / 316L is commonly considered before 304, but the real environment and maintenance plan still control selection.
Load-bearing frameDo not assume decorative mechanical tubing is automatically suitable. Confirm the design code, loads, section properties and required certification.
Worked example
Example of a clear square tube specification
A short, explicit specification is easier to review than a request that only says “304 stainless square tube.”
Example only
This is a sample buying format, not a stock promise. Replace each field with the actual project requirement before ordering.
ProductStainless steel square tube
Standard routeASTM A554
Grade304L
Size50 × 50 × 2.0 mm
Length6 m
FinishNo.4 brushed, visible faces protected
Order requirementState quantity, cutting, packaging and document requirements in the RFQ
M08 · Applications
Where stainless steel square tube is commonly used
Architectural frames
Visible frames, partitions, façade details and decorative support structures.
Handrails & balustrades
Square-section railing systems where clean lines and corrosion resistance are required.
Furniture & displays
Tables, shelving, retail fixtures and stainless framework with brushed or polished surfaces.
Machine guards
Fabricated equipment frames, guard structures and enclosures.
Food equipment frames
Non-product-contact framework where cleanability and corrosion resistance matter.
General fabrication
Welded frames, brackets and custom assemblies across industrial and commercial projects.
Important limitation: ASTM A554 square tubing is a mechanical / ornamental tubing route. Do not assume it is automatically pressure-rated or automatically compliant with a structural design code. For load-bearing, hygienic, pressure or regulated service, confirm the governing project specification before purchase.
M10 · Standards
Standards and purchasing references
Use the actual project standard as the governing requirement. Do not mix a cosmetic square-tube request with a structural or pressure-tube requirement without checking the applicable specification.
Welded stainless steel mechanical tubing. The standard covers square, rectangular, round and special shapes for applications where appearance, mechanical properties or corrosion resistance are required.
Specify the exact alloy designation required by the project rather than relying only on a marketing label such as “marine grade” or “food grade.”
For critical corner radius, straightness, polish, weld-bead appearance, fabrication or inspection, place the requirement directly on the RFQ or drawing.
M11 · FAQ
Stainless steel square tube FAQ
What is the most common stainless steel square tube grade?
304 and 304L are common general-purpose choices. 316 and 316L are often considered when the corrosion environment is more demanding, especially where chlorides are present.
How is square tube size specified?
Use outside side dimension × outside side dimension × wall thickness, for example 50 × 50 × 2.0 mm. Add length, grade, finish and any tolerance or fabrication requirement.
Is stainless steel square tube seamless or welded?
Most common architectural and mechanical stainless square tube is welded and commonly specified to ASTM A554. If a project needs another manufacturing route, state it explicitly.
What finishes are available?
Common market finishes include mill, satin / No.4, hairline and mirror-type decorative finishes. Availability depends on grade, size, wall and supplier process.
Can square tube be used as structural tubing?
It can be used in frames, but the engineering requirement must be checked separately. Do not assume an ornamental or mechanical tubing specification automatically satisfies a structural code or load requirement.
Product details
What buyers usually verify visually
Replace these three visual areas with your own square tube product, surface and packing images when the first-party media is ready.
Tube geometrySquare outside dimension, corners and weld-seam condition
Surface finishMill, satin / brushed, hairline or decorative finish
Packing & protectionProtect visible surfaces and edges for delivery
Square tube resources
Continue from technical research to purchase
M13 · Technical reference
Reference basis for this square tube guide
The page uses published ASTM A554 scope information plus common commercial square-tube size patterns. Project-specific requirements and actual supply availability should always be confirmed before order placement.
M14 · RFQ
Request a technical quote
For a faster review, include the grade, square size, wall thickness, finish, length, quantity, destination and any special fabrication or document requirement.
- Grade / material designation
- Outside size × wall thickness
- Finish and visible-surface requirement
- Length / cutting requirement
- Quantity and destination