Products Description
Product Specifications
| Standards | ASTM A554 |
| Steel Grades | 301,302,304,304L,305,309S,309S-Cb,310S,316,316L,317,321,330,347,429,430,430-Ti |
| Equivalent Standards |
EN 10296-2 / JIS G3446 |
| Outer Diameter (OD) | 10×10 mm - 250×250 mm |
| Wall Thickness (WT) | 0.5 mm - 8.0 mm |
| Length | Customized |
| Surface Treatment | No.4 Brushed, Hairline, Satin |
| Production Process | TIG Welding |
| Condition | Annealed |
The stainless steel square tube is manufactured from materials such as 304 and 316 stainless steel, offering excellent corrosion resistance. Grade 304 stainless steel contains 18% chromium and 8% nickel, enabling the formation of a self-healing passivation layer; it withstands over 1,000 hours of neutral salt spray testing-three to five times the performance of galvanized steel.
The tubes are produced using a fully automated tungsten inert gas (TIG) welding process, achieving a stable weld joint coefficient exceeding 0.9. The tensile strength of the weld zone matches that of the base material, allowing the structure to withstand the alternating loads generated by solar panels under dynamic wind conditions without cracking.
The tube surfaces undergo a brushed finish process, with the Ra value consistently controlled between 0.4 and 0.8 μm, followed by passivation to ensure corrosion resistance. Beyond its aesthetic appeal, the brushed surface is easy to clean and eliminates the need for the periodic coating maintenance required by galvanized steel.
Customized Services
- TORICH offers CNC precision cutting and custom sizing services, with a length tolerance of ±0.5mm.
- We provide precision machining services, including CNC drilling and punching (supporting various shapes such as round, oblong, and square holes), end slotting and notching, as well as end-forming processes like plain cutting, chamfering, swaging, and flaring.
- Surface finishing options include 240/320/400-grit hairline finishes, mirror finishes, and matte sandblasting; we also offer custom identification services, including laser marking, inkjet coding, and labeling.
Chemical Composition
| Element | C (max) | Mn (max) | P (max) | S (max) | Si (max) | Cr | Ni | Others |
| MT-301 | 0.15 | 2.00 | 0.045 | 0.03 | 1.00 | 16.0–18.0 | 6.0–8.0 | – |
| MT-304 | 0.08 | 2.00 | 0.045 | 0.03 | 1.00 | 18.0–20.0 | 8.0–10.5 | – |
| MT-430 | 0.12 | 1.00 | 0.040 | 0.03 | 1.00 | 16.0–18.0 | – | – |
Mechanical Properties
| Property | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) | Hardness (HB) |
| MT-301 | ≥ 515 | ≥ 205 | ≥ 40 | ≤ 90 |
| MT-304 | ≥ 520 | ≥ 205 | ≥ 40 | ≤ 90 |
| MT-430 | ≥ 450 | ≥ 205 | ≥ 22 | ≤ 88 |
Possible Alternative Grades
- TP304L is the most widely used standard grade in solar projects; as a low-carbon version of 304 stainless steel, it is well-suited for mounting systems requiring on-site welding and assembly.
- For coastal photovoltaic plants, intertidal "fishery-solar hybrid" projects, and industrial zones exposed to salt spray, TP316L is a suitable choice, offering significantly enhanced corrosion resistance compared to 304.
- For long-span, high-load solar tracking mounting systems, 2205 duplex stainless steel is an ideal option; with a yield strength twice that of 304, it enables reductions in both material usage and overall weight.
application areas
TORICH ASTM A554 welded stainless steel square tube is widely used in various solar and renewable energy projects. Typical applications include:
- Solar Photovoltaics (PV): Support posts and crossbeams for ground-mounted power plants; mounting rails for commercial, industrial, and residential rooftop PV systems; and structural framing for BIPV curtain walls.
- Concentrated Solar Power (CSP): Collector support structures, protective casings for high-temperature piping, and heliostat frames.
- Energy Storage Systems: Structural frameworks for battery energy storage container enclosures and internal module support beams.
- Other Green Energy Sectors: Internal ladders and platform grating for wind turbine towers, and railings for biomass power generation equipment.
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FAQ
Q: How should one choose between 304 and 316L stainless steel for solar projects?
A: The key factor is the environment. 304 is suitable for most inland and rural settings. 316L offers superior resistance to chloride ion corrosion, making it the recommended-and essential-choice for coastal areas, offshore PV installations, and highly saline or alkaline environments.
Q: Is your brushed finish achieved through a genuine physical brushing process?
A: Yes. We use precision oil-film brushing machines for physical abrasion to create a continuous, uniform texture. Unlike standard embossing, this process preserves the stainless steel's metallic luster while providing scratch resistance.
Q: Does contact between stainless steel mounting structures and aluminum components cause galvanic corrosion?
A: While a difference in electrode potential exists between stainless steel and aluminum alloys, galvanic corrosion is negligible in atmospheric environments-provided there is no continuous electrolyte (such as pooled water) between the two materials. In practical engineering applications, it is recommended to insert insulating gaskets between the stainless steel mounts and aluminum frames, or to use stainless steel bolts paired with nylon washers.
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