Square Pipe Solar Racking Factory
Square pipe solar racking is the backbone structural member of PV racking systems — used for columns, diagonal braces, purlins and rails in ground-mount, rooftop and carport installations across Southeast Asia. This page covers square hollow sections (SHS) in S350GD+ZM (Zn-Al-Mg coated, EN 10346) in the sizes EPCs and distributors order most: 40×40, 100×100, 120×120 and 140×140 mm. Our square pipes are produced exclusively for solar PV mounting structures — not for scaffolding, furniture, handrails, water supply or general construction use.
Why S350GD+ZM square pipe for solar Racking
Most commodity square pipes on the market are Q235B grade with hot-dip galvanized (HDG) pure-zinc coating. We supply a materially different product: S350GD+ZM — a higher-strength base steel carrying a zinc-aluminum-magnesium (Zn-Al-Mg) coating under EN 10346.
| Property | Our S350GD+ZM | Common Q235B + HDG |
| Yield strength | 350 MPa | 235 MPa |
| Coating system | Zn-Al-Mg, ZM275 (≥275 g/m² triple-spot) | Pure zinc |
| Salt-spray life (ASTM B117) | 2–10× longer | Baseline |
| Cut edges / drilled holes | Self-healing | Rust from the cut |
- Higher yield strength (350 vs 235 MPa)— design the same load with thinner walls or longer spans, cutting steel weight and freight cost.
- Self-healing coating— when brackets are bolted or holes drilled on site, the Zn-Al-Mg layer migrates to protect the exposed cut edge.
- EN 10346 recognized grade— structural engineers across the Philippines, Vietnam, Indonesia and Thailand are familiar with the standard, so calculation sheets and approvals go smoothly.
Square pipes sizes and specifications
| Section (mm) | Wall thickness (mm) | Typical use in PV mounting |
| 40 × 40 | 1.8 | Module rails & purlins (with clamps) |
| 100 × 100 | 2.0 | Columns & main beams |
| 120 × 120 | 3.0 | Columns — typhoon zones |
| 140 × 140 | 3.0 | Heavy columns / elevated structures |
Material spec: Grade S350GD+ZM (EN 10346) · coating ZM275 (≥275 g/m² triple-spot, all sizes) · wall thickness 1.8–3.0 mm · standard length 6 m or cut-to-length · custom sections on request. A Mill Test Certificate (MTC) is issued with every shipment.
Where square pipes are used in PV mounting structures
- Ground mount:vertical columns, diagonal braces, purlins — 100×100 and above carry the main loads.
- Rooftop (commercial & industrial):ballasted and penetrating racking frames.
- Carport solar:columns and roof beams for vehicle shading structures.
40×40 SHS pairs with module clamps for rail systems; 120×120 and 140×140 are specified for columns where wind load governs the design. If you are unsure which section fits your wind zone, send us your project parameters and we will confirm the recommendation.
Built for typhoon zones — Philippines, Vietnam, coastal SEA
Typhoon-prone markets are exactly where S350GD+ZM earns its keep. Philippine typhoons regularly exceed 200 km/h, and Vietnam’s central coast sits in the same belt. For high-wind projects we recommend 120×120×3.0 or 140×140×3.0 columns with Zn-Al-Mg coating: in marine salt air the maintenance and inspection cycle typically extends from roughly 5 years (HDG) to about 10 years with Zn-Al-Mg — fewer shutdowns, lower lifetime cost for the asset owner.
Corrosion protection — why Zn-Al-Mg beats hot-dip galvanized
Zn-Al-Mg is a three-element alloy coating (zinc + aluminum + magnesium). Two properties matter most for solar in Southeast Asia:
- Self-healing cut edges:magnesium ions migrate to cover scratches, cuts and drill holes — the exact points where HDG starts to rust.
- Longer salt-spray life:2–10× the service life of pure zinc in ASTM B117 testing, making it a strong fit for C4–C5 coastal environments.
For a project-by-project basis, ask for our salt spray test report and the EN 10346 coating certificate — both are standard documents we provide.
Export & customs compliance for Southeast Asia
- HS code:61 (welded square/rectangular tubes of iron or steel).
- Documents we provide:MTC (mill test certificate), EN 10346 coating certificate, salt spray test report, ISO 9001, and Form E Certificate of Origin for ACFTA preference.
- Philippines:the most open market — Chinese-origin tubes may qualify for 0% duty under ACFTA with Form E. Verify with your customs broker at the time of order.
- Thailand:an anti-circumvention duty of 19.19% (CIF) applies to certain Chinese welded steel pipes under HS 7306.30/7306.61 — confirm the current ruling before quoting.
- Vietnam:since July 2026, PV mounting structures imported into Vietnam require GB/T 19001 and ISO 55001 certification — confirm current requirements with your broker.
SGS/BV third-party inspection is available on request at your cost.
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