PRODUCT FAMILY 02 · OVAL TUBE
Oval arch tube: the section that makes a film house span 8 metres.
Oval tube puts more material where the bending moment is: at the top and bottom of the section. Compared with a round tube of the same weight, an oval arch is stiffer in the plane of the arch — which is why almost every multi-span film house is built on 30×60, 30×70, 40×80 or 40×90.
The oval is not a fashion choice. An arch carries bending, and a section's resistance to bending depends on how far its material sits from the neutral axis. Flattening a round tube into an oval moves material away from the axis in the direction that matters, so the arch resists snow and wind with less steel. The trade-off is torsional stiffness and a weaker axis in the other direction, which is why oval arches are braced and why the purlins matter as much as the arch.
| Section (mm) | Wall (mm) | kg/m | Typical arch spacing |
|---|---|---|---|
| 30 × 60 | 1.5 / 1.8 / 2.0 | ≈ 1.61 / 1.93 / 2.14 | 1.0–1.2 m (light houses) |
| 30 × 70 | 1.5 / 1.8 / 2.0 | ≈ 1.76 / 2.11 / 2.34 | 1.0 m |
| 40 × 80 | 1.8 / 2.0 / 2.5 | ≈ 2.58 / 2.86 / 3.56 | 1.0 m |
| 40 × 90 | 2.0 / 2.5 | ≈ 3.07 / 3.82 | 1.0–1.2 m |
| 50 × 100 | 2.0 / 2.5 | ≈ 3.48 / 4.34 | 1.0 m (wide bays) |
Weights calculated from the ellipse perimeter × wall × 7.85 g/cm³. Oval perimeter is an approximation; the mill certificate is authoritative.
Why the wall matters more than the label
Buyers compare “60 oval” against “60 oval” and assume they are the same product. They are not: 30×60×1.5 and 30×60×2.0 differ by roughly a third in steel. On a house with a 25 kg/m² snow requirement that difference is the difference between passing and sagging. We quote the wall on every line and refuse to quote “60 oval” without one.
- Sections
- 30×60 / 30×70 / 40×80 / 40×90 / 50×100 mm
- Wall
- 1.5 / 1.8 / 2.0 / 2.5 mm
- Length
- 6 m / 12 m, or bent to radius
- Bending
- CNC roll-bend to your radius, ±5 mm on chord
- Grade
- Q235B standard, Q355B for heavy snow
- Coating
- Z275 pre-galvanised · hot-dip on request
- Ends
- crushed / swaged / plain, per connector
- Packing
- nested bundles, arch-length
- Arches per bundle
- 20–40
- Bend radius
- from 1.8 m
- Cut tolerance
- ±1 mm
- Loading
- 40HQ / 40GP
Section by span
| Span | Arch section | Wall | Arch spacing |
|---|---|---|---|
| 6.0 m tunnel | 30×60 | 1.5–1.8 mm | 1.0 m |
| 8.0 m multi-span | 30×60 / 30×70 | 1.8–2.0 mm | 1.0 m |
| 9.6 m multi-span | 40×80 | 2.0 mm | 1.0 m |
| 12 m multi-span | 40×90 / 50×100 | 2.0–2.5 mm | 1.0–1.2 m |
| 14–16 m clear span | 50×100 or fabricated truss | 2.5 mm | 1.0 m |
Reference configurations we quote regularly. Your engineer's load case overrides this table — we do not size structures.
Section pages
Read next
Pages that answer the question this page raises.
- 04.01Round steel tubeRound galvanised steel tube for greenhouses: 1/2″ to 4″ outside diameter, wall 1.0–4.0 mm,→
- 08.08Oval vs round tubeOval versus round tube for greenhouse arches: section properties, bending in the roof plan→
- 05.01Multi-span film houseMulti-span film greenhouse frames: 6.2–12 m span, gutter-connected, galvanised oval arches→
- 08.03Snow loadGreenhouse snow load: ground snow load, shape and exposure coefficients, EN 1991-1-3 and E→
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