Greenhouse Hardware Fittings

Multi-span greenhouses have larger spans (8-12m/span), and the gutter drainage volume is 3-5 times that of single-span greenhouses. Therefore, the strength and sealing requirements for gutter connectors are higher—recommended Grade 8.8 or above bolts with EPDM sealing gaskets. The shading net drive system in multi-span greenhouses is also more complex, requiring consideration of synchronous transmission precision for gear and chain selection. Single-span greenhouses have a simple structure, and Grade 8.8 hot-dip galvanized bolts with standard film spring clips can meet most operating conditions.

No, it is not sufficient. Within 3km of the coast, the environment is classified as C4-C5 corrosion category. The lifespan of hot-dip galvanized coating (≥65μm) in a C4 environment is only 8-12 years, far less than the 20 years inland. Recommendations: (1) Upgrade key structural connectors to 304 stainless steel (A2-70); (2) Use Dacromet coating for ordinary connectors (salt spray resistance ≥720h); (3) Pre-apply anti-rust grease to all bolt holes before installation. For greenhouses immediately adjacent to the coast (within 500m), full 316 stainless steel is recommended.

Ordinary film lines (PE material) have a lifespan of 2-3 years (UV aging is the main cause). Immediate replacement is needed if: (1) The diameter of the film line decreases by more than 15% of the original diameter; (2) Obvious cracks appear on the surface; (3) Elasticity decreases, with rebound exceeding 10mm within 3 days after tightening. In northern heavy snow areas, it is recommended to tighten film line spacing before winter (from 1.0m to 0.6m), and add a transverse film rope at the highest point of the arch. In typhoon-prone areas, upgrading to 304 stainless steel film lines is recommended.

For conventional greenhouses, 304 stainless steel wire ropes (7×19 construction, Φ2-Φ3mm) have a lifespan of 15-20 years. Replacement criteria: when broken wires exceed 13 out of 133 total wires (10%), replacement is mandatory. Key inspection points: (1) Drive end — most severe wear occurs at the turning pulley transition; (2) Shade net buckle points — stress concentration areas prone to fatigue fracture. Perform a system inspection after each growing season.

For the EU market, CE certification is required, with greenhouse structures complying with EN 13031-1 and electrical systems with EN 60204. For the North American market, CNC certification (Canada) or compliance with IBC building codes (USA) is needed. The Middle East market requires high-temperature adaptability (60°C+) and dust sealing ratings (IP65 or higher). Additionally, if the greenhouse is used for vegetable export certification (GlobalG.A.P.), structural materials must meet food safety production requirements.