Zn-Al-Mg carbon steel brackets paired with stainless bolts cause severe galvanic corrosion under rain and dew electrolyte, especially for coastal PV stations. Only insulating isolation can block conductive circuit and eliminate pitting rust. This article provides graded isolation schemes complying with GB/T 10125.
| PV Location | Corrosion Level | Mandatory Isolation Scheme | Gasket Material | Min Gasket Thickness |
| Inland Mountain | Low | Single EPDM gasket | EPDM | 0.8mm |
| Riverside & Lake | Medium | Gasket + barrier coating | Hydrolysis-resistant EPDM | 1.2mm |
| Coastal Tidal Flat | High | EPDM gasket + plastic isolation sleeve | Salt mist modified EPDM | 1.5mm |
| Offshore Floating | Extreme | Full isolation + thread coating, 2205 duplex steel recommended | Fluororubber composite gasket | 2.0mm |
1. Clean bracket contact surface and dry before placing insulating gasket; 2. Keep gasket fully attached without offset to avoid direct metal contact; 3. Spray weather-resistant seal coating on bolt head and gasket edge for coastal projects; 4. Ordinary PVC gaskets are forbidden, they will pulverize within half a year outdoors.
Slight white rust: Polish rust, apply zinc-rich primer and seal coating, install thickened EPDM gasket; Base metal pitting: Replace damaged bracket and full isolation accessories, re-coat sealant annually; Thread seizure rust: Clean rust, apply outdoor anti-corrosion grease and reinstall with isolation sleeves.