Ground screw post supports
As foundation structure for grounding solar power station, ground screw post supports act as important connecting role between ground and solar supporting structure. Body of ground screw post supports is made of Q235 carbon steel pipe. As ground screw post supports was laid as foundation in the dark wet underground condition for long time, so it’s easy to get corrosion, thus it’s not only cause unstability or falling down of
support structure of partial power station, but also it will influence the service life of whole
photovoltaic power station. So it needs special attention on the corrosion issue of ground screw post supports.
As searched, to perform hot dipped galvanization treatment on the ground screw post supports body can effectively resist corrosion or rust. As shown in picture, Delingha 10MW solar power station use hot dip galvanized ground screw post supports, which effectively bear the structure and resist corrosion.
Analysis on corrosion environment and corrosion mechanism of ground screw post supports
1. Corrosion environment of ground screw post supports
According to different corrosion environment, there are atmosphere corrosion and soil corrosion.
Atmosphere corrosion mainly affect the part above the ground; while soil corrosion mainly affect the
part which is screwed into the ground.
2. Corrosion mechanism of ground screw post supports
There are two types of corrosion – chemical corrosion and electrochemical corrosion.
Chemical corrosion: for ground screws, it’s mainly the corrosion in the dry, high temperature air
and heavy pollutant environment.
Electrochemical corrosion: it’s mainly about water and air.
Principal of corrosion resistance of hot dipped galvanization
The key to measure HDG anti-corrosion feature is thickness of galvanization layer. The thicker,
the better to resist corrosion, rust. Thickness of ground screw is about 3~4mm, and standard request
galvanization layer to be at least 70um. At our factory, we HDG at least 80um.
After a series of analysis, 80um hot dipped galvanization ground screw post supports service life can be 25
years. That is to say, after at least 25 years, the steel will be exposed to the corrosion
environment.
Hot dipped galvanization standard ASTM A123/A123M-01
| Article thickness (mm) | Galvanizing layer thickness average (um) |
|---|---|
| Thickness>=6.4mm | >=85 |
| 4.8mm~6.4mm | >=70 |
| 3.2mm~4.8mm | >=60 |
| 1.6mm~3.2mm | >=50 |
| Thickness<1.6mm | >=45 |
Analysis on pull out hot dipped galvanization ground screw post support
In Inner Mongolia at the north of China, we pull out a ground screw post support whose body length is 1600mm. The part from sharp point to 1400mm was embedded into ground. Galvanization layer of thread part was broken in different degree, upper part of ground screw post supports was slightly harmed, but the whole ground screw was not corroded.
Through above analysis, it’s essential to investigate local soil condition, atmosphere condition
before choosing ground screw foundations. The laying place should be far away from heavy pollutant or strong corrosion site. The anti-corrosion feature of ground screw plays an important role in the operation of solar power station. By hot dipped galvanization, it can be effectively protect it from corrosion.
China ground screw
