From：Wholesale flat roof solar mounting from China Release time：2018-11-09
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Hot-dip galvanizing is an important quality and technical index of the pv bracket, which is related to the safety and durability of the structure. Although there are national and industrial standards, the underspecification of hot-dip galvanizing thickness is still a common technical problem of the scaffold.
Photovoltaic supports are usually carbon steel and aluminum alloy, while those using hot galvanization are carbon steel, and the carbon steel is usually made of Q235 and Q345. The steel coil is processed into supports by cold bending, welding and hot galvanization. The thickness of the support is generally greater than 2mm (for some coastal areas and high-elevation areas with high wind, it is recommended that the thickness should not be less than 2.5mm, otherwise the steel joint may be at risk of tearing.)
Hot galvanizing technology environment that is against the corrosion of steel surface treatment scheme of a more stable and reliable, and there are many factors that can influence of hot dip galvanized, such as: steel base material composition, surface state, such as roughness, base material internal stress, geometry size and so on, which affected by the thickness of the thickness of the base material for hot dip galvanized, generally thicker plate thickness of hot dip galvanized. The following is an example of a 2.0mm thick bracket to illustrate the thickness of the galvanizing layer to meet the requirements of environmental corrosion service life.
It is assumed that the thickness of the base material of the support is 2mm. It can be seen from the specification gbt13192-2002 specification.
According to the requirements of national standards, the local thickness of 2mm substrates should not be less than 45 (m) and the average thickness should not be less than 55 (m). According to the atmospheric exposure test results of 1964 ~ 1974 conducted by the Japan hot galvanizing association.
If the average thickness is 55 m according to the national standard, the amount of added zinc is 55x7.2=396g/m2, and the usable life under four different environments is about:
Heavy industry zone: 8.91, with an annual corrosion rate of 40.1;
Coastal zone: 32.67 years, with an annual corrosion rate of 10.8;
Suburban area: 66.33 years, with an annual corrosion rate of 5.4;
Urban area: 20.79 years, with an annual corrosion rate of 17.5;
If calculated according to 25 years of photovoltaic service life, the four zones in order are at least: 1002.5, 270, 135, 437.5, that is, 139 displacement m, 37.5 displacement m, 18.75 displacement m, 60.76 displacement m, so for urban areas
In terms of distribution, it is reasonable and necessary to set the thickness of galvanizing layer at least 65 mm. However, for heavy industry zones, especially those with acid and alkali corrosion, it is suggested that the thickness of the supports should be appropriately increased and the thickness of galvanizing layer should be appropriately increased.