What is the thickness of the galvanized photovoltaic support to meet the 25-year service life?
Release date：2018-06-28 author： click：
The problem of hot-dip galvanizing is an important quality and technical index of photovoltaic supports, which is related to the safety and durability of structural use. Although there are national and industry specifications, the thickness of the bracket hot-dip galvanizing is still a relatively common technical problem of the bracket, and the "thick" color change still exists.
Photovoltaic supports generally have carbon steel and aluminum alloy, and carbon steel is used for hot-dip galvanizing. Carbon steel is generally made of Q235 and Q345. The steel coil is processed by cold bending, welding and hot-dip galvanizing. Into the bracket. The thickness of the bracket is generally greater than 2mm (for some large areas and areas such as the sea, high-rise, etc., the recommended thickness should not be less than 2.5mm, otherwise the connection point of the steel has the risk of tearing.)
The hot-dip galvanizing process is a relatively stable and reliable steel surface treatment solution against environmental corrosion. There are many factors affecting hot-dip galvanizing, such as: steel substrate composition, surface state (such as roughness), substrate internal stress, geometry Dimensions, etc., in which the thickness of the substrate has a great influence on the thickness of the hot-dip galvanizing, and the thickness of the hot-dip galvanizing of the thicker plate is generally larger. The following is an example of a 2.0 mm thick bracket to illustrate the thickness of the galvanized layer to meet the environmental corrosion service life requirements.
It is assumed that the thickness of the stent substrate is 2 mm, which is known according to the specifications of the hot-dip galvanizing specification GBT13192-2002.
According to the national standard requirements, for a 2mm substrate, the local thickness should not be less than 45μm, and the average thickness should not be less than 55μm. According to the results of the atmospheric exposure test of the Japan Hot Dip Galvanizing Association from 1964 to 1974.
If calculated according to the national standard, the average thickness is 55μm, the zinc content is 55x7.2=396g/m2, and the usable period in four different environments is about:
Heavy industry zone: In 8.91, the annual corrosion degree was 40.1;
Coastal zone: In 32.67 years, the annual corrosion degree is 10.8;
Outskirts: 66.33 years, the annual corrosion degree is 5.4;
Urban zone: 20.79 years, the annual corrosion degree is 17.5;
If calculated according to the PV service life of 25 years, the four zones are at least: 1002.5, 270, 135, 437.5, ie 139μm, 37.5μm, 18.75μm, 60.76μm, so for urban areas
In terms of distribution, it is reasonable and reasonable to set the thickness of the galvanized layer to at least 65 μm. However, for heavy industrial areas, especially in industrial areas with acid-base corrosion, it is recommended to increase the thickness of the support, galvanized layer. The thickness should also be increased as appropriate.