Please have a read of the below article from Nuevosol which talks about corrosion in Pre-GI and Hot Dip Galvanised (HDG) Structures. Salient points are as below:
- Pre-GI can be used as long as it is 550 GSM steel. The galvanization coating thickness is a maximum of 20 micron each side for 550 GSM steel.
- HDG can also be used provided min zinc thickness is 80 microns.
- The mounting structure steel shall be as per latest IS 2062 : 2011 and galvanization of the mounting structure shall be in compliance of latest IS 4759, material thickness shall be minimum 2.5 mm.
I have also provided clauses from Gujarat, TamilNadu and Maharashtra Energy Development Agencies where they are specifying the galvanization thickness required in microns:
Gujarat – “Hot dip galvanized MS mounting structures shall be of 80 microns but it shall not be less than 60 microns at any point used for mounting the modules/ panels/arrays.”
Maharashtra – “Hot dip galvanized MS mounting structures may be used for mounting the modules / panels / arrays. Minimum thickness of galvanization should be at least 120 microns”
Tamilnadu – “Hot dip galvanised steel with a minimum galvanisation thickness of 120 microns or aluminium alloy”
These could be followed as standards for projects where you are proposing GI structures.