G40, G60, and G90 are different galvanizing levels used for galvanized steel coils. They refer to the amount of zinc coating on the surface of the steel, with G90 having the highest amount of coating.
G40 galvanized steel coil has a minimum zinc coating weight of 120 grams per square meter, while G60 has a minimum zinc coating weight of 180 grams per square meter, and G90 has a minimum zinc coating weight of 275 grams per square meter.
Galvanized steel coils with higher coating levels like G60 and G90 are typically used for outdoor applications, as they offer better protection against corrosion and weathering. They are also more durable and have a longer lifespan compared to G40 galvanized steel coils.
Overall, the choice of galvanizing level depends on the intended application and the required level of corrosion resistance and durability.