Hot dip galvanized steel.
Galvanized sheet metal g60 g90.
The a coatings have a dull gray color with no spangle while the g coatings are bright shiny and can have various sized spangle visible.
This specification is for hot dip galvanizing steel sheet using the continuous high speed galvanizing process.
Galvanized steel is the result of applying a protective zinc coating to steel to prevent it from rusting.
Others available upon request.
This makes it rust proof and easy to paint.
G90 galvanized steel has a longer service life than g60 g40 and g30 galvanized steel because g90 galvanized steel has a heavier coating weight of zinc applied to it at 0 90 oz ft 2 as opposed to g60 galvanized steel at 060 ox ft 2 and so on.
If it is for outdoor use or in a high moisture environment i would always specify g90 just because it seems to make a difference over time.
When exposed to the atmosphere pure zinc reacts with oxygen to form zinc oxide which further reacts with carbon dioxide to form zinc carbonate a dull grey fairly strong material that stops further.
I hope this helps.
Deep drawing steel and extra deep drawing steel are designations described in the astm specifications for steel sheet zinc coated galvanized or zinc iron alloy coated galvannealed by.
The corrosion resistance of the g type is directly related to the amount of zinc coating i e g90 will resist corrosion to the base metal longer than g30.
Hot dip galvanizing is the process of coating iron or steel with a thin zinc layer by passing the steel through a molten bath of zinc at a temperature of around 860 f 460 c.
It is a coating thickness designation in the galvanizing specification astm a653.
G60 0 60 183 g90 0 90 275 g115 1 15 351 g140 1 40 427 g165 1 65 504 g185 1 85 565 g210 2 10 641.
First of all g90 is not a galvanizing specification.