What G90 means?

Introduction
One of the most confusing topics related to coated-steel sheet products is the issue of coating weight
designations and what they mean with respect to product performance. This discussion is intended to help
clarify this issue.
Coating Weight Measurement Systems
Each coated-steel sheet product has a coating weight designation system that is in common use today. The
system for each type of coating is defined in the appropriate ASTM standard. For example, the most commonly
used ASTM standard is A 653/A 653M which covers hot-dip galvanized products.

The coating weight designation system is given in terms such as G60, G90, etc. These numbers refer to the weight (mass in SI nits) of zinc on the surface of the steel sheet in Inch-Pound (English or Imperial) units of measurement. That is,for G90, the coating on one square foot of sheet (total coating, both sides of the sheet) weighs a minimum of 0.90 ounces. If equally applied to both sides of the sheet, there would be a minimum of 0.45 ounces on each surface.

The other measurement system in widespread use today is the SI (Metric) system. The conversion from the
Inch-Pound weight in ounces per square foot (oz/ft2) to the SI mass in grams per square metre (g/m2) is:
1 oz/ft2 = 305.15 g/m2
To convert from oz/ft2 to g/m2, multiply by 305.15
Example: G90 (0.90 oz/ft2) = Z275 (275 g/m2)

Contact person: Irina Li

E-mail: [email protected]