ASTM materials and coatings · Lesson 2 of 4

ASTM materials and coatings: materials, standards and design constraints

Which ASTM standard covers galvanized, 55 % aluminum-zinc, prepainted, aluminum, copper, zinc and stainless sheet, what G90 and AZ55 mean, and why the same number does not mean the same coating.

You will be able to: Match each flashing metal and coating to the ASTM standard that usually covers it, read a coating weight designation, and tell a product specification from a finish performance specification.

13 min · 12 slides · 11 questions

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Slide 1 of 12

Galvanized steel: A653/A653M

ASTM A653/A653M covers steel sheet that is zinc-coated (galvanized) or zinc-iron alloy-coated (galvannealed) by the hot-dip process.

Its scope says product must also meet A924/A924M unless A653 states otherwise.

A653 is the product specification; its designations, such as G90, say how much zinc.

Sources

Glossary

Coating weight designation: A code in an ASTM sheet standard, such as G90 or AZ55, giving the minimum coating weight; each coated sheet product has its own system of designations.
G90: A galvanized coating designation in ASTM A653/A653M: a minimum triple-spot average of 0.90 oz/ft² of zinc, total on both sides of the sheet.
AZ55: A 55 % aluminum-zinc alloy coating designation in ASTM A792/A792M: a minimum triple-spot average of 0.55 oz/ft², total on both sides, which is not the same thickness as the same number of ounces of galvanized zinc.
Galvannealed: Steel sheet with a zinc-iron alloy coating made by the hot-dip process; ASTM A653/A653M covers both galvanized and galvannealed sheet.
FGIA/AAMA 2605: A voluntary specification for superior performing organic coatings on aluminum extrusions and panels, with a coil coating appendix.