Metals, alloys and protective coatings · Lesson 2 of 4

Metals, alloys and protective coatings: materials, standards and design constraints

Which standard covers which metal, what a coating weight does and does not tell you, how galvanized, Galvalume, paint, anodizing, copper, zinc and stainless differ, and the exposure limits published for each.

You will be able to: Match each AFS metal to the standard that names it, read coating weights and film thicknesses, compare paint tiers, and say what environment and contact limits each material carries, attributing every published value.

10 min · 12 slides · 7 questions

All lessons in this module

Slide 1 of 12

Which standard names which metal

Each metal has a product standard:

ASTM A653/A653M: zinc-coated (galvanized) steel sheet.
ASTM A792/A792M: 55% aluminum-zinc coated steel sheet.
ASTM B209/B209M: aluminum and aluminum-alloy sheet.
ASTM B370: copper sheet and strip for buildings.
ASTM B101: lead-coated copper sheet and strip.
ASTM B69: rolled zinc.
ASTM A240/A240M: stainless plate, sheet and strip.

Sources

ASTM A653/A653M Standard Specification for Steel Sheet, Zinc-Coated (Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by the Hot-Dip Process (public scope only) - ASTM International
ASTM A792/A792M Standard Specification for Steel Sheet, 55 % Aluminum-Zinc Alloy-Coated by the Hot-Dip Process (public scope only) - ASTM International
ASTM B209/B209M Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate (public scope only) - ASTM International
ASTM B370 Standard Specification for Copper Sheet and Strip for Building Construction (public scope only) - ASTM International
ASTM B101 Standard Specification for Lead-Coated Copper Sheet and Strip for Building Construction (public scope only) - ASTM International
ASTM B69 Standard Specification for Rolled Zinc (public scope only) - ASTM International
ASTM A240/A240M Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip (public listing only) - ASTM International (listing on the ANSI Webstore)

Videos for this lesson

What this video shows: A coil and panel supplier's overview of what Galvalume is and its pros and cons. Checked against the video's description; the coating itself is defined by ASTM A792.

Video: What is Galvalume® Steel and How is it Used for Metal Roofing? by The Metal Roofing Channel, on YouTube. Chosen from the video's published description.

What this video shows: Sheffield Metals staff compare Galvalume and galvanized steel. Checked against the video's description only; treat the opinions as one supplier's.

Video: Galvalume® vs. Galvanized: Which is Better? by The Metal Roofing Channel, on YouTube. Chosen from the video's published description.

What this video shows: Coating-maker staff explain PVDF and SMP paint choices for metal roofing. Checked against the video's description; compare products by their data sheets.

Video: What Paint is Best for Your Metal Roof? PVDF vs. SMP by The Metal Roofing Channel, on YouTube. Chosen from the video's published description.

Glossary

Coating weight designation: A code such as G90 or AZ55 giving the minimum average coating weight, in ounces per square foot, of both faces of a coated steel sheet together.
Z275: The metric equivalent of G90: a minimum average of 275 grams of zinc per square meter, both faces together.
AAMA 2605: The top tier of the AAMA performance standards for factory-applied organic coatings, listed by Tnemec at 10 years of color retention and chalk resistance.
SMP: Silicone-modified polyester, a factory coil coating used on roof and wall panels and trim; makers publish its AAMA tier.
Mil: One thousandth of an inch, the unit used for coating and film thickness.
Class I anodizing: An architectural anodic coating on aluminum at 0.7 mil thick or more; Class II is 0.4 to 0.7 mil.
H00 temper: The cold-rolled temper of copper sheet, by far the most commonly specified copper temper according to the Copper Development Association.
White rust: The bulky white deposit that forms on zinc when it is exposed to too much water and not enough carbon dioxide; light staining may not shorten life.