Dimensional inspection and tolerances · Lesson 2 of 4

Dimensional inspection and tolerances: materials, standards and design constraints

Thickness bands by material, which standard governs each, the AFS limits every piece must meet, what project specifications ask for, and flatness.

You will be able to: Find the thickness band for galvanized and copper, say which standards hold the aluminum and stainless bands, apply the AFS limits, and read a project specification for its acceptance language.

12 min · 11 slides · 11 questions

All lessons in this module

Slide 1 of 11

Thickness includes the coating

The scope of ASTM A924/A924M-26 states that the thickness of hot-dip coated sheet is the total of the base steel and the coating.

So a micrometer reading on galvanized includes the zinc, as the AFS register's 0.0276 in for 24 ga does.

Sources

ASTM A924/A924M-26 General Requirements for Steel Sheet, Metallic-Coated by the Hot-Dip Process (scope page) - ASTM International
AFS material register (alloys, thicknesses, weights and expansion coefficients) - Architectural Flashing Supply

Glossary

Coated thickness: For hot-dip coated sheet, the total of the base steel and the coating (ASTM A924 scope).
Minimum thickness (copper): The lowest thickness the CDA lists beside the nominal for each copper weight.
Gauge: A number naming a thickness within one table; the same gauge is a different thickness in galvanized and stainless.
Oil canning: Visible waviness in the flat areas of metal panels (MCA); generally an aesthetic issue.