The Rectangular Industrial Duct Construction Standards has many updates since the 1980 edition

FILE SIZE--4.48MB This second edition expands the scope of the 1980 version, updating original text to incorporate a revised theory of design, new materials and more “user friendly” tables. Included are new tables for stainless steels and aluminum, plus expanded chapters on materials, welding practices, and a guide specification. It covers the simple, low or moderate temperature and pressure (or vacuum) indoor systems as well as the more complex outdoor systems that operate at moderate to high temperature and pressure (or vacuum), and are subject to higher and more complex external loading.

Other versions of SMACNA - Rectangular Industrial Duct Construction Standards, 2004 Updated Version are also Available:
SMACNA - Rectangular Industrial Duct Construction Standards, 2004 Updated Version