Two basis shapes are used in forming ductwork; rectangular and round. The ductwork units carry large volumes of high temperature, dusty air, between pieces of process equipment. Having a good understanding of these materials will interact and behave under extreme and air is important to their analysis and design. Rectangular ductwork is covered be the ASCE "The Structural Design of Air & Gas Ducts for Process Power Stations and Industrial Applications".
The structural design of ductwork plate is based on buckling of the plate element. Round ductwork plate design is based on diameter to duct plate thickness ratios, and the allowable stresses are contained in multiple references such as US Steel Plate, ASME/ANSI STS-1, SMNACA, Tubular Steel Structures, and other references.