Flat oval duct combines the advantages of round duct and rectangular duct because it may fit in spaces where there is not enough room for round duct, and it can be joined using the techniques of round duct assembly. Spiral flat oval duct is machine-made from round spiral lockseam duct and is available in varying sizes and aspect ratios. It can be made with longitudinal seams.

Flat oval duct provides a more efficient alternative to rectangular duct . manufactures flat oval duct with the same techniques used to make round duct. As a result, flat oval duct shares many of the performance characteristics of round duct. Compared with rectangular duct, it provides lower installation costs and, because of reduced leakage and pressure loss, lower operating costs.

The range of Flat Oval sizes is particularly useful where designers have space limitations in ceiling voids or riser applications. It has the additional advantage of fewer site joints and supports compared with rectangular ductwork.