Durable semi-rigid single-layer flexible duct

A durable semi-rigid, flexible duct having an axis running the length of said duct, comprising:

• a single aluminum ribbon, having an innermost and outermost side;
• a resilient wound element, wherein said wound element is disposed at the mid point of the overlap region of said aluminum ribbon, such that said innermost side of said ribbon overlaps with the outermost side of a previous wrapping;
• wherein said wound element imparts corrugations to said aluminum ribbon, said aluminum ribbon being formed with a plurality of closely and evenly-spaced ridges embossed in between a pair of said corrugations, such that said duct is axially extendible between a compacted configuration suitable for storage and for shipping and an extended configuration suitable for installation in an air transport arrangement;
• wherein said aluminum ribbon is of a predetermined thickness rendering said duct substantially rigid when in said extended configuration and enabling said duct to maintain its substantial rigidity upon extension from said compacted configuration;
• and
• wherein said closely and evenly-spaced ridges impart additional rigidity to said duct, causing said duct to be resilient and withstand heavy impact forces, which might crush the duct and reduce its diameter.