Flexible and foldable conduit

Claim 1

A flexible conduit comprising: a. inner and outer flexible wAlls, at least one of said walls being fluid impermeable, said inner wall defining an enclosed passage of polygonal cross section, said outer wall defining an external surface of the polygonal cross section, b. insulation disposed intermediate said inner and outer walls, c. a plurality of elongate stiffening means disposed intermediate said walls, said stiffening means lying in axially spaced-apart planes oriented substantially perpendicular to the longitudibal axis of the conduit, said stiffening means being adhesively secured to one of said walls in said axially spacedapart planes whereby said conduit can be collapsed in an axial direction, each of said stiffening means comprising a plurality of separate elongate stiffening rod elements equal in number to the number of conduit sides and each of said elongate stiffening elements being capable of angular movement relative to other of said elongate stiffening elements in its plane wherein said conduit can be collapsed until said conduit is substantially flat in transverse cross section.