Cylindrical flexible joint unit

A cylindrical flexible joint unit for interconnecting a circular hot gas duct of circular cross-section to a further circular cross-section of another structure, said unit comprising an inlet annular flexible wall structure for connection to said hot gas duct and an outlet flexible annular connector, heat insulating means retained between said annular wall structure, said annular connector and an outer flexible annular membrane, said inlet wall structure being a metal wall and defining a cylindrical inner sleeve and an annular step connecting flange secured about an outer surface thereof, said inner sleeve having a duct connecting end and a free end, said step connecting flange having a short transverse connecting wall and an elongated annular spaced wall section extending from said connecting wall and disposed substantially parallel above said outer surface of said inner sleeve toward said duct connecting end of said inner sleeve and defining an air gap therebetween, a membrane connecting bracket connected to and extending above a free end of said spaced wall section to and connected with a side edge of said annular membrane thereabove, said free end of said annular sleeve being displaceably disposed with relation to said outlet flexible annular connector, said outlet annular connector having a duct connecting end for connection to said duct of another structure and having an opposed side edge of said annular membrane connected thereto.