Abstract: A flexible composite pipe for transporting a high-temperature fluid of the invention has an inner pipe for passing a high-temperature, high-pressure fluid therethrough, a reinforcing layer formed around the inner pipe, and a protective sheath layer formed around the reinforcing layer. The inner pipe consists of a material which is selected from a polyvinylidene fluoride copolymer resin, a blend thereof with a polyvinylidene fluoride resin, or a composition based on the polyvinylidene fluoride copolymer resin and which has, when hot pressed into a sheet, an Izod impact strength of 10 kg-cm/cm or more and an apparent Young's modulus in tension of 90 kg/mm.sup.2 or less.

Abstract: A flexible pipe for transporting various fluids such as oil, gas, water or the like. The flexible pipe comprises at least one internal plastic sheath which may be provided on an inner carcass, a short pitched metal armor layer provided on the internal plastic sheath to mainly share a circumferential force due to inner pressure, a long pitched metal armor layer provided on the short pitched metal armor layer to mainly share a longitudinal force and an external plastic sheath provided on the long pitched armor layer.

Abstract: A solute-separating membrane consisting of a polyoxadiazole series resin containing at least one of the structural units of formulae: ##STR1## wherein Ar and Ar' are same or different multivalent aromatic residues, and R is an alkyl, cycloalkyl or aralkyl group having from 1 to 7 carbon atoms, and swollen to a swelling degree of 1.7-15 with a swelling agent of water, a solvent miscible with water, or a mixture of water and the solvent has a high separating ability and further has high mechanical strength and chemical and thermal stabilities.