Patent ID: 7160591

Claim:
An elongate tubular heat transfer element having a longitudinal tube axis that runs through the hollow interior of the tubular heat transfer element wherein the tubular heat transfer element comprises a wall of monolithic construction having an outer surface and an inner surface, said wall being formed from a composite material comprising a matrix and rovings embedded in the matrix, wherein the composite material is in contact with the hollow interior, such that the inner surface determines a boundary of the hollow interior which extends longitudinally along the tube axis of the heat transfer element and wherein the matrix consists essentially of a fluoropolymer selected from polyvinylidene fluoride and copolymers of at least 80% by weight, based upon the weight of the copolymer, of vinylidene fluoride and up to 20% by weight, based upon the weight of the copolymer, of at least one other fluorine based monomer selected from tetrafluoroethylene, hexafluoropropylene and vinyl fluoride, and wherein the rovings embedded in the matrix comprise boron-free chemically resistant glass fibres, the rovings comprising from about 20% to about 60% by volume based upon the volume of the composite material and including rovings which extend longitudinally in a lengthwise direction parallel to the tube axis of the tubular heat transfer element and rovings which extend spirally around the tube axis.