Patent ID: 8084108

Claim:
A spirally wound tube, comprising: an inner zone, an outer zone, and an intermediate zone; the inner zone being located radially inwardly and including at least one inner layer, each inner layer including at least one inner ply; the outer zone being located radially outwardly and including at least one outer layer, each outer layer including at least one outer ply; and the intermediate zone being located between the outer zone and the inner zone and comprising: one to a plurality of support layers; a first intermediate layer disposed radially outwardly of and adjacent to an outer side of the support layers and including one to a plurality of first intermediate plies that are wound such that there are first gaps between adjacent edges of the first intermediate plies; at least one additional intermediate layer adjacent the first intermediate layer, wherein the at least one additional intermediate layer has one to a plurality of intermediate plies that are spirally wound with one to a plurality of gaps between adjacent edges of the intermediate plies such that the gaps of the at least one additional intermediate layer are radially aligned with the first gaps of the first intermediate layer; and a second intermediate layer disposed radially inwardly of and adjacent to an inner side of the support layers and including one to a plurality of second intermediate plies that are wound such that there are second gaps between adjacent edges of the second intermediate plies; wherein at least some of the first gaps are radially aligned with at least some of the second intermediate plies and at least some of the second gaps are radially aligned with at least some of the first intermediate plies, such that the first and second gaps allow radial displacement of the support layers into the gaps under radial loading of the tube, the support layers thereby acting as springs in the intermediate zone for absorbing radial deformation.