摘要 |
A spirally or convolutely wound multi-layer tube includes one or more plies or layers that have embossments formed therein and projecting from one or both sides of each such ply or layer. The embossments increase the effective caliper and volume of the ply without adding mass. The embossments can abut an adjacent ply or layer of the tube and space such adjacent ply or layer from regions of the embossed ply or layer between the embossments, thereby forming void spaces in the tube wall. |