Patent ID: 7690114

Claim:
A tube made of a profile rolled metal product, the tube comprising a first wall and a second wall forming two opposing walls of said tube, and a plurality of reinforcing structures connecting the first wall and second wall and forming longitudinal passages for transporting fluid between the first wall and the second wall, wherein each reinforcing structure comprises a longitudinal ridge on the first wall projecting towards the second wall, and a longitudinal ridge on the second wall projecting towards the first wall, each ridge comprises a base, a top and two longitudinal sides, the ridges engaging each other at their sides, and the ridges on the first and/or the second walls have a profile selected from the group consisting of a trapezoidal, a rectangular, and a cone-shaped profile, wherein the ridges on the first and/or the second walls are broader at the base than at the top, and wherein each wall has a profile of the ridges spaced from each other such that a groove is formed between two neighboring ridges, opposed sides of the neighboring ridges forming sides of the groove, wherein the two sides of a respective said ridge engage the two sides of a respective said groove in the opposing wall, thereby forming a longitudinal passage in the groove, wherein the respective groove of each wall has a base defined by the respective wall between the neighboring ridges on the respective wall, and the two sides of the respective ridge engage the two sides of the respective groove in the opposing wall with the top of the respective ridge and the base of the respective groove being opposed and spaced to form a longitudinal passage in the groove as a space between the top of the respective ridge and the base of the respective groove.