Tube formed of profiled strip

摘要

A tube made of profiled strip has an inner edge and an outer edge parallel to the inner edge and projecting away from the inner edge. A double-thickness rib extends between the edges projects transversely in a direction from the strip. A channel extending between the rib and the outer edge opens transversely of the strip opposite to the direction in which the strip projects from the strip. The strip is formed into turns centered on an axis with the rib projecting radially outward. The channel opens radially inward, and the rib of each turn projects radially into the channel of an adjacent turn.