Abstract: A method of forming a flexible spiral-wound tube includes the steps of spiral wrapping at least two webs of material in an overlapping relationship about a mandrel to form a multi-ply tube and advancing the tube along the mandrel and off a reduced diameter portion of the mandrel at a forward end of the mandrel. Advancement of the tube along the mandrel includes rotating the tube as the tube longitudinally moves such that the tube advances in a spiral manner. The method further includes the step of retarding movement of the tube along the reduced diameter portion of the mandrel by providing frictional resistance between the tube and the mandrel to form folds or pleats in the tube so that the tube becomes extremely flexible. The flexible spiral-wound tube has a uniform pattern of generally diamond-shaped folds therein.