Abstract: A deformable metal or plastic tube, the nipple end of which is provided with a plurality of circumferential ribs or grooves and a plurality of aligned longitudinal projections to provide a rough surface over which a resilient rubber or plastic end section of a flexible hose is placed and inwardly compressed against said roughened surface by a sleeve or band to form a fluid-tight seal between the hose and the tube. The grooves or ribs on the nipple portion of the tube are formed by a plurality of radially inwardly pressing dies surrounding the tube on a mandrel. These dies not only reduce the diameter of the nipple but also form aligned rows of projections on the outer surface of the tube by extrusion of the metal between the sides of adjacent dies. One or more and preferably two compressions of the dies are made in different angular positions of the tube. The nipple portion is defined by a previously outwardly pushed bead flange inwardly from the end of the tube.