Abstract: A drain pipe of corrugated form comprising corrugations of uniform inner diameter having axially in line alternating drain holes and outward protrusions in the corrugation troughs. The drain holes are cut by a stationary knife which engages the troughs of normally formed corrugations but which are set below the level of the protrusions, thus cutting a drain hole only in alternate corrugations. Preferably drain holes and protrusions are also staggered about the circumference of each corrugation trough.

Abstract: A perforated corrugated tube of thermoplastic or like material in which the tube is made with radially inwardly extending blisters in the valleys thereof which are sheared off to provide perforations through the valleys of the corrugations, the apparatus and method being characterized in that the perforated corrugated tube is made in a continuous manner by molding the tube with the blisters in a traveling mold and shearing the blisters as the tube emerges from the traveling mold. A further characterizing feature of the perforated corrugated tube herein rendering it useful as for highway drainage and frostproofing purposes, is that it is formed with a smooth walled channel-like bottom portion having upwardly diverging side walls merging with the remaining perforated corrugated portion of the tube.