Abstract: A machine (200) for winding a strip of material (212) into a helical pipe wherein adjacent convolutions of the strip (212) are interlocked. The machine comprises: a frame (220) having circumferentially spaced supports in the form of rollers (266, 276, 278, 286, 288, 296 and 298) adapted to bear against the inner periphery of the pipe being wound, the outer peripheral surfaces of the rollers forming a helical path for the strip (212) and along which the strip (212) is directed when the machine (200) is in use; driving rollers (224) mounted to the frame (220) for driving the strip (212) around the outside of the rollers so as to follow the helical path and cause the adjacent edges the strip (212) to interlock; and drive means (226) mounted to the frame for driving the driving rollers (224). The driving rollers (224) and the drive means are located wholly inside of the path formed by the rollers and no part of the machine (200) engages the outer periphery of the pipe being wound.

Abstract: A plastic profiled strip (10) is provided for producing helically wound tubes or pipes, the strip (10) having female and male joint formations (13, 14) extending along opposite longitudinal margins thereof and arranged so that upon spirally winding the strip into a tubular form, the joint formations (13, 14) can be interlocked to thereby lock adjacent windings of the strip together, the male joint formation (14) comprising a hinged flap (15) which is flexibly connected to the strip (10) for hinging movement between a disengaged or unlocked position displaced from the plane of the strip (10) and a locking position wherein it interlocks with the female joint formation (13) of an adjacent winding of the strip (10).