Abstract: The invention provides methods and apparatus for producing a spirally wound pipe or pipe liner, and also to a web for forming a spirally wound pipe or pipe liner. One aspect of the invention provides a method and an associated machine of winding a helically wound pipe from a web (200) having transversely spaced apart connecting formations (310, 320) adapted to interlock when the web is wound in a helical path and adjacent edge portions (300a. 300b) of the web overlap one another, wherein an exterior support means (400) for the connecting formation at the terminus of the pipe being helically wound from the web is provided, and a radially outwardly directed force is applied against an inner face (220) of the web and the support means (400) to pinch connecting formations into interlocking engagement. A further aspect of the invention provides an elongated web (200) comprising a wall portion (210) bound by edge portions (300a.

Abstract: An elongated web or strip (200) comprising a wall portion bounded by edge portions and adapted to form a conduit by spirally winding said web and joining adjacent edge portions. The edge portions (210, 220) are adapted to permit relative movement between adjacent portions of the spiral conduit and thereby provide radial alteration of the conduit. The web includes a compensation portion (300) to alter the dimension of the web (200) upon radial alteration of the conduit and thereby compensate for creep in the spiral conduit. In a particularly preferred embodiment the edge portion comprises a primary lock (214, 224) and a secondary or sacrificial lock (212, 222). The sacrificial lock is disengaged by release of the mechanism 215 to permit relative movement there between and thereby effect radial alteration of the conduit.

Abstract: An elongated web or strip (200) comprising a wall portion bounded by edge portions and adapted to form a conduit by spirally winding said web and joining adjacent edge portions. The edge portions (210, 220) are adapted to permit relative movement between adjacent portions of the spiral conduit and thereby provide radial alteration of the conduit. The web includes a compensation portion (300) to alter the dimension of the web (200) upon radial alteration of the conduit and thereby compensate for creep in the spiral conduit. In a particularly preferred embodiment the edge portion comprises a primary lock (214, 224) and a secondary or sacrificial lock (212, 222). The sacrificial lock is disengaged by release of the mechanism 215 to permit relative movement there between and thereby effect radial alteration of the conduit.