Kembla SWP DiaFit Pipe Lining System
The ASTT website says the following about SWP: “Spirally wound liners are formed by taking a strip of plastic and winding it, locking the edges together to form a ‘pipe within a pipe’. The most advanced forms of this technology can be expanded to maximise the liner‘s internal diameter, or are wound by a machine that traverses the pipeline winding the liner against the pipe wall.”
Kembla’s SWP DiaFit, as the name infers, is of the type that is expanded against the internal surface of the existing pipe, resulting in a tight fit to the internal diameter of the host pipe.
SWP is formed by a hydraulically-driven winding machine which is normally positioned in a manhole or small access excavation. The lead end of the tube rotates as it travels down the host pipe as further turns of the helix are added. The tube is of a smaller diameter than the host pipe and because it is not being simply pulled into the pipe (as with normal slip lining) the rotating tube “rides over” displaced joints etc.
During installation, the joint between adjacent turns of the helix is prevented from slipping by a secondary mechanical lock in the profile. Once the smaller-diameter tube has reached the opposite manhole, the winding machine continues to operate while a small wire is pulled through the secondary lock that releases the primary lock so that it can slide within itself. As this primary lock slides, the pipe expands progressively in diameter until a tight fit is achieved.