Jointing of Pipes
Plastic Pipes Conference Association # 1998 Gothenburg
Smith, Guzowski
Some forty years ago simple 0 ring joints for PVCu pipes were just being introduced as an alternative to solvent cemented joints. Rubber lip seal type of joints soon followed for both pressure and non pressure applications. Whilst in theory these designs were fine, both styles of joint had operational problems, mostly, but not exclusively, in the pressure pipe market.
The problem for these early joints was in being able to accommodate a wide range of tolerances for pipe spigot and socket, including pipe ovality, as well as those production tolerances of the gasket. Often it was the 'on site' condition that was more important than the 'in factory' dimensions that mattered .Whilst under pressure, in certain circumstances, some of the sockets could grow, distort or deform, leading to possible gasket movement and loss of sealing. Certain companies ensured the stability of their sockets by thickening the wall section or fitting a collar either internally or externally.
During this period of development, the concept of forming sockets on pipe, both in line and off line developed, with collapsible mandrel belling machines evolving particularly in Europe. Over the next ten years automatic belling machines and higher performmce gaskets evolved including the well known Anger B system. These joints and similar ones were a significant improvement and they paid a significant part in establishing PVCu pipe at the forefront of water and sewerage applications enabling PVC pipe to compete with ductile iron pipe with its tried and well proven Tyton rubber gaskets.
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