A Rieber type belling process specific for PVC-O pipes (i.e. polymer pipes with oriented molecules) has been developed by Sica, an Italian manufacturer of plastic pipe processing equipment. These pipes have wall thicknesses approximately 35-40% lower than those made of PVC-U with the same operating pressure and make it possible to create water supply pipes with operating pressures of up to 25 bar. Thanks to these and other premium features, PVC-O pipe systems are increasingly in demand on the market. Like PVC-U pipes, the PVC-O pipes are joined by means of a belling process. The socket, including the ring seat, is produced on extrusion lines using special belling machines.
PVC-U pipes may feature Anger type sockets, i.e. with removable and replaceable ring, or Rieber tyle sockets, i.e. with the ring inserted during the belling phase which cannot be removed during the assembly of the pipeline. The Rieber system is popular because it reduces the possibility of accidental displacement of the ring during the pipeline laying stage as well as the risk of water leakage and dispersion.
The belling of PVC-O pipes requires different processes than conventional PVC-U pipe belling. These specific processes, to date, have proven to be industrially viable only for Anger belling. Until now, the absence of the Rieber process in the PVC-O pipe sector prevented its application even where it is considered decisive for the operating conditions associated with the laying of PVC-O pipelines.
Sica's innovative and exclusive process for the Rieber belling of PVC-O pipes makes it possible to implement this system on the belling machines used in bi-oriented pipe production plants. In fact, these belling machines are able to process pipes both produced and oriented continuously on the extrusion line and pipes oriented off line in the vat. Sica's Rieber type belling process is suitable for PVC-O pipes that comply with all technical standards such as: EN 17176 (Europe), Ansi/Awwa C909 and Astm F1483 (United States), AS/NZS 4441 (Australia), CAN/CSA-B137 (Canada) and ISO 16422 (international).
As for Sica's Starbell belling machines, used for Anger processes, Sica's innovative method can be used for processing pipes with the maximum molecular orientation required by the various regulations, including ISO 16422 Class 500, which represents the most stringent standard for resistance to hydrostatic pressure of PVC-O pipe systems. The Sica machines implementing the Rieber belling process are available in three models depending on the size of the pipes to be processed.