Joining the Pipe

There are several types of fittings to go with rigid CPVC pipe and what they all have in common is that they need to be connected to the plastic pipe by ‘solvent welding’. What this means is that the ends of the pipe will have to be cleaned with solvent cleaner. Once this has been done, it is time to brush on the solvent weld cement. Then twist the pipe into the fitting and leave it to do its magic. What happens is that the cement kind of melts onto the pipe surface, fusing pipe and fitting together. It would be advisable to leave it for at least an hour and if you can – leave it in a well ventilated room as the solvent-weld cement will create some powerful and rather nasty fumes. If you are working on a hot water joint, you will have to leave it for longer. About four hours should do the trick.

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It is easier to make a polybutylene joint as the push-fit fittings used, comes with so called O-ring seals. Just push a stainless steel insert into the end of the pipe and it can then be connected to the fitting by applying a firm pressure to it. You will notice two points of resistance and the pipe has to go past the first point to do the job. Keep in mind that slimline fittings are permanent whilst demountable fittings are not. The pipe can however be rotated in both of the fittings.

Supporting the Pipe

If you are using a plastic pipe you will need to provide support at even intervals. The reason for this is that a plastic pipe has a habit of expanding if it is carrying hot water. So depending on what temperature water the pipe will be carrying, the supporting intervals might vary. Generally speaking, I would say that you should try to add supports for a minimum of every 33 cm for horizontal runs and about every 50 cm for vertical runs. Leave some space at the ends of the pipe so they will have room to expand. Avoid installing plastic pipe near appliances that get got. Another thing to keep in mind when working with plastic pipe is that the electric earth connection is lost. Basically all exposed metal fittings and metal pipe have to be connected to the main earth terminal. This means that you will have to run separate earth wires in all places where plastic pipes have been fitted.

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