All about plastic plumbing

Using either of the methods described above, but note that as it is more rigid, the radius of the bend needs to exceed ten times the external diameter of the pipe if it is bent in a cold state, and six times the external diameter if heat is used. As this type of polythene has a higher softening point, use a blow-lamp rather than boiling water, again keeping the flame moving.
Pvc and abs pipes have to be bent using a blow-lamp, but in this case a bending spring is not required. It is important to note that heat must never be applied near the mouth of a pipe, as small distortions may occur and prevent a good watertight joint being made. If you require a bend right at the end of a length of pipe, start with a longer piece of pipe, form the bend away from the en and then cutoff the excess.

Joining plastic pipes

There are three types of joint commonly used for jointing plastic pipes-compression joints, solvent welded joints and joints made by a rubber '0' ring contained in a socket or 14 special fitting. Always use the joint provided by the manufacturer for the system you are using and read the accompanying instructions very carefully before starting work as there may be slight variations on those given below.
Compression fittings are generally used for jointing polythene pipes. These fittings are of the non-manipulative type which means that you do not have to widen, or bell out, the end of the pipe when using them. The fitting may be made of plastic or metal, but note that the type of compression fitting used for jointing metal pipes is not suitable for jointing plastic pipes together as the plastic, being flexible, cannot be clamped firmly in the body of the fitting.

With compression fittings for plastic pipework a special sleeve is inserted inside the pipe end to prevent it becoming distorted when the nut on the fitting is tightened. If you have difficulty inserting the sleeve, carefully apply heat to the end of the pipe. This will soften it sufficiently to allow the sleeve to be slipped in.
To assemble the joint, start by placing the nut and then the compression ring on each pipe end. Insert the sleeve and then push one pipe end into the body of the fitting and tighten the nut by hand. Finally use a spanner on the nut but be careful to avoid overtightening (a couple of turns should be sufficient). Then repeat the procedure for the other pipe end to complete the joint.
Solvent welded joints are easy to make and exceptionally strong. A chemical is coated over both surfaces of the joint which welds the plastic surfaces together and, provided the instructions are followed carefully, there is little that can go wrong. Socketed pipes, or a special separate fitting, are used with this method.

First ensure that the surfaces to be welded are completely clean and grease free. Manufacturers usually supply a special cleaner for this. Then coat the two surfaces thoroughly with the special solvent cement. Note that you should always use the solvent recommended by the manufacturers as some solvents are not suitable for particular- plastics. When both surfaces have been coated all that remains is to Insert the spigot end of the pipe into the socket of the other or into the special fitting as far as it will go (a 'stop' is provided to prevent you pushing it too far). Then give the pipes or pipe and fitting a twist to distribute the solvent evenly. Wipe off any excess solvent squeezed out of the joint and leave the joint for between 12 and 24 hours (according to the manufac- pipe, at right angles to the ends.

Making a hole in a soil pipe to connect a self locking boss. This allows you to connect a domestic drainage pipe to the soil pipe. The hole in the soil pipe is made with a tank cutter. The boss is self locking so you do not have to fix it from the inside of the soil pipe. Solvent cement is also used with this joint.

The advantage that rubber ring-sealed joints have over other methods is that allowance is made within each joint for thermal expansion (see below). With this joint an '0' or'D' shaped rubber ring is first inserted into a groove in the socket end of one pipe (or into a separate fitting). A special lubricant-soap can be used if the manufacturer does not supply one-is smeared over the spigot end of the pipe and the pipe is then pushed firmly into the socket or fitting as far as it will go.

It is particularly important to ensure that the rubber ring does not become displaced during fitting, so the two pipes must be perfectly in line during this operation. Note that the end of the spigot should be chamfered to about 15° for easy insertion. This chamfer is normally included in the spigot end during manufacture, but if you have to cut the pipe use a file to chamfer the cut end,
When you have pushed the pipe right up to the stop, withdraw the pipe a certain distance to allow for an expansion gap. This gap varies according to the material used. Some manufacturers put a mark on the pipe near the end and others give instructions as to how far to withdraw the pipe.

Installation details

The manufacturer's instructions regarding the installation of their pipework should be closely,
studied and followed exactly. The main `f tor to take into account is thermal movement. If your pipes are jointed with the ring seal method - you have no problems as allowance is made, as described above, for expansion in every joint, You must still, however, be careful that no tight restrictions are placed on the pipes themselves. Pipe clips (spaced at manufacturer's recommended intervals) must not be so tight; as to restrict the expansion of the pipe. You must also leave suitable gaps wherever pipes pass through, walls.
The solvent welding method of jointing, however, prevents any movement in the joints and allowance has to be made elsewhere ,in t system. This is done by incorporating special - expansion couplings at specified distances apart.

Providing you take particular care to read-all" - instructions thoroughly the actual physical work' involved in installing a plastic pipework system is quite straightforward and easy, and you will have a system that should be maintenance free and exceptionally long lasting