How to Use Polybutylene Plumbing Pipe

Polybutylene tubing is brown in color and naturally flexible; in this respect it differs from CPVC tubing, which is rigid. As well as being available in 3m (10ft) lengths in all three diameters, it is also obtainable as a 100m (325ft) coil in the 15mm (1/2in) size, and as a 50m (162ft) coil in the 22mm (1/4in) size. This flexibility, and the long lengths in which the tubing is available, is particularly useful as it cuts down the time you need to spend on installation, and reduces the number of fittings necessary (which means less cost). You can thread polybutylene pipes under floors and between joists with minimal disturbance, their flexibility also allowing you to take them through apertures and round obstacles that would otherwise present serious difficulties. You can bend the tubing cold to easy bends with a minimum radius of eight times the pipe diameter; 15mm (1/2in) tube can therefore be bent to a minimum radius of 120mm (4 3/4in) and 22mm to a minimum radius of 176mm (7in). You must, however, provide a clip on either side of the bend to secure it. The flexibility of polybutylene tubing means that you will have to give continuous support to any visible horizontal pipe runs in order to eliminate the possibility of unsightly sagging.

polybutylene pipes How to Use Polybutylene Plumbing Pipe

You can cut polybutylene tube with a sharp knife or a hacksaw. However, for speed of operation and to ensure an absolutely square cut pipe end every time, the manufacturers recommend that you use their specially designed pipe shears. It would certainly be worthwhile investing in a pair of these shears before embarking on a major project that involved the making of a large number of joints.

You can join polybutylene tubing by using either non-manipulative (Type ‘A’) compression joints (as used with copper), or else the manufacturer’s own patent push-fit connectors. One of the advantages of being able to use Type ‘A’ compression joints with tubing is that it enables you to replace a length of copper pipe with polybutylene tubing using the existing compression tee or coupling.

When using polybutylene tubing with this type of joint the procedure you follow is identical to that which you adopt with copper pipe. But in order to prevent the collapse of the tube end when the cap-nut is tightened, you must insert a purpose-made stainless steel support sleeve into it. And if you use jointing compound to complete a threaded fitting connected to polybutylene pipe, make sure none comes into contact with the polybutylene

The patent polybutylene joints and fittings are available in the usual range of straight couplings, tees, elbows, reducing fittings and tap and tank connectors, and in appearance they resemble their brass compression counterparts. But there is one important difference – you don’t have to loosen or unscrew the cap-nuts to make a joint. To make a connection you simply have to push the prepared pipe end into the fitting. Polybutylene fittings have one further advantage in that they allow you to rotate a pipe that has been inserted into one of them, even when it is filled with water. This means, for example, that a polybutylene stop-valve can rest neatly against a wall until you need to use it. You then pull the handle away from the wall so you can open and close it easily.

Polybutylene pipe and fittings

1 The best way to cut polybutylene pipe is with the manufacturer’s shears. Alternatively, you can cut polybutylene pipe with a hacksaw or a sharp knife.

2 Before jointing the pipe, insert a stainless steel support sleeve into the pipe end. This prevents the tube end getting crushed within the fitting.

3 Polybutylene pipe can be used with ordinary compression fittings. Within a polybutylene fitting a grab ring holds the pipe in place, while an ‘O’ ring ensures a watertight seal.

4 The witness lines on the body of the fitting indicate the length of pipe hidden within it when the joint is assembled. Remember to allow for this.

5 Before inserting polybutylene pipe into a polybutylene fitting, apply a special lubricant to both the pipe end and the interior of the socket.

6 The pipe can be withdrawn only if you unscrew the cap-nut. To re-use the joint, crush and discard the grab ring, and then replace it with a new one.


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