Pipes, made of various types of plastic: PEX, PP-R, PP and PE, can be joined in several different ways: by pipe threading, welding, crimping and bolting. We provide advice on which pipe connection method to choose in which case and what to look out for when connecting plastic pipes.

Joining plastic pipes - important information

Today in residential buildings water supply, sewerage and heating installations are most often made of different types of plastics:

• PEX,
• PP,
• PVC
• PE
• PB

This type of pipe is used because dampen vibrations, mutes noise in installations and do not transmit vibrations. In addition, there are resistant to moisture and are not at risk of corrosion. These materials have no effect on taste or smellThey can therefore be used in drinking water supply systems without any problems. Other advantages of plastic pipes include light weight and in some cases tube bending capability. What this entails is that they are relatively easy to install.

The types of pipe and fitting connections can be separated into two groups:

• fixed (otherwise inseparable) - in this case, once the pipes have been joined, disassembly is not possible without destroying them. Such connections are made by welding, bonding of cables and clamping connection 
• disconnected - Pipes and other components in such connections can be repeatedly assembled and disassembled without damage. Examples of such joints are Threaded pipe connections, as well as Socket connections i flange.

Which pipe joint of plastics is the best ?

The most commonly available ways of joining pipes and fittings are a direct result of the choice of material and its properties. Water pipes made of PP-R, or polypropylene is most often connected through welding. PP-R pipes are usually joined using muffbends, elbows and tees, and when joining pipes of different diameters,  PP-R reducer couplings or PP-R reducer tees. Polypropylene pipe welding uses welding machine for thermoplastics. PP-R pipes can also be connected to thread. The following are used for this purpose Fittings with molded brass thread internal or external. These fittings allow connection to other PP-R fittings with threads, or connection to a system made of another material.

PP sewage pipes

It connects through  socket connection, in other words, Push-fit connection of pipes. Useful in making this connection correctly is the slip paste (e.g. SKIDOL sliding paste 1 kg). It reduces friction when the joint is made, which reduces the force required to push the end of the pipe into the socket and protects the socket gasket from damage. which should be distributed in the inside the cupand then pushes a pipe in there.

PVC sewage pipes

They come in two types of systems: combined lichowo and combined adhesive. Socket joints work identically to sewer pipes with PP. Using pipes glue-bonded PVC the connection shall be made by cutting the pipe to the required length and chamfering The pipe should be cut at the cutting point (by smoothing the edges). Lubricate the barefoot end of the pipe and the socket with glue, and turn the pipe 90° when inserting it into the socket.

Joining PEX-pipes

It is most commonly used in central heating and hot water installations. For joining PEX pipes, the following are most commonly used press-fit fittings. Specialised crimping machines are used for crimping. These are machines with suitable jaws adapted to the fittings systems of specific manufacturers, which make the connection in an automated and repeatable manner. Joining by pressing is indissoluble.

Joining PE pipes

In the case of PE pipes several combination methods can be used: butt welding, electrofusion welding or bolting. Welding involves the controlled heating of the surfaces of the pipes and fittings being joined to a temperature at which the material becomes plasticised. Once the joint is made and cooled, it is inseparable.

For butt-welding, welding machines are used, for example in the form of a heated plate to which the ends of the pipes to be welded are applied.  Once the desired temperature has been reached, the plate is removed and the parts to be joined are compressed together. This method is most commonly used for large-diameter PE pipes (e.g. Water pipe 125×7.4 PE/PE100 SDR17 TYTAN RC 2/2 L=12m blue with white stripe Kaczmarek).

Electrofusion welding uses a special type of fitting whose sockets contain special heating spirals. When connected to the fitting with an electrofusion welding machine, e.g. Electrofusion welding machine Eurotech 1000, the fittings are welded to the pipes.

Water pipes from PE small diameters can also be connected without special tools, using fittings twisted. Twisted fittings, e.g. PE 25 twist coupler is a type of compression fitting in which tightening the outer part of the socket causes the inner ring to clamp onto the pipe. It is a disconnected connection.

Pipe joining - summary

As you can see, there is no clear answer to the question: which joining method is best? The choice of how to join pipes in an installation depends on what kind of installation you are building, what material you decide on, what tools you have available, and whether you want to be able to modify the connections after they have been assembled. Remember that pipes can only be joined using fittings. You can read about the types of fittings in a separate article.