Pipes

How to connect plastic pipes: methods and their implementation

January 9, 2020

How to connect plastic pipes, depends on the material and specific operating conditions of the water supply. There are detachable and non-detachable connections. The latter are divided into welded butt and bell. Detachable connections of plastic pipes allow to dismantle the pipeline if necessary. Flange joining is the most time consuming.

The method of connecting plastic pipes depends on the purpose of the pipeline

The main types of polymer pipes

Currently, the most common are pipes made of such materials:

  • polyethylene;
  • polypropylene;
  • polyvinyl chloride (Pvc);
  • cross-linked polyethylene.

There are also metal-plastic pipes, having an internal structural aluminum component.

Polymer pipes have a smooth inner surface, which prevents the accumulation of sediment, allows to reduce noise level at movement of liquid and to show resistance to emergence of a rust. Such products should be protected from mechanical damage, shocks or sharp compression.

pay attention! During transportation of water with high temperature the pipe is capable to expand, which reduces the risk of its breakthrough.

In the case of significant heating, it may increase, this leads to loosening of the threaded connections. For polypropylene, the critical temperature is 140 ° C. From choosing that, how to connect plastic pipes, the durability of operation of a water supply system depends.

Modern industry produces various types of plastic pipes

Ways to connect plastic products

Plastic pipes can be connected in different ways. The main ones are:

  • into the socket;
  • using an adhesive composition;
  • threaded connection;
  • diffuse welding;
  • flange connections;
  • docking with the use of collets;
  • welding with the electric coupling.

Hand-held pipe connections are more commonly used in gravity systems, example, sewer. It can also be used for plumbing, working under pressure. Standard adhesive composition or "cold welding" can be used to connect plastic pipes, which involves dissolving the upper part of the polymer under the action of a specific component of the adhesive and the adhesion of two parts at the molecular level. This is how sewer pipes are connected, water supply systems and networks, transporting gas.

Electrocoupling welding is the connection of pipes with a heating element

Plastic pipes are connected to metal products as threads, and flange method. For diffuse (high temperature) welding is characterized by preheating of parts in a special device, and then their joining. At flange connection of pipes the metal overhead flanges or welded plugs under them are used by the hands..

Connections for plastic pipes with the use of collets are typical installation with crimp fittings. The teeth of the metal pipe, crashing into the product, form a joint. For welding with an electric coupling, the parts are cleaned and degreased. After the current is connected, the pipes are heated and the connection is formed.

PVC pipe connections

There are the following ways to connect PVC pipes with your own hands:

  • bell-shaped;
  • using an adhesive composition.

Polyvinyl chloride pipes have a bell at one end, in which the rubber seal is installed. At the initial stage of connection the pipe is cut by a pipe cutter or a hacksaw on metal into necessary segments. Further, the connecting end and the inner surface of the bell are stripped. The smooth end of a plastic pipe is inserted into it to the stop, which is lubricated with silicone composition. The pipe must be pulled out 7-10 mm, pulling on her. It is better to pre-label, to control the degree of extraction.

Sewer pipes are most often connected to the pipe

It is necessary to connect PVC pipes with the help of an adhesive composition:

  • sand the outer surface of the plastic pipe and the inner part of the bell;
  • degrease the bonded surfaces;
  • apply glue to the entire part of the pipe, which will be entered into the bell;
  • insert the prepared pipe all the way into the socket and return it to 90 degrees;
  • press the glued parts and hold for about a minute.

Degreasing, applying glue, the connection of the parts must take at least three minutes, which will ensure the quality of adhesion.

Wrinkle! It is better to use methylene chloride for degreasing.

The glue hardens completely in a few hours.

Methods of connecting cross-linked polyethylene pipes

There are several ways to connect cross-linked polyethylene pipes with your own hands:

  • compression fittings;
  • press fittings;
  • electrowelded fittings.

The latter method is rarely used, as it requires special equipment. In the case of a compression fitting, the property of cross-linked polyethylene to restore its shape after some deformation plays an important role., in which the polymer molecules on the fitting completely fill the gaps and depressions.

Compression and press fittings can be used to install cross-linked polyethylene pipes

For, to carry out the coupling work correctly with your own hands, two mounting sleeves are required, equal coupling, tool for flaring plastic pipes.

Using a pipe cutter, from the end of the pipe is cut off 5 cm of its length, the chamfer is removed at the end. A sleeve is put on the prepared part of the pipe. In it the end of a pipe is flared with use of the hydraulic or manual tool. Further, the coupling is inserted, on which the sleeve is pushed. Similar steps are performed for the other end of the cross-linked polyethylene pipe.

The coupling method of connecting plastic pipes is tight and reliable.

Features of polypropylene pipe joints

With their own hands pipes up to 6,3 cm are preferably connected by a bell-shaped method or by coupling welding. For pipes of large diameters it is recommended to apply butt welding. Welding of polypropylene pipes with a diameter up to 4 cm can be performed by manual welding machine, more 4 cm - a device with a centering device. Heating element (nozzle) is a sleeve and mandrel, which melts the outer surface of the pipe and the inner part of the bell.

Polypropylene pipes are securely connected by hot welding

Standard Teflon nozzles have a diameter 16-40 mm and after each case of welding are cleaned.

Importantly! It is inadmissible to clean a cold nozzle from a plastic layer.

The welding machine with the necessary nozzles is installed on a flat surface and fixed. The welding temperature of polypropylene pipes is close 260 degrees. Bell welding is performed in the following sequence:

  • the pipe is cut at a right angle;
  • the fitting bell and the end of the pipe are cleaned of dust and dirt;
  • a mark is placed on the pipe at a distance 2 mm more, than the depth of the bell;
  • a pipe is inserted into the sleeve, and a bell is put on the mandrel;
  • withstand the required heating time, remove the parts and join them.

Polypropylene pipes can be connected with compression fittings. No special equipment is required for installation.

Compression fittings are also an acceptable option for connecting PP pipes

Polyethylene pipe connections

The most reliable ways to connect polyethylene pipes with your own hands - butt and thermistor welding. Non-pressure structures can be glued. For butt welding, the ends of the pipes, to be connected, are installed in the hub of the machine. The ends are fixed, are aligned, are cleaned and mechanically processed by a butcher.

Further, the surfaces are heated, connected by a special tool, which is removed after melting of welded surfaces. The connection is formed by closing the ends of the plastic pipes with the necessary effort. The clamping pressure gradually increases to the required value. The joint cools down after a while and the joint is ready for use.

Butt welding is used for pipes with a larger diameter 63 mm Polyethylene pipes can be connected by means of a coupling with electrically heated mortgage elements. This joint is designed for pressure 16 atm.

One of the ways to install plastic pipes - butt welding

Detachable joints of small diameter polyethylene pipes (to 50 mm) can be obtained, applying fittings. The collet crimp connection is designed for pressure 25 atm. Thanks to a rubber sealing ring tightness of a joint is reached, and cutting the teeth of the plastic sleeve into the pipe - resistance to mechanical loads.

Joining of metal-plastic pipes

Welding is applied to metal-plastic pipes, because the temperature used is not enough to melt aluminum. The pipeline from similar materials gathers on fittings. With their own hands, the connection of plastic pipes with a metal layer is carried out using:

  • press fittings;
  • crimp fittings;
  • push fittings.

The latter method provides easy and quick installation, high degree of reliability, the ability to disassemble the joint if necessary. in addition, the connection requires a minimum number of tools - a calibrator and a cutter.

A special tool is required to install the crimp fittings

The installation of press fittings gives an inseparable connection. The formation of the crimping unit is carried out by a special device. First, the pipe is cut off and the end is processed with a calibrator. The crimp coupling is put on a pipe. After inserting the fitting, it is crimped with electric or manual press pliers.

Importantly! Re-compression of the coupling with press pliers is prohibited.

The maximum allowable pressure at the joint is 10 there is.

The choice of elements and methods of joining is quite wide. This allows you to find the most appropriate solutions when installing the pipeline, how to properly connect plastic pipes.