A polypropylene pipe is actively used in the arrangement of heating and water supply systems for private houses, apartments, enterprises and other facilities. Due to the fact that the pipe is sold in segments of 2-4 m, for a strong tight connection, individual segments have to be welded together. In addition, it is necessary to take into account turns, branches, the transition from polypropylene to metal and other nuances that will be encountered in the work.

Fitting options indispensable for the installer

A fitting will help solve these problems. It is an element of a reliable hermetic connection, which already from the factory is suitable for specific needs. This is either a turn, or a connection of two segments, or a transition from plastic to metal, as well as tees, couplings, and other options that are aimed at facilitating the workflow and the possibility of building heating and water supply systems of various configurations.

Specifications of polypropylene fittings

Understanding the technical aspects of a polypropylene pipe will allow you to install it correctly. Fittings are also made of polypropylene, we can accept the same characteristics for most offers on the market as for pipes. Actually, among the technical characteristics of modern polypropylene pipes and fittings, there are:

  • Density. This criterion allows achieving high load resistance, low abrasion over time, as well as hardness and fracture strength. The average density is 0.91 kg per cubic centimeter.
  • Thermal conductivity. Like a polypropylene pipe, the fitting does not form condensate on the surface, due to the low coefficient of thermal conductivity. That is why polypropylene pipes are conveniently mounted under the floor surface or in the walls, which adds additional strength.
Summary table of technical characteristics of pipes and fittings
  • High strength. With proper soldering, we are guaranteed to get a reliable connection that will last us for many decades. The main thing is not to drill the connection body, not to bend, not to subject it to tensile loads. Modern connectors easily withstand pressure up to 10 atmospheres of water.
  • Due to the chemically inactive environment, the products easily tolerate the impact of concrete, plaster and other finishing materials. Together with pipes, they can be used in enterprises and factories, in wet or too dry conditions.
  • Temperature resistant. Here, it is worth taking into account the type of liquid, as well as the use of connectors and turns indoors or outdoors. It is not recommended that the connection be exposed to negative temperatures, since under the expansion of water during freezing, polypropylene can easily burst. The brittleness temperature is fixed at -5 to -15 degrees. Don’t forget about wear and tear. The higher the temperature of the carrier, the less the product will last. It is believed that manufacturers test polypropylene at temperatures up to 40 degrees Celsius.
An example of product deformation under high temperature


This implies another technical feature, as a linear expansion. Thanks to this criterion, the material is stretched per meter by at least 10 mm, when operating the coolant from 40 to 90 degrees Celsius.

Main types

Types of modern fittings for polypropylene pipes are not always made only on the basis of this material. There are combined models that combine the transition from plastic to metal. There are varieties that involve the presence of a damper, they are a faucet, which provides control over the operation of a particular water supply circuit. Accordingly, fittings may differ in purpose, in the method of use and installation. The following varieties can be distinguished on the market:

Some coupling options on the market
  • Coupling. This is an adapter designed to connect two pipes of the same or different diameters. Accordingly, the transition from plastic to metal can be called a coupling, since it also allows you to connect two types of pipes. Couplings are characterized by the presence of a thread, a nut, an o-ring, which is especially typical for adapters from plastic to metal.
  • Adapter. Here we are talking about a polypropylene variety, which, for example, on the one hand has a diameter of 32 pipes, on the other, the diameter is underestimated, for example, 25 mm. Adapters are needed to narrow the contour of the pipeline system, which allows you to create excess pressure in the circuit.
  • Corner. With a corner, everything is clear. This option allows you to rotate the contour in the desired position. The angle is 90 and 45 degrees. Their diameters can be equivalent, that is, a 32-pipe entered the corner, and a similar one came out. It can be narrowed, which is just as easily achieved with an adapter.
American — one of the many options on sale


  • American. With the advent of this connection, installers were able to significantly facilitate their work. American is a combination of plastic and metal. That is, it is a detachable connection, which is sealed with a rubber insert. It is convenient to install American women in detachable sections of a heating and water supply system, for example, at the installation site of a circulation pump, as well as when connecting a hydraulic accumulator.
  • A tee is an element of the system that is designed to divert a pipe in one part or another. Tees are actively used when connecting a radiator, as they allow you to power this heating element and continue the system further. Like corners, they can differ in the diameter of the inlet and outlet holes.
Collector assembled on the basis of polypropylene
  • A polypropylene manifold is used to distribute liquid in the main pipe. With proper dexterity, the collectors can be assembled independently from tees, making the required number of bends for yourself. A collector of such a plan will be much cheaper than the usual metal collector of a warm floor in a private house.
  • Cross. This element is convenient for unsoldering boiler rooms. The crosspiece has four outlets, each of which is located at an angle of 90 degrees relative to each other.
  • Bypass. It is a means of transition, which is important when equipping a boiler room. Thanks to the bypass, you can bypass a hot or cold pipe without compromising integrity. The presence of such products significantly saves the installer’s time during work.

Design, functionality, connection type and main diameters of a polypropylene fitting

Like a pipe, a fitting has a smooth surface on the outside and inside. Therefore, it does not affect the throughput inside the closed loop. On each side of the fitting there is a round hole designed for the inlet and outlet of pipes, respectively. If the product is completely made on the basis of polypropylene, then before installation it must be heated using a special soldering iron, choosing the right temperature and heating time. In the case of a combined option, for example, with an American, soldering is performed on one side, and threaded installation is performed on the other using a gas or plumbing key of the Crocodile type.

Fitting in the projection «side» with the indication of the dimensions of the correspondence


Any fitting has a diameter, which is determined in millimeters or inches. Among the most popular sizes of fittings, models for 20, 25, 32 and 40 mm can be distinguished. When working with them, experience is important, since the heating time of the fitting and pipe, depending on the diameter, may be different. For example, for a diameter of 20 mm, it is recommended to hold 4-5 seconds, for 25 diameters 7-8 seconds, for 32 about 10-12. All this is individual, depending on the manufacturer of the material and the power of the soldering iron. The specified exposure time is relevant for the heating temperature of the soldering iron of the order of 250-270 degrees.

As for the threaded connection, when connecting to a metal section of the system or installing equipment, it is important to achieve tightness. To do this, use flax and plumbing paste in the complex, fum tape and other devices. Using flax, it is important to wind it in the direction of the screwed nut, because otherwise the tightness of the joint will be broken.

Scope of a fitting from polypropylene

The main field of operation of a fitting based on polypropylene is water supply and heating. Let’s look at an approximate heating scheme for a small house. Suppose that we removed a 32 mm pipe from the boiler room. To create excess pressure in the circuit, it is necessary to narrow the channel, making the transition from a diameter of 32 to 25 mm. To do this, you need to use a through fitting and, first, solder an adapter into it to a smaller diameter, and only then solder the main transition. Similarly, you can do it in the corner of the room, so that after turning a pipe of a smaller diameter goes.

Possible product options for work

In order to make a tap to the battery, you need a tee. The battery is usually connected with a diameter of 20 mm, so again a transition will be required. Corners and contours will be involved here. The quantity is calculated by the master individually for a specific drawing of the house.

In order to embed the circulation pump into the heating system of the house, you should use American women at the inlet and outlet of the equipment. They will also allow the installation of cranes that will facilitate the replacement of equipment in case of an unforeseen repair. The American is used wherever you need to install detachable equipment.

Possible way to connect the circulation pump to the heating system


The transition from plastic to metal to the desired diameter is used both when connecting a radiator and when installing a water supply circuit. It is on the external thread of the transition that a hose will then be wound, connecting the tap to hot and cold water.

The right choice of fitting by diameter — the main nuances of installation

The diameter of the fitting can be selected exactly by name. It is impossible to adjust the fitting in diameter by chamfering inside the product. When choosing, pay attention to the pipe with which you work. It always has a marking that shows the outer diameter of the product. Without heating, the pipe will not enter the fitting, as heating will help to remove the top layer.

If everything is clear with the choice of the diameter of the polypropylene part, then when choosing the thread diameter, you need to be careful. For example, a polypropylene plank with water outlets, for the most part, comes with a ¾ inch internal thread diameter. However, there are options with a thread diameter of ½, which should be taken into account for specific equipment and see the correspondence table.

As for the tips, during the soldering of the fitting, as well as after finishing work, you must adhere to the following rules:

  • After soldering, it is necessary to check by touch or visually that the hole of the inner diameter of the channel has not undergone deformation. Otherwise, if there is a seal, the water in the system will pass with an obstacle, which will lead to a decrease in pressure in the circuit.
  • If during soldering you overexposed the fitting, and at the time when the connection was made, it burst, it is recommended to cut off the damaged part. It is forbidden to use a broken fitting, especially if you are going to lay the water supply under the screed or into the wall.
  • After welding of the water supply or heating circuit is completed, it is recommended to perform a pressure test and check how well the circuit holds the set pressure. This is important before pouring the floor screed if the pipe is hidden.
  • Try to use fittings and pipes from the same manufacturer. Still, the composition of polypropylene, for better weldability of the material, should be the same.
  • To properly position the fitting relative to the plane in which it will lie, try on and mark with a pencil in the form of stripes. After heating, we simply join the notches. When soldering, make a notch on the pipe to a depth of 1.5 cm so that when it is pressed into the fitting, you do not pass or clog the hole inside.
  • Observe the temperature regime of the soldering iron, do not overexpose the fitting when heated, monitor its appearance and the absence of factory damage.


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