PPR fittings - rules for selection and use of connections

To replace an old steel water pipe with a new one made of polypropylene, you will need three things - polypropylene pipes, soldering iron with cutter and PPR fittings. You can master the assembly technology in 10-15 minutes, and the choice of pipe is usually limited to the selection of characteristics by cross-section and water temperature.

With PPR fittings, the situation is somewhat more complicated - there are many models, so it’s easy to get confused and buy unnecessary additional material. What should you pay attention to?

Where are they used?

The simplest solution is to use a ready-made catalog of PPR fittings from a well-known company that produces polypropylene pipes and additional elements for them. Such documents contain everything you need for the correct selection of fittings.

You can also look into GOST R52134-2003, but the standard is written mainly for specialists and companies manufacturing products made from PPR polymer, so it will not be of interest to the average user. Although it does contain interesting information about the durability of polymer parts made of PPR plastic.

Fittings are used for the following purposes:

• using couplings and adapters, they connect polypropylene pipes into one sealed structure, for example, a water supply system or a heating system circuit;
• both the pipeline itself is connected to sources of hot and cold water, air, liquid media, and various consumers are inserted into its body, from household plumbing to heating radiators.

All existing models of PPR fittings are mounted on polypropylene pipes only using hot soldering, at least on one of the mounting holes. No adhesive or threading methods are used to connect parts made of PPR polymer.

Hot welding provides a monolithic, seamless connection. This means that under radial or transverse load, the junction of the PPR fitting with the pipe will not fail due to fatigue failure of the seam. As happens with glued PVC, PD and crimp couplings of metal-plastic pipes.

Therefore, polypropylene systems with welded fittings can be used to heat the floor, any loaded surface. The layout and assembly of pipes on PPR couplings is somewhat different from the generally accepted one for plumbing or heating.

Types of PPR fittings

The simplest catalog of PPR fittings includes more than 40 models. Each type is manufactured for 10 main diameters of polypropylene pipes, from 20 mm to 63 mm.

The entire range of polypropylene PPR fittings is divided into four groups:

• couplings, adapters for splicing PPR pipes;
• elements for branching heating lines and water pipelines;
• taps, locking devices;
• service elements.

Some fittings are made by casting only from polypropylene and are connected to PPR pipes using soldering. Most of the range contains composite parts consisting of a polypropylene body and a metal threaded insert. This can be a soldered internal thread, an external fitting, a steel nipple with a brass union nut, or a valve stem.

Couplings and tees

Used for joining individual pipe blanks. PPR couplings are divided into transition and main ones.The first type of fittings is used to transition from a smaller diameter polypropylene line to a larger one, connecting to a steel pipe.

Basic couplings are used for soldering two or more polypropylene pipe blanks into one structure. In addition to the usual barrel or angle, tees and crosses are used for joining PPR pipes, both in a pure polypropylene body and with a metal insert.

It is necessary to additionally mention PPR corners or half bends. Craftsmen always purchase several types of corner turns with different angles for assembly. Usually it is a right angle, 30^O and 45^O. From such a set of fittings you can solder a bypass or transition of any configuration.

Cranes

In the polypropylene communications system, two types of locking devices are used. These are full bore ball models and valve type valves. The latter are characterized by increased hydraulic losses, but are more reliable when working with high water pressure.

Also Angle ball valves They are placed on heating radiators and on flexible hoses for connecting plumbing fixtures and boilers.

Regardless of the faucet model, coarse filters are installed in heating and water supply systems. PPR fittings with a ball or disk locking element are highly sensitive to contaminants in water.

Auxiliary products

Connecting consumers to the polypropylene pipeline is done using corner or double water sockets. For kitchens, showers and bathrooms, ready-made kits are used for installing faucets without the use of flexible hoses.

Also included in the service group are PPR bypass couplings, curved bypass pipes, and transition bridges, which are used to bypass obstacles at the pipeline installation site.

This also includes clips and fastening clamps, as a mandatory element of any polypropylene pipelines, although they are not full-fledged fittings.

What technical characteristics do they have?

The polypropylene mass of the PPR brand, from which pipes are extruded and additional elements are poured into them, is a random copolymer of polypropylene. The material is not afraid of cold and hot water, weak acids and alkalis.

Most fittings, except for simple and transition couplings, have a more complex structure compared to pipes. Therefore, for their production, more rigid polypropylene 80 is used. After leaving the hot stamp, the product does not deform or “float”, as when using a more plastic and fluid random copolymer.

The fitting material begins to melt at 250℃. With prolonged heating up to 150 ^OWith PPR, the coupling loses strength and begins to float under pressure, so it is better not to use polypropylene parts for steam heating. In this case, the pipe itself, if it is reinforced with fiberglass or aluminum foil, can remain intact.

The maximum operating temperature is considered to be +95 ℃; in such conditions, the PPR coupling can operate for at least 20 years.More complex products - corners, tees, filters made of polypropylene will last approximately half as long. Therefore, heating systems use metal fittings on adapter couplings. Polypropylene can be used for plumbing.

At room temperature, polypropylene fittings can withstand pressures of up to 100 bar for a short time. But it is worth remembering that this is not metal; any increase in water pressure by more than 20% of the working pressure leads to barely noticeable residual deformations.

Polypropylene water pipes are not tested at pressures higher than 20 bar for more than 10 minutes at room temperature. If you go beyond these limits, there is a chance that filters, taps or adapters with metal fittings will leak.

With heating or water supply systems soldered only using PPR fittings, you can experiment at higher pressures and at higher temperatures. Therefore, after soldering the pipes, craftsmen often do not connect the heating boiler (pressure restrictions up to 3 bar), but pressurize the line at a pressure of up to 30 bar for half an hour. If there is no leakage of water from the couplings, then the polypropylene part of the heating system is guaranteed to last 25-30 years.

Advantages and disadvantages

Polypropylene pipes with additional PPR elements have been used in practice for more than 20 years. The increased popularity of water supply and heating systems made of polypropylene, and their gradual displacement of old steel communications only confirms the correctness of the choice made in favor of polypropylene.

Positive aspects of using polypropylene parts

The most important advantage of using PPR fittings is the simple assembly technology. Soldering with a hand soldering iron It takes a few minutes to assemble one connection point, while ensuring reliable connection of the parts. At the same time, the quality of the joint on the PPR coupling is high.

A scheme for compensating for the movement of a pipe due to heating, which is welded into a heating or hot water supply line, can help assess reliability.

Due to the large coefficient of thermal expansion, a long polypropylene pipe changes its longitudinal size. Every time a hot water tap is opened or heated coolant is supplied to the heating system, the pipe lengthens by 4-10 mm and contracts as it cools.

Variable load can unbend the PPR corner hundreds of times during the day. The advantage of polypropylene fittings is that at this point it is impossible to replace them with brass or steel - they are not able to withstand such a load.

In addition, the advantage of PPR fittings is the high sanitary safety of polypropylene. The material does not release any substances into the water, so it can be used for drinking without restrictions. While brass couplings and adapters are made from brass with a lead content of up to 2.5%. As the nickel plating wears away, the metal may dissolve in water.

Disadvantages of using PPR fittings

The main disadvantage of using polypropylene couplings and taps is considered to be relatively weak resistance to contaminated water. The more microparticles of sand and rust in the water, the faster the fittings wear out.

Service life may vary for different models.For example, couplings installed using soldering technology can last for several decades. While transition couplings of the plastic-metal thread type, ball valves with a metal ball on hot water work for no more than 15-17 years, after which they need to be replaced. In clean, cold water, fittings will last up to 30 years.

How to install polypropylene fittings

Thanks to the use of a special tool - an electric soldering iron and trimming scissors - you can install a PPR coupling or any other fitting in 5-7 minutes, depending on the diameter of the polypropylene pipe. The larger the transverse size, the longer the workpieces need to be heated. It takes several times longer for the connection to cool down to a safe state.

If the coupling or tap has a fitting or an internal thread for fitting, then first of all you need to assemble it, pack it with FUM tape and screw the threaded connection. After the PPR fitting is soldered to the polypropylene pipe, it will be very inconvenient to install the fitting.

The installation process of a polypropylene fitting is as follows:

• We select a model that is suitable for the configuration. We remove the chamfer from the seat on the pipe, and then use a caliper to check the correspondence of the internal and external diameters of the parts being connected. A difference of 0.1mm is allowed;
• install a set of nozzles on the soldering iron, set the heating temperature;
• determine the correct relative position of the fitting to be welded and the pipe, it is advisable to immediately apply marks with a marker;
• We put the fitting and PPR pipe onto the nozzles by hand, wait a few seconds, remove them and insert them tightly into each other.

Set aside the soldered joint for 5 minutes, let it cool so much that the part can be held with the palm of your hand without much discomfort. We check the quality of the seam; melt or flash should appear along the connection line between the PPR pipe and the polypropylene fitting. In addition, you need to check the part for clearance - make sure that there is no melt plug.

Polypropylene lessons on welding pipes and fittings using a soldering machine: video.

The advantages of PPR fittings are simple assembly of parts, reliability, high connection strength at relatively low costs for components. In practice, things are not always as they are in theory; many shortcomings appear many years later. Share with like-minded people your experience, problems and their solutions when using additional elements for polypropylene pipes in the comments. Save the article to your bookmarks.