Metal-plastic or polypropylene pipes: the problem of choice

Comparison of polypropylene and metal-plastic pipes is probably the subject of the most fierce disputes among specialists. In fact, both materials are characterized by both pros and cons, and therefore it is possible to make an informed choice only after they have been carefully considered and only for a specific situation.

So below, we can hardly give an unequivocal answer to the question which pipes are better - polypropylene or metal-plastic, but we will definitely provide information for independent analysis!

Polypropylene

Design features

In order to reasonably decide whether it is better - polypropylene pipes or metal-plastic - it is necessary to carefully study the features of both varieties.

So we will, and first consider the products of polypropylene:

• Polypropylene is a synthetic substance that is widely used for the manufacture of tubular products. Pipes made of polypropylene are characterized by significant elasticity, resistance to chemical attack, ease of processing, etc.
• The maximum lifetime is 50 years, the upper limit of the working pressure is -25 atmospheres.
• The elasticity of the pipe walls not only facilitates installation, but is also a serious advantage when laying in unheated rooms: the risk of rupture during the formation of an ice block is reduced.

• Parts of both reinforced and non-reinforced propylene can be used for the manufacture of plumbing and drainage systems. The first option is more reliable, since the reinforcement cage enclosed in the pipe walls maintains the shape and reduces thermal deformations. At the same time, in some cases, non-reinforced varieties can also be used, especially since their price is much lower.

Note! PPL-pipes are characterized by a significant increase in length when heated: by 100⁰C it is about 150 mm by 10 m. The use of fiberglass reinforcement allows you to reduce this figure by 8-10 times, and the reinforcement of foil - 4-6 times.

• The main volume of the market for such products is occupied by products of Czech and Turkish manufacturers. The quality of European parts is somewhat higher, however, if you purchase materials for laying a pipeline in a private house (that is, where it will not experience extreme loads), you can safely take the "Turk" in order to save.

Mounting technology

Replacing metal pipes with polypropylene can be done independently. To do this, however, we will need to master the technique of welding plastic fittings and purchase (or rent) a special soldering iron.

Connect pipes with their own hands is quite simple:

• We select the pipe and fitting the desired diameter.
• We remove the chamfer from the edge of the pipe. If reinforced products are used for laying communications, we clean the foil at the point of contact, as it will interfere with the connection.
• We put nozzles on the soldering iron, the size of which corresponds to the size of the connected elements.
• We put the pipes on the nozzles and turn on the device. The warm-up time depends on the power of the device and the wall thickness: it is important not to overheat the blanks so that they do not lose their shape.

• When the plastic is heated to a state of fluidity, remove the pipes from the nozzles and insert the nozzle into the fitting. We join the parts, pushing one into the other without rotation, and leave until the molten material hardens.

Thus, it will take us only a few minutes to form one connection, which significantly reduces the time required to install the system.

Metal plastic

Pipe structure

The difference between metal pipes and polypropylene pipes lies in the fact that this type of wall product has a multi-layer construction:

• The top layer is cross-linked polyethylene (durable, chemical resistant polymer).
• Next is a layer of adhesive substance.
• Then - aluminum foil.
• Another layer of adhesion.
• And an internal sleeve from the sewed polyethylene.

Due to this structure, the pipe is quite stable, the walls are not deformed and do not heat well, and the plastic components have a minimal susceptibility to corrosion. At the same time, products of small diameters are easily bent, which facilitates installation and adjustment in size.

However, in terms of durability and durability, these products are somewhat inferior to polypropylene: they are designed for a maximum of 25 years of work and for pressures no higher than 16 atmospheres.

Connection methods

The installation manual for a pipe made of metal-plastic allows several methods of connection (see also the article Using an Apparatus for Welding Polypropylene Pipe).

For this, either crimp structures or press fittings are used.

• A crimp fitting is used where it is necessary to connect a pipe without a thread to the system.. In this case, the nozzle is inserted into the fitting, inside of which the annular insert-cracker is placed, and then fixed with a cap nut. Twisting the nut, we press the pipe to the right place, and the cracker clamps it inside with sufficient force.

Note! The main disadvantage of this connection is that with proper effort, the pipe can simply be pulled out. The risk of such a development should be minimized by fixing communications on the walls using special clamps on anchors.

• Press fittings work a little differently.. We put the part on the pipe section, install all the necessary gaskets, and then compress the structure using special tongs. Such fastening is more reliable in comparison with the previous technology, however, it requires the use of a special tool.

Selection Guidelines

Finally, it is possible to decide which pipes are better - polypropylene pipes or metal-plastic pipes, only after a comparative analysis.

So:

• If you take the life and reliability, the undisputed leader will be polypropylene. However, MP pipes will also last for a long time, so for private use this distinction can be considered insignificant.
• The strength of the connection again for propylene products. When soldering plastic, a monolithic structure is formed, while fittings used for metal-plastic pipes cannot boast a solid safety margin.
• In addition, over time, cap nuts tend to weaken, so that they have to reach out. The main inconvenience will be delivered by those masters who are planning a hidden installation: opposite each connection, they will have to make a separate inspection hatch.

Note! On the other hand, the welding of elements makes the entire system non-separable, so that in order to carry out repairs it is necessary to cut the pipes, then build them up and weld them again.

• Another disadvantage of crimp structures and press fittings is the narrowing of the pipe lumen. If for polypropylene the internal section of the entrance pipe at the junction is about 14-15 mm, then for MP - 8-9 mm. Accordingly, the pressure will change.
• A plus of the metal-plastic will be its flexibility: turns and knees of the system can be done with the help of an internal pipe bender without disturbing the integrity of the contour. But with polypropylene so do not learn from, and for each branch from the direct section you need to apply the appropriate fitting, so that the price will eventually grow quite significantly.

• As for the complexity of installation, it all depends on preferences: someone copes better with a soldering iron, and for someone, installing a crimp design is not difficult.

Conclusion

Summarizing all the arguments in the article about which pipe is better - polypropylene or metal-plastic, it can be concluded that both materials have undoubted advantages. However, metal-polymer products are still inferior to propylene in terms of reliability and durability, and at practically equivalent costs (fittings require more, but they are cheaper), the choice is often made precisely in favor of plastic on permanent connections.

If you want to familiarize yourself with the features of the above-mentioned technologies and materials in more detail, we recommend that you carefully study the video in this article.