Pipes for fire extinguishing systems: a comparison of metal and polypropylene

There are several types of plastic pipes for use in the installation of gas communications:

• Polyvinyl chloride (PVC) remains in high demand;
• Polyethylene pipes are somewhat inferior due to the fact that they are able to function only in an insulated form and under certain temperature conditions;
• Much more functional gas metal-polymer pipes;
• polypropylene is also popular. Chemical composition and resistance to aggressive environment, does not require isolation. Low thermal conductivity prevents the formation of condensation, and therefore does not damage the transported substance.

A distinctive feature of gas pipes is a yellow stripe applied to the surface, which does not allow it to be confused with the rest.

For a long time, it is plastic pipes that have occupied the leading place among components for various systems. Gas communication is no exception, which is fully capable of appreciating all the advantages of these pipes:

• longer service life than metal;
• current conductivity and non-contact with the ground;
• light weight, which is very convenient for transportation and installation;
• reasonable price, as a result, favorable cost of communication;
• ease of installation.

Particular attention should be paid to the low pressure of polyethylene gas pipelines, which allows transportation to the most distant points. Underground gas pipelines for combustible gases are also made from these pipes.

The sequence of replacing pipes in the apartment

It is strictly forbidden to work with gas communications on your own, because they belong to the category of increased danger. Seeking help from specialists of the gas service will significantly save not only time, but also become a guarantee of your security.

An experienced gas operator will first of all perform a preliminary inspection of the gas system and determine the degree of wear.

The replacement of gas pipes in the apartment is carried out in strict observance of safety rules.

First of all, it is necessary to ensure the presence of additional ventilation in the room, shut off the gas supply and be sure to blow through the pipes. The utmost attention is paid to the presence of an open fire nearby, which is unacceptable and requires intervention.

After completing all the preparatory measures, you can start disassembling the required section of the gas pipeline. No special tools are required for this, it is enough to have an ordinary hacksaw for metal or a grinder in the house.

The gas pipe is tapped using special fittings or overhead heating elements. Installation must be done in such a way that the structure is completely sealed and does not let gas into the room.

There is currently a fairly small selection of pipes available to the buyer on the market. On the one hand, these are steel pipes, which are very strong, but they are afraid of aggressive environments, and on the other hand, they are plastic pipes that are not afraid of corrosion, but they are much more fragile. But there are also metal-plastic pipes in which the advantages of both materials are combined. In this article we will talk about metal-plastic pipes for gas, their advantages and rules of use.

Types of pipes

First, it is worth familiarizing yourself with what specific areas the gas pipeline is actually divided into in a private house. it is more optimal to parse it in the table.

Line segment:	Highlights of operation:
Access to the house itself.	As a rule, this section of the "highway" is laid underground, respectively, here the pipes are required to be resistant to corrosion and the property is not to let water through.
Mains supply from the ground to the house and laying in the premises.	In most cases, this is done above the ground, therefore, it turns out that on this section of the motorway is most exposed to the risk of damage from mechanical shock.
Connecting line from an overhead gas pipeline to concrete devices.	The device can be a stove or, for example, a wall-mounted heating boiler. On such sections, the flexibility of the connector is primarily responsible, since the same boiler can fall off the wall. And if, in such a situation, the device is connected to the gas pipeline in a "solid" way, then gas outflow from the pipe may occur.

So, we have figured out the highlights of the device and operation of all sections of the gas pipeline, let's now move on to examining the materials existing on the market. Let's try to understand which option is most suitable for each specific section of the gas pipeline and start with the "classic".

Steel products

In general, a steel gas pipeline has the following positive qualities:

1. High resistance to mechanical shock and pressure... In addition, if the metal undergoes such an action, then the maximum that will happen to it is deformation. But the appearance of cracks through which the gas can "escape" is unlikely.

Note! There will be no cracks in the structure of the metal itself, but at the points of connection, "holes" can fully appear. Based on this, when laying the system, try to plan it so that there are as many welds as possible, and not those that are made by means of fittings for connecting pipes.

1. Steel helps for a long time due to the fact that it is not afraid of any atmospheric changes and temperature effects.

Such are the advantages of steel.

As for the shortcomings of products made of this metal, it is possible to single out such a moment as the high price of the material itself and installation work. In addition, steel is susceptible to corrosion.

It turns out that it is optimal to use steel pipes for gas in a house on sections that pass above the ground in buildings and beyond. On these sections of the gas pipeline, metal is still an irreplaceable material.

Now let's move on to considering products of a different type.

Polypropylene lines

Products of that type are at first glance very attractive for pipeline assembly.

Since they are distinguished by many positive qualities.

• First, they don't rust, respectively, help for a long time.
• Secondly, they do not need a protective layer of paint.... And, for example, the same iron lines have to be tinted every couple of years. This is especially a topical nuisance for street laying - there is also GOST for gas pipes, on the basis of which fines are provided for an unpainted external line.
• Thirdly, the installation of polypropylene is quite easy, so it’s possible to save both time and money. (due to the ability to do everything yourself).

This is all correct, only there is a nuance, as a result of which such products are not suitable for laying a gas pipeline - polypropylene is "hydrogen permeable"! And as we know, methane is a hydrocarbon. In other words, the leakage of the mixture from such a line is fully possible.

As for the order for products, like a metal-plastic pipe, then there is approximately the same picture - a huge risk of leakage, but already due to the huge number of connections. And in fact, the material for this is not recommended.

Note! There are metal-plastic pipes, which are intentionally produced for gas transmission.But skilled craftsmen do not advise using them due to the fact that this threatens problems with representatives of gas works. In most cases, it is easier to refuse in order to make a decision than to prove to the authorities that it is possible to do so.

And it remains to get acquainted with the HDPE pipes.

Low pressure polyethylene pipes

Products are a modern material that is not afraid of water, does not rust and is recommended for underground transportation of most gas mixtures.

The instructions for use are very simple - it is possible to use polyethylene for underground broaching only under the following conditions:

1. In case the pipes are guaranteed not to be influenced by the air space.
2. If the line will not be exposed to ultraviolet radiation.
3. If during the operation of the gas pipeline there is no risk of mechanical shock.
4. In the event that most of the trunk connections will be made by the "welded" method of connecting polyethylene pipes, in other words, without the use of many iron fittings.

Metal-plastic pipe device

A metal-plastic pipe has an aluminum layer between two layers of polyethylene. Such pipes are joined with a laser or ultrasound, making overlap seams. Thanks to the smooth inner surface, rust and other deposits do not accumulate in the pipes. The quality, strength, flexibility and durability depend on the adhesive with which the pipe layers are glued.

Reinforced plastic is a fairly versatile material, so such pipes can be laid both inside and outside buildings. After the appearance of this material, it became possible to install "warm floor" systems.

Construction of metal-plastic pipes

The following structure of metal-plastic pipes should be distinguished:

1. A layer of polyethylene.
2. Adhesive composition.
3. Aluminum layer.
4. Adhesive composition.
5. Polyethylene layer

Specifications

The working parameters of reinforced-plastic pipes are as follows:

• working pressure - 1 MPa;
• burst pressure - 4-6 MPa;
• hydrostatic constant pressure - 2.1-2.7 MPa;
• the minimum allowable bending radius is 80-160 mm.

disadvantages

Like any other material, metal-plastic has its own negative sides. Aluminum and plastic have different indicators of thermal conductivity - aluminum is higher. This can lead to the fact that when supplied through the pipeline in short periods of time, for example, first cold and then hot water, a leak can form at the junction of the pipes.

These nuances must be taken into account when laying such pipes. The pipeline should be laid with a margin, and expansion loops should be provided at the bend.

To obtain the correct bend, it is better to use a pipe bender, well, or manually. The bending radius and angle can be adjusted with the tube bender. To bend by hand, the pipe is first filled with sand and a spring is inserted inside. In any case, the spacing of the bends should not be less than 50 mm, in addition, the pipes must not be twisted.

Benefits

Such piping systems are more flexible than plastic or steel. No bends, corners or elbows are needed to get a bend, just bend it. The complete system is simply connected to the central line, without the need for welding.

Due to their versatility, metal-plastic pipes are excellent for use in communication systems, for heating and supplying both cold and hot water, for sewerage and gas supply, and even for laying electrical wiring.

Diameters of polyethylene pipes and other characteristics - SDR, weight, wall thickness

You are here: Kanalizaciya-Stroy >> Sewer pipes Add to bookmarks Print version

The main parameter for choosing plastic bends for the house is their size.All diameters of polyethylene pipes are standardized. Depending on the type of manufacture and the impurities used, the permissible overall dimensions can vary significantly.

GOST requirements

The basic requirements for the dimensions of polyethylene pipes for cold and hot water are given in the document GOST 18599-2001 for Russia and DSTU B V.2.7-151: 2008 for Ukraine. Both of these standards fully comply with the international ISO 4427-1: 2007. Its requirements apply to any plastic pressure pipe plastic products.

Appearance of PE80 pipes

Main parameters:

• Plastic pressure pipes must withstand a pressure of at least 6.5 MPa. At the same time, in the initial stressed state, the pipes with large diameters must withstand the impact of 100 MPa;
• Thermal stability at maximum water temperature (200 degrees Celsius) for at least 20 minutes;
• No less basic characteristics, the internal appearance of the nozzles is important. Their surface should not have any cracks, gas bubbles, roughness. Color: black to dark blue with distinct longitudinal stripes. At the same time, the protective shell should be of a bright blue hue, a slight blueness of the surface is allowed. This is an important difference between water pipelines and products for gas pipelines, etc .;
• In PE 32 (diameter 32 mm, in inches 1.25), the nominal elongation at breaking impact is 250%, in PE 100 (respectively, 100 mm) - 350;
• When heated, the maximum permissible change in length is 3%. This indicator is standard for all diameters and any wall thickness, including if they are corrugated;
• It is obligatory to have a marking, which indicates the batch number, date of production, the plant at which they are manufactured.

Diameter table and its explanation (as a table I will take - https://trubyplastic.ru/truba-polietilen/tablitsa-razmerov.html - you just write an explanation for it in the following subheadings)

Polyethylene grades

For the production of plastic pipes, low-pressure polyethylene or HDPE is used. This material is known as high density plastic. For the production of such polyethylene, basic grades of polyethylene (HDPE) are used.

Raw materials for the manufacture of pipes HDPE 273-79 second grade

Depending on the type of production, needs, equipment used, any HDPE is classified by quality. This material is of grade 1, grade 2 and higher. According to the area of ​​use, HDPE pipes, in turn, are divided into pressure and non-pressure.

• Pressure ones are used in forced circulation water supply systems;
• Non-pressure ones are used for arranging drainage and other systems with natural flow of drains.

Now such grades of polyethylene are used for the production of low pressure bends:

• PE 63. Least durable. They are used to protect the electrical cable from moisture, as well as (rarely) to pull the external water supply;
• PE 80. Ideal for sewage. Withstand pressure from 25 MPa at a normal temperature of 20 degrees and a minimum SDR 6. Under the influence of high temperature, standard dimensions may deviate from the indicators. The maximum deviation is 0.3 mm.
• PE 100. Suitable for heating and hot water supply. The main difference from 80 is its high strength and resistance to temperature effects. With a minimum SDR, such branch pipes, even with a large diameter, differ in indicators of the maximum deviation - 0.5 mm.

SDR polymer pipes

SDR is another important indicator of polymer products. This is a non-linear characteristic that determines the ratio of the outer diameter of the nozzle to the thickness of the plastic walls. Naturally, the SDR of gas pipes can be much larger than that of water supply conductors.

SDR Ratio

Depending on the needs, this indicator can have a ratio of 41 to 6.For example, a pipe with a diameter of 1000 mm and a minimum permissible wall thickness of 25 will have a ratio of 40. For high-density polyethylene, the ratio is maintained within the range of 15–20. According to SDR, experts calculate the maximum pressure that is permissible in the water supply system at a temperature of 20 degrees (for cold water) and 40 degrees (for hot).

Justification of using metal-plastic for gas supply

It is worthwhile to understand in more detail the question of whether it is possible to use metal-plastic pipes for gas.

Currently, steel and copper pipes are still in high demand in the gas industry. It was only a matter of time before alternatives emerged, as material was required that could be installed with less effort, while still achieving the highest safety and durability.

It is no secret that steel gas pipes are very difficult to install, while they are easily oxidized in corrosive environments, and, moreover, they require high maintenance costs.

Reinforced-plastic gas pipes can provide:

• Long service life - over 50 years, 2nd generation pipes can last over 100 years.
• Ease of installation work and low weight compared to pipes made of other materials.
• Due to the smooth inner surface, a large capacity of plastic pipes for gas in the house is ensured.
• Profitability. For the arrangement of pipelines, a minimum of fittings are required, since the pipes do not deform when bent.
• Versatility.
• A wide range of pipe and fittings cross-sections are available for sale - many varieties of gas equipment can be connected.
• The possibility of laying a hidden pipeline, which makes it possible to connect gas equipment at any point in the room.

Features when compared with steel counterparts

In addition to the advantages, any product has certain disadvantages, and plastic pipes for a gas pipeline are also no exception. Before installing them, please note that installation of such structures is impossible:

1. Ground and above ground. Plastic pipes for gas are intended for underground utilities located inside the ground.
2. In areas of increased seismic activity. This applies to areas where the level of activity reaches 6 points.
3. Within the city limits in high-pressure gas zones (in gas pipelines of categories 1 and 2).
4. Indoors, residential, commercial and industrial buildings, collectors. It is customary to use mainly steel structures.
5. Plastic pipe for gas is inferior to metal in terms of strength characteristics.

If we compare plastic pipes for a gas pipeline and steel communications, then you can notice some significant differences:

1. Cost. Since steel pipes require additional electrical insulation and protective layers, installation and maintenance are more time consuming and expensive. And the prices for steel are slightly higher than for plastic products.
2. Weight and transportation. Steel equipment weighs much more, making it difficult to transport. In addition, polyethylene products are transported in bays, which makes them more compact.
3. Versatility. If everything is simple with a plastic pipe for gas in a private house, then steel products must be used strictly taking into account the temperature, landscape conditions, and operational parameters. Depending on this, the required thickness and design features are selected.
4. Installation. Steel piping is somewhat more difficult to install than plastic piping.

Despite all the advantages of plastic gas pipes, it is prohibited to use them in high-pressure gas pipelines.

When choosing the right material, be sure to consider the above differences and features.

The process of laying metal-plastic pipes for gas

Now we know what pipes can be used to carry gas, water, and that the installation process is quite simple. It is worth noting that you do not need to look for complex equipment for this. These factors make the material quite popular among buyers.

Reinforced-plastic pipes are not subject to oxidation, exposure to chemicals, they do not clog and serve for a very long time without failures. In addition, such products are capable of operating at high temperatures, which makes them the main competitors for PP pipes. Even metal-plastic pipelines perfectly dampen noise, and this greatly increases living comfort.

When laying pipes, it is worth considering their location relative to heating devices, since they should not overheat.

Special scissors are used for cutting pipes. For flaring (making the end part of the pipes rounded), a calibrator is required, after which the fittings can be installed. The communications are fixed to the walls with fastening clips; when pipes of large sections pass through the wall, it will be necessary to install pass-through sleeves.

In this article, we learned why metal-plastic products are better than metal pipes for gas, water supply, or any other system, and how to properly install them.

If you intend to keep up with the times in everything, then it's time to think about modern plumbing.

If it seems to you that your old cast-iron pipes, firstly, “do not interfere” with you, and secondly, are still quite modern, then you are a little mistaken.

In European countries, they have long ago moved away from metal pipes. In our country, the transition to new technologies has not yet been carried out everywhere, but all this is available at an inexpensive price.

Why don't you learn more about the modern approach to gas pipelines? What are plastic pipes, and what are they good for?

Gas pipes have a yellow stripe

Pros and cons when comparing metal-plastic and polyethylene pipes

Transporting small diameter plastic or polyethylene pipes is equally easy. They are produced in bays of 50-500 m and weigh 2-4 times less than their steel counterparts.

Butt welding of gas plastic pipes is also cheaper than in the case of steel ones. This does not require additional consumables. And the process itself is much easier and faster. You can use thermistor couplings, which will also simplify the installation procedure. Such a pipeline can be laid by pulling. And it will serve for a long time, without requiring frequent intervention and repairs thanks to its smooth and elastic inner surface. Thick-walled polyethylene pipes can be used for a gas pipeline of the third and sometimes even the second category.

However, there are some differences between these types of material:

• at extremely low temperatures, gas polyethylene pipes lose their operational capabilities and breakdown is possible;
• PVC pipe is more durable and safer in terms of reaction with chemicals;
• polyethylene is not resistant to the negative effects of ultraviolet rays, so you need to install a plastic pipe for gas underground, and not in an open space or in a lighted room. Otherwise, it can lead to a decrease in the rock of the service and negative consequences. But for PVC pipes, this limitation is not relevant;
• it is possible to lay polyethylene pipes outdoors only into the soil in order to protect equipment from mechanical damage, while a metal-plastic pipe has greater strength.

A metal-plastic pipe has greater strength than HDPE, and it can be used where it is not possible to carry out a hidden laying of the pipeline

What are the plastic pipes

1. Polyvinyl chloride, or PVC, pipes are the best known.Their distribution on the market is largely due to their affordable price, because they are relatively cheap. However, in the process of use, as a result of chemical decomposition, these products release toxic chloroethylene. For this reason, they are not suitable for use in water supply systems. For sewer devices, these pipes are suitable as a cheap analogue of cast iron. Lightweight and cheap, they will replace their predecessors seamlessly.
2. Polyethylene pipes are a more profitable option, especially for those who want to arrange a cold water supply system. The insulated material of these pipes is stable. The temperature of liquids or gases that these products can carry reaches -25 degrees. This is much less than other plastic counterparts. Unfortunately, uninsulated polyethylene pipes lose their strength and, therefore, their effectiveness. Summing up, it should be said that this kind of pipes suitable only when insulated and only for cold transmission conditions.
3. Metal-polymer pipes are analogous to the previous ones, however, the polyethylene layer is in solid insulation. The benefit of the purchase lies precisely in the versatility of this type.
4. Polypropylene pipes are one of the most advanced options on the plastic pipe market today. The fact is that polypropylene is chemically inactive. Therefore, he does not need isolation. That is, it is highly resistant to external influences, which means it is permissible for use in various conditions.

The low thermal conductivity of polypropylene prevents condensation from forming, which means that the transportation of gases or liquids through such pipes does not damage the transferred substance itself. It is also possible to make pipes of any length and diameter, so they are suitable for operations of all sizes.

Benefits of using in laying a gas pipeline

Connect to device

Plastic pipes have got their place in the construction of gas pipelines, having a lot of advantages:

• Plastic pipes are ready to last much longer than metal pipes.
• They do not interact with the soil and do not conduct current, which allows their cathodic insecurity.
• In terms of their weight, gas pipes consisting of polyethylene are several times lighter than metal ones, so the construction of gas pipelines is faster.
• Prices for such pipes are lower, so the construction of gas pipes made of polyethylene is much more profitable.
• The replacement of plastic gas pipes is carried out faster, due to the availability and ease of installation of new ones. And this is another plus, since in case of failure of cast-iron pipes, tens and hundreds of people can remain without gas for weeks.

Gas polyethylene pipes have low pressure (hereinafter referred to as HDPE). They are able to transport water and gas over any distance. HDPE pipes transport natural gas from the mains to your apartment. They are also used for the construction of underground gas pipelines, through which flammable gases flow. This is, on the one hand, the transportation of fuel, and on the other hand, raw materials.

It can be used in both the household and industrial sectors. Nowadays, low-pressure polyethylene pipes occupy about 90 percent of all gas pipeline systems. It should be noted that when gas is supplied through the pipe, the sound is isolated. Plastic pipes for a gas pipeline have an aesthetic appearance.

Installation features

The installation of plastic pipes has its own secrets. Flexibility and high suitability for concealed installation make work easier. However, when installing, it is worth considering their low strength, thermal expansion and sensitivity to ultraviolet radiation.

The range of plastic pipes is wide

The fewer connections your system has, the stronger and cheaper your system will be.Polyethylene gas pipes must be installed in special conditions, in which there are no external influences. To increase the maintenance-free period, a network of gas pipes of the same material should be planned. Otherwise, various cracks and gaps will form at the joints.

In order not to damage the material, the elements should be connected by welding. Pipes that are not resistant to sunlight should be installed in dark places for durability. However, it is possible to determine how long the gas pipes will last at the installation stage, since if any material is made from low-quality raw materials or is already damaged, then problems will begin to arise when assembling the system.

Can polypropylene pipes be used for gas?

In Western countries, metal pipes are used only for the assembly of industrial pipelines. In the manufacture of water and gas supply systems, plastic elements are used. This is due to the performance characteristics of the material. Gas passes through the plastic pipe without any difficulty. Before putting the gas pipeline into operation, it is necessary to check the tightness of the connections of individual elements in order to prevent violation of the integrity of the system.

To figure out which is better - a pipeline made of metal or plastic, you can compare these two materials. Differences:

1. Weight - Plastic pipes weigh less than metal parts. Thanks to this, it is easier to mount them, they do not require additional fasteners on vertical surfaces.
2. Versatility - There are more factors to consider when choosing metal pipes than when using plastic parts.
3. Price - pipes made of polymers are cheaper than metal ones.

Metal tubes outperform plastic ones in terms of strength, durability, and resistance to mechanical stress.

Welding: little tricks

Special equipment was invented for. There are three welding methods: electrofusion, butt and socket welding.

1. Electrofusion welding uses the method of melting the plastic as a result of the thermal action of the current and the connection with the fitting. Such welding is used on sections of gas pipelines. Socket welding is often used for joints of polyethylene and polypropylene gas pipes.
2. Socket welding is used for connections in sewer systems. It is also suitable for repairing pipes with a diameter of 15 to 90 mm in bathrooms.
3. Butt welding is used for almost any plastic gas pipe with a diameter range of 5 to 16 cm. Gas pipes eliminate the need for laborious cutting work and in most cases eliminate the need for welding.

When choosing the nature of the installation and the technology by which the system will be installed, it is necessary to study the characteristics of the polymer and the joining conditions favorable for it. For example, polyethylene pipes, regardless of the place of assembly, are interconnected by attaching fittings. This method is the most durable only for this type of pipe.

You will need different fittings

For polypropylene pipes, an unusual welding method is used, in which the air heats up to about 270 degrees. With this method, the usual solder is absent. PVC pipes are adhered to glue, because all other types of installation are unsuitable for this type of polymer. Do not be bad about such fasteners, since modern glue is able to ensure the operation of pipes for several decades.

Basic documents to the definition

Regardless of the number of storeys, purpose and building materials, even the highest fire safety, the decision at what distance from the gas pipe a house can be built is made without fail before the start of its construction. Such problems need to be regulated at the stage of building design.

Gas pipes in the village

The residential building is no exception.Any citizen of the Russian Federation must coordinate the project of his future habitat with the supervisory authorities.

He will not have any obstacles to the start of land tenure development, if the plan is agreed and drawn up on the basis of existing and current regulatory documents - SNiP, Federal laws, building rules and government decrees.

These documents are registered by Rosstandart and can become guidelines. The necessary endorsement and approval of the developed construction plan will have to be obtained from several authorities.

Near town

The distance from the gas pipe to the house can be easily calculated, guided by the relevant documents. To do this, you should apply for the factual data and permission for the gas distribution station, the powers of which extend to the place of construction of the dwelling.

Having actual data on the pressure level in the nearby gas pipeline, you can refer to the following documents during design:

• SNiP 42-01-2002, which defines the main technical requirements for the design and reconstruction of consumer systems created to provide fuel;
• Federal Law No. 184 and Government Decree No. 858, which obliges to comply with the norms specified in SNiP, building rules at the level of the law;
• SP 62.13330.2011, in which the norms of distance SNiP 42-01-2002, necessary for safe operation, were updated or supplemented.

High pressure gas pipeline

These documents are registered by Rosstandart and can become guidelines if the developer independently tries to determine the distances for the design of the future building with reference to a specific area. However, the approval of a project or plan is a necessary measure to obtain a building permit, which every potential new settler must now have.

How to choose the right way

If you decide to start installing plastic pipes, then it is better not to resort to the welding method, since it is demanding on the conditions. This means that it can be of poor quality at home. In this case, it is better to choose metal-plastic pipes.

Pipes such as polyethylene or HDPE for home installation are not suitable, since they have high conditions, which are practically impracticable at home.

Metal-reinforced plastic can be given any shape, which makes the work easier for the installer. These pipes bend easily and are secured with crimp or compression fittings. The latter are more expensive, but their reliability is highly appreciated by experts.

The total cost of installation is made up not only of the cost of the material of the pipes used, but also of the quantity and quality of fasteners, the number of connections. It so happens that pipes are more expensive in one store, but fittings and other connecting things are cheaper, in other stores the opposite is true. Also, do not forget about shaped products, which will also have to be spent on.

It is worth remembering that nowadays plastic pipes are supplied to the market in huge quantities, so there is always plenty to choose from.

Output

Although household gas distribution wiring belongs to low pressure systems, you should carefully select gas plastic pipes for it, and it is better to entrust this to specialists. After all, gas is not a joke and a mistake here can be expensive (see also the article "Water and gas pipe and its features").

Butt welding.

Did you like the article? Subscribe to our channel Yandex.Zen

Are there any disadvantages to plastic pipes?

Now let's talk about the disadvantages of plastic pipes. Unfortunately, plastic pipes are unstable when used in chlorinated water. In those places where water with a high concentration of chlorine is used, they are subjected to various tests for resistance to exposure.

Also, with some heat or light effects, plastic pipes begin to emit more toxic substances. So, for example, PVC as a result of heating emit hydrochloric acid, which, instantly evaporating, causes various severe burns. Also, due to favorable conditions, bacteria form on the inner walls, which can penetrate through pipes into kitchens and other human habitats.

Be careful when buying cheap gas pipes because not all of them can keep your home safe. You should immediately set the maximum value of the temperatures that your pipeline can definitely withstand without various changes in its composition.

The disadvantages of modern plastic pipes limit their scope of application, however, in the gas sector, there are fewer problems with such pipes. This is due to the chemically inactive gases flowing through the pipes and the certain properties of gas pipes, which make it possible to build gas pipelines that are ready to serve for decades.

Gas pipes will serve you for a long time if they are in your house in conditions isolated from light and heat.

When arranging a gas pipeline in apartments and private houses, copper or steel pipes are traditionally used. Until recently, there was no alternative to this product in Ukraine. But now they are increasingly using metal-plastic pipes. In this article, you will learn the main characteristics of this product, its disadvantages and advantages, installation features, and you can also see its photo.

Gas pipeline types

From the user's point of view, the most informative is the classification according to the magnitude of the gas pressure in the pipe.

• If the pressure value is not more than 0.05 kgf / cm2, then the system refers to a gas pipeline with low pressure. In an apartment and in a residential building, consumers are faced only with this type of communication. This is more than enough for domestic needs.
• Pressure from 0.05 to 3.0 kgf / cm2 is called average. As a rule, these are city gas mains. They are not used to service consumer facilities, that is, proper residential buildings, institutions, and so on. The pipeline transports natural gas to regional regulatory stations, where the parameter is reduced to the required value.
• Pressure is called high from 3 to 6 kgf / cm2. Such a system is arranged to service enterprises, industrial boilers, and so on. There are options with pressures above 6 kgf / cm2, but only as separate, specially designed projects.

Manufacturing technology

The production of metal-polymer pipe products is strictly regulated by the approved state standard. Subject to technological standards, metal-plastic products receive excellent performance characteristics. They are devoid of the disadvantages that products made of metal have.

The production of metal-polymer pipes takes place in several steps:

1. The extruder is used to extrude the inner shell of the products.
2. From the outer part of the resulting shell, an aluminum layer is glued, laser-welded with an overlap, or butt-welded.
3. An outer shell is applied on top of the foil.
4. The resulting sandwich construction is pressed.

The outer polymer layer helps protect the metal from water and air. Aluminum gives the product strength and rigidity. In this case, the inner layer serves as protection against the appearance of condensation and the destructive influence of the pipeline carrier.

Metal polymer V.S. metal

The use of the technology described above makes it possible to impart good physical and mechanical properties to the product. It is thanks to them that metal-plastic pipes are in many ways superior to their metal counterparts.

They are characterized by:

• high throughput;
• resistance to the appearance of internal deposits;
• the ability to maintain its shape after bending;
• easy installation;
• excellent heat resistance;
• resistance to corrosive processes and aggressive environments.

Product labeling

Products made of metal-plastic can be used for laying water supply, sewerage, heating and gas supply systems.

There is an international labeling system for the products in question. It allows the consumer to get the maximum of the necessary information about the product. It is not a problem to understand it. The first thing to pay attention to is the type of polymer used to make the pipe.

The following encoding options are available:

• PP-AL-PP - the product is made of polypropylene;
• PE-AL-PE - material of manufacture: ordinary polyethylene;
• PERT-AL-PERT - the pipe is made of heat-resistant polyethylene;
• PEX-AL-PEX - products are made of cross-linked polyethylene.

Please note that products made of cross-linked polyethylene have additional letters in their marking. They indicate the method of stitching the material. There are the following options: C - electronic, B - silane, A - pyroxide.

The indicator of the diameter of pipes and their thickness is indicated by different manufacturers in different units of measurement. In most cases, this data is written in inches or millimeters.

You also need to pay attention to the nominal pressure that can withstand a particular type of product. If this indicator in the system does not exceed the factory limit, the service life of metal-polymer products reaches fifty years.

Maximum pressure is a parameter that is relevant for pipes used to deliver media with a high temperature reading.

The technical documentation for the product also lists the environments for which it can be used.

Product marking also contains the batch number and date of manufacture. When installing pipe structures, it is necessary to provide access to the information specified in the encoding. It can be useful in the future when carrying out repair work, if the need arises.

How are pipes connected?

When installing metal-polymer pipes, it is necessary to correctly join them together.

For this purpose, special connecting nodes are used, such as:

1. Press fittings.
2. Threaded fittings.

The latter option is characterized by ease of use. There is no need to use special tools for joining pipes through a threaded fitting with an O-ring. However, this connection method is not suitable for the arrangement of gas pipelines. At the joints of the pipes, the level of tightness decreases over time. Therefore, there is a high probability of gas leakage.

It is best to install the gas pipeline using the knots created by the press fittings. Such connections are distinguished by a high level of reliability. They are one-piece structures. To create them, you need to use a special press toolkit.

GOST metal-polymer products

High-quality pipe products made of metal-plastic must comply with the state. standard 53630-2009. The document contains the key requirements for the products in question.

1. The order of packaging products.
2. Requirements for raw materials required for the production of products.

1. The products are divided into two groups according to the specified working pressure. In the first category, this figure is up to 0.6 MPa, and in the second - 2.5 MPa.
2. The maximum temperature of the carrier in a pipeline made of metal-polymer pipes is allowed up to ninety-five degrees for nine thousand hours.
3. Product labeling is established (discussed above).
4. Depending on the diameter, structures are divided into two categories. The first includes pipes ranging in size from ten to sixty-three millimeters. The second category includes products with a diameter of seventy-five to one hundred and ten millimeters.
5. Methods of delivery of products are indicated.Pipes of the first category are delivered in the form of sections up to twelve and a half meters or in coils. In the latter case, the footage must be a multiple of one hundred. Products of the second category are supplied only in the form of sections of different lengths.

If the structures comply with the specified GOST, they must have a certificate confirming this. Consider this if you decide to buy pipes for arranging a gas pipeline in a private house or apartment.

How are gas pipelines classified

Gas will flow through plastic pipes or only the installation of metal is permissible, directly depends on the operating pressure in the system. The higher it is, the more stringent safety requirements are imposed on the material. After all, whatever gas is transported, all these objects are always classified as high hazard.

The structures that supply gas to our homes are divided into 4 main categories.

Plastic wiring.

1. Systems of the first category are designed for an operating pressure in the range of 0.6 - 1.2 MPa for structures transporting natural gas or gas-air mixtures... For LPG transportation, the pressure rate is 1.6 MPa. Such structures are mounted exclusively from steel, both externally and underground.
2. The second category regulates the supply of mixtures under pressure in the range of 0.3 - 0.6 MPa. These structures carry out the transportation of mixtures between intermediate city gas distribution stations.
3. Medium pressure designs are rated for 0.005 - 0.3 MPa. These are pipelines delivering the mixture from the intermediate gas distributor to several high-rise buildings or streets in the private sector.
4. Direct wiring to apartments or houses is performed by low pressure systems less than 0.005 MPa.

Small diameter flexible polyethylene.

Whether it is possible to use plastic pipes for gas or stop at metal also largely depends on the seismic activity of a given area, what kind of soil is in this area and the presence of stray currents.