Many people prejudicedly think that the connections of the metal-plastic pipe, as well as PERT and PEX pipes, with fittings are unreliable and leak. Let's figure out where such "glory" came from and why it does not correspond to reality.
How to properly connect metal-plastic and other similar pipes, and make heating and water supply pipelines out of them?
Several types of connections for metal-plastic pipes
Several types of fittings are used (crosses, angles, couplings ...) to connect metal-plastic pipes.
Push fitting connection
Here the pipe is put on a fitting with a seal, while it is crimped with a ring with antennae (dish washer). There is a clear click. The antennae of the ring are located against the direction of separation and do not allow the pipe to move back.
Push appeared relatively recently, and according to some experts, it appeared “for the sake of knocking money out with the help of advertising, since there is no utility in it.”
Indeed, manufacturers do not give the go-ahead to embed this connection in concrete. In appearance, the resulting connection is “flimsy”, the pipe rotates in the fitting, with great effort it can be undocked back.
In combination with the fact that the price of such a fitting is 2 times more than the usual compression or crimp fitting, it is difficult for this connection to gain popularity without advertising.
The main complexity of connecting with any type of fitting is to prepare a metal-plastic pipe - determining its length, marking, cutting to size, designing the cut edge, leveling the end part, chamfering, sizing.
And not at all in the process of docking. If you know all this, then Push-docking is even more presented as a thing necessary in the household in the very last place.
How should the pipe be prepared for joining?
To connect to a fitting of any type, a metal-plastic pipe must be prepared.
To do this, you need to have a couple of special tools - pipe shears and a calibrator with an internal chamfer function.]
The pipe is supplied in coils. After cutting with a metal hacksaw, a piece of a curved pipe is obtained, including one bent at the end, with a crumpled end of a semi-oval shape, with burrs along the edge and with sharp edges. Such a pipe will damage the seal on any fitting if you try to put it on the fitting.
Must be cut with scissors. If this expensive tool is not available, then after a hacksaw, you need to carefully align the end with a file and remove the burrs.
It is necessary to manually align the end section of the pipe, with a length of at least 5 diameters.
The outlet hole must be calibrated with force (make it exactly round) and at the same time the internal chamfer must be removed at an angle of 45 degrees.
Only after that you can start docking.
Reducing the labor intensity of docking with Push does not take precedence over its disadvantages ....
Press fitting connection
The most reliable, non-separable connection of metal-plastic pipes is with the help of a press joint.
Here the pipe is pushed onto a brass fitting with a pair of seals located in deep grooves.
The pipe around the fitting is crimped with a special metal sleeve, which is crumpled and crimped only with a special tool - pressing tongs. The pipe must be pushed up to the stop and visible in the sleeve window.
This connection, according to manufacturers, has a reliability close to 99.99%. The connection is recommended by manufacturers of press fittings for use inside structures, including in walls and screed (but any joints are unacceptable in underfloor heating loops).
The occurrence of a leak, except for the cases of the use of clearly counterfeit parts, was not recorded.
The connection of a metal-plastic pipeline with the help of a press is classified as professional. It is practically not feasible "with your own hands" because of the high price of a special tool - press tongs (manual (hydraulic, electric) press for crimping sleeves on plastic pipelines).
In order to assemble the heating in your house with your own hands, it is much more profitable to use compression fittings, or in extreme cases, a push joint, but do not purchase press tongs with nozzles “for fabulous money”.
Is it possible to rent such an instrument at a reasonable price ....
Connection of a metal-plastic pipe with a compression fitting
The oldest and most "problematic" connection is compression (or threaded ...). Fittings are usually brass. A PTFE thrust ring and a pair of rubber seals are installed on the brass fitting. But here the seals do not sit so deep in their grooves, so it is easier to rip them off.
The pipe should be put on these seals and move all the way into the PTFE. Then, a split ring, previously put on the pipe, under the influence of the nut, squeezes the pipe at the location of the rubber seals.
To assemble this metal-plastic pipe connection with your own hands, you will need a pair of keys.
With one key, the installer tightens the nut that compresses the ring.
The second wrench holds the fitting itself. Assembly is very easy, crackling at the joint is normal.
The connection is collapsible - it can be tightened (increase the tightening torque), it can be disassembled, the intact fitting removed and used elsewhere, replacing the penny seals.
The joint must not be bricked into the wall, according to the manufacturer's recommendations.
The advantage of docking is the ultimate affordability at the price of the fitting and the complexity of installation. All you need is two keys and a little diligence.
But this connection is leaking. Why?
With cold water, as a rule, there is no leak, but on hot water or heating, drips sometimes begin from under the nut. If the nut is tightened, then the leak is eliminated for a while, then it appears again.
A leak from a metal-plastic pipeline at a joint - why, what to do?
Optional -
Why is the metal-plastic pipeline flowing
The compression joint is the oldest, it was assembled by tens of thousands of many craftsmen. Often the assembly went like this - an oval pipe was forced onto the fitting, crushing and peeling off the seals with a sharp edge and burrs, shifting them to the thrust washer. Then the nut was tightened "on the conscience".
The cross-linked polyethylene (PEX) deformed and crimped the brass pipe securely. So much so that without a change in temperature, this place remained without leakage for the entire service life. But where there were significant thermal expansions, the elasticity of a thin-walled metal-plastic pipe was not enough.
When the connection cooled, a gap was obtained, and the flow of liquid began. After tightening the nut, the compression intensified, crushing the material, but because of the heating-cooling cycles, everything was repeated again. Until the next diligent tightening of the nut did not break the thread.
What to do so that the junction with the fitting does not flow
To ensure that the compression connection of the metal-plastic pipe with the fitting does not flow, the following must be done.
- Cut the pipe with scissors. If such a tool is expensive, then carefully apply a round file to the file, aligning the cut and removing all burrs.
- Align the end section of the pipe (from 5 diameters) manually.
- Calibrate carefully with a manual calibrator to achieve an even round hole. At the same time, remove the internal chamfer at 45 degrees with a quality calibrator.
- Lubricate the fitting, seals, with liquid soap.
- Put the pipe on the fitting, on the seals without distortion until it stops against the washer.
- Tighten the ring nut without applying excessive force.
As you can see, it is not very difficult to achieve the installation of a metal-plastic pipe without a leak with your own hands - you just need to follow the simple connection rules.
And yes ... .. - the connection to the proprietary compression fitting, made correctly, with the compression of the pipe on the seals located in the grooves, does not flow at all, including for hot water and heating.
From the author: Hello friends! Anyone who decides to do the laying of the plumbing system on their own is interested in the question of how to connect metal-plastic pipes to each other. The most important thing in this task is to make sure that the joints do not leak either by themselves or under the influence of external factors.
Given that the pipeline is usually masked in the walls, it becomes clear that any leakage will first be imperceptible, and then abruptly lead to very detrimental consequences. That is why the issue of joint reliability is so important. Today we will analyze in detail how it happens, and also disclose information about the selection of fittings. Let's get started!
Features of working with pipes
As soon as metal-plastic pipes appeared on the market, they immediately gained wild popularity and practically ousted their competitors. For example, their steel assemblies are no longer often used, because their characteristics and the complexity of installation leave much to be desired.
Metal-plastic, by virtue of its structure, has a lot of advantages. It serves for a very long time, calmly endures all external hardships, such as temperature changes, severe frosts (-50 degrees and below), pressure surges. At the same time, the pipes not only remain intact, but also do not change their size at all.
In addition, this material has a very low thermal conductivity. All the heat inside such a pipe remains there. This makes metal-plastic an ideal option for laying pipelines for hot water supply and heating.
Another significant advantage is the resistance of the material to various chemical influences. Neither rust nor scale forms on it, which allows the pipes to serve for such a long time without losing their functionality and throughput.
And the last plus, which should be mentioned separately, is the ease of installation of the pipeline. For beginners, this may seem strange - after all, at first glance, there are a lot of different connecting elements, and all this needs to be fixed somehow.
On the one hand, everything is correct. Connecting elements, which are called fittings, are really used quite a lot. The fact is that it is impossible to solder or weld, due to the peculiarities of their structure. Therefore, fitting connections are the only available option.
But, contrary to the first impression, these operations are not so difficult at all. And to understand the varieties of elements is even easier, because it suddenly turns out that in fact there are not so many of them.
Required Tools
Of course, laying a pipeline requires not only pipes and fittings, but also tools to work with all this constructor. The set, although small, is quite specific:
- pipe cutters. By the name it is clear for what purpose they are needed. The peculiarity of this equipment is that it allows you to make the cut of the pipe even and strictly perpendicular. For the assembly of the pipeline, this moment is extremely important. In principle, some use carpenter's must instead of pipe cutters. Using this tool, you can also achieve a perpendicular cut (with a careful approach), but you won’t get even edges, you will then have to manually clean off the burrs from each of them;
- calibrator. After you divide the pipes into segments, their edges will be slightly concave inward. The calibrator solves this problem. It is inserted into the inside of the pipe, and then rotated, thereby aligning the edges;
- countersink. Instead, you can take a knife with a sharp blade or sandpaper. These tools are necessary for chamfering each edge of a segment. With the help of a countersink (or its analogues), you need to slightly grind off the outer and inner layers of plastic, this is done at an angle;
- fitting tool. To understand which one, you must first decide what kind of connecting elements will be used. Depending on this, you will need either crimping pliers or wrenches. We will talk about this a little lower.
You may also need a special shaping device. Here it is worth saying right away that there is one general principle for the installation of any pipeline: the fewer connections, the better. Each joint, no matter how reliable it may be, in one way or another increases the risk of leakage. And only a solid pipe is a guarantee of the absence of such an opportunity.
Therefore, if you need to turn the pipeline line somewhere, it is better to form an angle not from two segments, joining them with a fitting, but from one, bending it properly. There is a special device for this, which is a spring with handles.
The principle of its operation is extremely simple: it is inserted inside the desired piece of pipe, and then bent along with it. Thus, you can control the formation of the desired angle, and at the same time avoid kinks in the segment.
In principle, metal-plastic can be bent simply by hand. But then there is a chance to “hush up” the pipe, and then you can’t fix the deformed sections in any way, you can’t use such segments in the pipeline. Therefore, it is still better to purchase a spring. Moreover, it is sold everywhere (in stores of the corresponding direction) and is inexpensive.
To facilitate the bending procedure, you may also need a building hair dryer. A heated pipe bends better, but you can’t use open fire for this, since you will most likely damage the material with it. Therefore, a building hair dryer is the best option.
Types of fittings
Well, we figured out the basics, now let's move on to a more detailed analysis of some points. Namely, to what is an integral part of any connection of metal-plastic pipes. As you may have guessed, we are talking about fittings. They can be either compression (screw) or crimp, which are also called press fittings.
The difference between them is that the former are only suitable for the installation of an open pipeline. This is because compression fittings periodically loosen and need to be tightened. And this should be done regularly, and not waiting for it to start leaking.
Press fittings are suitable for any pipeline, including those laid underground. Such connections are made once and for all, they do not require any tightening.
Compression fittings
The advantage of compression fittings lies in two factors. Firstly, they are cheaper (which is not surprising, given their lower reliability compared to their crimp counterparts). Secondly, only a couple of wrenches are needed for installation. The connection assembly procedure is as follows.
- We put a ring and a nut on the pipe section.
- We pull the edge onto the connecting element until it stops in a special ledge.
- Then we stretch the ring to the same level.
- Finally, tighten the cap nut. At first, this can be done by hand, and then pulled to the end with wrenches - with one of them we fix the fitting in place, with the second we work directly with the nut.
As you can see, the procedure is the simplest. If for some reason you need to disassemble such a connection, then this is also easy, but in reverse order.
Press fittings
Compression fittings require the use of a specialized tool - pliers. With their help, the element is pressed, which ultimately gives the most durable and reliable connection. Crimping pliers can be manual or electric. There is no fundamental difference, choose a tool according to your budget and ease of use. In any case, each of them will perfectly cope with the task.
Let's move on to the process.
- We put a crimp sleeve on the segment.
- We put a special gasket on the fitting, which will protect the element from chemical corrosion.
- We pull the segment onto the fitting so that the edge of the pipe is visible through a hole specially designed for this.
- Then we crimp the sleeve using the same pliers.
Assembling the pipeline using fittings is an absolutely easy procedure, comparable, perhaps, with the construction of a house from a children's designer. There are no dangerous or time-consuming operations here.
The only difficulty, perhaps, is to properly prepare for the installation procedure. Preparation consists in drawing up a diagram and in purchasing the necessary elements, and the second cannot be done without the first.
To get all the information you need to go to the store, first draw a plan of the house, keeping all dimensions to scale as accurately as possible. Then, on this plan, mark the routes of each pipe from the source of water supply to the location of the plumbing equipment that will be connected to each route. You need to draw each layer.
Mark on the diagram exactly which products will stand in one place or another: faucets, a shower cabin, a washing machine and a dishwasher - all this should be indicated.
Then mark the points on the pipe routes where the fittings will be placed. Sign each of them, which kind of element will be installed there: a tee, a corner, a cross, and the like.
Only after all this, you can calculate, referring to the diagram, exactly how many pipes and fittings you will need. Please note that connectors are quite expensive, so it is pointless to purchase them without prior planning, because this can lead to unnecessary costs. And if you, on the contrary, buy too little, then you will have to abandon the half-made pipeline and rush to the store for the missing fittings, wasting time on this.
Important installation details
In addition to the rules for connecting pipes using fittings, there are several more important points that must be considered when laying the pipeline:
- assembly and installation should be carried out at an ambient temperature of at least 10 degrees above zero. If the transportation of materials to the destination was carried out in the cold season, then you must first let the pipes lie down somewhere warm for at least a day;
- when installing fittings for connecting segments, make sure that the pipe is not squeezed;
- during planning, keep in mind that at the locations of the connecting elements, the diameter of the pipe will become slightly smaller, which means that its throughput will decrease. If the final indicator does not correspond to the working pressure of the water supply, then your structure will simply break, or its performance will be much less than expected. Therefore, it is necessary to calculate the diameter of the pipes according to those sections that will be compressed during the connection;
- it is equally important to properly fix the pipeline to the walls. This is done using special clamps and clips. The difference between them is that the clamps fix the structure at a certain point and subsequently prevent it from moving in any way. Clips also allow you to move the pipe along the axis. If you plan to make the water supply hidden in the wall, then you should pre-make the channels intended for this - strobes. Be sure to check the plan drawn at the beginning of the work in order to place the tracks exactly as needed;
- after all parts of the pipeline are connected and fixed on the walls, the provided plumbing equipment is connected to the outlets: faucets, household appliances, etc. If any of the exits is empty at first (for example, your washing machine has not reached you yet), you should close it with a special plug;
- The final step is to test the performance of the system. At the same time, it is important to check this moment not only at the usual working pressure of the water supply system, but also during the so-called water hammer. To do this, it is necessary to ensure that the pressure in the pipe is twice the norm;
- if you plan to make the pipeline combined - that is, one part will be made of metal-plastic, and the other will be made of plastic, then you need to connect segments of different materials to each other using two fittings. The fact is that polypropylene, unlike metal-plastic, can be welded. Actually, the installation of a pipeline from plastic alone occurs using this particular method. With metal-plastic, this trick will not work. Therefore, it is done as follows: one fitting is welded to polypropylene, another is installed on metal-plastic in the usual way, then these elements are connected to each other. Thus, we get a normal strong joint, taking into account the needs of both materials.
Dear readers, we have analyzed all the nuances and methods of connecting metal-plastic pipes. We are sure that now you will definitely be able to properly make plumbing in the house with your own hands without any problems. It is possible that this article will be useful not only to you, but also to your friends, so share it on social networks and come back to us again. We will definitely find something else to tell you. See you soon!
Pipes made of metal-plastic are good because they combine all the advantages of plastic and metal. Due to its multilayer nature, such pipes are quite durable. However, during the installation of the pipeline, the question often arises of how to connect them on their own, is it possible to do this at all? ..
Of course, this can be done. Moreover, as will be shown below, even in several ways.
What should be considered when connecting such pipes
Whichever connection method you prefer, a number of general rules will apply to them, which will need to be taken into account:
A metal-plastic pipe is a one-piece, laser-welded "butt" or ultrasonic "overlap" aluminum pipe, protected from the inside and outside by polyethylene layers.
- In no case should the slightest damage to the pipes be allowed, since cracks, cuts, any other - even the most seemingly insignificant defects - lead to leakage in the future;
- When unpacking the pipes, you also need to be very careful. The same applies to the process of their bending;
- The connection of metal-plastic pipes can be carried out by two types of devices - these are screw fittings for water supply and sewer systems and pressure fittings;
- In the event that compression (pressure) fittings were preferred, they should not be allowed to be immured into the wall. After all, only a soldered inextricable pipeline can be walled up tightly.
In the future, it will be discussed how it is possible to connect metal-plastic pipes to each other using these two types of fittings.
Connection of pipes made of metal-plastic using pressure fittings
To begin with, it will not be superfluous to figure out exactly what parts such a fitting consists of:
Press tongs for fittings - a device designed to install a part on a pipe. There are manual and hydraulic models.
- Brass fitting;
- Gasket ring designed to provide electrical insulation;
- O-ring made of polypropylene rubber;
- Crimp sleeve made of stainless steel;
- Directly a pipe made of metal-plastic;
- Crimp sleeve;
- And a shank.
Note! To successfully connect a metal-plastic pipe and a press fitting to each other, you need to use a specialized press machine. It can be either mechanical or manual. Such tools are commercially available, using only them, you can successfully connect pipes. To master them in the work is also not difficult.
- To begin with, with the help of specialized scissors, it is necessary to cut the pipes to the desired length;
- Then the internal chamfer is removed, if the pipe has lost its shape, then the position can be corrected by using a special calibrator;
- Then you need to remove the outer chamfer - using a beveler;
- The inner diameter of the pipe is also checked using a calibrator;
- The sleeve is removed from the fitting, the integrity of its rings and gaskets is controlled. If everything is in order, then the sleeve can be returned to its place;
- The fitting shank is inserted into the pipe with a certain force;
- Then the sleeve is inserted into the press fitting until it stops, the handles are connected.
Press fitting - a type of one-piece, maintenance-free fittings for connecting metal-plastic pipelines with increased requirements by mechanically pressing them with special press machines.
After carrying out all these works, it is necessary to check the integrity and quality of the connection made. If everything is in order, then we can assume that the assembly was successful.
Features of the connection using a compression fitting
The device of a compression fitting is somewhat different from the device of a press fitting. So, the compression fitting consists of:
- brass fitting;
- Insulating Teflon ring;
- Nickel-plated tightening nut;
- Crimp ring with a special cut;
- rubber sealing ring;
- metal-plastic pipe;
- And also from the shank.
The connection in this case occurs in the following steps:
Shears for cutting metal-plastic are a hand tool that is recommended to work with if the diameter of the cut products does not exceed 40 mm.
- To begin with, the desired section of the pipe is cut using special scissors;
- With the help of a chamfer and a calibrator, chamfers are removed from the inner and outer surfaces of the pipe;
- A tightening nut is put on one end of the pipe, then a compression ring is put on;
- The end of the fitting is inserted into the pipe. The end fitting of the fitting is also inserted into the pipe;
- Then the compression ring must be moved to the fitting, after which the tightening nut should be moved to it so that it closes the compression ring;
- To seal and seal the threads, you can use FUM tape or sealant paste;
- Finally, with the help of two wrenches, the tightening nut is screwed up to the stop. Two keys in this case are necessary in order to be able to hold the pipe stationary with one and tighten the nut with the other. In this case, excessive efforts should not be used, as there is a risk of damaging not only the threaded connection, but also the pipe itself.
Compression fittings are the ideal solution for plastic pipes. Such fittings are made of brass, copper, steel or plastic. They allow you to quickly and without special equipment to mount pipe structures.
If, after a thorough inspection, no damage and leaks were recorded, then we can assume that the connection process was successful.
How to connect metal-plastic pipes with pipes made of another material
Quite often, during repair work, it becomes necessary to connect pipes made of metal-plastic with pipes made of other materials. In this case, you can use a variety of methods. The choice remains at the discretion of the consumer and based on what kind of material one has to deal with in a particular case.
For example, to connect a metal-plastic pipe to a metal pipe, compression fittings must be used. It is important to follow the sequence of actions and be extremely careful. To make a connection, do the following:
The connection of pipes made of metal-plastic with metal occurs with the help of special devices - fittings. They have a different configuration and provide fastening, both in a linear plane and at an angle of 90 degrees.
- First of all, prepare a metal pipe. The essence of the preparation is that the pipe is cleaned to bare metal. It is necessary to remove rust, paint and any other contaminants from it;
- Now you need to screw the fitting onto the thread. In this case, it is better to pre-wrap tow on the thread - to improve waterproofing;
- A press washer with a nut is put on the metal-plastic pipe, calibration is performed, if necessary;
- Next, on the cone of the fitting, which is screwed to the metal pipe, you will need to put on the end of the metal-plastic pipe;
- Using a special open-end wrench, the nut is screwed on. As a result, the washer should compress the metal-plastic pipe as firmly as possible.
This type of connection is very strong, reliable and will not allow leaks. Here, however, the main thing is to choose the right fitting diameter.
If you need to connect a metal-plastic pipe with a pipe made of polypropylene, then for this you can use couplings, just designed for this. At one end, the coupling is soldered to a plastic pipe. At the other end of the coupling there is a special thread. A fitting with an external thread is soldered in a polypropylene pipe, where you need to screw a fitting for a metal-plastic pipe with an internal thread. They need to be tightly twisted together - and the connection can be considered perfect.
Fittings made in the form of angles, tees, etc. are available for free sale. They allow you to quickly and easily connect polypropylene pipes with metal-plastic ones. It is also recommended not to neglect the FUM tape or ordinary tow to ensure maximum tightness of the joints.
If you have to deal with PVC pipes, then they are connected to metal-plastic in exactly the same way as in the case of polypropylene. For this, almost the same fittings are used. The set of tools required to make connections is also similar.
Fittings are used not only for laying plumbing systems, but for their repair. If a defect is found on any part of the water supply, then it is simply removed, changing to a new section, which is attached using the same fittings.
What do the experts say about this?
Mikhail Semenovich Petrov, master plumber: In order to make sure that all pipe connection work has been done correctly, you can check the shape of the coupling. It should have the shape of regular even rings. But re-compression is absolutely impossible. If you neglect this rule, you can get cracks in the pipe body and, accordingly, leaks.
Petr Panov, master plumber: In the case of connecting pipes using press fittings, you can check the correctness of the progress of work if you look through a special viewing window in the fitting sleeve. There should be a pipe there. Moreover, to fill the entire viewing space.
Nikolai Ivanovich Lebedev, master plumber, 11 years of experience: Unfortunately, from time to time you can find fittings that are completed with defective o-rings. Therefore, do not rely too much on the integrity of the manufacturer. It is impossible to predict in which particular set the marriage will meet. It is better to personally unpack it immediately after purchasing the fitting kit and disassemble the device. In the event that there is a suspicion of marriage, in no case should you work with such a fitting. You can replace the entire set, or just the ring.
Summing up
Metal-plastic pipes are extremely common today. But no less common are pipes made from other materials. Fortunately, there are ways to connect both directly metal-plastic with metal-plastic, and with other materials.
As a rule, for this, it is still impossible to avoid the purchase of specialized equipment. So, if only one-time work is planned, then it will be necessary to take into account the economic component: whether to purchase special tools or invite a master will still be a more profitable solution.
In the first case, it will be possible to save on the services of a specialist, but only if really large-scale work is planned. In the second, you can be sure of the high level of quality of all the work done.
Pipe installation (Fig. 10) is carried out using special brass compression fittings. These fittings consist of a nipple, a split ring and a union nut and provide a secure connection of pipes and fittings with a simple wrench. When tightening the union nut, the press sleeve (O-shaped split ring) is compressed on the pipe and provides a tight seal between the fitting and the inner wall of the pipe.
Rice. 10. Connection of a metal-plastic pipe with a compression fitting
The main advantage of this connection is that no special equipment is required during installation, and if necessary, it is possible to dismantle any connection. Once assembled, the assembly can theoretically be disassembled and reassembled, but, as practice shows, it is better not to touch the connection. Therefore, in case of repair of the pipeline, it is necessary to cut out the damaged part and insert a new one, connecting it with fittings. When connecting a pipe to a used fitting, the gaskets on it must be replaced with new ones (Fig. 11).
Rice. 11. Gaskets on fitting nipple
The pipe is cut perpendicular to the axis with a special pipe cutter for composite pipes, in extreme cases with a fine-toothed hacksaw. The pipe is bent by hand or with the help of a special spring - a pipe bender. Two types of springs are used: some are inserted inside the pipe (practically not used), others are put on the pipe from above. The minimum bending radius of a pipe without a spring is 5 outer diameters of the bent pipe, with a spring - 3.5 diameters.
Almost all types of compression fittings produced in the world are present on the Russian construction market. Fundamentally, their designs differ little from each other, but there is still a difference: manufacturers produce detachable and one-piece fittings (Fig. 12), but this is not the main thing. When purchasing pipes and fittings for them manufactured in different places, you should make sure that they are compatible, since different manufacturers may not have the same outer diameters and wall thicknesses of pipes, even for the same nominal pressure. In other words, it is better to buy fittings and pipes, if possible, from one manufacturer.
Rice. 12. Schemes of compression fitting connections of various manufacturers
When fixing metal-plastic pipes, a minimum of clamps and clamps is required, since the pipes perfectly retain their shape. The installation of the pipeline is carried out both according to the collector and according to the tee installation scheme. When installing tee circuits (in the language of plumbers, this circuit is called a “comb”), the fittings can be connected in series to the pipe or the pipeline can be installed first, and then the fittings can be inserted into it (Fig. 13).
Mark the location of the fitting
Put a warming corrugation on the pipe (optional item)
Rice. 13. Example of connecting a compression fitting
The sequence of connecting metal-plastic pipes with compression fittings:
1. Level the pipe leaving a straight section of at least 10 cm before and after the cut.
2. Cut the pipe at a right angle according to the markup.
3. Process the end of the pipe with a reamer, first with the calibration side with a lead-in chamfer of no more than 1 mm, then with the other side at least up to the mark, ensuring the correct rounded shape of the pipe.
4. Slide the union nut and split ring onto the pipe.
5. Moisten the fitting.
6. Place the pipe on the fitting so that the end of the pipe rests against the edge of the fitting with its entire plane. Tighten the union nut by hand until it stops on the fitting. The nut should be easy to tighten, if this does not happen, then you are not turning it along the thread. Further forceful tightening of the nut will lead to damage to the thread and, as a result, to leakage of the connection and subsequent replacement of the fitting.
7. Holding the fitting body with one wrench, tighten the cap nut 1-2.5 turns with the other wrench so that 1-2 threads remain visible. The use of wrenches with additional levers is unacceptable - do not apply excessive force and do not overtighten the nut.
To prevent pipes from fogging or to insulate them, special corrugated hoses are put on the pipes, most often made of foamed polyethylene. If for some reason the corrugation was not installed, and the need for it appeared, then it can be mounted later. To do this, the corrugated pipe is cut lengthwise and put on the pipe, after which it is strengthened with adhesive tape.
Figure 13 shows the installation of a tee fitting, in fact, the range of compression fittings is quite rich, it allows you to assemble a pipeline of almost any complexity.
Nipple with internal thread (transition to pipe fittings) 16×1/2; 20×1/2; 20×3/4; 26×1; 32x1
Nipple with external thread (transition to pipe fittings) 16×1/2; 20×1/2; 20×3/4; 26×1; 32x1
Coupling (connection of two metal-plastic pipes) 16; twenty; 26; 32
Elbow with internal thread (transition to pipe fittings) 16×1/2; 20×1/2; 20×3/4; 26×1; 32x1
Elbow with external thread (transition to pipe fittings) 16×1/2; 20×1/2; 20×(3/4; 26×1; 32×1
Elbow (connection of two metal-plastic pipes) 16; twenty; 26; 32
Tee with female thread (transition to pipe fittings) 16×1/2; 20×1/2; 20×3/4; 26×1; 32x1
Tee with external thread (transition to pipe fittings) 16×1/2; 20×1/2; 20×3/4; 26×1; 32x1
Assembling communications from metal-plastic is one of the easiest ways to independently conduct plumbing, heating, and sewerage in the house. It does not require expensive fixtures, special skills, or welding to work. Installation of metal-plastic pipes is carried out using different types of fittings, the choice of which depends on the purpose of the pipeline and the conditions for its installation.
Metal-polymer pipelines are used for the installation of domestic plumbing, for underfloor heating, in sewer and drainage systems.
The characteristics and properties of metal-plastic pipes depend on the features of their structure.
The wall of the pipe material is a multilayer "pie" of five layers:
- Cross-linked polyethylene is an inner layer with a smooth surface and high resistance to high temperatures. The term "crosslinked" refers to the structural features of polyethylene at the molecular level. The organic polymer is subjected to additional action to connect the molecules with additional horizontal bonds. The firmware connects up to 85% of free molecules, giving polyethylene a high density, resistance to mechanical and thermal influences.
- adhesive layer.
- layer of aluminum foil.
- Glue.
- External, decorative and protective polyethylene layer.
Note! In their structure, metal-plastic pipes resemble reinforced polypropylene pipes. However, this is a pipe material with completely different characteristics, since the polymer layer has a different nature with different physical properties.
Positive properties of metal-polymer pipes:
- Durable. With a special connection, they can be immured into the wall.
- Plastic, which does not require additional fittings for bending.
- Corrosion resistant. The metal layer is reliably insulated with polyethylene from harmful effects.
- They have a high throughput, do not "overgrow" with deposits on the inner wall.
- They have good thermal conductivity, high sound insulation.
- Environmentally friendly.
- They are light in weight.
- Compatible with all types of pipelines.
- Available for self-assembly.
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