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Talking about the differences and similarities of any products makes sense if in reality they can replace each other when solving the same problem. For new construction, renovations and simple interior decoration, you need to decide which fittings to use and why.
Fitting, they are also called “connecting parts”, in addition to directly connecting pipes to each other, they allow you to simultaneously branch or join different types pipelines, for example, make the transition from a polymer pipe to a steel or copper one. We found out that the fitting solves several problems. What qualities should an ideal fitting have?
The ideal fitting should:
- Do not obstruct the passage of liquid, i.e. the internal diameter of the fitting should be as close as possible to the diameter internal section pipes
- Be 100% sealed
- Speed up the process of assembling connections (in other words, be easy to assemble
- Do not lose their properties over time, i.e. be durable
- Eliminate the possibility of errors during assembly, i.e. easy to install
- Have a reasonable price
Most often when connecting pipes made of pex and metal polymer pipes(metal-plastic) special types of fittings are used, but with equal wall thicknesses and outer diameters, fittings originally intended for metal-plastic can be used for assembly. On the contrary, you cannot do it.
Let's take a look first XLPE pipe fittings .
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Axial fittings with sliding sleeve – the most common connections for pex pipes. They are designed very simply and consist of two elements: actually, a shaped part with a fitting (that part of the fitting onto which the edge of the pipe is put) and a fixing sleeve. Both fittings and sleeves can be made of metal (brass and sometimes steel) or plastic (polyphenyl sulfone, polyvinyl fluoride, polyethylene). are axial type fittings and are made only from brass. To assemble the axial connection, a special tool is required. Due to the fact that the design of the fitting uses homogeneous maximum durable materials, the connections do not weaken over time and their service life exceeds 50 years and are therefore suitable for laying in concrete.
There are two types of fittings for connecting metal-polymer pipes: threaded crimp fittingsA and the so-called press fittings .
The first type of fittings for metal plastic pipes called "crimp" . It is a combination of a nut with a collet ring and a fitting with a union and external thread, which, when tightened, fix the edge of the pipe to the fitting. To assemble such a connection, it is enough to have a hex key. There are no other materials other than brass in these connections. However, such fittings are not suitable for installation in floor screeds or walls, because threaded connections may loosen over time and should always be open for inspection and tightening. This type of connection is most often used for finishing apartments and country houses or dachas.
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The next type of fittings for metal-plastic is press fitting . The name comes from the English press – i.e. compression. For such connections, a special tool is always used, which is a round pliers that compresses a steel sleeve (removable or fixed) around the fitting fitting, thereby sealing the connection. A feature of such fittings is the use of several materials in their design: brass (less commonly PPSU) for the fitting, of stainless steel for the sleeve, EPDM rubber for the seals on the fitting and paronite for the dielectric gasket. Due to the heterogeneity of these materials, they lose strength with at different speeds, which limits the service life of the entire connection to a maximum of 10 years. Such connections do not provide 50 summer term services, which is mandatory when placing them in concrete structures(floor screed, ceilings or walls). We can conclude that the use of such connections is justified only when finishing premises and when laying pipes in temporary decorative partitions(often made of plasterboard or other panels).
We have looked at three types of connections, one for PEX pipes(axial with sliding sleeve) and two for metal-polymer pipes (crimp and press connection). Only axial fittings have a service life of 50 years providing the reliability required in modern capital construction. Today in Russia during construction apartment buildings With horizontal systems For heating, most projects use cross-linked polyethylene pipes with axial fittings.
TECEflex is a polymer pipe system with a wide range of applications in indoor engineering systems. Brass fittings are certified and approved for pipeline networks drinking water, heating, gas supply and compressed air. The special design of TECEflex metal-polymer pipes makes them suitable for universal use. An exception is a gas pipe, in which the outer layer yellow color. Therefore, TECEflex is truly a universal piping system.
Universal piping system for all applications in building installations
- Can be used in drinking water, heating and compressed air pipelines - “5 systems - one fitting”
- O-ringless connection technology
- Pipes and fittings with almost the same internal cross-section
- Thick-walled, non-breaking metal-polymer pipes with diameters of 14-63 mm
- Installation error-resistant technology
- Simple tools
- Wide range of brass fittings with diameters 14-63 mm
- PPSU fittings (polyphenylsulfone) with diameters of 16 and 20 mm as an inexpensive alternative
- Error-tolerant and reliable
- High temperature resistance and compressive strength
Documents for download:
TECEflex pipes are permanently connected to fittings using the axial pressing method. Only the pipe material is used as a sealant. No other means such as O-rings or sealing tape are required. The O-ring-free connection technology is extremely resistant to installation errors and is particularly hygienic.
TECEflex offers wide range brass fittings. Universal brass fittings are used for pipeline networks of drinking water, heating, gas supply and compressed air. The fittings are made of special corrosion-resistant brass (low zinc leaching) recognized in Europe and recommended by the DVGW. In accordance with current drinking water directives, it is suitable for all water qualities.
The DVGW approval confirms the hygienic and biological suitability of TECEflex for drinking water and long term service - at least 50 years. Strength Also is the technology of axial pressing without sealing rings. There are no cavities in the connections, and water stagnation, which is important from a hygienic point of view, does not occur anywhere. The materials used for fittings are approved throughout Europe. Thanks to the use of corrosion-resistant (CR) brass, TECEflex fittings do not require additional protective layers with sophisticated technology application. The TECEflex system is suitable for drinking water of any quality.
The TECEflex metal-polymer pipe is equally suitable for drinking water, heating, radiant heating and compressed air pipelines. The gas supply pipe differs only in its yellow. Thanks to its special design, the universal pipe has a high reliability margin and retains round section when bending and does not form burrs when cutting. Inner pipe in contact with the medium, made from DVGW-registered polyethylene PE-Xc.
Up to a diameter of 32 mm inclusive, TECEflex connections can be made using hand tools. Most connections are performed using only muscular strength. No electricity or batteries needed. The tools are very light and extremely reliable. They do not require regular maintenance. To connect the pipes, you just need to slide the press sleeve onto the part of the pipe that covers the fitting - you get a hermetically sealed connection!
Good day to everyone who is reading this article. In it I will briefly talk about axial fittings and pipes for them. Nowadays they are becoming more and more popular. Especially among developers who use them everywhere they can and cannot. I try to start all my articles with definitions and there will be no exceptions here.
What is an axial fitting?
Axial fitting - brass or plastic fittings for pipes made of cross-linked polyethylene with a special sliding sleeve. The connection of such fittings to pipes is carried out using two special tools:
- Mechanical or electrical expander - carries out expansion polyethylene pipe. After this, it becomes possible to insert the fitting into the pipe.
- Axial press, electric or mechanical - this tool pulls the sleeve onto the fitting. This is done using special interchangeable lips.
As always, for a better understanding, take a look at the following pictures:
Electric axial press.
And one more picture:
Manual and electric pipe expander. All the equipment described above is sold in sets, which include an expander, a press and various attachments for them. Most sets of nozzles start at 14mm and end at 32mm. It looks like this:
Now, to broaden our horizons, let's talk about what cross-linked polyethylene is
What is cross-linked polyethylene?
Everyone who held in their hands plastic bag know what this material is. It is used for cold water supply, but this material is not suitable for heating and hot water supply. To increase the strength of such pipes, molecular crosslinking of polymer chains is used. This allows you to get good characteristics strength of the material with relatively thin pipe walls (pipes with SDR 7.4 are usually used for heating). There are several types of polyethylene cross-linking:
- PEX-a - chemical method crosslinking by adding peroxide.
- PEX-b is a chemical crosslinking method using the addition of silane.
- PEX-c is a radiation cross-linking method.
- PE-RT - cross-linking by adding a copolymer during production
In addition, such pipes are produced with an anti-diffusion layer of ethylene vinyl alcohol EVOH. Such a pipe will already be five-layered like metal-plastic. To make it clear, look at the picture below:
It must be said that if you cut such a pipe and look at its end, no layers will be visible. But this does not mean that they are not there and you were deceived, they are simply all transparent and smoothly transition into one another.
Now I'll give you specifications cross-linked polyethylene pipes:
Let me remind you that the higher the temperature, the shorter the service life of such pipelines. I say this specifically for those who want to connect such a pipe directly to a solid fuel boiler. Now let's talk about where axial fittings can be used. Yes, and I almost forgot! If you are going to make heated floors using such a pipe, then it is very desirable that the length of the circuit does not exceed 100 meters. Otherwise, due to the large circulation, there will be no circulation along the circuit.
Where can axial fittings and pipes for them be used?
Axial fittings, as mentioned above, are designed to connect sections of cross-linked polyethylene pipes. According to them, they can be used in heating systems of private and apartment buildings, in water supply systems and for transporting non-aggressive liquids (for example, refrigerants).
Heating systems in apartment buildings use pipes with thicker walls than in private houses and cottages. And for this you can use pipes with a wall of 2.0 millimeters. The fittings themselves can be made of either brass or special plastic - PPSU. This is my personal opinion, but brass seems more reliable to me. I repeat, it’s mine and not necessarily correct.
Now let's discuss the installation features of this material.
Installation of PE-RT and PEX pipes with axial fittings.
The main method of installing these types of pipes is hidden. That is, pipes are laid inside walls or floors. If we are not talking about water warm floors, then the pipe is laid in a corrugation, which protects it from mechanical and other damage. As for, a separate article was written about them, which I recommend reading. And in order not to be unfounded, I suggest watching a video dedicated to the installation of PEX or PE-RT pipes with axial fittings:
I can say that this method of installation can be done by anyone and there are no special wisdom or tricks here. The prices for the instrument, of course, are steep, but now you can easily rent it at the rental office or from the sellers themselves.
Summary of the article.
As a result, we can say that using cross-linked polyethylene for heating or plumbing around the house is an option worthy of your attention. The pipe itself will be much cheaper than a metal-plastic one and at the same time will have almost all its advantages. The only exception here is that it does not hold its bending shape as well as PEX-Al-PEX. PE-RT or PEX, in my opinion, are the most profitable solution for water heated floors and heating installations using beam distribution. If you take plumbing, then in price they can only compete with polypropylene pipes. There is no friend here for the taste and color. That's all, I'm waiting for your questions in the comments.
The piping system can be installed using Various types connecting fittings. The choice of one solution or another is not always obvious, because each type of fitting has its own advantages and disadvantages.
Compression fittings
Compression fittings are also called compression and collet fittings, which is due to the principle of operation of the crimp connection. Read more about compression fittings .
Advantages of compression fittings:
- Easy to install. No special skills or “golden hands” are required. Can be mounted in hard-to-reach places.
- Available tool. Installation using common open-end wrenches, no special expensive tools required.
- Demountable connection. If necessary, the connection can be easily disassembled using open-end wrenches.
- Reusable. Push-in fittings for metal-plastic pipes can be reused after disassembling the connection. You just need to replace the split collet ring that was deformed during installation.
Disadvantages of compression fittings:
- Low installation speed. The low technology of the process leads to a relatively long installation of compression fittings.
- Narrowing of the flow area. This leads to a loss of pressure in the system due to high local hydraulic resistance in the compression fittings.
- You can't monolith. Compression fittings are only suitable for open wiring because they require periodic monitoring and preventive tightening. Free access must be ensured.
Radial press fittings with press sleeve crimp
Radial press fittings were introduced later than compression fittings, but quickly became very popular among professional installers. .
Advantages of radial press fittings:
- You can monolith it. The high reliability of the radial press connection allows the use of radial press fittings for the installation of underfloor heating systems, hidden installation V building structures(walls, floors)
- Versatility. You can use pipes and fittings from different manufacturers. Table for selecting and replacing radial press fittings taking into account the crimp profile.
- Economical. The complete system is cheaper than other types of fittings
Disadvantages of radial press fittings:
- Requires special tool. When installing radial press fittings, it is necessary to use professional, expensive press tools.
- Single use. When dismantling the connection point, the press fittings are removed along with the pipe.
- Narrowing of the flow area. This leads to a loss of pressure in the system due to high local hydraulic resistance in the radial press fittings.
- Not suitable for hard to reach places.
Axial press fittings with sliding sleeve
Axial press connections were developed for cross-linked polyethylene (PEX) pipes and were later used for metal-plastic pipes.
Advantages of axial press fittings:
- Connection without O-rings. With axial pressing, the pipe itself becomes a seal. Therefore, the reliability of the connection increases and there is no need to calibrate the pipe with chamfering.
- Reduced narrowing of the flow area. Axial press fittings with a sliding sleeve are characterized by relatively small pressure losses, which distinguishes them favorably from other types of fittings for metal-plastic pipes (crimp, radial press and push fittings). This allows the use of pipes and fittings of smaller diameter with the same hydraulic parameters, in comparison with a system using radial press fittings.
- You can monolith it. The high reliability of the axial press connection allows the use of axial press fittings for the installation of underfloor heating systems, hidden installation in building structures (walls, floors)
- Reusable. Axial press fittings and sleeves made of brass, bronze and stainless steel can be reused. The connection can be disassembled by heating it with a hair dryer.
Disadvantages of axial press fittings:
- Requires expensive special tools. When installing axial press fittings, it is necessary to use two types of special tools: a pipe expander and an axial (slide-on) press.
- Not suitable for hard to reach places.Please note that the tool is difficult to use in hard-to-reach places.
Push fittings / push fittings
Push fittings (push - press, push in English) are the latest type of fittings for metal-plastic pipes in appearance. In a relatively short time, several generations of these self-locking fittings have been introduced.
The operating principle of a push fitting is to self-fix the pipe inserted into it. During installation, the pipe is pressed into the push fitting, sliding onto the integrated fitting with O-rings. A system of spring-loaded inner rings presses the pipe tightly against the fitting and prevents it from leaving the fitting. Two EPDM O-rings ensure the required tightness of the connection. The pipe must be calibrated and with the internal chamfer removed.
Advantages of push fittings:
- No special tool required. All you need is a pipe cutter and a calibrator.
- Easy to install. No special skills or “golden hands” are required. You can independently install a pipeline made of metal-plastic pipes using push fittings.
- Accelerated installation. Push fittings allow you to complete a large amount of work in a short time.
- Suitable for hard to reach places
- You can monolith it. Push fittings are reliable , sufficient for hidden installation in building structures (walls, floors).
Disadvantages of push fittings:
- Narrowing of the flow area. This leads to a loss of pressure in the system due to high local hydraulic resistance in the push fittings.
- High price. These are the most expensive fittings for metal-plastic pipes.
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Radial press fittings |
Axial press fittings |
Push fittings |
Compression fittings |
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Possibility of hidden installation |
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Reusable |
NOT REALLY |
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Availability of seals in fittings |
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Narrowing of the section in fittings |
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Time and ease of installation |
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Connection reliability |
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System cost |
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Cost of a set of tools |
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