Modern plumbing is rarely made of metal. He has worthy competitors - polymers, which are gradually replacing him in many areas. One such material is low density polyethylene. Pipes for pressure pipelines are made from this material, that is, for water pipes and even for gas pipelines. This type of material is becoming increasingly popular, as the connection of polyethylene pipes is easy to do with your own hands. You just have to follow very simple rules.
Advantages and features of the application
Polyethylene pipes are made from low pressure polyethylene. This material is abbreviated as HDPE. It is characterized by increased strength and elasticity, has good performance properties:
- chemically neutral, can be used for food transportation;
- smooth walls prevent the formation of plaque inside;
- not subject to corrosion;
- low coefficient of thermal expansion - about 3% at maximum heating (up to + 70 ° C);
- they normally react to the freezing of water inside, due to elasticity they increase in diameter, and after thawing they take on their original dimensions.
One moment to remember! If you need pipes that are resistant to freezing (for example, for), look at the description or technical specifications when choosing. Not all types of copolymers that are used for the production of pipes tolerate freezing well. So be careful.
The main disadvantage of polyethylene pipes is the restrictions on the temperature of the transported medium: it should not be higher than + 40 ° C, that is, only cold water supply can be made from HDPE, they cannot be used for hot water and, moreover, heating.
Another point: polyethylene does not tolerate UV radiation. With constant exposure to the sun, the material loses elasticity, and, after a while, breaks (some manufacturers make HDPE pipes resistant to ultraviolet radiation, but they are more expensive). Therefore, open laying of water pipes from plastic pipes is very undesirable. But it is very possible to lay a pipe in a trench from a well or well to the house, to make cold water distribution around the house. This is a fairly economical and convenient solution, since the installation and connection of polyethylene pipes is not a very complicated matter. If we are talking about a detachable connection, then no equipment is needed for it. All you need is fittings and hands.
Which polyethylene pipes are better
For the production of water pipes, two grades of polyethylene are used - PE 80 and PE 100. The hundredth polyethylene is denser and more durable than the eightieth. For water supply systems of a private house, the strength of PE 80 is more than enough - they can withstand pressure up to 8 atm. If you like a large margin of safety, you can take them from PE100. They work fine even at 10 atm.
What you should pay attention to is the country in which this product is produced. Quality leaders are European manufacturers. High precision execution guarantees high reliability of the system. Average quality and prices are from Turkish companies, in a cheaper price segment, Chinese manufacturers. Their quality, as usual, is also much lower. It is difficult to give advice here, everyone selects at their own discretion (or what is in the region).
Types of HDPE pipe connections
There are several types of connection of polyethylene pipes:
- detachable (on fittings or couplings);
- one-piece - by welding:
- using a special welding machine;
- electric couplings - a heater is built into such couplings, when an electric current is applied to it, polyethylene is heated and fused.
Weld mainly pipes of large diameters, which are used to create main pipelines. Pipes of small diameters - up to 110 mm, used in private construction, are mostly connected using fittings. Couplings are used more often during repair work, as their installation takes more time.
Fittings for polyethylene pipes are shaped parts (tees, crosses, angles, adapters, couplings), with the help of which the required system configuration is created. Since self-connection of polyethylene pipes is carried out more often with the help of fittings, let's talk about them in more detail.
Assembly on compression (crimp) fittings
On one or two sides of the fitting (sometimes on three), a whole system is installed that provides the connection. The fitting itself consists of:
How reliable is the connection
Despite the apparent unreliability, the connection of polyethylene pipes on compression fittings is reliable. Properly made, it can withstand operating pressures up to 10 atm and above (if these are products of a normal manufacturer). Watch the video for proof.
This system is good for easy self-assembly. You probably appreciated it already from the video. Just the pipe is inserted, the thread is tightened.
Summer residents, in addition to the ability to do everything with their own urks, like it because, if necessary, everything can be disassembled, hidden for the winter, and reassembled in the spring. This is in case the wiring is done for irrigation. The collapsible system is also good because you can always tighten the digging fitting or replace it with a new one. The disadvantage is that the fittings are bulky and internal wiring in a house or apartment is rarely made of them - the appearance is not the most pleasant. But for the water supply section - - it is difficult to find better material.
Assembly order
The pipe is cut strictly at 90 °. The cut should be even, without burrs. Dirt, oils or other contaminants are also unacceptable. Before assembly, chamfers are removed from the sections of the connected sections. This is necessary so that the sharp edge of the polyethylene does not damage the sealing rubber ring.
During installation, the connection of polyethylene pipes on compression fittings is tightened by hand
Spare parts are put on the prepared pipe in this order: a compression nut is pulled, then a collet, followed by a thrust ring. We install a rubber gasket in the fitting body. Now we connect the body and the pipe with the parts put on it, applying force - we must insert it all the way. We tighten all the spare parts to the body and connect them with a crimp nut. We twist the resulting connection of polyethylene pipes with force by hand. For reliability, you can hold out with a special mounting key. The use of other tightening tools is undesirable: plastic can be damaged.
Saddles and their scope
In addition to fittings, there is another interesting device that allows you to make branches from an already finished pipeline. These saddles are specially designed couplings. This coupling has one or more threaded holes. They usually put a tap in them, and a new branch of the water supply is connected to it.
Sedeki are put on the pipe, fixed with screws. After that, a hole is drilled in the branch with a drill and a thick drill in the surface of the pipe. When it is ready, a crane is installed, a branch is assembled further. So improve the system with minimal effort and cost.
Flange connections and transition to metal
In the water supply system, elements of the system that do not have a threaded, but a flanged connection can be installed. Usually these are taps or other shut-off or control valves. To connect with such elements, there is a special fitting for HDPE. On the one hand there is a standard compression version, on the other - a flanged version. Installation is standard - with a compression nut on one side, gaskets and bolts on the flange side.
When installing a water supply system from polyethylene pipes, questions may also arise about the connection of polyethylene and metal. For these cases, fittings are used, on one side of which there is a thread. It can be external or internal - it depends on the type of device or transition being installed. Such fittings are available in straight lines, in the form of a 90° angle.
The installation is standard - a thread (with winding neatly) on one side and a crimp nut on the other.
Compression mounting technology has several advantages:
- allows you to create a flexible and rigid connection;
- eliminates the need to thoroughly align HDPE pipes;
- ensures complete tightness of the polyethylene water pipe;
- does not require the use of a welding machine and the presence of special skills; allows you to create temporary networks and reuse fittings.
The design of compression HDPE fittings includes a body, a cover, pressing nuts, sealing and ferrules. For the production of these elements, a polypropylene copolymer, acetal resin, food-resistant rubber and stainless steel are used. The materials comply with sanitary standards and are suitable for drinking water supply.
The connection of HDPE pipes using compression fittings is called collapsible, because such a design can be assembled and disassembled several times. For installation, it is necessary to cut the pipe at a right angle, chamfer it and insert it into the connecting part until it stops. Then, using a compression wrench, tighten the press-in nut as much as possible. As a result, the crimp ring is tightly fixed on the segment and ensures a tight connection.
Compression HDPE fittings from OptiPlastic
Our online store presents products from reliable manufacturers: Kokhanovsky Pipe Plant (Belarus), Georg Fischer (Switzerland) and SAB (Italy). We have established partnerships with suppliers, so we can offer the best prices and delivery times.
The catalog includes about 200 items of fittings of various diameters:
- plugs, couplings, bends, tees Ø 20-110 mm, PN 10;
- flange connections Ø 50-110, PN 10;
- threaded saddles Ø 20-315, PN 10 and 16;
- ball valves Ø 20-63, PN 10 and 16;
- keys Ø 20-75 and 63-110.
Fittings are suitable for creating plastic plumbing systems from any grade of PE. If the required dimensions are not in the catalog, we will arrange their delivery as soon as possible. You can pick up the goods yourself from warehouses in Moscow, Klimovsk and Novomoskovsk or order delivery in Moscow and the Moscow region.
Polymer pipelines are a modern analogue of cast iron and steel communications. They are characterized by higher resistance to negative external influences, resistant to clogging, corrosion and temperature extremes. To connect these pipes, special PE fittings are used, which provide a tight and durable connection. They are widely used in heating and water supply systems. Communications made of these materials have a long service life, aesthetic appearance. Since the components of the pipelines are light in weight, there is no need to use powerful lifting equipment during their installation.
The production of these elements is carried out in several ways:
- by processing raw materials with nitrogen compounds;
- peroxide method;
- by silane gas treatment technology.
Regardless of the production technology, finished products meet high performance requirements.
Advantages of polyethylene fittings
The advantages of these shaped elements include:
- the absence of toxic components in the composition;
- resistance to deforming mechanical loads;
- chemical inertness;
- resistance to pest damage, rotting and destruction under the influence of moisture;
- wear resistance;
- ease of installation.
To order connecting fittings for polyethylene pipes, contact the managers at the phone numbers listed on the site or use the web form.
In the article we will try to systematize all the ways of connecting polyethylene pipes.
As part of the article, we will also touch on connections with various types of welding, and compression fittings for polyethylene pipes.
Material Features
What do we know about polyethylene pipes?
- They are plastic. The elongation at break of polyethylene lies between 500 and 600 percent; for finished products in GOST, a more modest value is fixed: 250%.
What does this mean in terms of connecting several pipes into a long water supply? Only one thing: on a relatively thin one, it makes no sense to cut a thread. She still can't handle a lot of pressure.
Tip: However, threaded polyethylene pipes are used in some applications.
In particular, for the use of HDPE pipes as casing when drilling wells for water.
Here, threaded pipes are the ideal material. They are connected without thickening and irregularities, which is very important in this case.
Such a connection is not suitable for a water supply system, but just right for a well
- They are fusible. The melting temperature of polyethylene lies in the range of 105-135 C, depending on the polymerization conditions, while the material begins to soften already at 80 C.
This, in turn, means two things: you cannot put polyethylene pipes on hot water; they can be joined by cheap and simple low-temperature welding.
Hence, there are two main ways to connect pipes: compression fittings for polyethylene pipes and welded joints of various types.
Connection methods
Butt welding
It’s worth mentioning right away: polyethylene pipes are not always connected using fittings. Pipes of large diameter are generally welded strictly end-to-end. In fact, fittings with a diameter of about a meter and heated on a soldering iron and put on a pipe in a few seconds until the plastic has frozen is a big problem.
For the installation of large diameter lines, special heating devices are used, which, after centering, melt the ends of the pipe and allow them to cool as a whole.
The strength of such a connection reaches 90% of the strength of a monolithic pipe; with a wall thickness of the main pipes of several centimeters, this is sufficient in excess.
Weld Fittings
Fittings for polyethylene pipes for welding neither externally nor structurally differ in any way from the same ones.
The principle of installation is exactly the same:
- Preparing the pipe and fitting. The pipe is cut strictly at right angles to its axis; chamfers are removed from the outside of the pipe and the inside of the fitting.
This is necessary so that the pipe enters the fitting without bumps and burrs. - The nozzle of the soldering iron is selected according to the diameter of the pipe. After it is warmed up, a fitting is put on its narrow side for a few seconds, and a pipe is inserted into the wide one.
The melted surfaces are combined and fixed until the polyethylene hardens. You can move on to the next connection.
Tip: when choosing a temperature, do not forget that polyethylene melts at a temperature of fifty degrees less than polypropylene.
Also, never twist the pipe while inserting it into the fitting. It will gather in waves, which will sharply weaken the connection.
Electrofusion connections
Before us is a special case of fittings for welding. The only difference is that they do not need a soldering iron: a coil of metal wire with high resistance is part of the fitting itself.
This drastically simplifies installation, making it extremely simple and fast:
- We fully assemble the plumbing in the configuration we need;
- We fix all its main elements with plastic latches or in any other way;
- And then we just go along the mounted water supply with a simple transformer or even a car battery with a couple of wires. Each fitting is energized for a short time. At the same time, it is fused with the pipe into a single whole.
Polyethylene pipes and fittings connected by welding have one drawback: all connections are non-separable. For the sake of any change in the configuration of the water supply, it will simply have to be cut and welded again using a new set of pipes and fittings.
This problem is completely devoid of the following installation method.
Compression fittings
Polyethylene pipes and fittings are connected in this case in much the same way as in the case of metal-plastic. However, the use of a split ring that compresses the pipe on the fitting nipple is not applicable here.
Soft polyethylene will simply warp or tear at the point where the most force is applied.
That is why compression fittings for polyethylene are actually a fitting body, a union nut and a rubber seal located between them and the pipe. The nut is screwed onto the thread of the fitting and compresses the rubber, sealing the connection.
The advantages of this method are obvious: the connection can be mounted without any tool, with bare hands. Of course, with a small pipe diameter: after all, compression fittings are available up to a size of 110 millimeters.
Unfortunately, the quality of the connection is very dependent on the reliability and durability of the rubber seal. Low-grade rubber is not applicable here: as soon as it loses elasticity, the connection will begin to flow.
In addition, resistance to external mechanical influences also leaves much to be desired. Just tripping on the pipe, it is not a problem to pull it out of the connection. In an apartment building, this is fraught with not the most pleasant date with the neighbors below.
Conclusion
Polyethylene pipes and fittings are undoubtedly an excellent choice for cold water supply systems. In terms of reliability and durability, welded joints are the leader, in terms of ease of maintenance, compression fittings. The choice is yours. Good luck!
Fittings have the following advantages:
- irreplaceable when laying a pipeline of any complexity;
- have a low cost;
- have a long service life;
- ensure the reliability of fasteners;
- have high elasticity;
- light in weight;
- they do not have condensate and grooves;
- have high resistance to corrosion;
- do not deform;
- presented in a wide range;
- provide trouble-free operation at any temperature conditions.
Depending on the material of the pipes and the type of pipeline, a certain type of fitting is used. The connection of HDPE pipes is carried out using polyethylene fittings. PND fittings are successfully used in the installation of water supply, gas pipelines. In addition, they are quite in demand when installing equipment for domestic needs: watering and irrigation, as well as transporting various types of liquids.
What should be guided by the choice of fittings?
To connect pipes of different diameters, it is better to choose reducing fittings.
If you need to connect polyethylene pipes of equal diameter, it is better to buy compression fittings.
In order to connect pipes and fittings without using welding, it is better to take compression fittings. Such connectors are produced already completely ready for installation, and no preliminary preparation of pipes is required for them.
In the case of installing a water or gas pipeline system, especially when welding is not applicable, the choice should be made in favor of electrofusion fittings.
What is the installation of HDPE fittings?
Installation of HDPE fittings will not be difficult. All that is needed is competent advice from the master and the usual technical training. Most often, fittings are used for the installation of water supply pipelines, for connecting different types of pipes, also for docking, or which can be bought as an alternative to steel ones. The use of fittings is not only a benefit, but also a significant simplification of the installation of a polyethylene pipe. The only thing, before you buy connecting fittings in Moscow for polyethylene pipes, you need to decide on the size and type of pipes that will be used.
