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Connecting fittings for polyethylene pipes low pressure

HDPE (low pressure polyethylene pipes) are one of the most modern and popular products for the construction of pipelines. for different purposes... In turn, each of them has an inlet and outlet, and almost each of them has different shut-off valves and branches, respectively, for this, fittings for HDPE pipes are also needed.

Types of polyethylene pipes, depending on the purpose.

There are a lot of them for HDPE pipes, which can be divided according to the principle of docking with the product. How to understand this variety and how is one or another shut-off valve selected correctly?

All types of HDPE pipe connections are divided:

• by rigidity: rigid and non-rigid (elastic) connection;
• by releasability: detachable and non-detachable connection;
• by the way the connection is made.

During installation, fittings for HDPE pipes, including stop valves, can be docked with the pipeline in various ways.

One-piece connection

Welding is the main type of connection. Exists different ways welding products. Some of these methods are more common, some are less common.

Diagram of butt welding.

Welding methods:

1. Butt welding is the most common method when the end of a product and a fitting is melted with a special apparatus and they are pressed against each other, as a result of the melt a monolithic seam is formed, which is similar in its properties to the pipe material. For this method, fittings and HDPE pipes must have the same diameter. Butt welding is very often used in the construction of internal water supply and heat supply networks, while "hand irons" are used. If in the welding machine the products are fixed with special accuracy in relation to the docking place, then when performing the work manually, it is necessary to pay Special attention the relative position of the products, and best of all - fix them with any devices until the seam hardens.
2. Socket welding - has the same principle, except that this method uses fittings for HDPE pipes with an inner diameter that is equal to the outer diameter of the product. If in the first method (butt welding) the soldering iron is made in the form of a disk, then in socket welding one side of the soldering iron is flat and equal to the diameter of the pipe, the other side looks like a rod, the diameter of which is equal to the inner diameter of the fitting.
3. Edge (press) welding - is used mainly for welding a product with the entrances of wells, etc., where it is necessary to weld a pipe to a plane that exceeds its diameter in size. For this, special PE electrodes are used. This method is used only in a non-pressure system that does not require absolute tightness.
4. Electrofusion welding - the welding process consists in melting polyethylene, while fittings and HDPE pipes must also have the same diameter. However, this method requires the use of a special coupler. The sleeve has a heating grid fused during production and two contacts. Each such clutch has a barcode. If using automatic welding machine, it independently reads the data and sets the optimal welding parameters. V otherwise these parameters must be set manually.

Electrofusion welding diagram.

Detachable connection

Proceeding from the fact that all welded fittings are permanent joints, they do not use shut-off valves and control devices... Since in the event of a failure of these devices, with an integral connection, their replacement requires significant effort.

The next type of connection is. They are used, as a rule, on external networks and the principle of their operation is the same. The compression fitting has a ring (split) and a tightening nut.

Flanged connection - used, as a rule, for with a large diameter, in places where shut-off and other valves are installed.

The nut, then we put the ring on the product, after which we tighten the nut. After it is tightened, this connection ensures that the ends of the product will not slip under tensile forces. In today's market, manufacturers offer both brass and compression types. As a rule, they are used when there is a threat of shock loads on this connection.

Based on the manufacturers' data, compression fittings are designed for a working medium pressure of up to 20 atmospheres, that is, they are suitable for use in pressure networks.

Flanged connection - used, as a rule, for joining pipes with a large diameter, in places where shut-off and other fittings are installed, or when connecting a polyethylene pipeline with metal sections. At the same time, in polyethylene networks, molded HDPE flanges are usually used, and if it is necessary to switch to metal, brass fittings equipped with a plastic outlet, which is designed for welded joint with a polymer product.

Threaded connection - an external one is used, which is cast on one of the ends of the pipe, and an internal one - on the other pipe of the connection or fitting. This connection is considered by experts to be not particularly reliable. Based on this, it is used for the installation of non-pressure fluid transportation systems or in the laying of cable communications.

Socket connection - based on fixing the end with a standard diameter of one product, inside the expansion at the end of another product or fitting. As a rule, this connection is used when installing a gravity drainage system (sewage) or when laying a cable.

Types of fittings

For laying a pipeline from, fittings are used in the following cases (by material and type):

Varieties of fittings for detachable joints of HDPE pipes

1. Equal bore coupling - produced with the same diameter at both ends. It is used for joining separate pieces of pipe or with other elements with the same diameter as the pipe.
2. Compensating coupling - used for the possibility of changing the diameters of the pipeline or installing an element with a larger / smaller size
3. Connection thread-plastic. When docking, for example, a polymer and metal fittings, a combination fitting is in progress. An embedded element with an external or internal thread is mounted in a plastic sleeve, usually made of brass.
4. Flanges - used for mounting removable fittings or docking with pipes made of other materials. There are combined and PE. Flange couplings are a variety of them.
5. Taps. Of course, polyethylene is a fairly flexible material, but still it should not bend too sharp. The use of bends allows the pipeline to change direction significantly. Bends for 45 °, 66 ° and 90 ° bends are available as standard.
6. Crosses and tees - with the use of such fittings, the pipeline can be docked with the required amount other sections of the network. Branches can be of the same or different diameters.
7. Plugs. This type of fitting allows you to preserve "blind" HDPE pipes. Such a situation can be, for example, if it is necessary to decommission a certain section of the water supply system, or they can be applied in places where a new connection will be organized later, etc.

In general, and fittings to it allows you to create a combination that will make it possible to build a pipeline for any task and in any conditions. Along with the relatively low price and high performance properties of HDPE products, this provides the polymer material with a well-deserved high popularity, both among private consumers and among installation organizations.

Low pressure polyethylene (HDPE) is a solid polymer material obtained by polymerizing ethylene. HDPE has the following physical and chemical properties:

• waterproofness;
• plastic;
• strength;
• lightness;
• acid-base, corrosion, temperature resistance;
• good heat and sound insulation.

The above properties determine the popularity of the use of low-pressure polyethylene in various industries industry. Primary processing of HDPE is carried out in four available ways:

1. Extrusion - Forcing molten material through an extruder. Allows you to receive food and garbage bags, conveyor nets, construction belts, sheets, pipes, etc.
2. Injection molding - injection of HDPE melt into a mold followed by cooling. The technology products are compression fittings for HDPE pipes, furniture fittings, plastic boxes, kitchen attributes, etc.;
3. Blowing - Injection of a polymer into a cavity in the form of an internal shape of the desired product. This technology allows you to receive cans, tanks, barrels, cisterns, etc.
4. Rotoforming - loading polymer in powder / liquid form into a hollow rotating mold with gradual melting and cooling in it. Used in the production of mannequins, traffic cones, parts for children's playgrounds, etc.

HDPE pipes and fittings for them

Properties and available market price HDPE determined the benefits of making plumbing and gas pipes... Installation of low-pressure polyethylene pipes (diameter from 10 to 1600 mm) is carried out in three available ways:

1. Bell-type - used for non-pressure systems (heating, sewerage) if there are bell rings on the pipes;
2. Compression - used in low-pressure systems (water supply, irrigation) by screwing a compression fitting onto the pipe;
3. Electro-welded - suitable for high-pressure systems (drains, gas pipelines), during the installation process, fittings for HDPE pipes and a welding machine are used.

The predominant method of connecting HDPE pipes is compression. It differs in:

• ease of assembly / disassembly;
• versatility (suitable for all types of pipelines);
• high rates quality, safety and hygiene.

As noted above, the compression installation of pipes is impossible without the presence of special connecting parts - fittings. Depending on the nature of the connection HDPE compression fittings can be of the following types:

• elbow, elbow;
• clutch;
• flange;
• tee, cross;
• plug;
• ball valve.

All of the above types of compression fittings have a similar design - a polyethylene body with external thread and a retainer, sealing and ferrule rings, bushing, nut-cover.

HDPE pipes and compression fittings in Moscow

Buy HDPE pipes and fittings for hot and cold water supply, heating, sewerage systems in Moscow on favorable price it is possible in the Terem online store. The company's catalog contains a wide range of products of the European (REHAU, TIEMME, STP) and Russian (CYKLON, RUVINIL, Dzhileks) manufacturers with detailed description technical characteristics, advantages, areas of application of the product, etc. All products of the online store comply with the ISO 9001 quality standard, are reliable and durable.

"Terem" - reliability, quality, stability.

Polyethylene compression fittings are compression type fittings for mounting PE 80 and PE 100 polyethylene pipes. Compression fittings for are made by molding from polypropylene copolymer. Polyethylene compression fittings are manufactured with various forms of internal and external threads: compression sleeves, compression tees, compression elbows and saddle compression elbows, compression plugs and flanged compression joints.

HDPE compression fittings are produced with a diameter from 16 mm to 110 mm and with a working pressure from 10 to 16 atmospheres (Bar): for a diameter from 16 to 63 mm up to 16 Bar, for a diameter from 75 to 110 mm up to 12.5 Bar. HDPE compression fittings are connected to PE pipes using a compression ring of the fitting, which is pressed onto the pipe. Compression fitting for polyethylene pipes is a collapsible design, which consists of modular components.

Areas of use

HDPE compression fittings are intended for connection and installation of PE80 and PE100 polyethylene pipes in places where direction changes: turns and branches, in places where the diameter of the pipeline changes, in places where it connects to pipeline fittings, as well as for the transition from polyethylene pipes to pipes from other materials. Compression fittings are used for the installation and repair of pipes of grades PE80 and PE100, which are used in drinking and industrial cold water supply systems (pipelines transporting drinking and food water, industrial water in irrigation systems, etc.), as sealed cable ducts. Also, these fittings can be used in any pipelines with a working medium, in relation to which the chemical resistance of the compression fittings themselves is ensured. Polyethylene compression fittings are widely used in automatic irrigation systems.

The use of compression fittings made of polyethylene of low pressure provides complete tightness between the mounted parts. Installation of HDPE compression fittings of small diameters is carried out manually without the use of special tools, large diameters using a special compression wrench. Compression fittings for PE pipes can be used in all weather conditions and negative temperatures... It is necessary to store compression products indoors, away from direct sunlight.

Compression fitting HDPE

Compression fitting for polyethylene pipes consists of five elements:

1 -Nut-cap is made of polypropylene copolymer, designed for fixing and crimping, has internal thread and external grooves for easy screwing.

2 - The crimp seam ring is made of polyoxymethyline, prevents movement and extrusion of the fixed pipe, as well as spontaneous unscrewing.

3 -The bushing with the pressing function is made of polypropylene copolymer, fixes the gasket in the correct stable position and limits its ultimate compression and deformation of the pipe.

4 -The O-ring-gasket is made of nitrile rubber, ensures reliable tightness of the connection with the pipe, even when it is kinked.

5 -The body of the compression fitting, made of polypropylene copolymer, has trapezoidal thread for the nut and the restrictor for the introduction of the pipe.

Main advantages

• Ease of installation: installation is quick and without preliminary preparation pipes, since the fittings are supplied ready for installation and do not require special skills and additional equipment.
• Ease of repair: when repairing compression fittings, you do not need special skills, additional equipment and a welding machine, you only need a plastic or metal compression wrench, and the repair itself takes place by replacing the internal components of the compression fitting.
• Multiple assembly and disassembly: assembly and disassembly of compression fittings for HDPE pipes can be carried out repeatedly up to 10 times.
• Corrosion resistance: there are no metal elements in HDPE compression fittings
• Hygienic: all compression fitting parts are made from materials that are suitable for transportation drinking water and food liquids
• Connection with elements of other materials: HDPE compression fittings have standard internal and external threads, so you can mount prefabricated elements for connecting pipes and fittings from different materials.

Properties and characteristics

Compression fittings for polyethylene PE pipes are highly resistant to temperature extremes and highly resistant to various chemicals... Compression fittings for HDPE pipes have high wear resistance when transporting various liquids and have a service life of more than 50 years.

Fittings for HDPE pipes (low pressure polyethylene) are in demand in residential and private construction, they are used as connecting fittings for cold water supply, sewerage systems and gas pipelines. As a rule, they can withstand a working flow pressure of up to 10 atm for gas or 16 atm if water is transported.

Fittings provide reliable and quality installation pipes NPD, which does not take much time and does not require special efforts for example, compression sleeves can be installed using only a wrench.

The sale of these products is established in almost any city, so there will be no problems with the acquisition. The cost of fittings is influenced by the type, size, and different kinds technical parameters.

Fittings used in the installation of pipes made of HDPE are usually classified according to the type of connection; the following options are currently practiced:

• the use of electrofusion welding;
• crimp (collet) connection method;
• butt welding;
• flange connections.

Accordingly, each method requires the use of its own type of pipe fittings. Let's consider each of them in detail.

Video: HDPE compression fittings, couplings, bends

Butt welding

For this method connecting fittings are not needed, since the pipes are welded directly end-to-end. Welding allows you to provide almost any design solution.

The figure shows all the stages of this process:

• a - centering the pipes relative to each other;
• b - a chamfer is removed from the ends of the pipes, its width is from two to three millimeters. After that, the ends are cleaned and degreased;
• c - ends are checked for alignment;
• d, e - using a heater fixed between the ends, polyethylene is melted;
• f - pipes are connected, during this process it is necessary to prevent them from turning and displacement.

The cooled connection is immediately ready for use.

Main advantages:

• low cost;
• quick installation.

Disadvantages:

• it is not possible to connect pipes without welding equipment;
• welding is permissible only when the pipe thickness is more than 5mm.

Electrofusion welded connection

This technology will help in cases where it is impossible to apply conventional welding, for example, when welding equipment cannot be installed at the joint. Connecting fittings for HDPE pipes are electrofusion fittings (couplings) on which an open electric heating coil is installed.

To connect pipes with this method, you need a welding machine equipped with a barcode scanner, a photo of such a device is shown in the figure below.

The connection process is performed according to the following algorithm:

• the preparatory stage, it consists in the fact that before welding the polyethylene pipes, their ends are cleaned and degreased;
• the pipes are pushed into the socket of the coupling, and the embedded thermoelement is connected to the welding machine;

• using the scanner, the barcode printed on the body of the connecting fittings is read, this is required to set the required mode;
• after switching on, the polyethylene layer melts, while the pipe expands from heating, as a result of which it is pressed against the sleeve;
• the device automatically turns off, according to the selected mode, after natural cooling, the connection is ready for use.

This method is good because it does not require special skills, it is completely easy to learn it. But there is a significant drawback of this technology for connecting HDPE pipes - high prices for welding equipment and fittings.

Crimp (collet) method

Threaded (collet) pipe joints made of HDPE are more popular than other methods, this is due to the fact that there is no need to resort to expensive specialized equipment.

Everything assembly work can be made with an ordinary tool, in rare exceptions a wrench may be needed (when crimping nuts with a diameter of 63 to 110 mm).

Note that, in addition to connecting pipe fittings for crimp connections, a shut-off valve is also produced, that is, on which taps are installed, which significantly expands the scope of its application when conducting a water supply system.

Using compression fittings for connecting pipes made of HDPE material with a diameter of 20, 32, 50 mm, etc., you can independently assemble a reliable and durable water supply system for a house or apartment. This is easy to do if you adhere to the following recommendations:

• choose pipe fittings renowned manufacturers, for example, Tiemme or Unidelta, this will avoid numerous problems during operation;
• connect to a standard thread, which it is advisable to pre-clean and calibrate;
• do not tighten the thread all the way, always leave one or two turns free;
• for sealing, you can use a special Teflon tape, sealant or, in extreme cases, linen tow. Remember that the fittings are plastic, not metal, so you do not need to apply great force to them when tightening;
• it is recommended to install the connecting elements in a straight section, in this case the risk that the pipe will be turned out or flattened is minimal;
• for secure fixation of pipes large diameter use a wrench when tightening the nut.

To connect pipes made of HDPE material together by a crimp method, you can also use brass fittings, which, although they are much more expensive, have many advantages, namely:

• couplings are more reliable and durable than polyethylene counterparts;
• they have a higher pressure head threshold, which ensures resistance to water hammer;
• the material is not subject to corrosion;
• when tightening the nut, you do not have to worry about the threads breaking.

The only drawback, as mentioned above, is the high cost, but if you can afford not to save on quality, then we recommend using this particular type of pipe fittings.

Flange connections (adapters for metal and metal-plastic pipes)

It is impossible to do without this type of pipe fittings if it is necessary to provide a transition from pipes made of HDPE to metal ones, for example, for connecting to a riser.

Approximate price level

We give the price level in various cities of Russia for the most common type of connecting elements for HDPE pipes, namely, compression fittings, this information can be useful if you are going to buy them, but there is no time to do a comparative analysis.

The average price level for fittings for HDPE pipes in different regions of Russia is approximately the same, the cost of the device is Nizhny Novgorod, Samara, Chelyabinsk and Moscow are approximately at the same level. The survey was carried out for retail prices, therefore, the wholesale price will be lower.