Fittings and taps for pipes pnd. Types and installation of fittings for HDPE pipes

Due to the wide popularity various kinds polyethylene pipes the demand for connecting elements, called fittings, is increasing. HDPE pipe fittings allow installation easily and in a short time. V this moment enterprises produce many different compounds. Fittings for HDPE pipes are made of various types of polyethylene, copper or brass.

Fittings for HDPE pipes are used:

For connecting pipes with the same diameter.
For joining pipes with different diameters.
For the arrangement of branchings provided for by the pipeline scheme.
For mounting pipe bends.
To install a plug on a PE pipe.
For connecting pipes with different fittings.

Connection points for PE pipes must be:

Reliable.
Durable.
Waterproof.
Resistant to possible effects of chemical elements.

Fitting classification

Professional pipeline installers distinguish between the connection of HDPE pipes with fittings according to:

Mounting method: compression, welded, electric welded.
Rigidity: flexible and rigid.
Detachable: detachable and one-piece.

There is another classification of connecting elements:

Straight lines used for joining HDPE pipes of the same diameter.
Reducing, used when connecting pipes of different diameters.

Let us analyze in more detail the first classification of fittings.

Fittings for various pipe connection methods

Depending on the chosen method of pipeline installation, there are:

welded fittings;
electrowelded connecting elements;
compression fittings.

Welded connectors

Weld fittings can be produced in two ways:

by the method of reflux occurring under high pressure(cast fittings);

by butt welding of small pipe sections (weld fittings).

Weld fittings are available in diameters from 63 mm to 315 mm.

This type of fitting is designed to connect pipes by welding. The low cost of welded fittings causes a wide range of their application. Almost all branches and plugs provided for by the pipeline design can be made with welded connecting elements.

Most often, welded fittings are used during installation gas pipelines and systems in which the temperature of the transported liquid does not exceed 40ºС.

Electrofusion fittings

Electrofusion or thermistor fittings are used to mount the pipeline structure in hard-to-reach places, that is, where conventional butt welding is impossible.

Equipped with a heating wire located on the connecting parts. Under the influence of temperature, these spirals heat up and melt the polyethylene pipe. After cooling, a strong weld is obtained.

Compression connectors

Compression fittings for HDPE pipes are designed to connect pipes without welding. With the help of such butt elements, a detachable connection is obtained.

Fittings of this type consist of:

polyethylene body;
sealing rings located at the joints;
clamping rings that protect connections from mechanical damage;
bushing that presses the pipe;
caps-nuts that securely close the docking area.

Issued from various materials. The connection diameter varies from 16 mm to 110 mm.

Features of installation with compression fittings

To properly connect pipes or make the necessary branches with compression fittings, you must follow the following instructions:

The HDPE pipe is prepared and the compression fittings are unscrewed a few turns.
A marking is applied to the pipe, indicating at what depth it is necessary to insert the pipe into the fitting. Before installation, it is advisable to lubricate the pipe section intended for docking with water or a light soapy solution.
Up to the drawn mark, the pipe is inserted into the prepared fitting. For the full entry of the PE pipe into the sealing ring, force will be required. Otherwise, the connection will not be tight.
The cap-nut is tightened until the end of the thread.

At correct installation compression fittings, a sufficiently strong and tight connection is obtained.

Separation of fittings according to the stiffness of the connection

According to the degree of rigidity, fittings are distinguished:

Rigid. Such connections completely exclude the possibility of moving pipes.

Flexible, which allows longitudinal movement of pipes by 3 - 5 mm and rotation of pipes at a small angle. When using a flexible fitting, all the properties required for the connection point remain unchanged.

Flexible connections are most suitable for laying pipelines in the ground, but also more expensive. Therefore, they are only used when absolutely necessary.

For the installation of the simplest piping systems, rigid fittings are more often used.

Types of fittings distinguished by the detachability of the connection

When installing the pipeline, both detachable connections and one-piece connections may be required. This is due to the location of the pipe joint and its application. For example, HDPE pipes for water supply: fittings at the first stage of installation are used to connect the pipeline to pumping station. At some point in time, it may be necessary to replace the pump and a detachable connection will simplify the necessary work as much as possible.

Plug connections

In most cases, installation is carried out with the compression fittings described above. But there are other ways to arrange such a joint:

Flange connection. A cast or brass flange is attached to the pipe by welding. This type of connection is mainly used for pipes of large diameter or for joining a polyethylene pipe with a metal one.
Threaded connection. Fastening of pipes is carried out using pre-prepared threads on pipes and fittings. Considered the least reliable. It can be used for laying cable pipelines or systems with low liquid pressure.
Socket connection. It is used extremely rarely. It is carried out by fixing one end of the pipe in the extension of the fitting or the other end of the pipe. Most often used for laying pipelines for cable.

For detachable connections can be used brass fittings for HDPE pipes.

Permanent connections

Permanent connections are most often used to connect structures located underground or in concrete, since this type is considered the most reliable. Pipe welding can be carried out in the following ways:

Butt. The most common way to join pipes of the same diameter;
Nest welding. For this method of joining pipes, fittings with an inner diameter equal to the same parameter of the pipe are used.
Press or edge welding. It is used for joining pipes with structures, for example, wells.
Electrofusion welding. It occurs with the help of electric couplings and is considered the most reliable connection method.

For the arrangement of a permanent connection, cast and electrofusion fittings are used.

Types of fittings

All fittings differ in their design features and, accordingly, the scope. Depending on this, fittings can be divided into:

Couplings that are found in three main types:
- Equal bore, connecting pipes with the same diameter.
- Compensatory, mainly used to switch to a pipe with a smaller diameter.
- Flanged, used for joining pipes with a large diameter.
Adapters. With their help, various fittings or another type of pipe, for example, metal, is attached to the pipeline.
Branches. They are used to change the direction of pipes, turn the system. Standard elbows are available with 45º, 66º or 90º swivel capability. Some firms are engaged in the production of fittings according to the customer's parameters. If the installation of the system requires bends with a different degree measure of the angle, then such a fitting can always be ordered from manufacturers.
Saddles. Designed for arranging various branches. The saddle for the HDPE pipe can be of two types:

Clamps that compress pipes from all sides.
Pads used to cut a new pipeline into an existing system.

Crosses and tees. They are used for the installation of pipeline branches and for connecting other devices to the network.
Plugs. They are used to temporarily block the incoming liquid or gas into the pipe.

A certain type of fitting is intended for the installation of a certain pipeline design.

Fittings are produced to facilitate the assembly of polyethylene pipes. A properly selected set of connecting elements will minimize the time required for the installation of the pipeline system and greatly facilitate the work of connecting pipes.

Currently, when laying communication lines for various purposes, polyethylene pipes are often used. low pressure(PND). Their installation is carried out using special fittings, which include ball valves. Next, we will consider what these products are, what they are and what their features are.

polyethylene ball valve 25 - 25 mm

Features of HDPE ball valves

Plastic ball valves for HDPE pipes are shut-off valves, which are designed to completely shut off the flow of liquid transported through the pipeline. They are called ball because the locking mechanism is made in the form of a ball with a through hole.

The ball can rotate 90 degrees in the body, which allows you to open or block the passage. The position of the locking mechanism is controlled by a lever. In cranes of large diameter (150 mm and more), the locking mechanism is controlled by an electric drive, pneumatic or hydraulic drive.

The body of these devices is made of HDPE, i.e. the same material as the pipeline itself. The locking mechanism is most often made from polypropylene or another type of plastic.

Advantages

The shut-off valve under consideration has many positive qualities, among which are:

Durability - the product can last 25 years or more. Durability largely depends on the operating conditions of the product.
Reliability, which is associated with simplicity of design.
Low price due to cheap materials.
Low weight products.
High degree of tightness.
Due to the fact that the device is made of plastic, it is not subject to corrosion, and besides, sediment practically does not settle on it.

Flaws

For objectivity, here are some of the shortcomings of the devices in question:

Cannot be used to regulate the flow, as in this case they quickly fail.
Like other HDPE fittings, they are designed for less pressure than metal fittings.
As the temperature rises, the strength of the device decreases.

Note!
Before using a plastic ball valve for HDPE pipes, you must make sure that its characteristics correspond to the conditions in which it will be operated.

Types of valves for HDPE

In addition to the fact that the devices in question differ in diameter, they can also be designed for different ways mounting:

Collet (compression);
Flanged;
Welded.

Below we will take a closer look at the features of each type of device.

collet

These devices are used for pipelines of small diameter - 20 mm - 110 mm. Their main feature is the ease of installation, which can be done by hand without the use of special equipment, and without the skills of such work.

Note!
For high-quality installation of the crane by the collet method, it is necessary to strictly perpendicular to their axis and chamfer a few millimeters, as shown in the diagram above.

As a rule, this shutoff valve is used in domestic water pipes. Below are the main characteristics of these devices:

Depending on the device model, the specifications may vary slightly. However, in general, they correspond to the data from the table.

I must say that compression valves can have both the same dimensions of the inlet and outlet pipe, for example, 32 - 32 mm, or different, i.e. can serve as adapters between pipes of different diameters.

In the photo - a flanged polyethylene valve

Flanged

Flanged ball valves HDPE are used for large diameter pipelines (up to 315 mm). They are connected to the pipeline by bolting using flanges. As a collet, this connection is collapsible.

Unlike devices of the previous type, flanged valves are able to withstand more pressure. Often these valves are used in the chemical industry, as they are resistant to acids and alkalis, and are not subject to corrosion.

Welded

This method of connection is used in cases where it is necessary to ensure tightness. Installation instructions in this case are more complicated.

Welding can be done in two ways:

butt- using a special welding machine that melts the ends of the two parts to be welded. Subsequently, the parts are joined under pressure.
Electrofusion method- the heating of the surfaces of the parts to be joined in this case is carried out with the help of shaped parts through which a metal spiral passes. As a result, the parts to be joined and the electrical coupling are welded together, providing a reliable connection.

Here, perhaps, are all types of polyethylene ball valves.

Conclusion

Polyethylene ball valves are reliable shut-off valves used for various types of pipelines made of HDPE pipes. As we found out, depending on the purpose of the line and its diameter, they can be mounted in different ways.

From the video in this article, you can get some additional information on this topic.

Connecting elements can be classified according to a number of features:

1. Purpose of application

connection of pipes with equal diameter;
joining pipes with different diameters;
creation of branches of pipelines;
pipe bending device;
for installation in a single pipe system with various fittings;

2. Mounting method:

compression;
welded;
electrowelded;

3. Hardness:

rigid - exclude any possibility of moving pipes;
flexible - slight longitudinal movement of pipes and rotation at a small angle are allowed. In this case, all created connections are not broken and remain unchanged;

4. Detachability:

detachable - allow you to create strong and tight connections, which can be disassembled if necessary, for example, for repair, reconstruction and change of the route of the pipeline;
one-piece - as a rule, they are used when creating pipe connections that are underground, in concrete, etc. This type of connection is the most reliable, but does not allow disassembling the system into separate components.

Where to buy fittings at an affordable cost

Our catalog offers a wide range of fittings for HDPE pipes. Here you will find compression, molded, electrofusion fittings. We supply products directly from the manufacturer, this allows us to form attractive prices without additional markups and overpayments.

Pickup points in the cities of Moscow, Klimovsk and Novomoskovsk will allow you to pick up the goods at convenient location. You can also order delivery in Moscow and the Moscow region.

Polyethylene compression fittings are compression fittings connecting parts compression type for the installation of polyethylene pipes of the brand PE 80 and PE 100. Compression fittings for are produced by injection molding from polypropylene copolymer. Polyethylene compression fittings are available with internal and external threads. various forms: compression couplings, compression tees, compression elbows and saddle compression elbows, compression plugs and flanged compression connections.

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

Areas of use

PND compression fittings are designed for connection and installation of polyethylene pipes of grades PE80 and PE100 in places of direction change: turns and branching, in places of change in pipeline diameter, in places of connection with pipeline fittings, as well as for transition from polyethylene pipes to pipes made of other materials. Compression fittings for are used in the installation and repair of pipes of grades PE80 and PE100, which are used in drinking and technical cold water supply systems (pipelines transporting drinking and food water, industrial water in irrigation systems, etc.), as sealed cable channels. Also, these fittings can be used in any pipelines with working environment, in relation to which the chemical resistance of the compression fittings themselves is provided. Polyethylene compression fittings are widely used in automatic irrigation systems.

The use of compression fittings made of low pressure polyethylene ensures 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 key. Compression fittings for PE polyethylene pipes can be used in all weather conditions and negative temperatures. It is necessary to store compression fittings indoors, protecting them from direct sunlight.

Compression fittings HDPE

Compression fitting for polyethylene pipes consists of five elements:

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

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

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

4 - The sealing ring-gasket is made of nitrile rubber, provides reliable tightness of the connection with the pipe, even when it is bent.

5 - Compression fitting body, made of polypropylene copolymer, has a trapezoidal thread for the nut and a pipe insertion limiter.

Main advantages

Ease of installation: installation is quick and easy pre-training pipes, as fittings are supplied ready for installation and do not require special skills and additional equipment.
Easy to Repair: Compression fittings do not require special skills, additional equipment or welding machine, you only need a plastic or metal compression key, and the repair itself occurs by replacing the internal components of the compression fitting.
Multiple assembly and disassembly: HDPE compression fittings can be assembled and disassembled repeatedly up to 10 times.
Corrosion resistance: there are no metal elements in HDPE compression fittings
Hygiene: all parts of compression fittings are made from materials that are suitable for transport drinking water and food liquids
Connection with elements from other materials: HDPE compression fittings have a standard internal and external thread, so you can mount prefabricated elements for connecting pipes and fittings from various materials.

Properties and characteristics

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