Polyethylene HDPE pipe connection with steel. Connecting polyethylene pipes to steel - is it easy to do it yourself? Cases of connection of dissimilar pipes

When installing water and gas pipelines, there is a constant need to connect pipes made of different materials. To connect pipes made of polyethylene (HDPE, PE) with steel pipes, use: special adapters polyethylene-steel (NSPS), threaded compression couplings or a sleeve for a flange connection.

Types of connection of PE pipes with steel.

1. Permanent connection polyethylene-steel (NSPS)

Permanent connection polyethylene-steel (NSPS) or adapter PE-steel used in the construction of gas pipelines, water pipelines, pressure sewerage to perform the transition from steel pipe on polyethylene HDPE or vice versa. Used during installation pipeline fittings or a tie-in into an existing steel pipeline. The steel-PE transition does not require maintenance; it can be placed directly in the ground without wells on straight sections of the pipeline.
The polyethylene-steel transition is a connection obtained by welding a steel pipe with a polyethylene pipe. The length of the branch pipes is regulated technical conditions for gas pipelines TU 4859-026-03321549-98, for pressure pipelines according to TU 2248-001-86324344-2009. Maximum working pressure for gas pipelines made of PE80 0.64 MPa, PE100 1.0 MPa. The maximum working pressure for pressure water pipelines is PE80 1.25 MPa, from PE100 1.6 MPa.
In the manufacture of an integral polyethylene-steel connection, a HDPE polyethylene pipe is used GOST R 50838-95 for gas pipelines and GOST 18599-2001 for water pipelines. And steel water and gas pipe according to GOST 10705-80, GOST 10704-91, GOST 8731-74, GOST 8732-78. NSPS is a connection that is made by welding a steel pipe with a polyethylene pipe. The length of the product is regulated by the TU for pressure pipelines and gas pipelines. Pressure for gas pipelines PE 80 - 0.64 MPa, PE 100 - 1 MPa; for pressure pipelines PE 80 - 1.25 MPa, PE 100 - 1.6 MPa.

Most often NSPS use for connecting metal locking devices to a polyethylene pipeline, gradual replacement of steel pipeline sections with polyethylene, tie-in polyethylene branch. The principle of the NSPS part is a strong and tight connection of a pipe or steel part with a polyethylene pipe of the same diameter.

The permanent connection to the end of the pipe occurs by means of thermistor welding, for which it is necessary special equipment... The end of the polyethylene pipe is heated to a viscous-viscous state and under pressure is connected to the steel end. To strengthen the connection, polyethylene couplings are used, but you can do without them. It allows this connection to be used in high-pressure pipelines.

NSPS allow:

Use them as stubs;
Use metal shut-off valves on polyethylene pipes on the HDPE
To produce gas inlets of various diameters on their basis
Drain from polyethylene into an existing steel pipe
Apply welding on steel pipelines with steel pipes in accordance with regulatory documents.
Installation of metal valves in HDPE polyethylene pipelines
Alternate replacement of sections of steel pipelines with polyethylene with permanent joints until the complete replacement of the existing steel pipeline with polyethylene
Tie-in of branches from HDPE polyethylene pipes with permanent joints into the existing steel pipeline
Welding with steel pipes in accordance with the current regulatory documentation for steel pipelines with permanent joints.

2. Threaded compression couplings

Compression polyethylene HDPE fittings. This type of fitting is called tube fittings. They are attached to the system using gasket material and crimp rings. To use this type, you do not need any optional equipment... In addition, when the cushioning material is used up, you can replace the old gasket with a new one. That is, HDPE fittings of this type can be used repeatedly, especially in hydraulic systems Oh.

Compression products are mainly used for hydraulic water supply systems. They can be built into such a system without even being fully assembled. This makes it possible to widely vary their application in water supply systems. Compression fittings are of the following types:

transitional couplings of different diameters;
couplings, including those with internal and external thread;
a tee without a thread and a transitional tee with a thread;
square;
branch;
stub.

They come with both internal and external thread... Like other fittings, these come in a variety of shapes. They are: coupling, triple, cross, plugs, flanges, bends.

They are made in different diameters: from 16 to 110 mm. The working pressure, depending on the diameter, can vary from 10 to 16 atmospheres.

All structural components are modular and disassembled. This has a good advantage, since in the future such pipes will be easy to replace, and the connection will be reused.

Application of HDPE polyethylene fittings

Most often, these fittings are used to connect pipes in those places where it is expected to change the direction of the pipeline, as well as the presence of branches or transitions to pipes of a different material. They are used for both technical and drinking water supply, in irrigation systems or as cable ducts. Thanks to the material, these fittings allow you to make a complete tightness of the pipe joint.

The use of compression fittings for connecting pipes

Also, their ease of installation allows you to install parts of small diameters without outside help and special equipment. These parts are stored in dark rooms, away from direct sunlight.

This part consists of 5 dismountable parts. To fix the crimp, there is a cover nut, which has external grooves for easy screwing and an internal thread. It is made of polyethylene copolymer.

A crimp ring is a part that prevents any movement of the pipe, including spontaneous unscrewing.

Compression fittings structure

The sleeve fixes the gasket in a stable position, limits its compression and deformation of the pipe. Made from polypropylene copolymer.

The gasket is made of rubber. Provides good tightness, even in the event of a kink in the pipe.

The body itself is made of polypropylene copolymer, has a special pipe stop and trapezoidal thread.

3. HDPE sleeve for flange

Polyethylene sleeveunder the flange it is used to connect a PE pipe to a steel pipe through a flange connection, as well as fasteners to control or shut-off valves.

Among the bushings made of HDPE, 2 groups are distinguished:

HDPE segment bushings - Such sleeves are butt-welded HDPE elements, partially or completely consisting of HDPE pipes.

Molded HDPE Fittings - differ from segment ones in that they are made by injection molding and do not have welds. Fitting large diameters sometimes produced by casting followed by machining.

The principle of using this fitting is to provide a stop for the flange that is put on the sleeve and excludes the possibility of disconnection of the assembly during its operation. A sleeve for a flange is used at the transition points of a polyethylene pipeline on a valve or a steel pipe, if there is a counter flange on it.

The HDPE flange sleeve is used in conjunction with a clamping flange, which must have a wider inner diameter than a conventional standard flange. The need for boring the inner part of the flange consists in the presence of reinforcing expansion of the polyethylene part of the sleeve at the base of the collar, which prevents the flange from tightly adhering to the clamping part.

After installing the sleeve on the pipe, using a steel flange and bolts with nuts, the pipe is attached to the valve, and the collar on the sleeve prevents the flange from jumping off during operation of the pipeline at operating and maximum pressures.

Using HDPE bushings

The installation of the bushings is quite simple, because everything modern elements fittings strive for ease of use. This saves time and money at the time of construction of the pipeline, and also allows you to achieve long-term system operation without problems. The benefits of mounting different types of system elements using bushings are as follows:

complete tightness of the joints and no risks of sudden breakdown;
the system does not need maintenance, any problems can be quickly corrected;
installation of HDPE pipeline elements is quick and very simple;
a wide range of bushing diameters are available from the supplier.

When organizing piping for liquid or vapor media, you can rely on the quality and reliability of molded plastic flange sleeves at the connection points. These elements will help to organize a reliable and durable pipeline system.

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When arranging modern systems sewerage, heating, water supply, polyethylene pipes are often connected with fittings. Also, when laying household communications, flanges are used, which make it possible to collect pipe products from different materials into one network.

In recent years, polyethylene (PE) pipes have been actively replacing traditional iron and steel products from the construction market. Plastic structures are superior to metal in a number of indicators. Therefore, such a process has a completely logical explanation - everyone wants to have in their home reliable and inexpensive in operation, heating, sewerage, assembled without welding. When installing, you have to face one problem. It lies in the fact that many elements of household piping in apartments are made of metal products.

Connecting plastic and metal pipes

And here it is important to correctly connect PE pipes with steel (cast iron) pipes. This can be done in two ways: using flanges and using fittings. Flange connection of polyethylene (polypropylene) pipes with steel pipes is recommended for cases when systems of products with a cross section of more than 50 mm are equipped. But pipelines with a diameter of up to 50 mm are best connected with fittings. They are special elements with a smooth socket for connecting PE pipes and a thread for metal pipes.

The flange is manufactured as a threaded part. It is most often used to connect metal and polyethylene water pipelines, as well as gas pipelines without welding. Flanges for assembling household networks from different materials have not only a thread on one side, but also an obligatory seal. The latter is located at the second end of the described element. The gasket guarantees a tight and truly durable connection, which can always be disassembled if necessary.

Flange connection example

For laying communications, you can use:

metal slip flanges;
flanges for special bushings (they are called collars).

Experts advise home craftsmen to connect PE pipes using the second of these methods. In this case, the connection is of the highest quality. Flanges for bushings are made of steel 20. Flanges for polyethylene pipes are designed for operating pressures up to 1.6 MPa. These parts are manufactured with a cross-section from 20 to 1200 mm. Therefore, problems with the selection of suitable elements for creating detachable connections never arise. There are several subtleties of assembling communications using flanges. We give them below:

flanges supported by cone-type bushings should be used when working with pipes with a cross section of more than 200 mm;
light pipe products made of PE with a diameter of 150–300 mm, as well as heavy ones with a cross-section of less than 150 mm, are best connected using flanges with a straight shoulder;
to increase the strength characteristics of connecting pipes made of different materials, you can use straight bushings with a special tapered transition.

When choosing flanges for making detachable connections, pay special attention to the quality of the fasteners. Burrs and sharp edges are not allowed on them. Such defects can cause damage to PE pipes. Flange connection of polyethylene pipes with a cross section of more than 50 mm is made according to a simple scheme. You need to evenly cut the pipe product in the place where it will dock with another part of the communication. After that, you gently pull the flange over the pipe and put on a rubber gasket on top.

Such a sealing element can go beyond the cut made by a maximum of 1 cm, no more. Then you slide the flange over the gasket and dock it (using bolts) with the counter flange. The bolts must be tightened very carefully. If you apply excessive force during this procedure, the plastic pipe may crack.

Individual elements of communications (heating, water supply) in an apartment or house are often connected with fittings. These elements are indispensable for connecting polyethylene pipe products to metal filters, meters, mixers, pipes and other details of a modern pipeline. An external or internal thread is cut on the fittings. Structurally, as noted above, they are special adapters with a thread and a coupling.

Pipe fittings

When choosing fittings, it is necessary to take into account the diameter of the metal pipe into which they will be cut.

Adapters are ideal for applications where piping has a lot of bends and bends. The assembly of the system (steel or cast iron pipes plus polyethylene) using fittings is performed as follows:

Unscrew the coupling of the metal pipe product. If the junction of the PE and the steel pipe falls on another section, you will need to cut the old metal product. And then you need to lubricate the cut edge with oil or grease and, using a thread cutter, make a new thread for the fitting. The operation for a more or less experienced self-taught craftsman is not difficult.
Thoroughly wipe the thread on the pipe, wrap it with fum tape or ordinary tow. Then apply silicone on top. Tape or tow is wound quite a bit. It is enough to perform a couple of turns. In this case, the edge of the wound material when clamping it must be directed along the thread.
Using your hands (do not use a wrench or other tool), carefully screw the connecting fitting onto the thread. Under strong pressure on the adapter, there is a high probability of cracking.
Insert the PE pipe into the socket on the second end of the fitting and solder it.
Treat the connection with a sealant.

Basically, that's it. You have connected a polyethylene (or polypropylene) pipe to a steel one. Turn on the water (if a water supply system was made) and check the fitting point for leaks. If there is one, simply twist the adapter a little. The final of the work is the treatment of the joint made with a sealant. You can fully use the pipeline in 3-4 hours. During this time, the sealant will dry completely.

When laying a pipeline from polyethylene pipes, a flange for PE pipes is used to solve problems related to their connection to each other or to reinforcement elements. What is a flange fittings, as well as the installation features of such a connection, are discussed in this article.

Flange - as an element of pipeline fittings

Product features

Structurally, the fixing flange for PE pipes is a flat ring, or rather a disc, in which holes are located at the same distance. These holes are used to secure the connection with bolts (studs). Flanges are installed with a collar or bushing.

The bushing for the PE flange immediately in front of the shoulder has a special expansion for reinforcement, due to which the flange does not fit tightly against the flange. To solve this problem, bored flanges are used. Such products differ from standard products in that they have an enlarged (bored) inner diameter to the required size so that the flange fits snugly on the bushing. All other parameters, such as the number of bolt holes, their diameter, center-to-center distance, fully correspond to a standard, flat, steel flange.

Flange Applications

Steel flanges are used to connect polyethylene pipes:

pressure and non-pressure mains;
systems intended for the removal of atmospheric precipitation;
storm sewer;
technical (industrial) pipelines, etc.

Thanks to the flanges, it is possible to create a reliable, detachable connection of pipe products with different valves, taps (valves) and other pipeline fittings. If necessary, such a connection can be quickly disassembled for repair or cleaning of pipeline products.

Flange varieties

Geometric standard sizes, as well as the manufacturing technology of these products fully meets the requirements state standards... To organize the connection of different pipes with fittings and devices, the industry produces a wide range of products. All flanges for polyethylene pipes are characterized by:

inner diameter;
external dimensions;
the diameter of the bolt holes;
weight;
working pressure.

Depending on the tasks performed, the following types of flanges are distinguished:

With special welded bushings.
Slip-on metal.
Free type, supported by collars, which can be straight and tapered.

For connecting polyethylene pipelines laid with medium and heavy PE pipes with a diameter of not more than 150.0 mm, as well as light pipes, but large diameter(up to 300.0 mm), the best option would be loose flanges that rest on a straight shoulder. Free-type flanges, but supported on tapered collars, are used for pipes with a diameter of 200.0 mm and more.

Flange Mounting Procedure

Due to the simplicity and speed of installation, this type of connection is very common when laying polyethylene pipelines. To obtain a flange connection with welded sleeves, you must:

Cut off the pipe at the place of the planned joint. Ensure that the cut is perfectly straight.
Weld a flange adapter for PE pipes (special sleeve) on the end of the pipe.
Install the flange itself on the welded sleeve using a threaded connection.

Flanges should always be carefully inspected prior to installation for burrs and sharp elements that can easily damage tubing and fittings.

Install a counter flange on another section of the pipe or other element of pipeline fittings in the same way.
After joining, the flanges are fastened together using bolted connections.

To use a free-type compression metal flange, you must:

In both cases, it is very important in the last step to tighten the flange bolts evenly crosswise. The effort must correspond to the technical documentation.

Thus, a steel flange for PE pipes is a reliable and durable element of pipeline fittings, with which you can mount a sealed, detachable connection of parts (assemblies) of a pipeline made of polyethylene.

Flange connection of polyethylene pipes

1. Polyethylene pipe;
2. Sleeve for flange;
3. Loose flange;

The choice of shut-off, control and other valves installed on polyethylene pipelines is carried out in accordance with the standards, specifications, catalogs, parameters of the transported substances, taking into account the requirements of the project and operating conditions.

Pressure polyethylene pipelines are connected to pipelines made of other materials using detachable steel flange connections.

The sleeve for the flange at the base of the shoulder has a special constructive expansion designed for more reliable connection of the shoulder. After all, it is on the collar of the sleeve that the main pressure occurs during the operation of the pipeline. Conventional flanges supplied for steel pipes in accordance with GOST 12820.80 cannot be freely installed on the sleeve due to their narrow inner diameter. Therefore, for flange connection of polyethylene pipes, free bored flanges are used in accordance with GOST 12822.80 with an increased inner diameter d1, which allows you to freely put it on the PE pipe.

Loose flange

d is the inner diameter of the flange according to GOST 12820.80;
d1 - free bored flange according to GOST 12822.80.

Connection types

Thus, to connect dissimilar pipes, use:

NPSP - one-piece connection in gas, sewer and water mains, for which an adapter is used special purpose... The connection is essentially a welding of a polyethylene pipe with a steel one.
Compression couplings equipped with a thread - compression fitting. It is used in conjunction with ferrules and gaskets, which can be changed as they wear out.
Flange transition.

What are flanges for connecting dissimilar pipes

Joining pipes made of dissimilar materials by means of flanges is optimal when installing a line in which it is required to connect a metal pipe with HDPE or locking devices. For this purpose, a sleeve is used together with a clamping flange, which in turn is fixed with bolts. The collar (the second name of the part) prevents the flange from sliding off when the pressure in the pipe rises.

There are two types of bushings:

Segmental, i.e. HDPE elements connected by butt welding.
Cast structures with no welded seams. The molded HDPE bushing provides the necessary support for the flange and does not allow the unit to come apart. It is also assumed that there is a second flange on the metal pipe.

The part is easy to assemble and does not require any special maintenance. Variety of standard sizes allows you to select sleeves of any size for any pipe diameter.

Flanges are also divided into two types:

Locking when the flange is put on metal pipe, and at the other end a pipe product made of HDPE is attached and the whole structure is fixed with a clamping ring and a seal.
Threaded - the flange has a thread on one side, onto which an HDPE pipe with a seal is screwed.

Note! When installing, it is important to pay attention to the smoothness of the steel parts: any burrs or protrusions can damage the polyethylene.

NPSP

The design is most often used when replacing a phased section of a metal system with a polyethylene one, as well as for mounting valves.

For installation, thermistor welding is used, when the end of a polyethylene pipe is heated with a special tool and melted to a viscous mass, and then under pressure is connected to a steel pipe. This connection is used for the installation of high-pressure pipelines.

Normative documents regulate the technical characteristics of the NPSP:

System pressure limits:

for gas lines PE 80 - 6.4 bar, PE 100 - 10 bar
for tap water systems PE 80 - 12.5 bar PE 100 - 16 bar

The length of the branch pipes is regulated by GOST TU4859-02603321549-98 - for gas, and TU2248-001-86324344-2009 - for water supply systems operating under pressure.

Compression sleeve connection

It is a collapsible modular design, the parts of which are easy to replace.

The body is made of polypropylene, equipped with a pipe stop and a trapezoid thread. The fixing sleeve with a sealing gasket, which ensures tightness, prevents the pipe from deforming and shrinking. The ferrule secures the pipe securely in a stationary position.

They are mainly used for plumbing systems.

Couplings come in different shapes:

transitional,
connecting,
square,
plug,
tee,
diversion.

They can have both internal and external threads.

The workpiece diameter ranges from 16 to 110, and the working pressure ranges from 10 to 16.

Methods for joining polyethylene pipes

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During major or current repairs, the question often arises - how to connect a plastic pipe to a metal one, which is associated with the need to replace worn-out sections of communications of various lengths. A similar problem may appear during the construction of a private household - when connected to centralized engineering systems. Correct joining of pipes made of different materials is not inferior in reliability to joints of identical pipes, so it is important to find out in advance how to connect dissimilar sections.

Cases of connection of dissimilar pipes

Partly cases where connection is necessary plastic pipes with metal, described above. In most cases, the metal systems are installed a certain time ago. Currently, plastic is chosen not only because of the reasonable price and good technical characteristics, but also because of the large selection of standard sizes of pipes and fittings, which make it easy to find components of any configuration for replacement.

An example of connecting a plastic pipe to an iron pipe

Sometimes pipes made of different materials (metal and plastic) are used when installing a system from scratch. For example, when laying an outdoor section of water supply or sewerage in a private house, sometimes you have to lay pipelines under a car entrance or parking lot. The dynamic load on the ground surface during the movement of vehicles will be transmitted to the communications located in the ground. It is recommended to install metal pipes in these areas, however, the use of metal for the installation of the entire system is economically impractical and less practical.

Methods for connecting metal pipes with plastic

There are two ways to connect plastic pipes to metal pipes, which are used for steel pipelines.

Threaded joint is used in cases where the diameter of the pipes to be connected does not exceed 40 mm.
Flange connections are optimal for large diameters, since it can be difficult to tighten the threads in such cases.

Features of threaded connections

In order to understand how to connect a plastic pipe with a metal pipe using a thread, you should study the fittings used for this purpose. They are adapters, on one side of which there is a thread for connecting a metal pipeline and a smooth coupling for soldering plastic pipes on the other. There are also models for connecting more dissimilar lines, as well as fittings for making turns and bends.

Polypropylene threaded fittings for PP to metal conversion

The threaded connection of steel and plastic (polypropylene) pipes is performed in a specific sequence.

The junction is being prepared from the side of the existing metal communications. If this place already had threaded connection, it unwinds. If the pipes were welded or the place of installation of the plastic insert is in the middle of a whole steel pipe, the latter is cut, after which grease is applied to the edge and the thread is made using a thread cutter.
The threaded end of the steel pipe is cleaned and a sealing material is applied to it: tow or fum tape with silicone grease. In order to eliminate the likelihood of leaks, it is important to properly seal - to lay no more than 1-2 winding turns with the direction along the thread.
The threaded end of the fitting connects to a metal thread. In this case, one should not only not use special tools, but also not over-tighten the connection by hand. Severe force can lead to cracking of the fittings. It will not be difficult to tighten the threads additionally if, after installation, during the test filling of the system, a leak is found.
After completing work with the threaded part of the connection, a plastic pipe is fixed on the smooth sleeve of the fitting by welding.

A fitting for polyethylene pipes (HDPE) at one end has a thread for connection with metal, and at the other end there is a compression lock for HDPE pipes - in contrast to polypropylene pipes welding is not required here

Making flange connections

The connection of a plastic pipe to a metal pipe without a thread is performed using flanges. Its advantage is the ease of dismantling for repair or cleaning communications.

Flanges are the connecting elements for detachable connections of dissimilar pipelines. of various types.

Lightweight structures with a diameter not exceeding 300 mm, as well as medium and heavy pipes up to 150 mm, are connected using free flanges, with a straight shoulder for support. Such modifications are most common when installing communications in private households and high-rise apartments.
For pipes of any type with a diameter of up to 200 mm, loose flanges with a tapered shoulder can be used.
A shaped flange and a steel shoulder using a wedge-type connection is a universal option.
Maximum strength can be achieved with a straight tapered shoulder.

Flange connection for HDPE pipes

As a preparatory work before installing the flange connection, it is important to carefully inspect the prepared flanges. They must be free of burrs, which during installation may damage the plastic part of the connection. In most cases, these burrs are easy enough to remove.

The assembly procedure for a flanged assembly is as follows:

Mounting a plastic pipe to a metal pipe using flanges

The steel pipe is cut at the point of the intended tie-in. In this case, it is important to make the cutting line evenly and accurately.
The flange is pushed onto the pipe.
For the tightness of the connection, a rubber gasket is installed, the size of which must be such that it does not go beyond the cut line by more than 10 mm.
The main elements of the assembly are connected - the flange put on the pipe is aligned with the gasket and fastened to the second flange using bolts.

Tightening should be done by evenly screwing the thread of the fastener around the entire circumference and avoiding unnecessary force.

If you are interested in what is better to make a suburban water supply, we recommend that you read our article "Plastic pipes for water supply in the country." Types and tips for installation.

The easiest way to install HDPE pipes is to use fittings. About compression fittings for polyethylene pipes, we have another article.

If you need to choose a press tongs for the installation of metal-plastic pipes, then here you will find useful information.

Features of the connection of sewer pipes

When installing a sewage system, it is often required to connect a cast-iron pipe with a plastic one, which is structurally different from the joints of steel and plastic pipes. For such connections, special accessories are required:

cuffs,
corrugations,
seals.

Transition collar cast iron-plastic

In most cases, it is not difficult to select and purchase components. At the same time, and in those rare cases when it is not possible to find a suitable seal, the problem can be solved with the help of materials at hand. The sealant can be cut to the correct size from foam rubber, such as an old car carpet. A long narrow tape is placed in the gap between the elements to be connected and sealed with a blunt, wide screwdriver. Sealing is done without undue effort so as not to damage the plastic. If a leak is found during a test filling of the system, the connection can be re-sealed.

Sealing the connection by means of embossing or cement mortar are not acceptable.

When embossing, the plastic plastic pipe is deformed, the joint will not be tight, and there is a high probability of leakage.
The cement mortar will not last long. Due to the large difference between the coefficients of thermal expansion of materials, the seam at each drain hot water will loosen. In the near future, the cemented joint between the plastic and cast-iron sections of the pipeline will get cracks and will no longer be hermetically sealed.

The connection of plastic pipes with copper is extremely rare, however, you can also find special fittings for such connections on sale. They have two smooth couplings - one for soldering copper piping, the other for connecting to a plastic pipe.

Benefits of using HDPE pipes

It is easy to assemble a water supply from HDPE pipes

Today pipes made of low pressure polyethylene are in great demand. This is facilitated by positive traits such products. Namely:

Long service life (more than 50 years).
Immunity to aggressive environments.
Corrosion of such pipes is not terrible.
It is possible to carry out installation using a trenchless method, which significantly reduces the cost of all work, but limits the period of use of such a water supply system.
The inside of the pipe is very smooth. This prevents the formation of deposits and build-ups, which eliminates the appearance of blockages.
The pipes are very light, this greatly facilitates and speeds up the laying of pipelines;
HDPE products are not afraid of temperature extremes.
Pipes are very flexible. The constructed pipeline easily transfers ground movements. That is why such pipes are often used in earthquake-prone regions.

But there are also some disadvantages. So, HDPE pipes do not tolerate ultraviolet radiation well. Also, such pipelines are not intended for pumping liquids with high temperatures, as a result of which they can deform.

Butt welding

Butt-welded HDPE pipe

Special equipment is used for butt welding of polyethylene pipes. At the same time, it is very difficult to do such work on your own; for this you need to have special qualifications. Butt welding of HDPE pipes is carried out in two ways:

using a mechanical welding machine;
using an electro-hydraulic welding unit.

The first method is used only when installing pipelines with low pressure. These include sewerage systems and sewage disposal systems for industrial enterprises... Electro-hydraulic equipment is capable of creating pipelines for any purpose. Connections made using this method are strong and durable. The pipelines themselves are able to withstand high pressure and any mechanical stress.

Welding the bend

Various HDPE parts can also be used for pipe welding. So, the industry produces bends, crosses, tees, transitions, etc. With their help, you can create a piping system of any configuration.

But, as mentioned above, welding requires the use of special equipment and sufficient experience. For these reasons, this method is rarely used in everyday life. Simpler but no less reliable way to connect HDPE pipes (and not only to each other) is the use of fittings.

Using fittings

HDPE pipes can be connected using special fittings. Such designs are used when creating communications from pipes of small diameter (up to 50 mm). In this case, you can use the following types of fittings:

electrowelded;
compression;
reduction.

Electrofusion sleeve connection

The first option is a clutch with an electric heating element inside. When connected (after being connected to electricity), the fitting heats up and melts the polyethylene. The result is durable and reliable connection, but not collapsible.

To carry out work, you must first clean the pipe and fitting from dirt. Then they are set along one axis, while achieving the immobility of the entire structure. After that, the connecting element is connected to a current source specially designed for this purpose. As a result of heating, the plastic begins to melt, hermetically connecting all the elements. You can learn more about working with such connecting elements by watching a video from the Internet.

Fitting

The easiest way to connect HDPE pipes is to use a compression fitting. Anyone can cope with this task, even without having any skills. Such fittings consist of:

polyethylene body;
sealing rings;
clamping rings (they protect the connection from mechanical damage);
bushings;
caps-nuts.

Before starting work, you need to disassemble the design of the connecting element. Then at the end of the pipe we mark the distance at which it should go into the fitting. Next, after moistening it in water, we put on the connecting element. The last action is to tighten the nut-cap (you do not need to use excessive force). The result is a collapsible connection without the risk of leakage.

In addition, compression fittings have one more advantage - it is the ability to make connections of different (by material) pipes. Very often, when renovating an apartment, it is required to connect communications to old metal pipes. Compression fittings make this connection very easy. The work process is the same as in the case of joining two polyethylene pipes.

Reducing fitting

Reducing fittings are used when it is necessary to connect two pipes of different diameters. The principle of using this connector is the same as for the compression one.

Connection of polypropylene pipes with each other

Diffusion welding

Now the question of how to connect polypropylene pipes is popular. The most common method is diffusion bonding. In order to securely fix them, fittings are used: couplings, corners, adapters.

When installing a cold water supply system, polypropylene pipes will definitely last up to fifty years. They will serve for approximately twenty-five years when installing a hot water supply system. Remember that the operating time depends on the inlet pressure and temperature.

Polypropylene products are very durable, able to cope with any changes in the system. High pressure and low temperature conditions can in no way affect the duration of their operation. High pressure and temperature, which are recorded at the same time, will reduce the durability of pipes by five to seven years. In domestic pipelines, there are no extreme loads that can deform them, so there is no need to worry.

Fusioterm device

If you are interested in connecting with each other, pay your own attention to this unit. Cold products made of polypropylene are connected, then the joint is processed with the Fusioterm device. If you need to weld 2 ends of the pipes, they are inserted into a special hole in the device, after preheating the device to two hundred and sixty degrees. Then they are pulled out and connected.

Socket soldering

If the radius is less than twenty millimeters, then it is possible to connect them by hand welding. A different method must be used to connect to a metal part. You will need a special soldering iron for socket soldering.

1. Cut a piece of the product with special scissors. If there is reinforcement, process it, clean the reinforcement layer in the cut area.

2. Put on gloves, warm up the soldering iron and start soldering.

3. Do everything quickly so that the seam area does not deform.

Connection of polypropylene pipes with metal

The question remains, how to connect polypropylene pipes (under high pressure conditions) with metal ones? There are 2 methods. You need to choose one of them, starting from the radius.

1. For products with a radius of up to 20 mm, use threaded connections on the metal part of the system. Fittings, on one side of which there is an ordinary coupling for mounting to plastic, and on the other - the required thread, are sold everywhere. To seal steel thread, use linen with drying oil or modern sealing materials. This will ensure the durability of the connection.

2. For larger sizes, it is better to use flange connections. Iron threads with a radius of 300 mm cannot be screwed by hand, even if you are a strong man. So how, then, to combine a metal pipe and polypropylene, if they are large in diameter? Use special adapters available from the store.

Threads and flanges allow connecting metal and polypropylene pipes without soldering, which is very convenient.

The right choice of polypropylene products

It is difficult to choose anything specific from the wide range provided by many manufacturers. There are criteria that must be followed when purchasing.

1. Products must be in accordance with the characteristics of the plumbing / heating system.

2. In order to properly assemble the system, you need to purchase all the parts from one manufacturer. This approach will create a reliable and durable structure.

3. When choosing, pay attention to the quality of pipelines, fittings. Evaluate the following:

smoothness of the inner / outer surface;
the presence of cracks, chips, bubbles, heterogeneous structure, foreign particles;
correct geometry;
the same wall thickness.

4. Remember that polypropylene products are designed to operate at a temperature of at least minus twenty. Ask the store for how to store them during the winter. Improper storage leads to deformation of products.

5. If water for drinking will go through the water supply, ask the seller if the product meets the standards of sanitation and hygiene.

6. Buy only straight pipes, no bends. In stores, they are stored vertically, so they gradually bend, they cease to be even. Be sure to pay attention to this.

7. Choose products from trusted manufacturers who have proven themselves well, have all the necessary certificates. Trying to save money, you can buy a low-quality product that will not be able to serve you for the entire operational period. Therefore, it is better to pay a little more once than spend money again and carry out complex repairs of the water supply / heating complex.

Connection methods

Polyethylene pipes low pressure can be connected in detachable and non-detachable ways. Below we will discuss each of these methods.

Detachable connections

This type of connection is used for diameters up to 315 mm inclusive, but it is advisable to use it for diameters not exceeding 110 mm. It is as reliable as the one-piece methods.

Its advantages:

quick and easy installation;
cost-effectiveness - no special equipment is required; couplings and other fittings are not too expensive;
accessibility - can be used in confined spaces, under water, for example.

Connectors (fittings, couplings) are mounted in the following order:

the ends are carefully cut perpendicular to the length of the pipe; deburred;
chamfer is removed at the ends (using a special device or a sharp knife);
a connecting element is pushed onto the ends (it fits into the adapter quite tightly);
then the nut on the fitting is carefully tightened.

Coupling connection

This is the fastest and least expensive method of assembling pipelines. It can be easily applied at home.

Polyethylene couplings are of several types:

connecting - connect pipes of the same diameter;
reduction - used as a transition for different diameters;
compression - designed to connect PE pipes with various shut-off equipment, steel, propylene or PVC pipes.

Couplings are straight and angled. The types of couplings are shown in the table.

Fitting connection

Compression fittings are a type of plumbing fittings.

Installing them is similar to installing couplings.

Flange connection

It is used on main pipelines of large diameter (at least 40 mm) for the installation of valves, valves, regulators (for their subsequent removal for repair or replacement).

To fix the flanges, special couplings are welded to the ends of the pipeline, then the flanges are screwed onto them.

One-piece connections

Only possible method connections of large diameters.

Butt welding

Such welding is desirable to connect workpieces with a wall thickness of at least 5 mm.

The ends are cleaned, the chamfer is removed, inserted into a special heater, melted, then the workpieces are joined, pressed and held motionless until completely cooled.

Electrofusion welding

The two pipes to be connected are inserted into a special sleeve, inside which there is a heating element. Then voltage is applied to it from a special apparatus, the coupling and workpieces are heated and welded. A very convenient way to weld. And very expensive. On large diameters, the cost of the coupling will be much higher than the cost of the pipeline at your site.

When performing this type of welding, special attention should be paid to preliminary cleaning of the ends and immobility of the connection until the moment of complete cooling.

Pipes with a noticeably pronounced ellipse should not be connected - the quality of the seam will be unsatisfactory.

After welding, the welded assembly must be stationary until it cools completely.

Do not neglect cleaning the ends of the earth, dust, sand, shavings and degreasing - these little things noticeably affect the quality of the seam.

How to connect HDPE pipe with polypropylene

Polyethylene and polypropylene are not welded. Correctly connect them together only with fittings. On the ends to be connected, weld on or put on an MRV (couplings with an internal thread) from the appropriate material, screw a quick-detachable threaded connection ("American") onto one MRV, then connect two MRVs using a union nut.

How to do the joining of polyethylene and steel pipes

Such joining is performed similarly to joining HDPE and polypropylene. Steel piping is usually threaded. You can use the drive instead of the American woman - but this option has already outlived its usefulness.

On large lines, a valve or gate valve is usually mounted at such joints - in this case, a flange connection can be used.

We hope that our article helped the reader understand the intricacies of connecting low-pressure polyethylene pipes with his own hands. Share useful information with friends and acquaintances on the social network, invite your friends and subscribe yourself to our newsletter - and you will always be fully armed to start any home repairs.

For sewerage and water supply systems, durable and affordable PE pipes are often used. To connect such a communication, you need to know how the compression connection of polyethylene pipes with metal pipes, fittings and flanges is carried out.

By design features installation of polyethylene pipes and their connections with pipe fittings, there are the following types of connection:

Detachable;
Non-detachable.

Depending on the diameter of your water supply, you need to choose the appropriate type of connection. For small pipes at home or in the country, compression fittings or flanges are most often used. One-piece fasteners are made with special welding machines and couplings.

In the first case, you get a convenient connection that allows you to clean the water supply at any time, sewer pipe or connect another pipeline. At the same time, one-piece fastening is a guarantee of the reliability and durability of the sewage system.

Photo: fitting

How is the detachable connection

Flanged socket connection is the most popular type of fastening of polyethylene pipes at home without welding. It is convenient to perform it on water pipes with a diameter of 50 mm. On smaller diameters, you need to work with fittings or special clamps or clamps. Also flanges are used to install the connection of copper, metal or cast iron pipelines with polyethylene.

Photo: flange for polyethylene pipes

A flange is a threaded part that is used to connect various types of pipes. Mostly metal flanges are used for gas communications, metal water pipelines, as well as for connecting water supply systems from different material... At the same time, for the installation of polyethylene pipes with metal pipes, a special type of flange is used, which has a thread on one side and a seal on the other. This allows you to provide the most durable and tight connection.

How to make a threaded connection of PE pipes with your own hands:

Prepare the piping. To do this, cut the plastic pipe at a right angle, the same must be done with the metal one;
If there is no metal thread in the place that needs to be connected to the polyethylene pipe, you need to do it. This work is done using special threading nozzles;
Further, it is necessary to fasten the flange to the pipe thread, do not overtighten, so as not to disrupt the self-tapping connection. In this case, it is advisable to treat the threads with sealants or mastics before starting work in order to avoid leaks. It is sometimes permitted to protect the threaded joint with a resin treated cord;
Now a plastic pipe, also treated with special substances, is inserted into the free end of the flange.

It is very convenient to work with flanges at home, but only if your pipe diameters are not too large, otherwise you will need special tools to install the connections. Their main advantage is that they are suitable for plastic pressure pipes. At the same time, fittings are very different: compression fittings, electrically welded from alloy steel, cast from polyvinyl chloride.

Photo: pipe connection

Fittings are used to connect non-pressure polyethylene and polypropylene pipes with a diameter of up to 50 mm. The technology is as follows:

Before starting work, make a project to calculate the number of fittings. You also need to define required diameter these connectors and their material;
Take care of buying tools for the job. You will need a shaped key, special clamps, sealants;
Disconnect the water supply. The pipes must be dry;
Apply sealants to the surface of water supply lines that protect against leaks;
Then insert the fittings into the pipe disconnection points. It is advisable to cut each communication to create a right angle in the structure;
This plastic pipe connection does not require any threading knowledge or experience. All that is needed is to cut the pipe to the required dimensions and connect it using fittings.
After the end of the work, the water cannot be turned on immediately, it is necessary for the sealant to dry and harden. On average, its hardening period varies between 3 - 8 hours.

Fastening with a clamp is used only for non-pressure polyethylene pipes, otherwise the sewer will break through. A similar connection is used to fasten asbestos-cement pipes using non-pressure concrete rings.

Photo: fitting for polyethylene pipes

Welded connections

Work must be done with electrowelded equipment:

Welding inverter for PE pipes;
With a special coupling.

The welding machine is used for sewer and water pipes under high pressure. Due to the heating of individual communication elements, the diffusion of molecules occurs, as a result, you get a durable and reliable fastening.

How to connect polyethylene pipes by welding:

Cut the material to the desired size, check that the corners of the section are even;
For pipe centering, special devices are used - centralizers. They allow you to fix communications coaxially with respect to each other. You need to install two communication ends in such a centralizer and tighten the mechanism;
When the pipes have reached their maximum connection, they are fixed. Now comes the turn of temperature exposure;
With the help of a welding machine, the fastening seam is processed. The welding head is put on over the joint and put into operation. The clutch works in the same way, but only it is put on conventional plot pipe connections. The difference is that the coupling is used for large diameters, and the welding inverter is used for small ones;
This method of connecting black polyethylene pipes is not used for their combination with steel communication, but it can help to combine the two types plastic fasteners... After installing the piping, leave the seam to cool. Water must not be allowed in for 5-8 hours.

One-piece methods are most often used to connect plastic plumbing, but there are certain rules according to which you need to work with polyethylene pipes. Firstly, communications must be degreased and cleaned of abrasive particles. Secondly, after installation, you need to fix the pipes in an even position, otherwise the seam may turn out to be thin and unreliable. Thirdly, pay special attention to the alignment, the result of the work depends on it. Control over the process is described in the set of instructions in accordance with GOST 16971-71 (seams of welded joints of plastic pipes of the PE class).

Photo: electric clutch

Connection of pipes and reservoirs for water drainage

In addition to the general arrangement of the sewer or plumbing system, it is necessary to provide for the possibilities and options for attaching communications with reserve or drainage tanks. To make the connection of polyethylene pipes in the wells, press welding is used.

For its implementation, you will need a special knee fitting, which will be processed by an automatic welding machine. A feature of edge or press welding is that the work can be carried out using a conventional inverter and electrodes. Well-pipe assemblies created in this way are very strong and durable. In some cases, the use of threaded fasteners or fittings is allowed (with small wastewater heads).

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