Connection methods

• The links are connected into a single string using special equipment in three main ways:
  
• Butt welding.
  
• Electric couplings with embedded heating elements. For welding work where there is not enough space (wells, small widths, chambers, etc.)
  
• Compression fittings (diameter up to 63 mm). To obtain detachable connections.
  

In this article we will tell you how to install polyethylene pipes with your own hands. This will allow you to save several times when laying most communications. There are different types of products mentioned, as well as ways to install them. This article will cover all these aspects.

Application area

Polyethylene is widely used in the production of various products. This is a polymer that has a number of very useful properties. For example, it is resistant to most acids, gasoline, various oils and other solvents. This means that when exposed to an aggressive environment, the service life of such material can be very long. In industry, these raw materials are used in the manufacture of packaging for various food products. The material does not have a harmful effect on the human body, although it is a product of the oil industry.

In addition to all of the above, this polymer can be easily processed. In order to make a planned product from it, no special unique conditions of temperature or pressure are required. It easily produces pipes that are used for various purposes:

• gas lines;
• pipelines for transporting chemically aggressive substances in industry;
• irrigation systems;
• for transporting liquids containing abrasive inclusions;
• systems designed to lower water levels.

This widespread use is due to the ease of installation and high flexibility of the final product.

Types of polyethylene pipes

All polyethylene pipes are divided according to the pressure they can withstand. There are three main types:

• PVD. Such products can withstand high pressure. They are used on high-pressure lines and sections. Their diameter can exceed 1 m. They are relevant for organizing water supply to microdistricts or even cities.
• HDPE. The most common and frequently occurring type. Low-pressure plastic pipes are used for water supply, in which case they most often have a blue stripe along their entire length, or can be completely painted blue. Material with a yellow stripe is used for laying gas lines.
• The third type is made from recycled materials. Typically, such pipes are used for laying various communication lines. The products serve as sleeves that prevent harmful effects on the cable.

The advantages of such products are:

• corrosion resistance;
• high flexibility and ductility during installation;
• ease of connection;
• high mechanical strength;
• impossibility of formation of growths and blockages due to the smoothness of the walls;
• resistance to water hammer (short-term excess of the permissible pressure by several times is allowed);
• good dielectric;
• Possibility of installation in limited space;
• the value of hydraulic losses is lower than that of other materials;
• higher density than steel - 8 times;
• weld seams are stronger than the pipes themselves;
• relatively light weight;
• 50 years of service without the need for maintenance.

Note! Polyethylene is not suitable for organizing hot water supply and heating systems. This is due to the fact that some of its types lose their strength already at 60°, and at 100° they begin to melt and spread.

Installation methods

Even a beginner can handle the installation, provided he has the necessary tools and basic knowledge. All types of pipe joints of this type are divided into two main categories:

• Detachable. Special fittings have been developed for them. Assembly of the entire structure is possible with basic tools that any owner possesses.
• Monolithic. In this case, there are two options that can be used. One of them involves gluing using a special composition that does not have a negative effect on the body. The second is soldering. It has its own subspecies. It is carried out using a special apparatus that heats the ends, after which joining occurs. Special couplings have also been developed, in which spirals are built in (they are also called elements with an embedded heater) that carry out welding.

Practical guide

The first connection method discussed above is often used at home. Tools that will be needed when assembling the entire structure:

• pipe scissors or hacksaw;
• special key with chain;
• fitting;
• roulette.

Note! Often the chain wrench is replaced with a regular gas wrench or simply tightened by hand. To ensure the highest reliability, it is better to use products designed for this purpose.

The entire installation process will be as follows:

• The entire pipe is produced in coils, so it will need to be conveniently placed to simplify the task. The required length is measured and cut from the coil using a hacksaw or scissors.
• The edge that will fit into the fitting is well aligned. This must be done so that skew does not occur later and that the grip is uniform.
• The chamfer is removed under the cone, this will make it easier to pass the sealing gum.
• The coupling is unscrewed from the fitting.
• The sealing ring is removed.
• First, the coupling and then the sealing ring are put on the pipe.
• The ring must be turned so that its conical part rests against the coupling, and its edge against the fitting.
• The pipe is wetted with water or soap solution. This will help fix it easier.
• The fitting is pushed onto the pipe until it stops. In this case, you need to make sure that the rubber seal that is located in it does not wrap inside the hole. If this happens, then you need to remove the fitting and repeat everything from the very beginning.
• Before filling the pipe with soil, it is advisable to test it by applying operating pressure.

For an overview of the compression fitting for polyethylene pipes, see below:

Note! Fittings with metal threads are ideal for transitioning from a metal pipe to a polyethylene pipe. This will be the key to a high-quality connection that will not fail during a pressure surge.

The butt joint is somewhat more complicated and requires specialized tools. The main one is the welding machine. It consists of the following blocks:

• Centralizer. A special fixing clamp that allows you to position two parts clearly opposite each other. Also, with the help of this element, fixation and pressure are carried out so that a high-quality seam is formed.
• Trimmer. A small tool with an electric motor that has two cutting heads. Its purpose is to process the edges so that they have an even plane.
• Hydraulic block. Designed to move two parts of the centralizer. It has a pressure gauge, which makes it possible to select the required value in bars.
• Heater. This is a kind of soldering iron that melts the edge for subsequent joining.

If you plan to do professional installation, then it makes sense to purchase such a device, otherwise it’s enough to just rent it. The sequence of actions will be as follows:

• One of the parts to be welded must be movable. If this condition is not met, then the centralizer will not fulfill its role.
• Using a caliper, check the ovality of the pipe. The diameter should be the same at any point where the gauge is applied.
• The compliance of the actual wall thickness with the declared one is checked. It must be the same for two elements. If they are unequal, then the soldering will not achieve the required strength.
• The elements are installed in a centralizer. It is necessary to maintain such a distance between them that in the open position it is possible to safely install the trimmer and a heating element.
• The clamping is carried out in pairs. The rear clamps can be tightened a little more than the front ones. It is better not to overdo it with the latter, so as not to disturb the correctness of the end circumference.
• The pressure for movement is set. In order to do this, you must first unscrew the valve to bleed the air. Next, by twisting it, the value at which movement begins is determined.
• The compression pressure on the solder is calculated. This is done according to the table, which is usually located on the unit. If it is not there, then you can use the following formula: divide the area of ​​the pipe end by the total cross-sectional area of ​​the cylinders, multiply the resulting result by 0.15 and add resistance pressure.
• The parts that will be welded are cleaned of sand and other dirt with a damp cloth.
• Edge processing is in progress. To do this, a trimmer is installed close to one pipe. It turns on and using a hydraulic unit, two workpieces are moved. The process continues until 3-4 turns of solid chips are formed on each side.
• The pressure is released and the parts move apart.
• The cutting tool is retracted into place.
• A test docking is performed to ensure that the process went as expected.
• The ends are cleaned again. But this time you need to use alcohol or a special solvent.
• The soldering iron turns on and heats up to the required temperature.
• The timer for the planned soldering is set. It is usually also indicated in the table.
• The tip is installed between the pipes.
• The pipes are brought together to the soldering iron. It is necessary to wait until an influx of 1 mm thickness is formed. After this, the pressure is released and the time for welding is noted.
• After the welding time has expired, the soldering iron is removed. There will be 5 seconds to bring the details together.
• After docking, you will need to wait about 5 more seconds under pressure, after which it is released and the timer starts to cool down.

The cooling process should not be accelerated by any means. Also, during this time, you should not turn the pipe or try to remove the centralizer. Otherwise, the joint will be broken, and subsequently depressurization will occur.

The video shows the butt welding process in detail:

Electrofusion welding is an achievement that allows seams to be joined in places where other methods are simply not applicable. The advantages of this solution are:

• high speed of ongoing processes;
• minimal probability of errors;
• high safety of the entire process;
• possibility of articulation of fixed workpieces;
• the internal diameter of the pipes remains virtually unchanged;
• simplifies the process when performing tasks with large pipe diameters;
• the advantage of working with workpieces of various diameters and wall thicknesses;
• minimal consumption of electrical energy when performing tasks.

The tools you will need are:

• Special cleaning liquid. It can come with fittings or be purchased separately. The use of acetone or other solvents not intended for this purpose is not recommended.
• Oxide layer remover. Its role can be an ordinary pig or a device that is installed directly on the pipe. For larger diameters, using the second one is preferable. The fact is that it is necessary not only to create a rough surface, but to remove about 0.1 mm of material so that adhesion can occur.
• Welding machine. In this case, a special development is used. Its task is to supply a specific voltage to the coupling for a certain period of time. It is assembled using semiconductors, which explains its efficiency and high performance. On the front panel, as a rule, there is a digital display, which makes it possible to check the correctness of the entered data. The design includes a port for connecting a scanner; it is necessary to automatically enter the required parameters through the barcode that is printed on the fitting. Information about the work done is recorded in the internal memory and can subsequently be transferred to a flash drive if there is a USB port.
• Retainer or positioner. For this type of connection, it has a slightly different structure than in the previous case. Its main purpose is to compensate for ovality that may be present due to the pipe being stored in a coil or under load.
• Pipe cutter In order for the edges to be flat and without jagged edges, it is advisable to use this particular tool. A hacksaw and a knife will be bad helpers in this case.
• Permanent marker. It should be white or yellow so that the applied marks are clearly visible on the pipe.
• Roulette.

To achieve an ideal result, you will need to follow these steps:

• The ends are being prepared. To do this, they are cut using a pipe cutter.
• Using a tape measure, measure the total length of the coupling.
• Each pipe is marked. It should be located from the edge at a distance of half the size of the fitting plus 2 cm of margin.
• The top layer in which the reaction with oxygen has occurred is removed. To make it easier to maintain uniformity, it is necessary to apply several longitudinal lines from the mark to the end. As the tool progresses, it will be clear which part has not been sufficiently covered.
• The end will be chamfered into a cone to make it easier for the pipe to enter the fitting.
• A positioner is installed on each pipe. It is clamped until the pipe is perfectly round.
• Both the pipe itself and the inner walls of the fitting are treated with a degreasing composition.
• The coupling is placed on the pipe up to half the depth of its size. Usually there is a limiter inside that will not allow you to go further.
• The second pipe is brought in and inserted.
• The evenness of the entire plane is checked.
• The terminals from the welding machine are connected to special connectors.
• A scanner is used to read the applied barcode.
• The entire process is launched. It is important to wait not only for the welding time, but also for the complete cooling time, which is also shown on the display. During this period, you must not touch or try to change the configuration of the equipment. This can lead to poor quality articulation.
• At the end of the procedure, data about the operator, time, temperature and date are applied to the joint.

There are basic mistakes that are very important to avoid. For example, it is necessary that the pipe and fitting are not at an angle. This will cause the molten mass to simply flow out. If the ovality is not compensated, then the coupling will simply be impossible to put on, or the formation of a monolithic adhesion will not occur. If the pipe is not immersed at an insufficient level, the spiral will simply melt the material inside, but jointing will not occur.

Installation of cross-linked polyethylene pipes

This type of pipe is rather an exception to the rule. It can withstand temperatures up to 120° and can be safely used for heating and hot water supply systems. This material is produced by bombardment with ions, which leads to the formation of a unique structural lattice. It is this that is the key to strength. Interestingly, when exposed to temperatures above 400°C, the material breaks down into carbon dioxide and water. Other interesting characteristics are:

• Low temperature resistance. The pipe feels good even at -50°. In this case, physical impact does not have a detrimental effect.
• High elasticity. The pipe can be bent in half without breaking.
• Resistance to cracks during operation.
• High smoothness of the inner surface. This reduces noise during water circulation.
• The product shrinks. When exposed to sufficiently high pressure, the material tends to expand and after some time return to its original shape.
• Abrasion resistance. This means that the pipe can be walled up in the screed and not worry that something will happen to it.

Installation can be carried out using two types of fittings:

• Threaded. In this case, no special tools are required, and the general process resembles the installation of metal-plastic pipes.
• Crimping. For this option you will need a special expander and a special hand vice.

The process for the first option boils down to the following steps:

• Using scissors, the pipe of the required size is cut.
• The nut is unscrewed from the fitting and the o-ring is removed.
• The nut is first put on the pipe and then the O-ring.
• The part of the pipe that will fit onto the fitting is flared.
• The O-ring is moved as close to the fitting as possible.
• Using one wrench, the connector is held in place, and the nut is tightened with the second. It moves the seal to the designated position and further presses the pipe walls.

With the crimping method, everything happens as follows:

• A ring is put on the pipe. It moves from the edge to the distance that the inside of the fitting will extend.
• A head of the required diameter is installed on the expander. It is inserted into the pipe and the handles are compressed. Then they quickly unclench, the tool rotates a little, sinks a little deeper and the handles are brought together again. Such actions are carried out until the end rests against the limiter.
• The fitting is inserted.
• Using a hand vice, the ring is pressed onto the upper part of the connection.

Note! There is another progressive method. Instead of a metal ring, a special polymer is used. It is put on the pipe so that part of it protrudes by 1 mm. Then the pipe expands along with it. When the fitting is inserted, automatic shrinking occurs. Within an hour, the rigidity of the connection reaches such a level that it can withstand a pressure of 15 atmospheres.

Perhaps you also had experience when installing a water supply system from polyethylene pipes or other communications. Share your best practices and tricks acquired in the process. Leave comments on the article.

Laying and installation of polyethylene pipelines

The company AOS LLC is the official supplier of PE and HDPE pipes, which indicates the high quality of the supplied products.

We have implemented more than 5 0 objects in Russia and Kazakhstan. The geography of supplies of polyethylene pipes is constantly expanding.

Laying methods. Excavation

Choosing a pipeline laying method

The choice of method for laying pipelines should be made on the basis of technical and economic calculations, taking into account the physical and chemical properties of the transported substances, pipe material, operating conditions, climatic characteristics of the construction area, the load-bearing capacity of the pipeline and material consumption.

External networks made of polyethylene pipes are recommended to be laid underground, because... When laying above ground, the pipeline must be protected with thermal insulation materials to prevent freezing of the transported substance at subzero air temperatures and excessive heating of the pipe walls when exposed to solar radiation and elevated air temperatures. For external gas supply networks made of polyethylene pipes, only underground installation is permitted.

Polyethylene pipelines can also be laid:

• in buildings (in-shop or internal pipelines) on suspensions, supports and brackets; openly or inside furrows, shafts, building structures, in canals;
• outside buildings (inter-shop or external pipelines) on overpasses and supports (in heated or unheated boxes and galleries or without them), in channels (through or non-through) and in the ground (channelless installation).

Technology for laying PE pipelines in trenches

The elasticity of the material and the low weight of PE pipes give them certain advantages over pipes made of “hard” materials such as cast iron and fiberglass. In particular, during the construction of pipelines, individual strands of maximum length (from well to well) are often welded at the edge of the trench, which are then lowered into the trench, where all that remains is to connect them to the fittings or weld several assembly joints.

Since, in this case, the width of the trench can be significantly reduced, this leads to a reduction in the amount of excavation work, limiting the mass of material supplied for backfilling and the need for its transportation. Although the trench can be as narrow as possible, it must provide the opportunity for high-quality soil compaction.

Work on the construction of trenches for PE pipelines is carried out in compliance with normal safety measures.

Trench profile

The profile of the trench for laying PE pipelines is determined by the project. The width is determined based on the conditions for ensuring the convenience of installation work. At the level of the horizontal pipeline diameter >710 mm, the trench must correspond to the outer diameter of the pipe + 0.4 m.

Trench bottom

The bottom of the trench must be leveled, without frozen areas, and free of stones and boulders. The boulder excavation sites must be covered with soil compacted to the same density as the foundation soil. In soils prone to displacement or with a high probability of leaching of bedding and backfill material by groundwater, it is necessary to take appropriate measures to keep the soil surrounding the pipe in a compacted state. In particular, the bottom of the trench can be strengthened with geotextile material.

Pipe base

The normal thickness of the bedding layer is 0.1 m. On rocky soil, bedding must be installed. If the bottom of the trench is rocky or there are stones larger than 60 mm in the bottom of the trench, it is necessary to increase the backfill until the bottom of the trench is completely leveled.

For backfilling, sand or gravel is used (maximum grain size 20 mm). In some cases, it is possible to use material with a larger granule size. In any case, the material used for backfilling should not have sharp edges. If the local soil meets these requirements, backfilling is not necessary.

The bedding should be smooth and not compacted. The material filling the depressions formed after the excavation of boulders and other large objects is subject to compaction to the density of the main soil.

Fig.2 Base layer for the pipeline (backfill, pillow, bed)

Pipeline coating

The soil extracted when tearing off a trench can be used to fill the pipe, provided that it does not contain stones (their maximum allowable size is 20 mm, individual stones up to 60 mm can also be left in the soil). If the soil for filling is intended to be compacted, it must be suitable for such an operation. If the extracted soil is not suitable for filling the pipe, then sand or gravel with a fraction size of up to 22 mm or crushed stone with a fraction size of 4-22 mm should be used for this purpose.

Sprinkling should be carried out across the entire width of the trench until a layer with a thickness of at least 0.3 m is obtained above the surface of the pipe (after compaction). The first layer should not exceed half the diameter of the pipe, but not more than 0.2 m. The second layer is poured to the top of the pipe, but also no more than 0.2 m. During sprinkling, the primer must be applied with minimum height. Do not dump masses of soil directly onto the pipe. Pipeline sprinkling is usually carried out after the installation and acceptance of the pipeline has been completed.

Fig.3 Pipeline coating

Soil compaction

The soil filling, compacted in the sinuses of the pipeline, provides a slight reduction in the tensile forces on the side walls of the pipes from the internal pressure of the transported medium. The degree of compaction depends on the purpose of the area above the pipeline and should be determined by the design.

To avoid subsidence of soil over pipelines located under roads, infill compaction of at least 95% of the modified Proctor value is recommended.

For deep trenches (over 4 m) the degree of compaction is 90%. For other cases - 85% or according to the instructions given in the project. Tamping must be done in layers with a thickness of OD to 0.3 m, compacting each layer. The thickness of the compacted layers depends on the equipment and compaction conditions. You must be careful when performing this task. Compaction of the first layer (to the level of the pipe axis) should not lead to its lifting. Tamping must be done simultaneously on both sides of the pipeline to avoid its movement. When adding soil and backfilling the pipeline, care must be taken to ensure that the soil does not contain large inclusions. The soil is compacted directly above the pipe, having previously ensured a distance of at least 0.3 m to its surface.

Final filling of the trench

The final filling of the trench can begin after backfilling the pipeline and compacting the soil.

It is recommended to place warning tape over the pipeline during backfilling. Warning tape must be placed over gas pipelines. To make it easier to identify pipelines in the future, the use of such tape is also recommended on other pipelines.

For backfilling, you can use soil taken out of the trench, or another, according to the project instructions. The diameter of the particles of the material used to fill the trench should not exceed 300 mm. Do not throw stones, rubble with sharp edges or large sizes. The soil should not be frozen or lumpy.

Thickness of compacted layers and number of tamping passes

Note: coarse-grained materials, such as crushed stone with a fraction size of 8-12 mm, 8-16 mm or pebbles 8-22 mm, are self-compacting materials and when used for backfilling in layers 0.15-0.20 m thick, compaction >93 is ensured % modified Proctor value.

Fig.4 Final filling of the trench

Trenchless technologies for laying PE pipelines

Trenchless technologies allow you to avoid the costs associated with excavating a trench, backfilling it, compacting it with a tamper, etc. No need to stop traffic. The costs associated with the production of new surfaces (after filling an open trench), temporary roads, detours, as well as other related costs are practically eliminated.

Laying using horizontal directional drilling in the ground (puncture, mole method)

The horizontal directional drilling method is the most popular and widely used. It is very economical in situations where it is necessary to lay a pipeline under the roadway, and it is not possible to lay it in open trenches. The method makes it possible to lay underground PE pipes with a length of more than 100 m and a diameter of up to 1200 mm or more, with an accuracy of several centimeters.

Rice. 5 Laying using horizontal directional drilling

In the work carried out on laying a pipeline using this method (Fig. 5), three stages can be divided into three stages.

At the first stage, a special drilling rig drills along a given trajectory (from mark A to mark B). In this case, the drill has a smaller diameter than the pipe intended for pulling.

At the second stage, at point B, preparations are made for pulling the pipeline: the drilling head is replaced with a head of larger diameter, and a PE pipe prepared for pulling is attached behind it (polyethylene pipes are used, supplied in coils or welded into a string on site).

At the third stage, the pipeline is directly pulled from mark B to mark A. Drilling rig pulls the PE pipe into the channel prepared at the first stage. In this case, the head comes first, having a slightly larger diameter than the pipe attached behind it.

PE pressure pipe is the most suitable material for installation using horizontal directional drilling. Polyethylene pipes have sufficient flexibility and strength and can withstand significant tensile loads.

As a rule, for trenchless installation there is no need to use any special PE pipes and ordinary pressure PE pipes are used for the corresponding operating pressures.

Gasket by pulling with simultaneous destruction old pipe or without it

The most common trenchless technologies include the “relining” technology, which involves pulling a PE pipe through a worn-out pipeline, both without destruction and with destruction of the latter.

METHODS OF CONNECTING PE PIPES. CONNECTION REQUIREMENTS

The most important requirement for connections is reliability, which is understood as their equal strength to pipes under operating conditions.

Polyethylene pipes are increasingly replacing metal pipelines. This is due to a number of their advantages. Experts attribute the advantages, first of all, to ease of use, low price and durability.

To create, it is not necessary to seek help from specialists. Do-it-yourself connection and installation of polyethylene pipes is discussed in this article.

There are two main methods for installing connections:

1. Non-separable, not implying the possibility of repeated disassembly. These include butt welding and connection with electric welding fittings.
2. Collapsible, which allow the connection to be adjusted in the future. Steel flanges are used for installation. Instead, you can use compression fittings.

The communication system can be assembled from large quantity elements connected to each other various methods. Most often, if the pipeline requires significant strengthening, a non-dismountable method of installation is used. Temporary connections can be made using steel flanges or compression fittings.

How to connect polyethylene pipes

There are several connection methods. This can be done by welding or using couplings. The choice of one or another technique should be made, first of all, on the basis of what kind of connection needs to be made - collapsible or non-demountable.

Electrofusion welding

Initially, you need to prepare two pipes by cleaning them inside, ends and degreasing outer surface. The pipes should then be coupled together and secured in the positioner. Once this is done, the electric heaters of the welding equipment need to be connected to the coupling.

The process of connecting pipes is carried out automatically. This happens at the moment when current flows to the couplings. Because of this, the polyethylene heats up and melts. As soon as material begins to protrude through the special holes, you should stop supplying electricity to the area. After this, all that remains is to cool the products naturally.

Couplings

In order to connect two polyethylene pipes using couplings, no additional plumbing tools are required. It is enough to have only a wrench with you. On one end you need to put a nut, which was previously removed from the fitting. You can start working only if the pipe has been chamfered at an angle of 45 degrees.

In order to simplify the process of inserting into the fitting, the workpiece can be treated with a soap solution or a special pipe lubricant.

Once the workpieces are placed in the fitting to the required length, the nut should be tightened. This process can be done either wrench, or with my own hands. In the first case, you should be as careful as possible. To ensure a tight seal, do not under any circumstances need to tighten the nut.

Butt welding

Welding of polyethylene is carried out using so-called “irons”. Therefore, it is not often used by home craftsmen. Initially, it is necessary to melt the ends of the two products. Then you need to heat them to a certain temperature. There is no need to apply pressure at this stage. Next, you should remove the heating element from welding and quickly connect the two pipes until they lose the resulting thermal energy.

The melting point of polyethylene is 270 degrees Celsius. If they are installed correctly, you can achieve a homogeneous connection, the strength of which will be equal to 80-90% of the strength of the monolith.

The process of upsetting the resulting joint occurs immediately after cooling the products. Temperature loss should occur naturally. Experts do not recommend lowering it forcibly.

Types of detachable fittings

Most split fittings do not require special tools and are well suited for home installation. The most common are:

• adapters (collet-nut, collet-fitting, collet-collet);
• tees (two collets-nut, two collets-fitting, three collets);
• Eurocones;
• crosses;
• corners;
• water sockets.

They significantly save installation time of polyethylene pipes, ensuring their reliable connection and long-term operation.

Features of installation of cross-linked polyethylene pipes

Cross-linked polyethylene is special kind a material that loses its properties when melted. That's why It is unacceptable to use any type of welding work:

• butt welding;
• electric welded couplings.

When installing communication systems made of cross-linked polyethylene, the connection can only be made using crimp or press fittings.

How to bend and unbend a PE pipe

There are two main ways to bend a polyethylene pipe:

1. Using special molding equipment. In this case, you first need to prepare a template from sheet material, such as fiberboard. With its help it will be possible to protect the workpiece from damage. Afterwards, a silicone shell should be made for attaching the deformable product. It is necessary to place a pipe in it, attaching the latter to the fiberboard frame. This structure must subsequently be placed in a molding machine. It needs to be heated and bent, after which it must be completely cooled.

1. Using a hair dryer at home. Initially, it is necessary to heat the previously prepared surface using the device. In order for the welding to proceed as evenly as possible, the product must be gradually rotated. After this, the hot workpiece must be placed in the forming frame. Once this is done, you need to carefully bend the pipe, making sure that it loses its shape. When the angle is fixed, the product should be cooled naturally.

If the pipes have been bent for a long time, alignment must be carried out before installation. This can be done either naturally or artificially. The first method can be used if you have time and clear and warm weather. In this case, it is necessary to stretch the products in an area under the sun and fix them with any in an accessible way. After some time they will level out. To speed up this process, you can use hot water and a hair dryer. Before this, the pipes must be stretched accordingly.

Fasteners

In order for a polyethylene piping system to function reliably, it must be properly secured. This can be done using fasteners:

• hooks providing free fastening;
• clamps for rigid fastening.

Basic rules for using fasteners:

• each individual joint must be fixed;
• if the pipeline sections are straight, fasteners should be used every 10 meters;
• The clamp must be used with rubber gaskets.

To create a free fastening, you can use clamps without rubber gaskets instead of hooks.

Do-it-yourself pipe installation

Self-installation of a polyethylene pipeline can be divided into stages:

1. First you need to inspect the fittings. It will not be superfluous to analyze them, allowing you to understand the process of assembling these elements.
2. The workpieces should be cut to the previously determined size. To do this you need to use scissors. If they are missing, they can be replaced with a hacksaw. The edge of the products must be perpendicular to the surface.
3. The edges must be processed to remove any burrs that have formed. To do this, you can use sandpaper or a round file.
4. You must first put a nut on the end of the pipe, then a compression washer and a seal. The rubber ring must remain in the fitting body. Having lubricated the edge of the product, it must be pushed all the way into the connecting element.
5. The compression ring must be brought close to the connection and tightened with a nut.

A pipeline made of polyethylene pipes must be attached to the wall or ceiling using special clips or clamps.

Required Tools

To install a pipeline made of polyethylene pipes yourself, you must first prepare the following tools:

• scissors for cutting products;
• soldering equipment;
• gas keys.

Soldering equipment is equipped with several nozzles that differ from each other in diameter. If nozzles are not included in the kit, these devices must be purchased at a hardware store before work.

Drawing and diagrams

Before starting the installation of polyethylene pipes, it is necessary to draw up a drawing or diagram. This could also be a small hand-drawn sketch with step by step plan works It should indicate the following:

• lengths of straight sections;
• number of turns;
• number of taps;
• connection types;
• number of couplings used, etc.

The more detailed the pipeline diagram is, the easier it will be to install it in a house or apartment.

Work order step by step

In order to cope with the installation of a pipeline made of polyethylene pipes, it is necessary to follow the work order. It consists of the following steps:

1. Drawing up a drawing or diagram.
2. Blank necessary tools, devices and materials.
3. Creating holes in walls.
4. Installation of fasteners.
5. Assembly.
6. Laying polyethylene pipes.
7. Check the system for leaks.
8. Final fastening of all elements.

When all the above stages have been completed, you can put the system into operation.

Pipe laying

If laying a pipeline in the ground is required, both trench and trenchless methods can be used. Both options have their own characteristics.

Laying polyethylene pipes in the ground

The trench for polyethylene pipes must be properly prepared. If its bottom is hard and dense, the creation of a “pillow” is required. To do this, it needs to be paved with a thickness of 10 to 15 centimeters. It should be compacted at a distance of 2 meters from the inspection well.

There should be no stones, frozen lumps of soil or any debris at the bottom of the trench. If the soil is too loose, it needs to be further strengthened. For this you can use geotextiles.

If the soil characteristics are optimal and the bottom of the trench is flat, you can do without laying a “cushion” of sand. In such situations, experts only recommend making a small notch at the base.

Trenchless pipeline laying

If it is impossible to dig a trench due to its intersection with a road, rails or some other obstacle, a trenchless horizontal directional drilling method can be used to lay a pipeline made of polyethylene pipes. In this way, systems up to 100 meters long and up to 630 millimeters wide can be installed underground.

Drilling can be of two types such as:

1. Managed. It is done with the help of tunneling machines. They may use flush or pilot soil drilling.
2. Uncontrollable. It is produced in two ways: without siege pipes (ramming rocket, displacement or auger drilling) and with casing pipes(drill injection, puncture drilling, impact and ram drilling).

The video shows the drilling process (puncture) for underground pipe laying.

The choice of one or another method of trenchless pipeline laying depends on the capabilities of the customer and the characteristics of the soil.

Common installation mistakes

When installing a pipeline made of polyethylene pipes, novice craftsmen often encounter the following errors:

1. Incorrectly measured pipe sizes. As a result, material consumption increases.
2. Leaky connection. Most often, this is due to the fact that the pipes were not completely seated in the fitting, and a loose connection was formed.
3. Retightening the nuts. They can squeeze out the O-ring, which in turn will lead to a quick leak in the pipeline.

To prevent adverse consequences, you must carefully check your actions at each stage of work.

Do-it-yourself pipeline on video:

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Construction of a pipeline from polyethylene pipes

Most of all pipelines laid in cities date back to Soviet times. The deterioration of heating mains, sewerage, gas and water communications reaches 70%, which is due to the material from which the pipes are made. This is steel that is subject to intense corrosion. The construction of gas pipelines from polyethylene pipes is becoming more in demand today. As the service life expires, many accidents occur on various pipelines: under high pressure Pipes break, numerous leaks form, which lead to significant water losses. Performance indicators deteriorate: by reducing the cross-section of pipes, their throughput is reduced, the water becomes polluted, and its biological indicators decrease.

Advantages of polyethylene pipes

Pipes made of polyethylene (PE) are a modern alternative to their physically and morally outdated metal predecessors. They have whole line undeniable advantages compared to products made of steel or cast iron.

1. No corrosion, which minimizes installation, maintenance and repair costs.
2. Ease of use: polyethylene products are easy to cut, so they can be easily adjusted to fit construction site, and in the field when laying pipelines.
3. High throughput due to the fact that the inner walls of PE products are smooth.
4. Polyethylene pipes have an elastic structure of the internal walls, on which scale does not form as a result and they are not clogged from the inside by various suspensions contained in the liquid.
5. Polyethylene is chemically inert and successfully resists aggressive influences, therefore, it does not require additional special protection.
6. Polyethylene is not electrically conductive, so it is not afraid of stray currents that destroy metal pipes.
7. The bending radius of a polyethylene pipe can be up to 10 of its outer diameters, depending on temperature, which reduces the cost of connecting parts and facilitates the design and construction of pipelines.
8. Polyethylene pipe has high flexibility: the minimum bending radius is 25 pipe diameters at 200°C.
9. Significantly less weight compared to metal pipes, which facilitates installation and installation.
10. PE pipes are resistant to temperature changes and have high sanitary and hygienic characteristics.

Scheme of deformation of polyethylene pipes depending on the type of soil.

Important note. Freezing of the soil leads to the movement of pipelines into vertical plane. These movements are uneven, resulting in deformations (bending). Predicting these conditions, it is necessary to determine how much the bending radius of a polyethylene pipe depends on the level of temperature reduction. In order to determine the bending radius, it is necessary to make special calculations. Or refer to special tables that indicate the minimum bending radius for specific type pipes

The minimum bending radius of a polyethylene pipe is recommended by the manufacturer for each type and grade of pipe. If it is not possible to obtain the required bending radius, then bends, tees, etc. should be used.

Thanks to its technological and operational characteristics polyethylene pipes received wide application: they are used in the construction of new pipelines and in the repair of old communications that have expired.

Scope of application of polyethylene pipes

Polyethylene products are widely used in modern construction.

They are used in the construction of water supply, sewerage, and gas pipelines. PE pipes are used in pressure and gravity sewers and serve as protective cases for electrical and telephone wires.

Old networks are being reconstructed using polyethylene pipes. Replacement can be carried out with the destruction of worn-out communications, but it is possible to lay new ones in parallel with the old ones, which does not require stopping the water supply to the population and blocking the sewerage system. Reconstruction of wells and other communication and plumbing structures depends on the degree of their deterioration. Partial replacement individual parts (necks, shut-off valves etc.), if necessary, is carried out major renovation with complete replacement of pipelines.

Installation of polyethylene pipes for sewerage

Sewage networks are internal and external. Their purpose is to collect and transport sanitary and stormwater waste water, having different chemical composition. Any problems in the sewer system dramatically affect the quality of life.

Elements and assembly for polyethylene pipes internal sewerage

Polyethylene pipes for sewerage began to be produced not so long ago, and today they fully meet high requirements due to their inertness to the effects of mineral acids, alkalis and other aggressive substances. PE sewerage pipes have high throughput due to the absence of internal roughness. When settling in external systems sewer systems use frost-resistant PE pipes. Installation of internal sewerage does not require pipes with such high performance characteristics.

Sewage pipes are attractive to specialists working on the construction of similar systems the fact that their installation is much simpler in comparison with traditional sewer networks. Installation of internal sewer communications When using polyethylene pipes, it does not require complex special equipment. Small diameter polyethylene pipes are mounted using compression fittings.

Equipment external sewerage produced by butt welding: special welding equipment allows installation, reducing the number of joints up to five times in comparison with metal sewer pipes

Connection of water supply polyethylene pipes

PE products are connected in three main ways:

1. contact butt welding,
2. sleeve welding with embedded electric heaters
3. installation using compression fittings.

A detachable connection is also possible, which is carried out using steel clamping flanges. Installation of pipeline turns and branches is carried out using welded or cast fittings.

Different connection methods are used depending on operating conditions. If there are conditions for placing welding equipment, then butt welding is necessary. Butt welding is used when working with large diameter pipes (from 630 mm).

Limited working space (wells, chambers, trenches) requires electrofusion welding using embedded heaters.

If it is necessary to connect pipes with a diameter of up to 63 mm, compression fittings are used, which creates detachable structures. This connection is easy to operate, has high performance indicators, and does not require complex special equipment. Compound internal systems pipelines are most often carried out in this way. Their installation is accessible even to non-professionals.

Pipe laying

Laying polyethylene pipelines carried out in two main ways. These are traditional pipe laying in an open trench and trenchless laying - a deep directional drilling method.

Using the open method, polyethylene pipelines are laid in a trench, the width of which is determined by the need to create working conditions. Water supply and sewerage equipment requires a trench width 40 cm greater than the outer diameter of the pipeline. These parameters are most often specified in the project. Long polyethylene pipes are often laid in a trench dug using a narrow-section chain excavator. In this case, the width of the trench decreases.

The trench must be properly prepared. Its arrangement depends on the condition of the soil. If the bottom of the trench is hard and dense, then a cushion is needed. The bottom is covered with a layer (about 10-15 cm) of sand or other granular material and leveled. At a distance of 2 meters from the inspection well, the pillow is compacted. There should be no stones or lumps of frozen soil at the bottom. When working with loose soil that is at risk of displacement, it is necessary to strengthen the bottom. In such cases, the bottom of the trench is strengthened with geotextiles.

With a flat trench bottom optimal characteristics No soil cushion is needed. You can get by with a small excavation of earth at the base of the pipe to its width and replace it with a softer one.

Backfilling the trench

The soil removed during the construction of the trench, which does not contain 20 mm stones, is used for primary filling. It is made along the entire length of the pipe, about 15 cm high from its top. If it is necessary to compact the pavement, the soil must meet certain requirements. You can use fine gravel (20-20 mm) or crushed stone (4-44 mm). Soil must not be dumped directly onto the pipeline. The pipeline laid at the bottom of the trench and sprinkled needs to be compacted. The filled soil is compacted in layers of 20 cm on both sides of the pipe so that it does not move. The soil is not compacted directly above the pipe.

Backfilling is done after compaction and a compacted layer of about 30 cm on top of the pipe. The trench can be backfilled with extracted soil; the size of the largest stones is allowed no more than 300 mm. Even with a layer of protective pavement about 30 cm thick, the size of the stones in the soil used for backfilling cannot be more than 60 mm.

Trenchless pipeline laying

In some cases, when pipeline lines intersect with a railway, busy highway, river or other obstacle, laying an open trench is not possible. The reason may also be the need to minimize the cost of digging a trench. This is the basis for using the method of trenchless laying of polyethylene pipelines. The method of trenchless installation of horizontal directional drilling (HDD method) has become widespread.

Horizontal drilling is a special method of installing communications without opening the soil. Work begins at the point where the pipe comes to the surface. Technology guarantees high accuracy bringing the drill out to the expected location of reaching the surface. The method makes it possible to lay underground pipes with a length of more than 100 m and a diameter of up to 630 mm or more. There are two main ways horizontal drilling: controlled and uncontrolled.

Controlled horizontal drilling is carried out by tunneling machines, through flushing and pilot drilling.

Uncontrolled horizontal drilling is carried out using two methods: 1) without casing (ram rocket, displacement drilling, auger drilling) and 2) with casing (drill injection, puncture drilling, percussion drilling, ram drilling).

Horizontal drilling methods and trenchless laying of polyethylene pipes are considered the most modern technology.

To enlarge the well, a special drilling enlargement is used. To improve the drilling, the well is treated with a drilling clay mud, which forms and lubricates the channel itself.

Thus, the characteristics of polyethylene products allow them to be installed and laid using any currently known method, taking into account the restrictions imposed by the minimum permissible radius of their bending. A polyethylene pipe that is pulled or pushed is able to repeat the configuration of the old route, which has a radius of curvature of more than 120 diameters of the pipe itself. Hardware

they practically do not have such a bending radius.

Organization of installation work Welding is carried out either according to the basic scheme or by the route method. The basic method is used in cases where the site is located close to the welding site, where the pipes are pre-joined and then transported to the pipeline route. The length of the section can reach more than 30 m. On site they are welded into a single thread, which must then be carefully laid in a trench so as not to disturb the bending radius.

Route welding begins along the trench. Then installation and welding is carried out using mobile welding units. Small diameter pipes can be laid in the trench manually. However, pipelayers or cranes are most often used. The finished thread should be lowered without jerking, evenly, having previously secured it hemp ropes or soft slings, which should be located at a distance of 5-10 meters from each other. The solid welded thread must be lowered into the trench carefully so that the critical bending radius is not exceeded during installation. You should first wait at least 2 hours after welding the last link.

Disadvantages of polyethylene pipes

Problems with polyethylene products are related to the characteristics of all viscoelastic thermoplastics. Their strength largely depends on the degree of bending and compression, and in general it is relatively small. Polyethylene is sensitive to ultraviolet radiation, which has to be compensated for by adding coloring additives (usually carbon black) and using protective paint. The thermal expansion of polyethylene is quite high and has to be compensated for using a structural L- or U-shaped bend of the pipe.

Today, domestic underground pipelines have a length of about 2 million km. These are mainly steel pipelines. For example, polyethylene pipes account for about 10% of the total length of gas pipelines. Other networks also do not have very high scores for this parameter. However, there is a strong tendency that modern pipelines percentage changes in favor of polyethylene pipes.