Connection methods

• The links are connected into a single string using special equipment in three main ways:
  
• Butt welding.
  
• Electric couplings with embedded parts 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.
  

Due to their high performance qualities, polyethylene pipe products are widely used in the arrangement of engineering communications when carrying out renovations in an apartment or during the construction of their own household. The work is simple, so information on how to connect polyethylene pipes with your own hands will not be superfluous.

They are used for laying water supply, sewer, gas and heating communications, both in everyday life and at industrial facilities. To obtain a high-quality result when installing polyethylene pipes, you must adhere to certain rules.

Tool for creating PE pipeline

To install polyethylene pipes with your own hands, you need to prepare the following tools:

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

The soldering device is equipped with a set of nozzles of different diameters. Instead of scissors, you can use a jigsaw. But still, when cutting pipes, it is more convenient to use scissors, since with their help the edges will be smoother, without burrs and notches.

Installation of a pipeline made of polyethylene pipes is carried out using a gas wrench. To ensure a more reliable connection, a linen seal is used. Tools intended for laying polyethylene pipelines, sold in construction stores. Typically, a soldering iron with attachments is offered to customers complete with scissors.

Preparation for installation work

Before installing PE pipelines, you must:

1. Calculate the amount of required building materials depending on the length of the designed communication, the number of turns and corners.
2. Before starting work, you need to turn off the water supply and prepare building materials in accordance with the project.
3. It is necessary to lay a polyethylene pipeline from the heating boiler if an autonomous heat supply is installed in the house.
4. After the dimensions have become known, they begin to connect polyethylene products and solder fittings and metal pipes.

Learning how to use a soldering iron will not be difficult even for a novice home craftsman. But at the same time, many technical points related to the process of assembling polyethylene pipelines must be observed.

Installation by welding

The laying of communications in this way occurs in the following sequence:

1. After a piece of pipe of the required size is cut using special scissors, a chamfer is removed from its edge at an angle of 45 degrees. Read how to cut a pipe at 45 degrees so that everything turns out perfectly.
2. The prepared section of the product is installed on the soldering iron nozzle, the same is done with the connecting fitting, which is placed on the second nozzle.
3. The parts are then heated to a predetermined temperature, usually about 270 degrees, after which they are quickly removed from the attachments and connected.
4. Then the docking area should cool down for several minutes. This procedure should not be done forcibly, as this will have a very negative impact on the quality of the seam.
5. According to the project documentation, it is necessary to lay communications, connecting all PE pipes with fittings and heating radiators in a certain sequence. The soldering is completed at the output element near the heating boiler.
6. After the system is filled with water, turn on the heating unit. All connections are carefully checked for leaks. If everything is in order, the pressure is set on the boiler and air is released from the radiators.

Connection fittings for polyethylene pipes

If, when laying a pipeline, it is necessary to install polyethylene pipes, fittings are used for this. Let's figure out how to connect polyethylene pipes for water supply so that there are no problems later. These parts are divided into types depending on the chosen method of work:

• welding of products;
• gluing;
• mechanical type threaded connection.

Depending on the pipe laying method used, fittings for polyethylene pipe products are:

1. Electric welded, equipped with embedded heating parts. When the wire is heated using electricity to a certain temperature, the polyethylene begins to melt. As a result, a homogeneous dense formation is formed in those places where the transition is made from one section of polyethylene pipe to another. Modern equipment designed for welding polyethylene fittings allows you to set the required voltage and time to obtain a high-quality result.
2. Compression. They are not much different from the fittings used when installing copper or plastic products. The difference lies in the material from which they are made. This type of fitting is convenient to use, since its installation does not require special qualifications - the fitting is almost ready for installation.
3. Connecting elements for butt welding. For this purpose, Spigot PVC fittings (cast elements) are used. The joining process involves heating the end of the pipes to a viscous-flowing state of the material, and then they are joined under pressure. The connection point, provided that the welding technology is followed, is homogeneous with the pipeline.
4. Reductive. These elements are used for the installation of PE pipes of different diameters. They are equipped with a threaded connection for quality results. Threaded fittings are used to connect polyethylene pipes to metering devices and water distribution equipment.

Thus, correctly selected fittings make it possible to perform high-quality installation of PE pipelines for water and heat supply with your own hands without special training.

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 into the trench. 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.

Laying by pulling with or without simultaneous destruction of the old pipe

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.

The DVN-Stroy company carries out work on laying polyethylene pipes of various diameters, from 50 to 630 mm.

Polyethylene pipes found wide application in construction. They are used when laying water supply networks, gas distribution systems, pressure and gravity sewer networks, and as protective cases for electrical and telephone cables. Pipe laying is carried out traditionally open method or trenchless method. The production of PE pipes is carried out by continuous extrusion from low-density polyethylene.

The DVN-Stroy company uses only. For pipes with a diameter of up to 315 mm, the Italian machine GF Omicron 315 is used. For pipes 315-630 mm - Ritmo Delta 630. Socket welding is performed using a Hurner HST300 machine.

Methods for installing polyethylene pipes.

Polyethylene pipes are installed mainly in three ways: using butt welding, electrofusion welding with embedded heaters, and using compression fittings. Pipe turns and branches are made using welded or cast fittings: bends, crosses, tees, bushings for flanges.

Remoteness of the object;

Availability or absence of electricity, etc.

The cost of the work is estimated after reviewing the design documentation or visiting the site by a specialist.

You can also send drawings or a pipe laying diagram to email [email protected] This will allow us to more accurately estimate the cost of work and materials (polyethylene pipes, bends, fittings, tees, valves or Ball Valves, bushings, flanges, electric couplings), estimate the time frame for completing the work.

An example of installation of polyethylene water pipes.

Most city utilities built in Soviet times are worn out by 70% or more. Almost all water supply pipelines were made of steel pipes which are most susceptible to corrosion. The wear and tear of these pipes is expressed in constant emergency situations- pipe breaks, reduction of pipe cross-section and its throughput, water pollution according to biological parameters.

The figure below clearly shows the condition of a steel water pipe after a long period of use.

One of the options for reconstructing worn-out ones is laying polyethylene pipes. Replacement of pipes can be carried out along an old pipe that has been destroyed, or laid next to an existing pipe, without stopping the water supply to residential buildings and other consumers. Wells and chambers, depending on their condition, are subject to replacement, complete or partial reconstruction (for example, replacement of necks, ladders and hatches).

At the first stage, after excavation of trenches and pits, polyethylene pipes are welded into a string using butt welding, in a trench or on the surface of the earth.

Installation of polyethylene pipes each other is performed in the following sequence.

1. The pipes are aligned and centered relative to each other as much as possible. The surfaces of the pipes are prepared for installation: they are cleaned of dirt and degreased.

2. Insertion into the main pipe can be done in several ways, for example using a flanged cast iron tee TF or plastic tee. The figure below shows an option for inserting using a saddle. HDPE bushings with boring flanges are mounted at the ends of the pipes using electric couplings.

It is very important to correctly install the unit on a free pipe. The distance between the flanges must be such that later, when installing the valve and tightening the bolts, the connection will be sufficiently watertight. In the future, the connection must withstand hydraulic tests of 8-12 atm, while the polyethylene pipes should not experience unnecessary tensile stresses, which will ensure a long service life of the laid water supply pipes.

3. Next, the flange valve is installed. All work is carried out in the existing chamber. After switching the water supply to a new line, the old worn out water pipes subject to dismantling and washing with cement-sand mortar.

Water pipes made from polyethylene pipes have high performance characteristics. Polyethylene has high chemical resistance, is not subject to corrosion and low temperatures. Due to the high smoothness of the pipe walls, their throughput is 25-30% higher than that of steel pipes.

The service life of polyethylene pipelines is at least 50 years.

Rules for laying and installing polyethylene pipes.

When performing underground laying of polyethylene pipes, it is necessary to remember and observe following rules. The depth of pipe laying should be 0.2 meters greater than the freezing depth of the ground (in the Moscow region this is 1.5 meters). The width of the trench along the bottom should be 40 centimeters greater than the diameter of the pipe being laid. If HDPE pipes are butt welded in a trench, its width should allow the welding machine to be placed there.

Before installing pipes, to avoid damage to them, the bottom of the trench must be carefully leveled. If the base of the trench has solid inclusions, it is necessary to arrange sand cushion made of sand 10-15 centimeters thick. If there is a need for foundation and backfilling, there is no need for it.

After laying the pipes, backfilling. The initial sprinkling is done with sand, to a height of 15-30 centimeters above the top of the pipe. Further backfilling to the top of the trench can be done with local soil of stones or construction waste larger than 20mm in size. Under the designed roads and driveways, the trench is backfilled exclusively with sand with layer-by-layer compaction.

Advantages of polyethylene pipes.

Modern polyethylene pipes are made from polyethylene grade PE80 m PE100 according to GOST 18599-2001 and have many advantages over other types of pipes:

The cost of polyethylene pipes is lower than steel pipes;

Service life of at least 50 years;

HDPE pipes are not subject to corrosion and are also resistant to aggressive environments;

Due to their low weight, installation of polyethylene pipes is carried out without the use of heavy-duty equipment;

Installation of polyethylene pipes by butt or electrofusion welding is simple and reliable;

When water freezes inside a pipe, it does not collapse;

These undeniable properties of polyethylene pipes have allowed them to be widely used in all areas of engineering communications construction.