In order to form and install water supply and drainage networks, it is necessary, first of all, to use water flows made from polyethylene pipes, taking into account all the advantages of such water flows over steel or cast iron products. A significant drawback of pipes made of metal, especially for steel products, is their short service life due to exposure to corrosive processes.

When installing any pipeline system, its operational characteristics will be determined by how scrupulously and carefully the workers adhered to the installation technique of the drains, no matter what material they were made of - metal or plastic. Each type of pipe has its own rules and installation technologies. Laying pipelines from polyethylene pipes has its significant differences. First, you need to measure the width of the trench. It should provide excellent convenience during installation and installation of the pipeline. The main thing to take into account: the width of the ditch should be approximately 40-50 cm larger than the diameter of the pipes. Such conditions must also be met when laying sewer pipes, and when laying water pipes. If laying gutters is carried out in hard or dense soil, then be sure to build a sand embankment approximately 10 centimeters wide.

It is imperative that any stones are removed from the bottom of the trench and the bottom must be made smooth and level. You should ensure that the soil at the bottom is not frozen. If the soil for laying a pipeline made of polyethylene pipes is loose, then it may be necessary to use technologies to create the effect of strengthening the ground. If there is a possibility of soil displacement, then in order to ensure a static position of water flows in the ground, geotextiles are laid out at the bottom of the ditch.

Most often, the installation of a pipeline made of polyethylene pipes begins with laying a special cushion, which is a certain material, namely gravel or sand. The thickness of such a pillow can vary depending on the characteristics of the soil, but on average it is 10-15 centimeters. It is necessary to seal the pillow only in the vicinity of manhole. Workers make pits in places where water flows are connected to each other. When an analysis of the soil reveals its ability to experience strong internal friction, then the cushion need not be laid. Then, at the base of the track, the hardened soil is removed, and earth that is softer in structure is laid out in its place. The excavated soil can later be used to backfill the pipeline, but it must first be ensured that it does not contain large rocks. You can also fill the water supply pipe with sand or fine gravel. First, the pipe is backfilled along the entire perimeter, at a height of more than 15 cm from its extreme point. If the soil has to be made more dense, then backfilling is done in small layers of 20 centimeters. Under no circumstances should you compact the soil directly above the drain.

After installation pipelines made of polyethylene pipes backfilling is most often carried out with seized earth, but it must first be cleared of stones if they exceed 6 cm in size, and if there are boulders, then 30 cm.

PVC pipes are most often attached to each other using glue in the socket. However, it must be taken into account that for gluing it is necessary to thoroughly clean the surfaces and apply adhesive base very neat. The joint edges should not be allowed to bend. IN last years For the installation and fastening of drains made of polyethylene materials to each other, socket joints have become very popular, which are sealed using rubber cuffs of various profiles. In this case, gutters are made with sockets that contain circular grooves inside. If necessary, attach polyethylene pipe to steel or cast iron, then you need to use flange connections. Where they are laid sewer systems from polyethylene drains through the walls of wells; fastening couplings with a single rubber ring are used as sleeves.

Welding is carried out mainly by the contact method, it is carried out in a socket or butt with shaped compartments. When welding polyethylene pipes It is necessary to very accurately observe and monitor the diameters of the drain and their circumference.

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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: pipes break under high pressure, 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 field conditions 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, 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 makes installation and installation easier.
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 movement of pipelines in the 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 a specific type of pipe.

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 are widely used: 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. Individual parts (necks, shut-off valves, etc.) may be subject to partial replacement; if necessary, 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 sewer pipes have a large throughput due to the absence of internal roughness. When installing external sewerage systems, frost-resistant PE pipes are used. 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 lines when using polyethylene pipes does not require complex special equipment. Polyethylene pipes are not large diameter 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.

It's also possible plug connection, which is carried out by 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 pipes large diameters(from 630 mm).

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

If necessary, connect pipes with a diameter of up to 63 mm, use compression fittings, 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 is carried out in two main ways. These are traditional pipe laying in an open trench and trenchless laying - a deep directional drilling method.

Pipelines made of polyethylene with open method 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 which is at risk of displacement, the bottom needs to be strengthened. In such cases, the bottom of the trench is strengthened with geotextiles.

If the trench bottom is level and has optimal soil characteristics, a cushion is not 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 fill, 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 carried out 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 methods of horizontal drilling: guided and unguided.

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 pipes(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 pulled or pushed polyethylene pipe 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 facility is located close to the welding site, where the pipes are pre-connected and then transported in finished sections 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 then must 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 with 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 by constructive L- or U-shaped bending 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 in percentage are changing in favor of polyethylene pipes.

Used in systems whose maximum operating pressure is no more than 0.16 MPa.

Polyethylene pipes low pressure simple and easy to install.

Not so long ago, the main products in the free-flow drainage and sewerage system, both industrial and domestic, were widely used pipes made of various materials. Along with asbestos-cement products, reinforced concrete non-pressure products were also actively used.

But this area of ​​water supply and sewerage began to be actively conquered by non-pressure polyethylene pipes.

The main factors that significantly influence the choice of low-pressure polyethylene pipes are their highest performance qualities:

• no corrosion;
• excellent resistance to various chemicals;
• long service life;
• simplicity and ease of installation;
• relatively low cost.

Three types are produced for water supply and sewerage:

• non-pressure smooth HDPE pipe;
• non-pressure corrugated HDPE pipe made of polyethylene;
• spiral free-flow pipe.

Free-flow smooth pipe

Connecting a non-pressure smooth pipe with clamp fittings.

Smooth non-pressure polyethylene pipes have Orange color and are produced in sizes:

• diameter from 20 to 560 mm;
• length from 500 to 1300 mm.

Types of products based on the ring stiffness class:

• SN2 - installation depth no more than 1 meter;
• SN4 - installation depth no more than 6 meters;

Installation of this product is carried out in a socket. One side of the HDPE pipe has a socket in which it is located. Installation of sewerage is very simple; to do this, you need to insert one product into the socket of another. If it is necessary to connect elements with different diameters, there are special adapters for this. For ease of installation, various tees, couplings and angles are provided.

It doesn't cause any problems either. Ceiling or wall mountings are made using simple latches (clamps), which are fastened to the wall or ceiling with screws.

Corrugated non-pressure pipes

Installation of sewerage is very simple; to do this, you need to insert one product into the socket of another.

This type of HDPE pipes is also used for sewerage and drainage systems. This type of non-pressure pipes can be made from polyethylene, polypropylene and their combinations.

Polyethylene pipes of this type have differences in design and production technology. These products are produced in a two-layer version and have a smooth inner surface and a corrugated outer surface. The outer wall of the product, which is black, guarantees high protection from ultraviolet radiation; it also serves to ensure the necessary annular rigidity of the HDPE pipe and its resistance to deformation. White color, which has an internal wall, facilitates visual diagnostics of the sewer system.

This product is available with the following classes of ring stiffness:

• SN4 - installation depth no more than 4 meters;
• SN6 - installation depth no more than 6 meters;
• SN8 - installation depth no more than 8 meters;
• SN16 - installation depth no more than 16 meters.

Available in sizes:

• diameter - from 110 to 1200 mm;
• length - 6 or 13 m;
• profile width - from 6 to 41 mm;
• wall thickness - from 1.2 to 5 mm.

Here are some positive factors:

The rubber gasket is installed inside the corrugation, which prevents it from moving during installation.

1. High impact resistance (even at low operating temperatures).
2. Good resistance to chemical and mechanical stress.
3. High ring rigidity as a result of the use of special grades of polyethylene and optimal design in production.
4. Ease of installation: the connection is made using a rubber gasket (O-ring) and a coupling or butt welding. The rubber gasket is installed inside the corrugation, which prevents it from moving during installation. Thanks to its special shape, the rubber gasket prevents not only leakage from the product, but also groundwater from entering it.
5. High versatility due to the possibility of using a wide selection of fittings, which allows connection to any type of pipe.
6. The low weight of the product allows it to be conveniently stored, mounted and transported.
7. The excellent flexibility of the product makes it possible to easily bypass various obstacles when laying a pipeline system.
8. Long service life at low operating costs.
9. Excellent value for money.

Features of installation and installation

For pipes with a diameter of 250-1200 mm, the sealing ring is inserted into the groove of the first corrugation.

This product is intended for underground installation with a maximum depth of up to 16 m and a minimum depth of at least 1 m. It is very important to choose the right material for backfilling the formed trench. The granulometric composition of this material should densely fill the corrugated products, that is, the particle size should not exceed the width of the profile.

A connection using an o-ring and a coupling is performed as follows: for a product that has a diameter from 250 to 1200 mm, install the o-ring in the groove of the first corrugation. For a product that has a diameter from 110 to 200 mm, in the groove of the second corrugation. After this, we install the coupling, and the force should be constant and equally distributed.

One of the important advantages of corrugated free-flow pipes is that they can be connected using butt welding. This became possible due to the sufficient wall thickness and the distance between the corrugations. Performance welding work is a complex process that should only be performed by an authorized and qualified professional. However, it should be remembered that butt welding is used to seal pipes and cannot provide the same ring rigidity as a coupling.

Spiral free-flow pipes

Thanks to geometric shape pipe wall profile, spiral pipes have the highest resistance to deformation for free-flow networks.

A spiral-shaped non-pressure product is used for the construction of a non-pressure sewerage and drainage network, often of large diameter (more than 1000 mm). This type of free-flow pipe is made of polyethylene by winding a continuously produced profile onto a rotating cylindrical drum while simultaneously welding the turns together. Due to the geometric shape of the pipe wall profile, it has the highest resistance to deformation.

This product has several types:

1. SPIROLINE has ring stiffness SN2, SN4, SN6, SN8, SN16, which allows its installation to a depth of up to 16 m. A wide range of internal diameters - from 500 to 2400 mm. The length of the segment is from 0.5 to 13.5 m.
2. KORSIS has ring stiffness SN4, SN8, which allows it to be laid to a depth of up to 8 m. The internal diameter is from 800 to 2400 mm. The length of the segment is from 0.5 to 13.5 m.
3. VEHOLIGHT has ring stiffness SN2, SN4, SN8. Inner diameter - from 280 to 800 mm and from 360 to 3000 mm. The length of the segment is from 0.5 to 13.5 meters.

The connection is made by directly screwing one product into another with further end welding. These polyethylene pipes can also be installed using different shaped elements (bend, transition, tee, tank, well).

Polyethylene multilayer pipes are often used to lay water pipes in household plots. Pipes are produced using a method without using high pressure, due to which the pipes become flexible and durable.

The abbreviation “LPD” stands for low-density polyethylene. This marking indicates that the pipes were manufactured without the use of high pressure. Suitable for laying water pipes drinking water and serve cold.

What are HDPE pipes made of:

• There are several layers, the first one is the inner or cross-linked polyethylene layer. Formed by stitching the edges of the workpiece under the influence of high temperature;
• adhesive: the layer is strong, designed to withstand water pressure, so the pipes can be installed in summer cottages and garden plots for organizing irrigation, etc.;
• Between the adhesive layers there is an air cushion or oxygen barrier. Pipes can be called durable, but subject to the presence of a protective layer. Then you can install an external water supply ( open method);
• The outer layer of polyethylene is a durable layer that provides reliable protection. From the information indicated on the front of the pipe, you can find out about the stitching method and the type of pipe (marking: numbers, letters).

Selection of polyethylene pipes

To install the pipeline according to all the rules, you need to start with the selection of polyethylene pipes. There have been cases when everything was done correctly, but the pipes began to leak after just a couple of years of operation. Although such water pipelines must cope with loads for several decades. What is the reason? It turns out that you need to know how to choose the right pipe. There are pipes on sale that are made from plastic waste through recycling. Such pipes will be 2 times cheaper, but there is not much benefit from them: the strength is low, and the water flowing from such pipes “catches” the pungent smell of plastic. There is no point in hoping that the smell will fade over time.

That's why. Before you begin installing the water supply system, you need to understand and find out how to choose pipes:

1. We inspect the pipe: if the product is not marked (there are no letters and numbers), there are inclusions and stripes, there is a sharp bad smell, they are unsuitable for laying pipelines. Such materials are used only for supplying process water.
2. Polyethylene pipes intended for supplying drinking water are painted only black, with a blue stripe (one or more) running along the top of the pipe. The color is rich, uniform, the surface of the pipe is smooth, without dents or bulges. Wall thickness - according to GOST (18599-2001), the diameter of the product, information about the manufacturer and the strength of the product must be indicated.
3. Marking 100 - pipes are strong and dense, withstand higher pressure than pipes marked PE-80.

Using HDPE pipes

According to regulations and standards, polyethylene pipes are used:

• for supplying drinking water up to 40 degrees;
• for transporting technical water, up to 40 degrees;
• for gaseous liquid medium(transportation), provided that the temperature of the substances will not be higher than +40 degrees and that the medium is inert to the substance from which the pipes are made;
• for insulation or for laying electrical cables.

If all standards are observed, polyethylene products will last about 50 years.

Advantages and technology of connecting HDPE pipes

HDPE pipes intended for supplying cold water, compare favorably with cast iron pipes and steel, they are not subject to corrosion, do not change the taste and quality of drinking water.

Advantages of HDPE pipes:

• long service life - about 50 years;
• affordable price - this is due to low cost, because the production of pipes does not require expensive equipment and the purchase of raw materials;
• low thermal conductivity;
• no condensation forms on the surface;
• pipes do not corrode;
• HDPE pipes are plastic, so they can be laid not only in a trench, but also on the surface;
• subsidence of buildings and structures, as well as low temperatures, such pipes are not afraid;
• installation of water supply systems in closed and open ways is carried out in any weather;
• pipes do not pollute environment, do not emit harmful substances;
• weight is minimal, sold in coils, which greatly simplifies not only installation, but also transportation.

What are the disadvantages of HDPE pipes

Each material has not only advantages, but also disadvantages, which it is advisable to know about before everything is purchased and a water supply installation plan is drawn up.

Flaws:

• as the temperature rises higher permissible norm, the material becomes fusible;
• under the influence of direct sun rays, pipes age faster.

This disadvantage is compensated for in this way: a special coating is applied to the surface by thin spraying.

HDPE pipe connection technology

You will need the following tool:

• hacksaw or special tool for cutting polyethylene pipes;
• a cone-shaped knife to process the cut edge;
• if you use fittings, then you won’t need anything else, but some craftsmen advise having an adjustable wrench so that when tightening the connections, you don’t have to tighten the nut too tightly. Otherwise, the clamps may not hold up and will burst, or the gasket-seal will be damaged. If the nuts are not sufficiently secured, then the tightness of each joint will suffer.

Compression fittings for HDPE pipes. Installation features

When installing a water supply system, you cannot do without special connections or fittings. They can be straight to connect 2 pieces of pipe and transitional when you need to connect pipes of different diameters. In addition, fittings will help connect the pipeline in several directions, make the desired bend or angle, reduce or, conversely, increase the diameter of the pipes.

Installation of a pipeline with fittings is carried out in several stages. The work is not difficult, so even a beginner can do it, and no special tools are required.

How to install:

1. Prepare the pipes, calculate in advance how many meters of pipe will be needed to lay the pipeline.
2. Unscrew the fittings 1-2 times.
3. Mark the work surface and lubricate the joint soap solution(you can just use plain water).
4. Insert the pipe into fastener to the mark. Make sure that the pipe section rests against the ring. To achieve this, you need to apply a little more force.
5. If you don’t try hard at this stage, the connection will not be 100% tight.
6. Tighten the nut until it stops so that there are no loose threads left on the threads.

Flange connections for HDPE pipes are one of the methods for installing a water supply system from HDPE pipes, in which, if necessary, the assembled unit can be disassembled. The flange connection is used for joining control and shut-off valves. For installation you will need a polyethylene pipe, a metal sleeve and a free flange.

To obtain a reliable pipe connection, another method is used: one-piece or welded joint for HDPE pipes.

Performed in 2 ways:

1. Joint to joint.
2. Connection using an electrical coupling.

Butt welding is performed using a special welding machine. If you really want to, you can master the joining technique in order to lay the water supply yourself, without the involvement of specialists.

How to connect pipes butt to butt using a welding machine:

1. The ends of the pipes (provided that the pipe diameter exceeds 50 mm) must be secured in special clamps welding machine.
2. Bring a heating plate to the cut site.
3. Wait until the plastic warms up and reaches its melting temperature.
4. After this, you need to remove the slab, and immediately connect the pipes to each other, applying force.
5. Wait a few seconds for the seams to cool, after which you can remove the clamps and remove the device.

What is important with this method:

1. Materials are used only of one diameter, otherwise nothing will work.
2. Wall thickness – no more than 5 mm.
3. You can work on outdoors, at a temperature not lower than +15 degrees and not higher than 45 degrees.
4. The welding machine operates from the mains, it does not consume a lot of energy, so this method can safely be called the most economical. Even though the cost of the device is very high, in order to install the water supply system yourself, the device can be rented.

Hydraulic testing of HDPE pipes

Any pipeline, even one made by experienced specialists, must be tested. The first launch is the most important; it will show all the weak points.

Work progress:

1. External inspection of the water supply system, removal of air from the system.
2. The inspection is carried out one day after completion of installation.
3. Before starting work, you need to clean the pipe cavity from dirt and open the valves to bleed air.
4. Install water drainage at the lowest points (drains).
5. Connect pressure gauges on both sides.
6. Connect the pipeline to the water supply or sediment to create pressure and fill the system.
7. With the air vents closed, you need to gradually increase the pressure and hold it for a quarter of an hour. For the test to be successful, water must be gradually pumped in to stabilize the pressure.
8. Then reduce the pressure to working standard, leave for half an hour. During this time, it is necessary to have time to perform a visual inspection of the pipeline, especially paying attention to all joints.
9. The water supply passed the test if no leaks or ruptures of the connecting elements were detected.

Errors when installing polyethylene pipes

Installing HDPE pipes is not a difficult task, it is difficult to make a mistake and do something wrong, but mistakes are no exception.

Common mistakes:

• if the pipes used are different. Beginners may not understand and purchase different pipes. And each type of plastic has its own standards, so the tightness at the junction may be compromised. Result: leaks and cracks at the joint;
• Over-tightening the nuts can cause microcracks to appear. At the initial examination finished work they will not manifest themselves in any way, but under pressure the crack may increase and then there will be a water leak;
• a weak puff, like a strong puff, is also not good;
• uneven edges of the joint: if you use welding machine, then you need to clearly adjust the edges. A trimmer is used for these purposes.

Video instructions for installing HDPE pipes with your own hands:

For laying pipelines of water supply and sewerage systems, pipes are mainly used from low-pressure polyethylene (HDPE), high-pressure polyethylene (HDPE) and polyvinyl chloride (PVC), and for water supply purposes polyethylene pipes are used.

When laying external water pipes from HDPE and LDPE, the main method of connecting pipes is to butt weld them with a heating tool. When installing gravity sewer pipelines, HDPE pipes are connected in the same way.

PVC pipes are connected mainly with socket glue. However, given that careful cleaning of the surfaces to be bonded and careful application of glue are required, recently socket joints that are sealed have been widely used to connect PVC pipes. rubber cuffs various profiles, as well as O-rings.

Welding of polyethylene pipes, most often contact welding, is carried out end-to-end (butt welding), into a socket with cast fittings, and into a molded socket (socket welding). When welding pipes Special attention should be addressed outside diameter pipes and their ellipse (ovality). When butt welding, the maximum discrepancy between the edges should not exceed 10% of the wall thickness. The ends of the pipes when socket welding must have an outer chamfer at an angle of 45°.

Welding of plastic pipes in installation conditions As a rule, they are performed on welding installations that provide mechanization of the main welding processes and control of the technological regime. In inconvenient places (trenches, channels, wells, etc.), pipes are welded manually using devices for trimming and centering, as well as heating tools. The latter must be electric with the ability to maintain a constant temperature on the working surface of the heater by a thermostat and an autotransformer. To prevent adhesion of the molten pipe material, the heater should be covered with a cover made of a heat-resistant anti-adhesive coating (glass cloth impregnated with polytetrafluoroethylene), a film of this material or silicone varnish.

contact welding pipes are carried out in the following sequence: installation and centering of pipes in a clamping centering device; pipe trimming and degreasing of ends; heating and melting of welded surfaces; removing the welding heater; connection of heated welded ends of pipes under pressure (sediment); cooling of the weld under axial load. To obtain strong and high-quality pipe joints, it is necessary to strictly observe the basic welding parameters - temperature and heating duration, melting depth, contact pressure during melting and upsetting. The basic requirements that must be observed when welding pipes are given in Appendix 3.

Bonding of polyvinyl chloride (vinyl plastic) pipes is carried out mainly in a socket. The process of gluing PVC pipes and fittings consists of the following operations: preparing the ends of pipes and sockets for gluing, gluing and curing the joints. The bonded surfaces of pipes and sockets are degreased with methylene chloride. After this, the glue is applied in a thin layer to the socket and in a thick layer to the end of the pipe. Pipes and fittings can be glued at an outside temperature of at least 5 °C. Glued joints within 5 minutes. should not be subjected to any mechanical stress. Before installation, glued lashes and knots must be kept for at least 24 hours after gluing.

Connection of PVC pipes on sockets with rubber rings. Pressure socket pipes in the trench are connected in the following order. First, the smooth end and socket of the pipes being connected are cleaned of dirt and oils, after which the depth of insertion into the socket is marked on the smooth end with a pencil or chalk. Then insert a rubber ring into the groove of the bell, lubricate it and the smooth end liquid soap, after which it is pushed into the socket to the mark. When connecting free-flow sewer pipes made of PVC, couplings are used along with the socket, and the technology for connecting them using rubber rings is similar to that described above. Tensioners are used to assemble socket connections of pressure and sewer pipes.

Equipment for welding and installation of plastic pipelines. Mobile installations and installation devices have been developed and produced for welding polyethylene pipes. Three types of installations are used for welding pipes with a diameter of 160 - 315, 355 - 630 and 710 - 1200 mm. A mobile installation for welding pipes with a diameter of 160 -315 mm (Fig. 6.18, a, b) includes movable and stationary clamps for clamping pipes, a mechanism for processing pipe ends before welding, an electric heating disk for melting pipe ends, a mechanical power system for creating pressure in the process melting and precipitation, as well as a control panel.

Rice. 6.18 – Installation and equipment for welding plastic (polyethylene) pipes: a – installation for welding pipes with a diameter of 160 – 315 mm, b – detail of the welding unit, c – installation for welding pipes with a diameter of 355 – 630 mm, d – the same, with a diameter of 710 – 1200 mm, d, f, g – kit for welding pipes with a diameter of 710 – 800 mm (d – centralizer, f – facing device, g – electric heater with power source); 1 – fixed clamps, 2 – electric heating disk, 3 – end mechanism, 4 – movable clamps, 5 – switch, 6 – welded pipe, 7 – roller, 8 – pressure gauge for force control, 9 – switching system, 10 – clamp, 11 – end mechanism drive, 12 – trolley, 13 – control panel, 14 – mounted station, 15 – pipe-laying bulldozer, 16 – welding installation, 17 – guide tracks, 18 – hydraulic cylinders, 19 – guides

The installation for welding pipes with a diameter of 355 - 630 mm is shown in Fig. 6.18, c. It consists of lifting and lowering hydraulic cylinders, mechanisms for processing pipe ends, roller supports and a tent. The installation for welding pipes with a diameter of 710 - 1200 mm (Fig. 6.18, d) consists of the welding installation itself, portable guides on supports, a basic lifting and power supply machine (pipe layer - bulldozer, equipped with an electric generator).

The laying of plastic pipelines in a trench is carried out according to two main schemes for organizing welding and installation work - basic and route. In the basic scheme, pipe welding is carried out near the facility warehouse with preliminary connection of pipes into sections up to 18 - 24 m long or more, which are delivered to the route and there welded into a strand or a continuous thread for laying in a trench. In the route scheme, pipes are laid out along the trench and welded using mobile welding units into a continuous thread using the extension method.

Laying pipelines with separate pipes. Before laying, pipes are carefully inspected and rejected. The pipes on the trench berm are often welded into sections or strands, which are then lowered into the trench on soft towels. In production conditions, especially in winter period, the installation of pipelines is carried out from individual pipes and connects them in a trench by gluing or on rubber rings using the extension method.

Laying in links (sections) and lashes allows you to significantly reduce the number of welded joints on the route, increase labor productivity, the pace of pipeline laying and the quality of work.

The sections are delivered to the track and laid out along the trench, and then laid in the trench and connected there. Sometimes sections are pre-connected on a berm into a lash 100 - 200 m long, after which they are lowered into a trench. The prepared lash is lowered into the trench manually (if the pipe diameter is small) or using cranes. It is allowed to lay the whip in the trench no earlier than 2 hours after welding the last joint. Lower it into the trench smoothly using hemp ropes, soft towels or belts, located at a distance of 5 - 10 m from each other, avoiding sharp bends of the whip. Throwing welded lashes to the bottom of the trench is not allowed.

The laying of plastic pipelines of large diameters (1000 mm or more) is done by pulling a string along the bottom of a trench or lowering pipes suspended from a tap. The pulling method is used to lay pipelines in dry soil conditions. In this case, the welding installation stationary type and guides are placed in the trench, after which the pipe is sequentially connected into a continuous thread. The trimmed pipes are lowered into the trench and placed on the clamps of the welding installation, then they are welded, after which the pipeline is pulled forward with a winch or other mechanisms.

In dense and hard soils, before laying pipes at the bottom of the trench, it is necessary to make a bed of bulk soil with a layer of 10 cm, and when laying PVC pipes on an artificial (concrete) base, make a sand bed. When filling these pipes, a protective layer of sandy or local soil 80 cm thick must be installed above their top. To reduce stress in the plastic pipeline or its deformation in summer time It is recommended to fill it with water before filling, and to fill it in the coldest time of the day.