Decoding pnd

Features of installation and operation

Installation of pipes made of cross-linked polyethylene is carried out only using fittings. Welding is not used here, as in working with other polymer pipes.

There are two common ways to connect polyethylene pipelines:

• compression - using a union, tightening nut;
• pressing - using a special press sleeve.

Compression fittings will require two adjustable wrenches or a set of wrenches. For pressing, you need special tools - press tongs and an expander that will match the diameter of your pipes. You can buy them complete with pipes and fittings, branded from the manufacturer. But it's cheaper to use a rental tool.

For preparatory work, you will need a tool for cutting pipes. Here it is better not to save money and use a professional pipe cutter. Only with such a tool can you get a high-quality, suitable for further work, cut. It must be a cut strictly perpendicular to the guide axis, without burrs, with an undeformed circle.

Installation of a compression fitting is as follows:

• a union nut unscrewed from the fitting is put on the prepared pipe;
• then fix the split ring 1 cm from the edge;
• a fitting fitting is inserted inside the pipe;
• move the nut onto the ring and tighten it with the keys (one holds the fitting, the second tightens the nut).

The press fitting is non-detachable. The procedure is as follows:

• a crimp sleeve is put on the pipe;
• expand the diameter of the cut to the size of the fitting;
• insert a fitting;
• stretch the sleeve and press it in with press tongs.

The press-on connection has increased strength, it is used in the installation of heating systems and hot water supply systems.

Advantages and disadvantages of gas PE pipes

The material for the manufacture of pipes for a gas pipeline can be not only polyethylene, but also steel or polypropylene, however, it is PE pipes that occupy the leading positions in the market for components for gas pipelines.

The wide popularity of PE gas pipelines is due to the many advantages of polyethylene pipes:

• Long service life - at least 50 years: polyethylene does not decompose in the natural environment, is neutral to many chemically active substances, as a result of which it is not prone to a decrease in the internal diameter due to the formation of deposits and is not subject to corrosion, resistant to weather changes.
• Reliability and safety: gas-tight and durable pipe walls do not form leaks, a smooth inner surface allows free movement of gas, and unlike steel pipes, polyethylene pipes do not conduct electricity.
• Ease of installation: pipes are light in weight, produced in the form of long lengths, which, together with their elasticity, allows laying gas pipelines with a minimum number of connections, water and gas impermeability of the walls makes it possible to do without installing waterproofing, protective equipment and sophisticated equipment are not required for work.
• Environmental friendliness: polyethylene does not emit harmful substances into the environment.
• Profitability: polyethylene gas pipes have a low cost of both the pipes themselves and components, installation also does not require serious financial costs.

With all the advantages of polyethylene pipes, they are not without drawbacks:

• Under the influence of sunlight, the structure of polyethylene is gradually destroyed.
• This material does not withstand intensive loads, therefore, under roads and communication lines, PE pipes must be laid in a metal case, and in regions with increased seismic activity they cannot be used even in combination with a casing.
• The range of withstand temperatures is small - from -15 to 40 degrees, which, coupled with the instability of pipes in front of ultraviolet radiation and intense loads, requires laying the gas pipeline to a depth of about 1 meter.

Types of polyethylene

Pressure pipes were the first plastic products that were invented for the transport of cold liquids. Today, cold water pipes in most cases are made of low-density polyethylene. Today, manufacturers offer different grades of similar products (PE 100, PE 63, PE 80), while the higher the grade, the greater the strength characteristics of the product.

Thanks to this quality, it is possible to reduce the thickness of the pipe wall, make it lighter and cheaper. Pipes made of low pressure polyethylene have a fairly high strength, they are resistant to internal pressure and mechanical stress.

Pressure pipe for water supply

Production of polyethylene pipes

Products of this type are obtained from polyethylene by extrusion. The production technology lies in the fact that polyethylene is supplied in a softened form under pressure through a hole of the size of the future product, after which it solidifies in the form of a pipe.

Before taking the final form, it is calibrated in a semi-amorphous state by a vacuum unit, obtaining the appropriate dimensions. Then the product is wound into separate coils of several tens of meters or cut into separate segments and sent to storage facilities.

The equipment on which PE pipes are made is not very bulky and does not differ in increased complexity. More complicated is the technological process in the manufacture of reinforced polyethylene pipes.

PE pipes are quite sensitive to the sun's rays, with their prolonged exposure, deformation of this product is possible. Therefore, storage should be used in a place most closed from sunlight.

Equipment for the production of polyethylene pipes

Connection methods for gas pipeline installation

Connection of pipeline sections is carried out by three methods:

• compression - using compression fittings,
• welded electrofusion - using thermistor fittings,
• welded docking - without shaped elements.

The simplest to perform is a compression connection. The fittings used consist of a body and ferrules. To connect pipes, the rings are twisted from the fitting and put on the pipes so that the thread is on the cut side. Sliding the ring away from the edge, put the pipe on the nodal element until it stops. Then slide the ring back to the fitting and tighten tightly. No additional tools are required to make the connection, and the knot turns out to be detachable, but not the most reliable.

For electric welding, an electric welding machine and a thermistor fitting are used. An electrical coupling is a connecting element with a polyethylene housing, inside which a heating wire is laid in a spiral, two terminals are brought out.

To make a connection, an electric coupling is put on the end of the pipe, a welding machine is connected to the terminals and turned on. The veins of the fitting, through which the current flows, evenly heat the connected products almost to the melting point, due to which the pipe and the coupling are firmly welded. After turning off the electric welding device, the resulting assembly is left to cool. The resulting connection is reliable, but one-piece.

To perform the pipe connection in the last way, you will need a special butt welding device, consisting of:

• trimmer or centralizer in which the ends of the pipes are clamped,
• heating element - welding mirror.

The ends of the pipes are fixed in the trimmer and moved apart in different directions. An switched-on welding mirror is placed between the ends, and then the edges of the pipes are strongly pressed against it.When the pipes begin to melt, the heater is removed, and the swollen edges are pressed against each other with the help of a trimmer and held in this state until cooling.

The resulting connection is one-piece, reliable, but has a significant drawback: inside and outside the seam, a so-called burr is formed - an influx of polyethylene that reduces the diameter of the pipe at the junction. It is impossible to remove the burr, since it acts as a connecting element. Therefore, butt welding is used only to connect pipes with a diameter of more than 5 cm - in this case, the internal influx will reduce the throughput of the assembly insignificantly.

HDPE pipes for home heating systems

One of the most basic stages in the construction of houses and cottages is the design and installation of water supply and heating systems. After all, the comfort and convenience of living in finished housing depend on the efficiency of these systems.

Today, HDPE pipes are considered the most popular material for equipment of such systems.

This type of building materials deserves a similar demand due to the combination of good performance characteristics and the fact that the installation of polyethylene pipes is considered a fairly simple and understandable operation.

Characteristics of HDPE pipes

The name "HDPE pipes" stands for pipes made of low pressure polyethylene. They are made using continuous screw extrusion technologies.

Polymeric ethylenes obtained in a similar way have a number of parameters that make them even for transporting water of different temperatures and other liquid and gaseous substances. Among these parameters, one can single out inertness to the effects of aggressive chemical and radioactive substances, environmental friendliness, frost resistance, resistance to corrosion and the absence of prospects for "overgrowth" of the tubal lumen.

Also, the list of advantages of HDPE pipes includes a long service life (up to fifty years) and a low price. The listed characteristics make them an excellent material for equipping heating systems and organizing water supply for residential buildings.

As a circulating fluid in a HDPE pipe system, water or a heat carrier for heating systems can be used. The best option for using HDPE pipes will be low-temperature heating systems that do not require heating the energy carrier to extremely high temperatures.

Such systems include heating systems with surfaces (heated floors, walls, ceilings). In the case of using liquid energy carriers heated above 90 degrees for heating, instead of HDPE pipes, it is better to use plastic pipes that can withstand a higher temperature regime.

For example, reinforced propylene pipes.

Installation of HDPE pipes - basic specifics

HDPE pipes are produced in the form of coils (bunions) with an indication of the length and diameter of a particular product. When equipping a water supply system, HDPE pipe installation is carried out by the method of electrodiffusion welding - heating the edges of the connected pipes.

Joints in pipelines are connected using couplings and connectors using embedded thermocouples. Mechanical connection is also possible using collet or crimp couplings and connectors.

When installing heating systems, the number of connections is very small and does not require the use of connectors. For equipment of underfloor heating systems, a solid HDPE pipe of the required diameter is used, which evenly lays down and fastens on the selected surface. In this case, a solid HDPE pipe of the required diameter is used, which is installed and fixed on a surface selected as a heat source.

Before laying pipes, the surface is prepared, the placed pipes are treated with insulating material, poured with concrete mortar; on top of this "pie" lay the flooring. Antifreeze for heating based on glycerin or another selected liquid is launched into the finished system.

For long-term operation of the heating structure and prevention of expected leaks, when laying pipes, it is necessary to avoid their excessive bending, taking into account the kinetic force of the liquid circulating in them. In order to increase the service life of similar heating systems and avoid possible problems, since when placing plastic pipes, it is necessary to try to provide for the kinetic energy of the circulating energy carrier and prevent unnecessary bending of the pipes

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Polyethylene pipe and its SDR

What is SDR

One of the main indicators characterizing a PE pipe is SDR. It displays the ratio of the outer diameter of a polyethylene pipe and its wall thickness, it is calculated according to the table or according to the formula:

SDR=D/s,
where

• D = external diameter of the PE pipe (mm);
• s = pipe wall thickness (mm).

This indicator characterizes the strength of the pipe: the higher it is, the weaker the pipe and vice versa.

Accordingly, a product with a small SDR is able to withstand more pressure than the same product with a higher SDR. Thus, polyethylene pipes whose wall thickness is more able to withstand quite a noticeable pressure.

The ability of polyethylene to be resistant and neutral to gaseous and liquid substances determined the scope of its application. In addition to gas and water mains, PE pipes are used in the transportation of gaseous and liquid materials and for other purposes.

Polyethylene pipes with different SDR

Each type of pipe has its own characteristics, consider them:

1. Polyethylene brand 100:
   • The PE 100 SDR 17 pipe is irreplaceable in systems of gas pipelines and pressure water supply, especially in pipelines of big cross section. Its technical characteristics allow the use of such pipes for the installation of a pipeline with a long length. Such a polyethylene pipe SDR 17 belongs to a new generation of products, which is obtained by using modern technologies used in the manufacture of PE 100. Excellent performance characteristics of pipes made of this material are achieved due to the high strength properties of polyethylene.
   • The pipe polyethylene SDR 11 is made from the polyethylene received at a low pressure. Moreover, its high density makes it possible to use these products on high-pressure water pipes. In addition, this type can be used for arranging sewer collectors due to its resistance to aggressive environments. Laying can be carried out in almost any soil.
   • Products made of polyethylene PE 100, such as the PE SDR 26 pipe, can withstand pressures up to 6.3 atm., It is used mainly in non-critical water supply systems, in gravity sewers and to protect communications.
   • Pipe PE SDR 21 grade 100 - its main purpose is to install water pipes, according to experts in this product, the water does not have an extraneous taste and retains its taste qualities well.

1. Polyethylene brand 80:
   • A product such as a pipe PE 80 SDR 11 belongs to a new generation of products, the characteristics are much higher than those of PE 63. Its main purpose is the supply of cold water, in addition, if necessary, it can be used for sewerage and gasification.
   • Pipe PE 80 SDR 13.6 is used for installation and repair of water pipes and pipes of liquid chemicals, to which polyethylene is neutral.
   • PE 80 SDR 17 pipes are the best choice for low-rise construction, as they have sufficient strength for it and at the same time affordable cost.

1. The pipe PE 63 SDR 11 is made from various kinds of polymers. It can be used for plumbing in the water supply system, as sewer pipes, as well as a protective case for communication communications and power supply.

GOST requirements for PE pipes

Brief provisions

PE pipe GOST 18599 2001 is the main document regulating its use. In addition, GOST reflects the manufacture of polyethylene pressure pipes, as well as describes the technical standards and requirements that apply to the final product.This standard applies to polyethylene products transporting liquids (water, milk, juices, etc.) and gaseous substances at temperatures not exceeding 40 degrees.

Here are the main provisions of GOST:

1. Pressure PE pipes are used in places where there are no high temperatures, namely: General points:
   • at the device of pressure drinking and economic water supply systems;
   • for installation of low pressure gas pipelines;
   • for pressure and non-pressure sewerage;
   • when drilling wells and in wells;
   • for irrigation of farmland;
   • as dielectric protection for electric and low-current lines.

1. General points:
   • When supplying water through these products in the operating temperature range, there should be no emissions that are harmful to health.
   • During transportation, warehousing and storage, all required safety measures must be observed.

1. Appearance and dimensions of polyethylene pipes:
   • The polyethylene pipe GOST 22689 2 89, both pressure for water supply and used for sewerage, should not have visible defects.
   • Pipes are usually produced in black (with longitudinal blue stripes) or blue, gas pipes have longitudinal yellow stripes.
   • Polyethylene pipes are stored or delivered to the consumer in the form of straight sections up to 24 meters long or coils (bays).

PE pipes during long-term storage and transportation must be protected from clogging of the pipe cavity and mechanical damage.

1. Product marking:
   • It is applied to the surface of a polyethylene product for almost every meter.
   • The marking applied to the pipe indicates the name of the manufacturer, the purpose and its characteristics (brand, SDR, nominal diameter, etc.).

Storage and labeling of products

1. Consumer qualities of the product. As you know, polyethylene comes in several grades. The PE 80 pipe and the PE 100 pipe are considered the most popular and in demand in the construction of small-section water conduits: GOST, regulates the pressure that they must withstand. At the same time, PE 100 pipes with a large cross section make it possible to save on material, having a good SDR. Moreover, GOST prescribes the use of high-density polyethylene pipes to provide water to residential buildings.

1. Features of laying polyethylene pipes. When installing PE pipes into the soil, a number of mandatory measures must be observed:
   • under the product at the installation site there should not be foreign objects and large stones that can damage the pipeline;
   • directly under the pipeline there should be a well-compacted substrate of sand, slag or crushed stone;
   • the sewer pipe at the junction of the pipes should be slightly buried in the substrate.

Sewage pipe

For the installation of a gas pipeline, mainly PE 100 or PE 80 pipe brands with the appropriate marking are used. Everything is regulated by the relevant GOST. Also, the construction of the gas pipeline is regulated by another regulatory document for the application and design - SNIP Polyethylene pipes.

In general, polyethylene pipes can be considered universal, although they are used for their intended purpose as water, sewer and gas pipes. At the same time, depending on the situation, they are often used in ventilation, drainage system and other places.

Conclusion

The conclusions are obvious: polyethylene pipes are an excellent material for cold water systems, sewerage and gas supply, but they are very limitedly suitable for hot water and heating systems. You can find additional thematic materials by watching the video in this article. I look forward to your comments. Good luck, comrades!

In recent years, polyethylene pipes (PE) have been widely used, especially in the construction industry. PE pipes are used in the installation of gas pipelines, water pipelines, swimming pools are equipped with it, irrigation is automated, and are widely used in other industries.Polyethylene itself is a thermoplastic material, obtained by polymerization of a petroleum product. In this article, we will consider the characteristics of various types of products and understand what the marking “PE SDR pipe” means.

The equipment used for the production of such pipes is not cumbersome and particularly complex. and are made of various diameters in accordance with GOST, they are marked accordingly. Depending on the purpose, they differ in characteristics, each type of PE pipe has a corresponding brand.