The weak point of any pipeline is the connection. No exception and pipes made of low-density polyethylene (HDPE), which are used to supply water and natural gas. Their long and trouble-free operation will be ensured only by the correct connection of HDPE pipes, because the polyethylene itself is quite strong and durable.
Types and methods of docking
Engineering networks are made not only from polyethylene, but also from other materials that need to be connected to each other. In the production process, performers have to connect communications from the following materials:
HDPE pipelines - among themselves;
Connection of HDPE pipes with metal sections or fittings;
Making joints of polyethylene with highways made of other polymers - polypropylene and metal-plastic.
Depending on the laying conditions and the transported medium (water or gas), as well as taking into account the requirements building codes the way in which the pipes should be connected is selected:
1. Split flange.
2. Collapsible connection of HDPE pipes with compression fittings without the use of special tools.
3. One-piece. Produced by welding parts.
With small diameters in non-critical sections of water pipes, the pipes are connected by compression fittings. Docking by welding is suitable for any conveying media, line sizes and laying conditions. An exception is the connection of a HDPE pipe with steel pipe and sections of other polymers. Flanges are placed at the joints of large diameter water pipes (DN50 and more), gas pipelines, as well as when connected to stop valves.
According to the norms, the connection of HDPE pipes underground must be carried out by welding, and in places of collapsible joints it is necessary to arrange water wells.
Using compression fittings
Fittings are shaped products (elbows, tees, transitions) made of plastic or brass. With their help, joining pipelines is quite simple, since special tools and equipment are not required. On the other hand, the connection of HDPE pipes with fittings is not the most reliable; it cannot be used for underground laying of the main line, followed by backfilling in a trench. Although in practice, the owners of private houses bury such joints in the ground under their own responsibility.
Norms are not allowed to connect with compression fittings network engineering supplying natural gas.
Reliable connection of the HDPE pipe with the fitting is carried out by a nut pressing the collet and clamping ring, sealing is provided by a rubber sealing ring. Design shaped products from brass is slightly different: the clamping ring, where the collet presses, has a slot and a sharp notch on the inside. When tightening the nut, the notch cuts into the polyethylene, preventing the element from moving.
The technology for connecting HDPE pipes with fittings is as follows (step by step):
1. Cut off a section of the measured length, preferably with a pipe cutter for plastic pipes(as an option - like this). An ordinary hacksaw will leave burrs that will have to be removed with a sharp knife.
2. Disassemble the fitting, leaving the rubber rings inside.
3. Put the parts on the pipeline in the following order: nut, collet in the form of a cone, compression ring.
4. Insert the pipe into the hole until it stops, applying some force.
5. After sliding all the parts to the fitting, tighten and tighten the nut by hand.
The collapsible connection of the HDPE pipe with a tap or valve is carried out through a compression adapter, which has a counterpart in the form of a thread or a flange. Before tightening, the tap thread should be packed with flax, and a gasket should be installed between the flanges and tightened with bolts.
Connection by welding
Welded connection methods are the most reliable and durable, although they require equipment and strict adherence to technology. There are 2 welding methods:
1. Butt. The heating elements of the welding machine heat the ends to be joined to a certain temperature, which is why they are fused into a single monolithic section.
2. Electrofusion couplings with built-in heating coil.
When performing butt welding, it is necessary to fix the entire structure so that it does not move. It is equally important to withstand the warm-up time, so that the connection is reliable. Welding is made and flange connection HDPE pipes, for which a special sleeve is soldered to the end, and the flange is put on the pipeline in advance.
You can weld sections at different angles if the performer is sufficiently qualified. A more convenient way is to make a turn or tie-in using cast fittings designed for soldering.
The electrofusion sleeve is equipped with its own heating element in the form of a spiral. The connection of the HDPE pipe occurs as follows: the stripped ends of the pipelines are inserted into the coupling, wires from the apparatus designed for this type of work are connected to its contacts. The spirals heat up the plastic of the coupling until it fuses with the HDPE. The welding machine determines the heating time independently, guided by the barcode on the product nameplate.
Before welding sections of the water pipe, it is important to make sure that their material is the same. It is impossible to weld parts made of polyethylene of different grades, for example, PE80 and PE100. The joint will come out unreliable, despite the fact that it can pass the initial pressure test. For the same reason, it is unacceptable to weld a HDPE pipe with polypropylene and other polymers.
Docking with pipelines made of different materials
The transition from plastic to metal is one of the most common connections. It is impossible to perform it purely on welding for obvious reasons. Therefore, the connection of the HDPE pipe with a metal pipe is made in 2 ways:
Through a compression or molded threaded fitting;
On the bolts tightening the flanges.
The first option is for small diameter lines, where it is possible to cut external pipe threads with a manual lerk. Then an adapter or compression fitting is screwed onto it, attached to the polyethylene section. Pipelines with a diameter of DN50 and more are connected on flanges fixed various types welding.
Since it is unacceptable to connect HDPE pipes to a polypropylene water supply network by welding, only mating on threads or flanges remains. The rule is the same as when switching to metal: diameters up to 50 mm are connected through compression fittings, over 50 mm - using flanges.
Although metal-plastic pipelines are also made of polyethylene, they cannot be welded with HDPE products. The reason is different grades of polyethylene and aluminum reinforcement in the walls of the metal-layer. In addition, their maximum size (DN40) does not allow the use of flanges for joining. The connection of the HDPE pipe with the metal-plastic system is carried out only through a compression or welded fitting with an internal thread. The counterpart on the side of the metal-layer is also a fitting, but with an external thread. You can use 2 elements with external threads by connecting them with a coupling.
HDPE pipes are currently one of the most popular building materials. They are used at many stages of the construction of modern buildings - most often in the arrangement of sewer and water supply systems.
Due to the fact that the material is very easy to work with, it is flexible and versatile, it becomes possible to lay pipelines in the shortest possible time and at low cost. In this article, we will tell you how to connect polyethylene pipes for water supply, which are made using low pressure technology using fittings and welding.
Characteristics of polyethylene pipes
The main characteristics of this material can be considered its main advantages:
- The pipes are able to maintain their integrity at temperatures ranging from -60℃ to 90℃. Most Acceptable temperature regime for normal operation from 0℃ to 40℃.
- The production offers a wide range of polyethylene pipe sections - from 10 mm to 1600 mm. Thin pipes with a diameter of up to 160 mm are delivered to the points of sale rolled into coils or coils. The length of the pipe in such a bay reaches 500 m. If the HDPE diameters are more than 160 mm, then for sale they are cut into pieces of measured length according to GOST.
- Polyethylene pressure pipes are able to work effectively at a constant pressure up to 20 atmospheres.
- Polyethylene pipes are resistant to aggressive environments - acids, alkalis, alcohol-containing substances.
- Corrosion does not occur in such pipelines.
- Thanks to an absolutely smooth inner surface, any liquids are freely fed through the pipes without encountering obstacles.
In order to qualitatively connect PE pipes using fittings, a person does not need to have the special skills of a plumber or welder.
The entire list of works should be performed in the following sequence:
- make a markup where the cut is planned;
- cut the pipe at an angle of 90 degrees;
- trim the ends of the pipes so that the circle is perfectly even;
- insert the pipe into the fitting as far as possible, guided by the mark made in advance;
- at the end, tighten the nut without applying much force.
In this article, we figured out how to connect polyethylene water pipes. When choosing a connection method, it is very important to consider that the welded method is the most reliable, providing a durable connection, and compression fittings are much easier to maintain.
Pipes made from low pressure polyethylene (HDPE) are used for laying pressure and non-pressure pipelines. This material has a lot of advantages - flexibility, light weight, ease of installation, and more. In addition, practically any cold, up to 40 ° C, liquids and gaseous substances can be transported through such pipes.
In addition, in order to assemble a system from HDPE pipes, you do not need to have professional skills; even a person without any practical experience can handle it. Such pipelines are used both in production and in housing construction. In the article, we will consider how and by the method the connection occurs.
Methods for connecting HDPE pipes
Connection methods can be divided into two groups:
- one-piece;
- detachable.
Each of these groups, in turn, is divided into several subgroups:
One-piece:
- butt welding;
- electrofusion.
Detachable:
- With compression fittings.
- Clutch connection.
The choice of connection depends on the specific type of pipeline. For example, for pressure systems, butt welding or electrofusion is used, and for a non-pressure pipeline, simpler detachable ones are used.
Video: Assembly of HDPE connections and pipes
plug connection
In this way, the pipes are fixed in the event that dismantling may be necessary in the future or the use of welding is impossible, well, or impractical. Of course, such a fastening is not as reliable as welding, but still it has its advantages:
- Savings - no need to purchase additional equipment.
- Fast installation - the pipeline is assembled in almost a couple of hours.
- Detachable connections are carried out where welding is not available, for example, under water.
On a note!
The socket connection is mainly used for the installation of a gravity pipeline, for example, for sewerage. The connection with the help of fittings is similar in reliability to welding, so it can also be used for installing water pipes.
So, for a system in which the fluid is transported by gravity, one of the two simplest methods is used:
- In the socket - one end of the pipe is inserted into the socket of the previous one, and rubber or silicone seals are used for tightness.
- Fitting or flanged - the pipeline is connected using special parts.
Coupling
Couplings are made of polyethylene and are widely used in the assembly of pipelines. In addition to the fact that with their help you can quickly and without unnecessary trouble assemble pipes into a single whole, they have a number of other advantages:
- It turns out a reliable fastening with a long service life;
- Withstand temperature extremes and mechanical stress;
- Can be used for all types of pipelines.
- Affordable price.
Pipeline installation is carried out using couplings of various types:
- Compression - may have different thread: external or internal. Compression sleeves can be used even during assembly gas systems and plumbing.
- Connecting - connect elements of the same diameter.
- Reducing - indispensable for connecting elements of pipes of different diameters.
Fitting connection HDPE
This method is used when connecting pipes of small diameter: 20 - 35 mm. The assembly, like the previous method, is not something super complicated and is carried out as follows:
- Remove the nut from the fitting.
- The end part of the pipe is cleaned and chamfered, for this a special tool is used - a chamfer or, in its absence, with a sharp knife.
- At the edges, a mark is made on the depth of entry into the fitting, and they are lubricated with soap or silicone grease.
- The pipe is inserted into the fitting to the mark and the nut is tightened.
Permanent connection
When assembling pressure pipelines, it is necessary to make strong and reliable connections, so welding is used for them. There are two types of such welding:
- Butt.
- With the help of electric clutches.
It is not difficult to fulfill them, you can do it on your own, the main thing is to get essential tool and equipment.
Butt welding
This method is used to assemble systems from pipes with a diameter of 50 mm or more. This requires a soldering iron for welding HDPE. Such equipment is inexpensive, and is sold in almost any hardware store, so there should be no problems with the purchase. The process goes like this:
The ends of the pipes are fixed in the apparatus, after which a heated plate is brought to them. When the polyethylene begins to melt, the plate is removed and the pipes are connected to each other under slight pressure. After the seam has cooled, the clamps are removed and the pipes are removed.
Technological features of the method:
- Used to connect elements of the same diameter.
- Do not weld parts with a wall thickness of less than 5 mm.
- Welding is possible only at temperatures from +15° to +45° С.
Electrofusion welding
The pipeline assembled with the help of electric couplings is able to withstand pressure up to 16 atmospheres. But, for each joint, it is necessary to purchase special linings - electrofusion couplings. These parts are quite expensive, so if you plan to make a lot of connections, it is better to use butt welding.
Conditions that must be met before starting work:
- End cleaning;
- Rigid fixation of welded elements.
The process itself looks something like this:
- The ends of the pipes are cut to make a right angle and chamfered;
- The ends are cleaned;
- The pipes are fixed in the coupling and power is supplied to the terminals;
- The device is turned on, with the help of heating the surface inside the coupling is softened;
- The device and wires are turned off;
- The resulting joint is cooled.
Conclusion
When choosing a method for connecting HDPE pipes, consider the nuances and sequence of installation. Installation of almost any pipeline can be carried out independently, without resorting to the services of construction companies.
Video: KELL 3000 electrofusion welding machine for PE pipes
Today, pipes made of polymeric materials have significantly squeezed metal counterparts on the market. The big advantage of plastic pipes is that pipelines can be assembled with your own hands. To make connections, it does not require expensive equipment and extensive welding experience. Let's consider how the elements can be connected when assembling a pipeline from HDPE pipes, and also how HDPE pipes can be connected to metal pipes.
Pipes made of HDPE are allowed to be used for the assembly of pressure and gravity pipelines. The advantage of this material is its elasticity, low weight, ease of processing. The material is resistant to a wide variety of media; pipelines assembled from HDPE pipes can transport almost any liquids and gases at an operating temperature of the medium of 0-40 degrees.
The big advantage of low-pressure polyethylene pipes is that even without much practical experience, you can connect HDPE pipes with your own hands. Consider what types of connections exist and how to connect polyethylene pipes to each other and to parts made of other materials.
Connection methods
All methods of connecting elements that are used in the assembly of pipelines from HDPE pipes can be divided into two large categories. The first should include permanent connections, these include:
- Butt welding;
- Welding with electric couplings.
- Connection with compression fittings.
- Coupling connection.
- Flange connection.
Advice! When assembling gravity pipelines, a detachable type of connection is more often used, since it is simpler and faster. However, if fluid is to be moved under pressure, wedged connections should be used.
Plug connections
When assembling sewer pipelines, through which the liquid moves by gravity, you can use the most simple ways connections:
- Socket connections. In this case, one end of the pipe is carefully inserted into the socket of another element. To ensure the tightness of the connection, elastic cuffs made of rubber or silicone are used.
- Fitting connection. In this case, a special part is used to connect the two elements of the pipeline - a fitting.
Couplings
When assembling pipelines, couplings are widely used. These parts are made of polyethylene using the extrusion method. The use of couplings allows you to quickly and without the use of special equipment to connect the elements of the pipeline. The main advantages of using this method are:
- Reliability of fastening and long service life of pipelines.
- High degree of resistance to mechanical stress and temperature changes.
- Wide scope. This type of connection is used in the installation of pipelines for almost any purpose.
- Cheapness. Polyethylene sleeves are inexpensive.
For the assembly of pipelines, two types of couplings are used:
- Compression. This type of connecting elements is available with two types of thread - external and internal. The use of compression couplings is permitted when assembling gas and water supply systems.
- Connecting. The simplest version of the coupling allows you to connect elements with equal diameters.
- Reduction. This type of coupling is indispensable if it is necessary to connect pipeline elements of different sizes.
Compression fittings
It is easy to connect HDPE pipes with compression fittings. The work is done like this:
- Dismantle the compression fitting by unscrewing the cap nut.
- The end of the pipe is prepared for connection: it is cleaned of contaminants, at the end it is necessary to chamfer.
Advice! To carefully chamfer, it is convenient to use a beveler, and in its absence, a regular, well-sharpened construction knife.
- A mark is made on the pipe with a marker, marking the depth to which the pipe will enter the fitting.
- To facilitate the introduction of the pipe into the fitting, its end is lubricated with silicone grease or just liquid soap.
- After the pipe enters the fitting to the required depth (the introduction is carried out with force), all that remains is to screw the nut into place.
Advice! The nut must be tightened by hand, as it is easy to tighten it when using a tool.
Using this method, it is possible to connect polyethylene pipes with a metal-plastic part or polypropylene parts.
flanges
Often used and flange connection HDPE pipes. This option is chosen if it is necessary to connect HDPE pipes of large diameter - 110 mm or more, or to dock HDPE pipes with a steel main.
Also, with the help of flanges, HDPE pipes are connected to additional elements, such as taps, pumps, valves. The connection is detachable. The flange coupling consists of two elements:
- compression;
- mounting.
The compression component is used on the side of the connection with the polypropylene pipe. The second part is a conventional flange that is attached to a pipe made of metal or an attached element, for example, a pump nozzle.
Making permanent connections
In the construction of pressure pipelines, one-piece connections are often used. They are performed quite easily, so anyone can learn this operation.
Welding with an electric clutch
To implement this connection method, special couplings are used, into which electrospirals are inserted. Applying voltage to the coils heats up the element, resulting in welding of the elements to be joined with the walls of the coupling. Basic requirements for the process:
- Preliminary preparation of pipes - cleaning their ends.
- The need to ensure the immobility of the parts to be joined during the welding process.
The advantage of this method of welding can be recognized as the simplicity of its execution. The disadvantage is the high cost of connecting elements - electrofusion couplings. If you need to make a lot of connections, then it is more profitable to use contact welding.
Butt welding
As for polypropylene pipes, for HDPE parts, welding is often used. Such a connection is very reliable, it can be used for 50 mm pipes and more. Butt welding is an inexpensive connection option, unlike electrofusion. Indeed, in the latter case, the purchase of a special expensive fitting for each joint is required.
To perform this type of connection, you must have a special device - a soldering iron for polymer pipes. It is relatively inexpensive, so its purchase will not be too burdensome for the budget. Especially if you calculate how much money you can save on paying for the services of professional installers. Stages of work:
- Installation of the ends of the elements to be welded in the clamps of the welding machine and their centering.
- Heating elements to melting temperature.
- Removing the soldering iron from the welding area and connecting the heated ends of the elements to be joined.
- Seam cooling.
Connection of pipes made of metal and HDPE
If a partial repair of the pipeline is carried out, then it becomes necessary to connect the metal and plastic pipes. As a rule, two types of connections are used:
- Threaded. This method is used for pipes with a small diameter. For its implementation, it is necessary to purchase special fittings that have a thread for a metal pipe on one side and a smooth sleeve for a plastic pipe.
- Flanged. This type of connection is used for large pipes. To carry out the connection, the bushings for the flanges are welded to the ends of the pipes or cap flanges are used. This type of connection is often used where it is necessary to ensure the possibility of quick disassembly of the connection.
So, there are different options for connecting pipes made of HDPE. When planning to assemble the pipeline with your own hands, it is worth studying the method that is supposed to be used. To do this, you should read the instructions, watch the training video and practice on unnecessary pipe sections. Having mastered the connection, you can begin to assemble the pipeline.
Modern construction is not complete without the use of polyethylene pipes. These products are produced under low pressure and are used in the construction of non-pressure and pressure pipelines. To obtain such pipes, polyethylene is used, which has the grades PE 100 and PE 80. The material has a high elasticity, so it is very easy to work with it, and the laying of the pipeline is carried out in a short time and with less labor. Among the advantages of using such pipes are a long service life, no corrosion, resistance to negative factors, the possibility of trenchless laying of the pipeline, as well as a smooth surface, which ensures the unhindered passage of liquid.
Among other things, polyethylene pipes are lightweight and allow you to quickly mount systems of complex configuration. The material is resistant to temperature changes, has high ductility and mechanical strength. This product can be used in regions with high seismicity as the systems undergo ground movement.
Varieties of polyethylene pipe connections
If you are thinking about how to connect HDPE pipes, then you should first familiarize yourself with the methods of work. Depending on the purpose of the piping system, one of two methods can be used: detachable or one-piece. The first technology provides for the possibility of dismantling during operation. Whereas they do not provide for the possibility of subsequent disassembly. If you decide to use a detachable connection method, then you should use flanges that are made of steel. In this case, the connection is called flange.
Before connecting HDPE pipes using the one-piece method, you should acquire a welding machine, while the pipes will be welded end-to-end to each other, and the master will have to use superimposed couplings. Electrical heating elements are connected to the connection. Among other things, you can use which requires the use of compression fittings. This technology is used on pipelines of small diameter.
Why choose a detachable connection
If you are thinking about how to connect HDPE pipes, you should think about the methods of work. Recently, experts have increasingly advised using the split method, which has a number of advantages over the one-piece method. Firstly, detachable connection allows you to save money, secondly, it is more affordable, thirdly, the master will be able to increase the speed of the work. If we consider the first option, then you will not need to use special expensive equipment for welding polyethylene products or pay for the services of a specialist. Moreover, a detachable connection can be made even where the use of welding is not possible, such as underwater conditions. And finally, this method allows you to connect products at high speed.
Detachable connection features
Before connecting HDPE pipes with a detachable method, you should choose a method that can be socket or flange. In the first case, elastic seals should be used, which are most often used in the arrangement of free-flow sewer pipeline systems. As for the fitting, or in these two cases, fasteners are used.
If you are faced with the question of how to properly connect HDPE pipes, you should become more familiar with the features of using couplings. These parts are elements of polyethylene, and extrusion technology is used in their manufacture. This method eliminates the use of welding machines and does not involve the purchase of expensive equipment. As practice shows, couplings are cheap, and their use allows saving on construction.
Why else should you use clutches
Couplings are quite common when connecting polyethylene pipes for the reason that they have a long service life, which reaches several decades. As a result, it is possible to obtain the most reliable fastening, which is resistant to aggressive environments. The coupling has a wide area of use and can be used for arranging pipelines for almost any purpose.
Use of fittings
Novice craftsmen often wonder how to properly connect HDPE pipes with fittings. When carrying out such work, certain rules must be followed. They provide for the need to disassemble the compression fitting by unscrewing. The pipe must be cleaned of dirt, and a chamfer must be made at its end. To do this, you need to use a beveler, but in the absence of this tool, you can use a sharp knife. If you are faced with the task of how to connect pipes with HDPE fittings, then you need to make a mark on the product with a marker, which will determine the depth of entry into the fitting. Before introducing the part, the pipe must be moistened with liquid soap. Next, the introduction is carried out, and when performing this action, you will have to make an effort, since the rubber seal creates a certain resistance. At the final stage, the fitting nut is tightened. In this case, it is important not to overdo it so that the connection is not overtightened.
Connecting a plastic pipe to a metal
If it is necessary to lengthen an old metal pipeline, it often becomes necessary to connect it to a polyethylene product. To do this, prepare two sliding keys, tow or Teflon tape. You will need an adapter with one end in the form of a metal product, and the other end should be in the form of a socket for a movable connection of a plastic pipe. If you are faced with the question of how to connect a HDPE pipe to a metal one, then at the first stage it is necessary to unscrew the pipeline coupling in the place where the connection is planned.
One needs to hold the coupling, and the other - the pipe. If it is not possible to unscrew the connection, an oil with increased penetration can be used. The next step is to use the plastic pipe tool and seal threaded connection. This will prevent leakage later on. On the pipe, clockwise, several turns of the tape should be made, closing the thread. If you are thinking about how to connect a HDPE pipe to a steel pipe, then at the final stage you need to install and tighten the adapter. The connection is tightened until you feel resistance. It is not recommended to screw fittings with PVC female threads onto metal, as these two materials have different thermal expansion.
Connection of a polyethylene pipe with a faucet
The most popular method of joining a polyethylene pipe with a ball valve is butt welding. It should be carried out using a special installation in which both edges of the workpieces to be welded are fastened. The surface is cleaned of dirt and degreased. The heating element will increase the temperature of the edge of the polyethylene pipe to a viscous state, while the mechanism of the apparatus will help strengthen the elements to each other. After it was possible to connect the HDPE pipe to the faucet, it is necessary to leave the elements to cool completely. If the work is carried out correctly, the welded joint will look like an even seam of the same height around the entire circumference.