How to connect HDPE pipes: types of connections (fittings, couplings, welding) and their features. Methods for connecting HDPE pipes and the necessary fittings for this Coupling for connecting HDPE pipes

There are often cases when, when making a pipeline, you have to face the problem of connecting pipes from different materials. In this article we will look at how to connect a HDPE pipe to a polypropylene pipe.

Types of polypropylene pipe connections

To connect polypropylene pipes with other types of pipes, there are special threaded fittings. One side of the fitting is welded to a polypropylene pipe, and the second side, with a thread, is connected to a thread of the same diameter on another pipe. The thread on the fitting can be internal or external. There are also combination couplings. We'll look at them later.

Another type of polypropylene pipe connection is based on a flange connection. This type of connection is used in large pipes. To attach the flange, a sleeve is welded onto the polypropylene pipe, onto which the flange is then placed. Another mounting option is carried out using slip-on flanges. Their device resembles a compression clutch. The flange connection is attached to the edges of a pipe of the same diameter and tightened with union nuts.

Types of HDPE pipe connections

The HDPE pipe has approximately the same connection devices. The most common is the collet connection. To connect pipes, a coupling is used, in which there is a collet on one side and a thread on the other. To fasten the coupling, the clamping nut is unscrewed and put on the HDPE pipe. The collet is inserted inside the pipe, the clamping nut is put on and tightened tightly.

Note! The clamping nut should not be pressed too hard, otherwise it may burst or the collet will crush the edge of the pipe.

After connecting the collet to the other end of the threaded coupling, you can screw another threaded pipe of the same diameter.

The flange connection of HDPE pipes is made in the same way as the connection described above. A sleeve is welded to the edge of the HDPE pipe, onto which the flange is attached. And the same device with a slip-on flange, where the connection is installed on the edges of the pipes and pressed with union nuts.

Connection of two pipes

Using the pipe accessories discussed above, you can easily connect a HDPE pipe to a polypropylene pipe.

• In the first case, you attach a threaded collet to the HDPE pipe, and a combined threaded coupling to the propylene pipe. Wrap FUM tape around the threads to seal and twist them.
• In the second case, you connect two pipes with flanges. Insert a rubber gasket between the flanges to seal and tighten them with bolts.

Combination couplings

If everything is clear with the collet connection for HDPE pipes, then the combined couplings (fittings) for polypropylene pipes are varied. Let's take a quick look at them:

1. A coupling with an internal thread is used to connect a pipeline with another type of pipe or devices that have an external thread. It consists of a polypropylene blank with a metal coupling pressed inside, on which a thread is cut inside.
2. A coupling with external thread performs the same functions as discussed above. The only difference is that a metal sleeve with external thread is pressed into the polypropylene blank.
3. A coupling with a turnkey internal thread consists of a polypropylene blank into which a metal sleeve is pressed, protruding beyond the edge of the polypropylene with metal edges. The edges are designed for an open-end wrench. There is a thread cut inside the edge. It is convenient to screw such a sleeve onto another thread with a wrench. There are also models of couplings with turnkey edges.
4. A coupling with an external thread on a turnkey basis is the same as the coupling described in paragraph 3, only it has an external thread.
5. A split coupling with internal thread consists of two metal parts for an open-end wrench. Moreover, one metal part is connected to a polypropylene blank. Such couplings are installed in places where it is necessary to disconnect the pipeline or remove devices. Another name for this coupling is American. It unwinds with two keys.
6. The detachable coupling with external thread is similar to the previous American type. The only difference is the external thread instead of the internal thread.
7. The coupling with a union nut consists of a polypropylene blank into which a fitting with a turnkey union nut is pressed. It is installed in the same way as the American one: in the places where the pipeline needs to be connected.

With such combined couplings, soldered to a polypropylene pipe, it is easy to connect to a HDPE pipe that has a collet with a similar thread.

Soldering PP fittings

Before connecting two pipes with fittings, they must be secured to the pipe. We discussed the fastening of the collet to the HDPE pipe above. Now let's look at the connection of a polypropylene pipe with a fitting.

Polypropylene fittings are connected to the pipe by soldering with a special soldering iron. The soldering iron with nozzles is placed on a stand and heated to 260 o C. The edge of the pipe is cleaned of dirt, chamfered and degreased along with the inside of the coupling. The pipe and fitting are simultaneously put on the heated nozzles. After heating, the pipe is inserted straight into the fitting without turning and allowed to cool. This completes the soldering process.

After reading this article, you can easily connect a polypropylene pipe with a HDPE pipe. All possible options for the correct connection are presented here. There are enthusiasts who claim on construction forums that these two pipes can be soldered with a coupling at different temperatures. But the thing is that polypropylene and HDPE consist of different materials, they have different melting temperatures, so such a seam can burst or even melt. If you decide to save money and experiment, you do so at your own peril and risk.

Video

One example of how to replace a section of an iron pipe with a polypropylene one. Using the same principle, you can connect plastic pipes from various materials:

Currently, more expensive and heavier pipes made of metals and alloys are being replaced by products made of various types of polymers - polypropylene, polyethylene, etc. Such pipes, although they cannot yet completely replace metal ones, are actively used in almost all areas of industry and in urban communications. Products made from low-density polyethylene (HDPE) are especially popular; Below we will talk about its application and how to connect HDPE pipes to each other and to products made from other materials.

Application areas of low-density polyethylene pipes

Due to the lightness, strength and variety of ways to connect HDPE pipes, they are used in many areas, for example:

• arrangement of water supply systems;
• installation of sewer circuits;
• as boxes protecting power cables and wires when creating electrical networks;
• as water-repellent shells when laying heating mains;
• to prevent damage to communication system cables;
• when digging artesian wells;
• as molds for casting;
• for supplying water to vegetable gardens, greenhouses, etc.

Methods for connecting HDPE pipes

If possible, both connecting HDPE pipes and disconnecting them back together, fastening methods are divided into:

• detachable– additional parts (reinforcement) are used to fix the elements; the structure can be assembled and disassembled many times, individual components can be replaced;
• one-piece– welding, gluing, etc. are used to fasten elements; It is impossible to disassemble the finished circuit without damaging the components.

Advantages of the first method:

• efficiency– detachable connection allows you not to buy extra parts if you need to replace only one; in addition, there is no need to purchase specific devices for welding or soldering pipes;
• ease of operation– connecting HDPE pipes with fittings is quite easy and does not require excessive physical effort; in addition, it is possible in conditions that do not allow the use of welding machines, for example, in the thickness of liquid. At the same time, welded fittings for HDPE pipes will last for many years;
• rapidity– with the necessary skill and quality of consumables and fittings, the work can be completed in a short time

Design of detachable pipe connection

This type of fastening of parts can be done in two ways:

1. Into the bell. In this case, the narrower end of one pipe is inserted into the extension - the socket - of the other and sealed using special materials. In most cases, it is used in the construction of non-pressure (gravity) sewerage.
2. Fitting and flange connection of HDPE pipes - as the name suggests, to ensure this method of fixation, special devices are used: flanges, couplings for HDPE pipes and others.

Couplings for plastic pipes

Like the products themselves, couplings for HDPE pipes are made of polyethylene. When producing products, an extrusion technique is used.

Advantages of using couplings:

• durability - the product can last for decades;
• reliability of pipe fixation and tightness;
• resistance to temperature changes and external mechanical loads;
• chemical neutrality;
• versatility of use;
• the ability to both connect a HDPE pipe with a polypropylene pipe, and to fasten pipes made of the same type of plastic.

Types of couplings:

1. Compression. Both external and internal threads are applied to it. The fitting is usually used when installing heating and gas supply circuits. It is this type of coupling that solves the problem of how to connect a HDPE pipe to a metal one: for this, a metal thread is applied at one end of the product. Read also: "".
2. Simple coupling. Used to connect homogeneous plastic products having the same cross-section.
3. Reduction. It is used in cases where it is necessary to fasten pipes of different diameters. As you might guess, the input diameters of such a coupling are also different.

Compression connectors

Procedure for working with compression fittings:

1. The product is disassembled by loosening the union nut.
2. The surface of the pipe section is cleaned of dust, dirt, grease, etc.
3. Chamfers are made at the end of the pipes using a special device - a chamfer - or a simple sharp knife. The second method is less accurate and poses a certain danger to the health of the worker.
4. On the surface of the pipe, mark with a marker how far it will go inside the fitting.
5. Before insertion, the end of the pipe is treated with liquid soap for better sliding.
6. The pipe (with force) is inserted into the fitting, carefully, avoiding damage, overcoming the resistance of the rubber seal.
7. Check the accuracy of the connection and tighten the union nut without applying excessive force to avoid damage to the fitting. Read also: "".

Permanent connection of polymer pipes

Types of pipe welding:

• butt;
• using electric couplings.

When using the first method, a welding machine for pipes is required, which heats their ends to the melting temperature. After this, the ends of the products are pressed against each other until cooled and a homogeneous mass is formed.

• pipes must be round, without deformation;
• the seam must run across the entire thickness of the wall of the product;
• elements cannot be shifted by more than 1/10 of the wall thickness;
• the height of the welding bead for products with a wall thickness of no more than 5 mm is 2.5 mm or less, for thick-walled pipes (6-20 mm) - more than 5 mm.

When welding using an electric coupling, special polyethylene couplings with built-in electric spirals are put on the ends of the pipes. After voltage is applied, the ends of the pipes are heated, melted and welded to the coupling. Before carrying out the operation, the surface of the pipes must be cleaned, and during heating and cooling, the products must not be allowed to move relative to their original position.

The connection of HDPE pipes has many variations, is quite simple in execution and, with proper quality of work, is durable and reliable.

Modern water pipes are rarely made of metal. It has worthy competitors - polymers, which are gradually replacing it in many areas. One such material is low-density polyethylene. Pipes for pressure pipelines, that is, for water pipelines and even gas pipelines, are made from this material. This type of material is becoming increasingly popular, since connecting polyethylene pipes is easy to do with your own hands. You just need to follow very simple rules.

Advantages and features of application

Polyethylene pipes are made from low-density polyethylene. This material is abbreviated as HDPE. It is characterized by increased strength and elasticity, and has good performance properties:

• chemically neutral, can be used for transporting food products;
• smooth walls prevent the formation of plaque inside;
• not subject to corrosion;
• small coefficient of thermal expansion - about 3% at maximum heating (up to +70°C);
• They react normally to the freezing of water inside, due to elasticity they increase in diameter, and after thawing they return to their original dimensions.

One point to remember! If you need pipes that are resistant to freezing (for example, for), when choosing, look at the description or technical specifications. Not all types of copolymers used for pipe production tolerate freezing well. So be careful.

The main disadvantage of polyethylene pipes is the restrictions on the temperature of the transported medium: it should not be higher than +40°C, that is, only cold water supply can be made from HDPE; they cannot be used for hot water and, especially, heating.

Another point: polyethylene does not tolerate UV radiation well. When constantly exposed to the sun, the material loses its elasticity and, after some time, breaks (some manufacturers make HDPE pipes that are UV-resistant, but they are more expensive). Therefore, open laying of water supply pipes from plastic pipes is very undesirable. But it is very possible to run a pipe in a trench from a well or borehole to the house, and distribute cold water throughout the house. This is a fairly economical and convenient solution, since the installation and connection of polyethylene pipes is not very difficult. If we are talking about a detachable connection, then it does not require any equipment. All you need is fittings and hands.

Which polyethylene pipes are better?

For the production of water pipes, two grades of polyethylene are used - PE 80 and PE 100. The hundredth polyethylene is more dense and durable than the eightieth. For water supply systems in a private home, the strength of PE 80 is more than enough - they can withstand pressure up to 8 atm. If you like a large margin of safety, you can take them from PE100. They work normally at 10 atm.

What you should pay attention to is the country in which the product was produced. The leaders in quality are European manufacturers. High precision execution guarantees high system reliability. Average quality and prices are from Turkish companies, in the cheaper price segment are Chinese manufacturers. Their quality, as usual, is also much lower. It’s difficult to give advice here; everyone chooses at their own discretion (or what is available in the region).

Types of HDPE pipe connections

There are several types of connections for polyethylene pipes:

• detachable (on fittings or couplings);
• one-piece - by welding:
  • using a special welding machine;
  • electric couplings - a heater is built into such couplings; when electric current is applied to it, the polyethylene heats up and fuses.

They mainly weld large-diameter pipes, which are used to create main pipelines. Pipes of small diameters - up to 110 mm, used in private construction, are mostly connected using fittings. Couplings are used more often during repair work, since their installation takes longer.

Fittings for polyethylene pipes are shaped parts (tees, crosses, angles, adapters, couplings) with the help of which the required system configuration is created. Since independent connection of polyethylene pipes is carried out more often with the help of fittings, let’s talk about them in more detail.

Assembly on compression (crimp) fittings

An entire system is installed on one or two sides of the fitting (sometimes on three) to ensure the connection. The fitting itself consists of:

How reliable is the connection?

Despite the apparent unreliability, the connection of polyethylene pipes with compression fittings is reliable. Properly made, it can withstand operating pressures of up to 10 atm and higher (if these are products from a normal manufacturer). Watch the video for proof.

This system is good because it is easy to install yourself. You probably already appreciated this from the video. Simply insert the pipe and tighten the thread.

Summer residents, in addition to the opportunity to do everything with their own lessons, like it because, if necessary, everything can be disassembled, hidden for the winter, and put back together again in the spring. This is in case the wiring is made for irrigation. The dismountable system is also good because you can always tighten the undercut fitting or replace it with a new one. The disadvantage is that the fittings are bulky and internal wiring in a house or apartment is rarely made from them - the appearance is not the most pleasant. But for the water supply section it is difficult to find better material.

Assembly order

The pipe is cut strictly at 90°. The cut should be smooth, without burrs. There should also be no dirt, oil or other contaminants present. Before assembly, the sections of the joined sections are chamfered. This is necessary so that the sharp edge of the polyethylene does not damage the rubber sealing ring.

During installation, the connection of polyethylene pipes on the compression fittings is tightened by hand

The spare parts are put on the prepared pipe in this order: the crimp nut is tightened, then the collet, then the thrust ring. We install the rubber gasket into the fitting body. Now we connect the body and the pipe with the parts put on it, applying force - you need to insert it all the way. We pull all the spare parts to the body and connect them using a crimp nut. Tighten the resulting connection of polyethylene pipes with force by hand. For reliability, you can tighten it with a special mounting key. It is not advisable to use other tools for tightening: the plastic may be damaged.

Saddles and their scope

In addition to fittings, there is another interesting device that allows you to make branches from a ready-made pipeline. These saddles are specially designed couplings. This coupling has one or more threaded holes. A tap is usually installed in them, and a new branch of the water supply is connected to it.

The sedeks are put on the pipe and secured with screws. After that, a hole is drilled in the pipe surface with a drill and a thick drill in the branch. When it is ready, a crane is installed and the branch is assembled further. This is how the system is improved with minimal effort and cost.

Flange connections and transition to metal

System elements that have a flange rather than a threaded connection can be installed in the water supply system. Usually these are taps or other shut-off or control valves. To connect to such elements there is a special fitting for HDPE. On one side there is a standard compression version, on the other there is a flange version. Installation is standard - using a crimp nut on one side, gaskets and bolts on the flange side.

When installing a water supply system from polyethylene pipes, questions may also arise about the connection between polyethylene and metal. For these cases, fittings are used, on one side of which there is a thread. It can be external or internal, depending on the type of device or transition being installed. Such fittings are either straight or in the form of a 90° angle.

The installation is standard - a thread (with careful winding) on ​​one side and a compression nut on the other.

The abbreviation HDPE stands for low-density polyethylene. The production process is based on the use of a screw extruder. The result is a flexible, lightweight pipe that is resistant to corrosion. The scope of application is wide: gas pipeline, water supply, sewerage. Various cables are also laid and used as casing sleeves when constructing wells. In this material we will look at how to properly connect HDPE pipes.

Methods for connecting HDPE pipes

If you ask a specialist a question about how to connect a HDPE pipe, he will probably smile. The docking process is so simple that anyone can do it. There are two types of connections for vinyl pipes: detachable and permanent. The first option occurs using fittings and can be done at home. The second is based on soldering plastic and is most often used in production.

Permanent joining of HDPE pipes

Permanent connections are usually used during the construction of pressure pipelines and when it is necessary to lay a solid pipeline without a detachable fitting. There are two types of connecting HDPE pipes using welding.

Welding with electric couplings

Connecting two pipeline elements of equal diameter using electrofusion welding is considered the simplest method of permanent joining. To perform the work you need a special fitting - a coupling. A heating element - a spiral - is mounted inside this part. After applying voltage, the heater melts the inner wall and surface of the HDPE pipe. The result is reliable welding of two workpieces of the same diameter to each other.

The soldering process consists of the following steps:

• two ends of pipes of the same diameter are cleaned of dirt and degreased;
• the workpieces are inserted into a coupling of the appropriate diameter, after which the unit being connected is secured.

There are two terminals on the coupling. Wires from the power source are connected to them. After applying current, the plastic melts, resulting in a strong connection. You can use the welded workpiece after the joint has completely cooled.

Docking by contact welding

The second method of permanent connection is based on the use of special equipment - a soldering iron. Contact welding is used to connect elements of a plastic pipeline with a diameter of 50 mm or more. The advantage of this method is that it is cheap. If you need to make a lot of joints when installing a highway, it is more profitable to buy a soldering iron. This tool is affordable and may be useful in the future for welding various pipes and flexible hoses.

The connection is made by contact welding according to the following principle:

• two workpieces of the same diameter are fixed in the clamps of the machine;
• after centering the pipes, begin heating their ends until the plastic begins to melt;
• the soldering iron is removed, and the ends of the molten workpieces are tightly connected using a clamping machine.

After cooling, a monolithic seam is obtained, which is not inferior in strength to the wall of a plastic pipe.

Detachable joining of HDPE pipes

At home, it is enough for the owner to know how to connect HDPE pipes with fittings, because a detachable connection is much more convenient than soldering. By the way, the simplest joining method is called “into the socket”. It is applicable when laying sewers made of low-density polyethylene and is based on inserting one end of a polypropylene pipe into the socket of a second piece. Silicone or rubber cuffs are used to seal the joint.

Connecting pipes with fittings

Before we tell you how to properly connect HDPE pipes for water supply with fittings, let’s look at what this part is. Detachable fittings are designed to connect pipeline elements with a diameter of up to 50 mm. The manufacturer produces elbows, tees, crosses and straight adapters. There are two types of PVC fittings:

• compression - for joining workpieces of the same diameter;
• reduction - for joining workpieces of different diameters.

How are HDPE pipes connected to plastic fittings? The design and principle of using the clamps are the same. The fitting consists of a body into which two ends of the workpiece are inserted. The clamping nut-cap is used to tighten the connection, screwing it onto the fitting body along the thread. The O-ring ensures a tight seal. Knowing how to connect HDPE pipes with fittings, you can join pipes made from other materials, for example, polypropylene or metal-plastic.

Connecting HDPE pipes with flanges

For joining a plastic pipeline with pumping equipment, metal shut-off valves or connecting a large diameter pipeline, use. The detachable assembly consists of two parts:

• the compression flange is designed for fixation on the HDPE pipe;
• The mounting flange is used to clamp the first part, fixing it with bolts to a similar element on the shut-off valve or pump.

The principle of fixing the flange on a polyethylene pipe is the same as in the case of a compression coupling.

*To connect HDPE 160 mm without welding, use flanges.

As you can see, you can even connect HDPE water pipes yourself at home without special knowledge. You just need to choose the right docking method, taking into account the stated advantages and disadvantages.

Size chart for HDPE gas pipes

Diameter (mm)	Thickness (mm)	Pressure (atm.)	Quantity per bay (meters)	Cost per linear meter
20	2	6	100 or 200	20
26	2	5	100 or 200	23
26	2,4	5	100 or 200	30
33	2,4	5	100 or 200	40
33		6	100 or 200	45
41	3	5	100 or 200	55
41	3,8	6	100 or 200	65
51	3,8	5	100 or 200	80
51	4,6	6	100 or 200	95
63	4,6	5	100 or 200	115
63	5,8	6	100 or 200	140

Installation features

The assembly of almost any system using the components under consideration involves connecting parts resembling couplings. The pipe and fitting are fixed with a socket-type or butt-type soldering joint. The connection is possible without soldering, with the inclusion of compression parts in the design, but their cost is higher when compared with parts for soldering.

The most expensive, but also quite practical connecting parts are electric welded couplings. Special heating elements are installed in the end parts of such products, which solder individual parts of the structure.

Due to the certain novelty of HDPE, quite often there is a need to combine polyethylene parts with metal parts that have not yet worn out. In the process of the manipulations under consideration, a chamfer is used, consisting of two halves: the first of them is put on the metal part and fixed there, the second, respectively, on the plastic part.

The individual parts are bolted together, and an O-ring is placed between the two halves, sometimes for reliability. This is the method used to connect HDPE pipes to metal pipes.

In cases where we are talking about a permanent connection, we can say that the strength of the connecting part is inferior in a similar parameter to the main structure by no more than 10%. But those discussed above are of the detachable type.

The strength is not inferior to soldering, but it has one significant advantage: if during the assembly process or after its completion there is a need to change the configuration of the mounted system, then dismantling will take much less time than in the case of one-piece systems.

Options for plastic compression fittings.

When can butt welding be used?

The method under consideration is usually used in cases where the wall thickness exceeds 5 mm. Preparation of material for the start of work is organized within the framework of the following scheme:

• Align the end of the product relative to the axis of the pipe;
• Remove the chamfer using a sharp knife or (this option is more preferable) a special unit - a chamfer remover;
• Total cleaning and degreasing of the end sections.

It is also necessary to ensure that the main and auxiliary areas that will be in contact with each other are aligned with each other. In simple terms, coaxiality involves installing one part into another in such a way that the pipe in the pipe fits tightly and fits 3/4 of the depth of the coupling, these are the requirements of the technology;

After this (if we are talking about ) put both soldered parts on the “iron”, let it heat up for the time specified in the instructions for the device and connect, checking the tightness after cooling.

Is it possible to perform high-quality installation without involving professionals?

The answer to this question is simple and unambiguous - and/or made from low-density polyethylene is quite feasible independently, at home. If, then the right decision would be to take care of the availability of equipment in advance; its list is as follows:

• A sharp tool for cutting components in accordance with a pre-designed pattern;
• Tape measure and marker for marking;
• appropriate diameter;
• Bevel remover.

Socket and flange connections require only the fittings themselves, as well as O-rings and a wrench of the appropriate size.

Often, HDPE plumbing is used for the installation of drainage (sewer) channels. As in the cases discussed earlier, combining into a single structure will not cause serious trouble, provided that the work is conscientious. In a sewerage situation, both (less often) and non-pressure (in most cases) components can be used.

Additionally, HDPE plumbing fixtures are used for rainwater systems.

Along with HDPE, it is also used for laying electrical wiring. and direct HDPE wire protection elements are made from non-flammable raw materials, which in itself eliminates the possibility of fire.

Contrary to the widespread, erroneous belief, the use of corrugated HDPE components does not in any way limit the maintainability of the structure; moreover, it significantly increases it.

The fact is that without the use of a “cover” made of the polymer in question, installation of internal wiring usually takes place inside the walls. What's wrong with this option?

Firstly, it is a fire hazard, which in itself is a weighty argument, and secondly, the need to repair such wiring will necessarily be associated with the need to dismantle the wall cladding or any other surface under which the wire passes. It is logical that such actions will entail the expenditure of money and time.

But the use of corrugation allows you to simply disconnect the cords of interest and carefully remove them using a probe (a wire used to thread and then remove the cord), and then replace them using the same wire.

The use of the corrugated structures under consideration makes it possible to protect the object not only from fire, but also to protect the wiring itself from unwanted climatic and various force (dynamic and static) influences, even regardless of the type of installation in question: underground, ceiling, wall or hidden.

Considering all the advantages of HDPE materials that were described above, it is not at all strange that the materials in question enjoy unlimited popularity among domestic consumers.

Video tutorial on how to make the transition from a metal-plastic pipe to a polypropylene pipe: