When conducting a major overhaul in a room, it may be necessary to partially replace the sewage and water pipes. Of course, it is desirable to replace the entire system, but because of the complexity of the installation process and the high cost of the material, often the owners of apartments and office spaces get by with "little blood" and simply connect the new plastic and old metal pipes.

Knowledge and skills how to connect a plastic and metal pipe, will be needed and with the total replacement of pipes in your own apartment when the pipeline of a neighbor made of metal on the riser comes into contact with your already updated.

Twenty years ago, nobody heard about such a problem - plastic was not widely available at that time, and, therefore, any repairs and replacement and assembly works for the sewerage, water supply and drainage were solved in one method - with using a welding machine.

Today, consumers are increasingly inclined to buy modern materials that are environmentally friendly, highly wear-resistant and easy to install. That's why we have to combine elements of different texture and design. The strength and longevity of the communications depends on how well the joints and seams are adequately sealed.

Features of the use of metal and polymer pipes

Main characteristics

The properties of metal pipes initially depend on the material from which they are produced:

• steel - easily amenable to corrosion, on their inner surface of the elements, accumulations of impurities and dirt can form;
• galvanized steel has proven itself with respect to resistance to corrosion processes, but experts note the complex installation process;
• stainless steel is still the most expensive metal, difficult to handle, but serving for many years;
• cast iron, used for laying the pipeline in Soviet times, is still considered to be a fragile material that easily collapses as a result of strikes. The analogue of cast iron is the VCHSH - a relative novelty in the market of plumbing devices.

In turn, polymer components are also divided into several main types:

• PVC devices are used for bookmarking autonomous sewerage, this is due to the fact that they do not withstand the circulation of a large flow of water;
• polyethylene are suitable both for sewage lines and for water supply;
• often purchased material - polypropylene PPR devices - easy to install and do not require special care.

When is it necessary to combine plastic and metal?

In addition to repairing communications, situations may arise that require different parts of the engineering laying of water supply and sewage systems with materials that have different parameters.

For example, it is necessary to ensure the protection of a polyethylene structure, which is responsible for supplying liquid to a private house, by means of equipment at the top of the reinforced concrete frame. Experts give advice on a less costly solution to the issue - by replacing the pipe section with galvanized material. In this case it is important to achieve complete tightness of the joints of the components.

Step-by-step instruction for connecting plastic and metal pipes

Connection types

To date, there are two types of plastic and metal joints, successfully used in plumbing works by masters and beginners:

1. Threaded connection. In order to fix metal and plastic communications that are moderate in size (diameter no more than 40 mm) to each other, it is preferable to use fittings intended for this purpose equipped on one side with a thread and on the other side with a coupling. The thread fixes the metal element. To fix it was dense and reliable, put the flax fiber pre-wetted in linseed oil.
2. Flanged connection provides for operation with a larger pipeline, because you can not turn the 700 mm threads by yourself.

Application of fittings with thread

It should immediately be noted that the thread can be hidden both inside the fitting and placed outside. The sequence of connection of components is approximately the following:

1. Get rid of the coupling of steel communications in the area where you want to combine them with plastic, or cut a section of the old pipe from metal, at the end apply salt oil or oil and make your own hands carving with a special device - threading.
2. Walking on the carving with a rough rag, fix a piece of pakli or a ribbon tape on top, cover the surface with silicone. Wrap the threads 1-2 turns, make sure that the edges of the tape with the clamp go along the thread.
3. Wrap the pressfitting without using a key, which can lead to cracking of the product. If a leak is detected while opening the tap, fix it by an additional scrolling of the fitting.

The convenience of the fitting design is that the part simplifies the process of connecting the pipes to bends and turns. It is interesting that if you want the shape of the fitting can be changed - warm the device with a construction hair dryer, setting the heating temperature within 140 degrees. If the fitting is made of polypropylene, although it does not have flammability, when heated to over 350 degrees the material will burn.

An interesting property of polypropylene pipes - it has been experimentally observed that under the influence of communication temperatures, they tend to narrow and on the contrary expand. Therefore, it is desirable to further insulate such a pipe with tubular insulation, especially at the branching points of the system.

Connection with flanges

As for the flanges, they can be wraps made from metal sheet, or welded to the edges of the pipeline, but in this case also do not do without bushings. Flanges allow you to combine the following elements:

• polyethylene pipes with pumps, pipes and valves made of steel;
• large-sized parts.

Also, the flanges simplify the process of dismantling, if necessary, to begin cleaning the inner surface of the elements.

To connect plastic and metal pipes, you must follow the step-by-step instructions:

1. Apply the marking on the pipeline and follow the straight line, cut off the pipe.
2. Place a metal flange on the product, it is better to purchase a model of a free sample.
3. To seal, place the rubber gasket, taking into account that the inlet should not exceed the pipe boundaries by more than 1 cm.
4. Slide the flange to the spacer bar and fix it to the other flange using bolts ...

How to connect a plastic pipe to a metal pipe: expert advice ...

In the process of building new or upgrading existing pipelines, there is often a need for docking modern plastic pipes with traditional metal products. Despite the fundamental difference between these materials in terms of chemical composition and physical and technical characteristics, several variants of connection of parts engineering communications. Correctly chosen method of joining polymeric and metal pipes intended for installation of domestic and industrial pipelines will allow avoiding leaks and emergency situations.

When is a similar connection required?

Modern repairs often require the joining of plastic and metal pipes

The need to connect polymer and metal pipes can arise both during construction and during the modernization or repair of existing pipelines. Let's consider the most typical cases when such a docking is necessary:

• In the process of construction, cases of inconsistency of actions of various contractors are frequent, therefore cases of installation of communication elements from various materials are possible.
• In most cases, plastic pipes are connected to the metal terminals of the equipment.
• During partial replacement of emergency communications.
• If it is necessary to connect the pipeline to equipment that has a temperature critical for plastic products.
• For laying sections of highways subject to increased thermal and mechanical loads.

All these cases differ among themselves for a number of factors, so the methods of the most reliable connection depend on the type and purpose of the pipeline.

Different kinds

In modern construction, several types of plastic pipes are used. These products are made of polyethylene, polypropylene, metal-plastic, polyvinyl chloride and their derivatives. Any of them can be connected to the metal element of the system in two ways: by means of a threaded or flanged connection.

Threaded connection with fitting

This type of connection is used for medium or small diameter pipes (from ¼ to 1¾ ²) and is carried out by means of special fitting adapters. On one side of these parts is a coupling of the correct size for connection plastic pipe, and on the other - a threaded part for docking with a metal pipeline.

The tightness of joints is ensured both by the standard packing of the fittings, and by sealing the joints with a FUM tape or a paste with applied plumbing paste.

Manufacturers of fittings take into account a variety of connection options. The components are produced in the form of corners, tees, etc. In this case, they differ in size and thread type (internal or external).

Flange for polyethylene pipe

For large diameter pipes (from 2 "or more), use a connection using flanges. On the side of the plastic pipes, flanges of a free type are used with the support of the collars. Medium and heavy pipes of polymers up to 150 mm in diameter and light plastic pipes up to 300 mm in diameter require fastening with support on free flaps. When connecting pipelines with a diameter of more than 200 mm or to increase the strength of the joint, the pipes are connected by free-type flanges with support on conical or straight beads with transition to a cone.

Often used and wedge joints with shaped flanges. They are suitable for pipes of any diameter.

A flange of a free type is welded to the counterpart of the metal tube. Between each other the pipes are connected by means of bolts, and the rubber or paronit gasket provides tightness of the joint.

At low pressure in the system, the joint is sealed by special cuffs, corrugations or seals. For example, in this way docking is performed sewer pipes   from PVC to cast-iron risers.

Flange connection 'metal-plastic'

Installation work

If necessary, to connect the plastic pipe to the metal, first determine the type of connection (threaded or flanged), and after the preparation of materials and tools, they begin to install.

Mounting technology with fittings

The connection of polypropylene or metal-plastic pipes with metal elements of water or heating systems is easiest to perform with the help of fittings. These products have a threaded part on one side, and a coupling on the other. Fittings can have both external and internal threads.

Video: connection of plastic and metal pipes

The connection is performed in this order:

• Clean the threaded part of the metal pipe from dirt and old paint. If necessary, cut off the unnecessary fragment and cut the thread. For this, the chamfer is removed, the edge of the pipe is lubricated with machine oil or a solidol, and a threaded thread with a die of the desired diameter cuts a new thread.
• The threaded part is lubricated with silicone or plumbing paste and wrapped with a towel or a foamed tape. In this case, the direction of the edge of the winding must coincide with the thread.
• The fitting is wound by hand. Clamp the connection with a key should be extremely careful - brass parts have increased brittleness. It is best to tighten the connection only when there is a need to repair the leak.
• In the mating part of the fitting, install the edge of the metal-plastic pipe and tighten the joint. When using a press fitting, its fastening is done with a press clamp. Polypropylene tube in the mating part of the fitting is welded using a special soldering iron.

If it is necessary to mount a detachable joint using a polypropylene pipe, an American fitting is installed. Its construction consists of two parts, freely rotating relative to each other. When tightening the thread, the "American" elements are compressed, and the gasket located between them provides the required tightness.

To connect a polyethylene pipe to a metal pipe, a special HDPE compression clutch is installed on its edge. A strong connection with the pipe provides a tapered inner part with a sealing ring, and the male or female thread on the body of the pipeline affords an outer or inner thread. If the metal pipe has a suitable diameter, the coupling can be made by a two-way HDPE coupling without a threaded connection.

Connection of plastic and steel pipe by means of HDPE compression clutch

Flanged pipe connection

In the event that a flange is welded into the metal pipe, it is not difficult to connect the elements. First, a coupling with a counter flange of the same diameter is installed on the plastic pipe. Then tighten it, then tighten the two flanges with bolts. The tightness of the connection is ensured by a sealing gasket located between them.

When connecting with a flange of a free type, the work is performed according to the following scenario:

• Cut the edge of the pipe as close as possible at the junction.
• A flange is mounted on the pipe, followed by a rubber seal. It is not permissible to let the flange beyond the pipe cut more than 10mm, otherwise it will not be possible to achieve the required tightness of the connection.
• The flange is pushed to the edge, pressing against the gasket, and connected to the counterpart.
• Install and tighten the bolts.

Bolts of flange connection should be tightened evenly, with the moment, according to the manufacturer's instructions.

At present, sets of flange connections with couplings for plastic pipes of any type are produced. When installing, you must always follow the manufacturer's requirements and adhere to the operating rules, as some of them are not designed for high pressure   in system.

Features of some types of connections

While building new ones or repairing existing pipelines, one will have to face the need to connect plastic pipes not only to steel, but also to cast-iron or copper elements of communications.

Sewer pipes

It is not difficult to connect a plastic sewer pipe to a cast iron pipe. Since the pressure in the sewerage system is small, there are enough seals, cuffs and corrugated adapters for docking. In the sales network you can find products of the right size and configuration.

When installing a plastic pipe in cast iron, never use a caulking or cement mortar for compaction. Due to the difference in the coefficients of linear thermal expansion, the joint will lose its tightness after the first heating-cooling cycle.

The required seal can be cut from any suitable piece of rubber, it is important only not to overdo it during installation - plastic can crack.

Connecting sewer PVC pipes to the riser

Heating or plumbing

High pressure in the heating system or water supply requires a reliable, tight connection. And the choice here is only between two options - fitting or flange. In everyday life, pipes of small diameter are most often used, so it is easier to use a fitting connection. Most likely, you will have to deal with steel pipes, but if you need an exotic combination of plastic and copper, know - such fittings are also produced by individual companies. The installation of these parts is practically the same as working with polypropylene pipes. The only difference is that the coupler of the fitting is made of copper, and accordingly the soldering is performed by copper brazing and a burner.

Water supply of a suburban area

When constructing a water pipe in the country, it is required to connect a polyethylene pipe to the pump in a well or a village road. In such cases, the compression HDPE couplings will solve the problem. They provide a reliable threaded connection and can withstand pressures up to 16 atmospheres.

When installing the HDPE coupling, make sure that the pipe does not have sharp edges, which can damage the sealing element.

Specialty stores offer a variety of solutions to the problem of docking of metal and plastic pipes. Successful implementation depends on the right choice and the ability to work with materials and tools, so in the installation process, follow the rules and recommendations of experienced plumbers, perform work accurately and accurately. Only in this case the operation of the water supply system or heating system   will not bring you disappointment in the form of accidents and leaks, and the result of the work will add self-confidence ...

During the installation of water pipes and gas pipelines, there is often a need to connect pipes made of different materials. In the process of joining pipes made of polyethylene, with steel pipes special polyethylene-steel adapters are used. This connection is one-piece and helps to reliably connect pipes made entirely of different materials.

When an all-in-one connection is used

The polyethylene-steel adapter is used in the following cases:

- when it is necessary to cut a pipe made of polyethylene into a steel pipe;
  - If a steel pipe fitting is required on a polyethylene pipe.

Also, a non-detachable polyethylene-steel compound is used in the form of a cap on pipes made of polyethylene.

How does an all-in-one connection look like?

Connections of polyethylene pipes with steel are carried out with the help of a special adapter, which looks like a product, one half consisting of a polyethylene pipe, and the other - of steel. The polyethylene tube has a certain length and diameter. With a steel pipe it is connected strictly according to TU 4859-026-03321549-99. The steel pipe is pressed into a polyethylene tube certain pressure. Thanks to the special production technology, the one-piece joint is characterized by high strength and complete tightness of the formed joint.

Advantages of an all-in-one connection:

- with the help of the polyethylene-steel adapter it is possible to cut the polyethylene pipe into a steel pipe without the construction of wells;
  - installation using an integral connection can be made directly into the ground;
  - After installation, you do not need to service the adapter.

Types of all-in-one connections

A non-detachable joint designed to connect polyethylene pipes to steel pipes can be of two types:

1. Adapter with reinforcement clutch. The coupling is put on top of the joint of the polyethylene pipe with the steel pipe. This kind of permanent joints can be used actively for the installation of high pressure pipelines. Such adapters are as strong as possible and can withstand a high load. Adapter with reinforcement coupling, made in part from polyethylene pipe PE 100 SDR 17, is able to withstand a continuous load of 1 MPa

2. Adapter without reinforcement coupling. These all-in-one connections   can withstand a pressure of 0.6 MPa.

As an adapter polyethylene-steel is connected to pipes

To connect the adapter with polyethylene and steel pipes, the method of butt or electrofusion welding is used from the side of the plastic pipe, and the method of electric welding on the side of the steel pipe.

How else can pipes from polyethylene to metal

The connection of polyethylene pipes with metal pipes can be made in two forms:

1. Threaded connection. For this type of connection special fittings are used. They have a thread intended for a metal pipe, as well as a smooth coupling for a polyethylene pipe. With this method, pipes with a diameter of up to 40 millimeters are fastened together.

2. Flange connection. This connection of metal pipes with polyethylene is carried out by means of various flanges.

Sometimes when installing communication systems, you have to combine elements made from different materials. Especially often in construction practice, there is a connection of plastic pipes with metal tubes, which can be used in various ways.

Usually when laying plumbing, sewer or other systems, builders try to use the same material. However, in some cases, you can not do without combined structures. The most common reasons are as follows.

Planned replacement and urgent repairs. Cast-iron communications, which are equipped with houses built several dozen years ago, are gradually breaking down. Over time, metal elements are corroded or clogged, which is why they need their planned or emergency replacement.

It is quite natural that in this case old cast-iron or steel pipes are replaced by polymeric ones, which are less expensive and easier to install.

In old houses with long-paved communications to metal (usually cast-iron) risers, modern polymer pipes are often connected

Building. The process of individual or public erection of houses is connected with the laying of heating mains, sewerage, water supply. Often the installation of various systems involved in different organizations, because of the uncoordinated work of which the construction is supplied several types of pipes - both from metal and plastic.

Special cases. In some situations, combining heterogeneous materials is an urgent necessity, for example:

• connection of the pipeline to process equipment, the high temperature of which can not withstand low-melting plastic products;
• laying of the main in areas subjected to high loads, for example, under busy roads or when leaving the garage. In this case, in more complex areas, stronger metal elements are laid, and on the rest - polymer ones.

As we see, the need to combine different types of pipes arises quite often.

Types and characteristics of pipes

For the correct connection of pipes made of different types of materials, you should know the main types and properties of similar products.

Option # 1: Metal

Such elements, differing in hardness and mechanical density, are capable of withstanding considerable loads. A common disadvantage of metal products is the high cost.

Metal pipes from copper, steel, cast iron have high rates of rigidity and strength, but are not always able to resist corrosion, and are prone to blockage

Among the most common options are the following types of pipes.

Cast-iron   pipes. The most popular material, which is characterized by good durability, durability, as well as a relatively low price. A negative factor is the fragility, because of which these products require careful treatment when storing and transporting. Before starting work, it is important to inspect the cast iron elements for chips, cracks and other defects.

Steel   pipes. Under this name are connected different versions of products:

• Pipes from ordinary steel are easily covered with rust, and also tend to overgrow internal space, which leads to clogging.
• Galvanized steel is not prone to corrosion, but it is quite difficult to install.
• The highest consumer properties (resistance to aggressive substances, strength) has a "stainless steel", but products made of this type of metal are expensive and require laborious processing.

It should be noted that the steel elements are more expensive than the cast iron ones.

Copper pipes. A rare occurrence, since such products have a high cost. However, such high-quality elements are sometimes used for communications (elevator units) in the construction of private houses.

Option # 2: Plastic

For the laying of communication systems, pipes are used, for the manufacture of which various kinds of polymers are used. All plastic products are characterized by such important advantages as inertness to chemical media (even aggressive), resistance to corrosion, unwillingness to create clogs, as well as affordable cost.

Polymer pipes are widely used in modern construction work due to low cost and excellent resistance to aggressive substances

At the same time, a number of characteristics of pipes directly depend on the characteristics of the plastic from which they are made. The most commonly used are:

• Polyethylene: products made of this polymer have good elasticity and sufficient density. However, they are not able to withstand high temperatures (PET softens already at 80 degrees Celsius), which makes them undesirable to use for transporting hot liquids and gases.
• Polypropylene: pipes made of this plastic are most widely used, because this material ideally combines light weight with strength and durability. Polypropylene elements can withstand high temperatures, which allows them to be used in hot water systems even without reinforcement.
• Polyvinyl chloride (PVC). The least common option, since the products made of this plastic are fragile enough. Such pipes should be laid only in places where they do not fall loads, most often they are used to create sewer systems.

In everyday life, all of the listed types of pipes are used.

Option # 3: metal-plastic

Combined material, recently received great recognition, consists of five layers, including two plastic shells (inner and outer), two layers of glue and aluminum foil.

Metal-plastic pipes have a combined structure, which includes, besides two layers of polymer, an adherent layer of aluminum foil. Such products are of high quality, combining aesthetics with strength and light weight

Such products differ not only in high consumer qualities (durability, reliability, ease), but also with a beautiful appearance that allows using them without additional finishing. Metal-plastic pipes can be used for laying various communications: water pipes, sewerage, heating and drainage system.

How to connect sewer pipes

Depending on the purpose of the system, metal and polymer elements can be mounted in different ways. Most simple way   is the connection of sewer pipes made of different materials. In order to combine them, special products (corrugations, cuffs, seals) are used, which can have different sizes and configurations.

Transition cuff is an excellent option, allowing to join the pipe from polyvinyl chloride with a cast iron neck. This method is usually used for the installation of sewage pipelines

Using such a device, it is easy to connect the polymer pipe with a cast iron neck. In order for these products to fit tightly to each other, it is important to choose a cuff or corrugation, suitable for the parameters. If this is not possible for some reason, you can use fine-pored rubber (even an old car rug).

A long narrow tape is cut from the material, which fastens the fastener between the pipes. Such an operation is convenient to make with a wide, unshielded screwdriver, while working should be carefully, but carefully, remembering the possible deformation of the plastic.

It is strongly recommended not to compact the plastic element in the socket of the metal by means of embossing or to seal the joint with cement. In the first case, you will not be able to achieve a tight connection, because because of the plasticity of the polymer pipe will deform. In the second - a good result will prevent the thermal expansion of the plastic: under the influence of a hot pipe, the fasteners will be broken and the joint will lose its tightness.

Connections of heating and water pipes

This option is considered more complicated, since the communication system is under pressure. In this case, you can apply several methods of connecting pipes:

Threaded

For pipes whose diameter does not exceed 4 centimeters, the best option   is the connection with fittings. Such convenient devices may have different configurations and parameters, but have a common constructive feature. One end of the fitting ends with a smooth coupling intended for the polymer element, the other end has an internal or external thread on the end intended for securing the metal tube.

Threaded fittings designed to create reliable connectors between plastic and metal pipes can have a wide variety of shapes and sizes

For more complex connection options, a tee fitting is provided, using which you can connect two plastic and one metal (usually steel) element to a single system.

Flanged

For large diameter pipes (60 cm or more) it is better to use special detachable fasteners-flanges, which consist of two identical parts, connected by bolts.

Various types of flanges can be used to connect dissimilar pipes (free, curly, with support for the collars), which differ in size and design features

This avoids manual tightening of threads, which is difficult to do on large parts, but at the same time create a strong, reliable fasteners.

Species

Other types of fittings can be used for joining the parts, for example, a special coupling or fittings of the Gebo type. The latter option is especially recommended for combining small length pipes or systems located in difficult places (for example, close to the floor).

Metal hose

To combine plastic elements   with metal pipes, you can also use a special device - metal hose, which is designed to work in arhyslozhnyh conditions (high pressure, exposure to corrosive substances). Usually such a device is used for laying gas pipelines or installing systems in chemical plants, but it can also be used in construction.

With the help of metal hose, you can create an elastic joint. Such an adaptation is usually used in industry, including in complex and dangerous works

A metal hose is attached to a metal pipe using ordinary threads (in case of connecting large diameter elements, a flange of the appropriate size can be used). At the second end of the metal hose, an additional fitting with a polymer clutch is put on, which joins the plastic product.

A particular advantage of this method is the possibility of creating a flexible connection, so that the design is able to "bypass" various obstacles.

Below we will discuss in detail the installation of connections of different types.

Features of mounting threaded fittings

Thanks to various types of threaded fittings, the installation of the pipeline makes it possible to perform the most complex bends and turns.

The most common method of joining metal / plastic structures is an American fitting. Such an element, which has a clutch and thread on the ends, makes it possible to quickly and easily connect heterogeneous parts

The most popular device for the joint of polymer and metal elements is the "American" fitting, which is available in various sizes. Convenient adaptation with plastic clutch and metal thread is extremely convenient in installation, allows for a short time to create a reliable sealed connection.

Step-by-step installation instructions

To connect a metal pipe to a polypropylene or other plastic pipe, it is necessary:

• Using a special soldering iron, weld the coupling of the fitting to the end of the polymer pipe, then wait for the joint to cool.
• Bring the detail from the metal to the other end of the "American" and then twist the thread. To seal the joint it is desirable to additionally wind along the thread by one or two layers of a FUM tape, a tow or a linen fiber (in addition it can be covered with silicone).
• The fitting must always be twisted by hand: the use of tools is undesirable and even dangerous. Special equipment does not allow full control over the applied forces, which can lead to damage to the part.
• After completion of the work, it is important to check the strength of the received fastener. To do this, just turn on the water and make sure there is no leakage. If, however, the moisture is filtered through the joint, you can try to tighten the bolt a little more. With further flow of water, it is necessary to unscrew the thread again and carry out all the manipulations anew.

The shape of the finished connection can be changed if the plastic part is softened with the help of a construction hair dryer, and then the necessary bend is made.

Connecting a metal pipe without thread

There are situations when a plastic pipe needs to be connected to a metal analog, which has no thread.

The thread on the pipe can be applied using a special tool - screwdriver. In specialized stores you can find both mechanical and electrical models of such a device

A similar problem can be solved by a special tool called a "threader" or "thread cutter", by means of which it is possible to apply grooves on a part made of steel or cast iron. There are two options for adaptation:

• Electric, which includes a set of cutters, designed for pipes of different diameters. Such models are comfortable and easy to operate, however they have a high cost.
• A manual threading machine is much cheaper, but working with it requires more physical strength and certain skills.

When using threaded cutters, you should follow a few simple rules:

• The tool can not be operated if the pipe is a short distance from the wall.
• The electric screwdriver quickly heats up, so when processing several elements you will have to periodically rest.
• When working with a manual device, it is important to follow the alternation of movements, performing a half-turn forward and a quarter turn back, until you cut the thread to the desired length.

To cut the thread on the pipe, it is necessary to thoroughly clean the pipe, if necessary, remove the existing paint and wipe out metal streams. Then thread using electric or carved tools.

The cut grooves are well cleaned and greased with a solid oil, oil or other lubricant, and then used for connection with the fitting.

Features of flange mounting

This variant of fixing polymer and metal pipes uses special detachable devices - flanges. They not only make it possible to create a strong joint, but also allow access to the pipe joint (for this it is enough to unscrew the bolts).

The diagram shows the connection of a metal and plastic pipe with a flange. Such fasteners can be used on large parts

There are several options for such devices, among which are especially common:

• Free flanges resting on a straight shoulder. Such parts are designed for installation of light elements with a diameter of up to 30 cm, as well as for medium and heavy pipes, in which this figure does not exceed 15 centimeters.
• Free flanges with support for a conical shoulder will help create structures from pipes with a diameter of not more than 20 cm.
• Blade fasteners with a shaped flange and steel projection are considered universal, they can be used for joints of different elements, it is important to pay attention to the size.
• A straight shoulder with a conical transition makes it possible to significantly increase the strength of the joint.

Regardless of the flange model used, the following work procedure should be followed to create a connection:

• Before starting the manipulation it is important to select an element of the required type, the size of which corresponds to the diameter of the metal part of the pipeline.
• You should carefully inspect the selected flange: there should not be sharp burrs on the part, which can scratch and damage sufficiently brittle plastic cords.
• On the steel (metal) pipe, the location of the proposed tie is determined, then it is gently cut (the edges must be flat).
• Then a flange is put on the metal part. To ensure a tight connection, a rubber gasket is added to it, which should not extend beyond the cut line for more than one centimeter.
• Next, you need to connect all the elements of the fastening unit, fixing with a bolt a flange on a metal pipe with a similar element mounted on the polymer part.

The tightening of the bolts must be carried out smoothly and evenly, making a complete turn of the thread and avoiding excessive force application, so as not to damage the fragile enough detail.

Special types of pipe joints

In some cases, it is advisable to use fasteners with other types of fittings. Let's consider two variants of such works.

Fastening with a special clutch

A fairly simple detail can not only be purchased in building materials stores, but also made independently.

The device consists of the following parts:

• body made of cast iron or strong steel;
• two nuts, which are located on the two sides of the part;
• rubber gaskets for hermetic sealing;
• four metal washers, which must be in the inner cavity of the coupling.

The parameters of all elements must correspond to the diameter of the pipes on which they will be used.

Instructions for use: Insert the pipe ends up to the middle of the coupling, passing them through the gaskets, washers and nuts, and then tighten them last enough to squeeze the gaskets.

Mounting clamping-coupling (Gebo fitting)

Docking of metal and polymer pipes by thread provides a sealed seal, but this method is not always possible.

With an insignificant length of the metal pipe or its contiguity to the horizontal surface, it is advisable to use a clamping-coupling, which is also called a Gebo fitting (eg HEBO-QUIK).

Clamping-coupling (Gebo fitting) is especially recommended for the installation of dissimilar pipes located in difficult access areas (for example, close to a wall)

Such a device consists of the following parts:

• housing;
• mounting nuts;
• clamping, clamping and sealing rings.

Work does not require special skills, special equipment or a long time.

Procedure:

• Clean the edge of the metal pipe from dirt and old paint.
• Completely unscrew the coupling.
• Consistently put on the cast iron or steel element all the fasteners, with the O-ring should be at a distance of 1 or more centimeters from the end of the product.
• Insert the end of the metal pipe into the body of the coupling, move all available rings to it, and then tighten the bolt.
• To the thread located on the other side of the coupling, the "American" fitting should be attached, having previously soldered a polymer pipe to it.

To check the strength of the fasteners, gently pull the element, holding the pipe to which it is attached by hand. The fitting must not move along the structure. If it reacts to your touch, you should tighten the thread. Movement in this case will mean that you have incorrectly chosen the size, so that the clutch sits on the pipe loosely.

All the types of fasteners described above can be used to connect metal pipes with metal-plastic elements.

On the videos placed in this section, the order of the work of fastening the pipes made of metal and polymers with the help of an American fitting and a flange connection is clearly demonstrated.

Advantages of using "American":

Practical application of the flange:

The process of joining metal (cast iron, steel) and polymer pipes requires certain strengths and skills. Regardless of the type of fasteners, for perfect joints it is important to select the right parts for the right size, and carefully follow the instructions.