Production of propylene pipes. Method of cold welding of polypropylene pipes. How to weld polypropylene pipes by yourself

First of all, it must be said that polypropylene is a synthetic material obtained in the process of polymerization of propylene with ethylene, while maintaining their specific relationships. Production technology polypropylene pipes  is designed for a large area of ​​application for heating and water supply systems within various structures and buildings.

The process of manufacturing pipes

1. The process of making pipes begins with the falling of granulated raw materials in a special bunkr. Here the material begins to melt. The entire cylindrical device is divided into sectors. In each sector a strictly regulated temperature is set. The screw of the device is constantly in rotation and the granules of the raw material are mixed, and then their melting begins. At the output from the device under high pressure  with the help of special forms a polypropylene pipe is formed.

2. The formation of the shape of the pipe occurs in the extrusion heade. There are molds that limit the outer and inner diameter of the product. The head is attached to the cylinder of the hopper by a flange.

3. The process of polypropylene production is automatic from the moment of filling the granules into the hopper and until the finished of products. All equipment for the production of polypropylene pipes extrusion line is controlled from one command unit. It is enough to load the necessary heating program of the material, the order of its transfer from one mechanism to another and the line for the production of polypropylene pipes starts its work in an automatic mode.

4. The vacuum calibrator is responsible for the accuracy of the specified parameters. The pipe enters the device, it is fixed to the outer diameter and is locked in two from both sides in a vacuum calibrator. Then, under pressure from the nozzles, cold water enters the calibrator, and the material finally cools and solidifies. In addition to the cooling bath, the calibration of the pipes is carried out by means of a pulling device. The inner diameter is controlled by pulling the part.

The final process in the production of pipes

The complete process of manufacturing by itself implies the production of a pipe of presentation. The pipe must have all the geometric dimensions and technical parameters required of it. Pipe cutting is performed by a special cutting device. This saw is disk or guillotine type. On what saw will cut the pipe, it all depends on the diameter of the product. Such equipment can also operate in manual mode, and the cutting begins if the switch that is installed on the stacker is turned on. In automatic mode, the equipment operates when cutting modes are set from the control panel. Cut off pipes of a given length the stacker throws on a special rack. There they are sorted and packaged. The method of cutting pipes with a circular saw is considered to be the best, because the end of the pipe is better. When cutting with a guillotine saw, the end of the product becomes slightly flattened. If produced reinforced pipes, then perform operations to reinforce the outer or inner diameter of the pipe. This is done using an aluminum foil with a thickness of 0.15 mm and an adhesive special layer, which is responsible for fixing the protective metal layer to the polypropylene.

Materials for the manufacture of polypropylene pipes:

— random-copolymer polypropylene. It represents the copolymerization of propylene with ethylene in the prescribed proportions. From it, pipes for water supply are made. It's sad that a good compromise option for this type of material, produced by foreign manufacturers, is not yet available on our markets, and probably is not foreseen soon;

— homopolymer polypropylene. To a greater extent it is used for manufacturing sewer pipes and fittings. This material is brittle and at a temperature below zero the pipes are not installed, therefore such polypropylene pipes are suitable only for internal sewerage. Similar models of pipes are thin-walled, the thickness of the walls will not be more than 2.0 mm.

Before we begin to describe the technical process, which is used for manufacturing of pipes from polypropylene, let's study the material and products obtained from it a little. Synthetic material polypropylene has already received a large number of positive reviews and praise, thanks to its positive characteristics.

First of all, you need to know that polypropylene is a synthetic material that is produced in the process of polymerization of ethylene and propylene, maintaining certain quantitative ratios. Manufacture of polypropylene pipes  is designed for a wide range of applications for water supply systems inside buildings and structures. Such pipes are suitable for supplying both hot and cold water, they can be stacked for the arrangement of heated floors and used as wiring for heating appliances. The material has high strength properties and is not susceptible to corrosion, eliminates the formation of deposits in the form of rust and limescale.

Speaking of their durability, the polypropylene pipes for heating can serve for more than fifty years and the system operated from them will not require replacement of any part, there will not be a need to clean it. Polypropylene can quench vibration, and the pipes will not produce increased noise. To all these properties of pipes, it is necessary to add also that they calmly transfer the successive cycles of thawing and freezing, and their weight is ten times smaller than their metal counterparts.

Line for the production of polypropylene pipes.

Production of polypropylene pipes in Russia begins with the fact that granular raw materials are being loaded directly into the hopper of an extruder that rotates inside another cylinder. Inside this installation there are heaters, in the form of rings, equipped with temperature sensors. The sensors are located along the entire length of the extrusion bunker, which allows you to set and monitor the individual temperature for each site separately. Through these controlled by temperature conditions, the melted polypropylene mass passes, and constantly rotates.

After that, already turned into a plastic mass, the flow under high pressure is squeezed into an extrusion head equipped with annular type heaters in order to maintain the temperature necessary for forming the blanks. It is at this stage in the production of polypropylene pipes that the form of the billet is used. The passage between the external matrix and the shaping inner mandrel gives the finished semi-finished product, which is then subjected to a calibration process, a vacuum bath, specially designed for this purpose. The workpiece of the pipe through which smoothly stretches. The internal pressure creates the tube to expand, pressing against the surface of the calibration form.

To ensure that the shape of the pipe is not broken and its parameters remain unchanged, it enters the cooling bath, which is equipped with a tape and caterpillar machines with pneumatic clamping of the tracks. There comes a time when the production of polypropylene pipes and fittings has come to its final stage, they are cut using guillotine and circular saws, according to the established dimensions. Choose sawing devices in the envy of the diameter of the pipe, which lies under the blade.

Today, polypropylene pipes are welded in various ways.

New construction materials, including polypropylene, allow creating reliable and durable mechanisms of water supply, heating and sewerage.

The technology of welding polypropylene pipes is well developed.

Purposefully for these needs, equipment has been created that is easy to handle. In real conditions, polypropylene pipes are welded by hand using a soldering iron.

The use of this or that method is determined by the concrete situation.

In order to qualitatively perform the installation of the pipeline, it is necessary to know the technical and operational characteristics of products made of polypropylene.

The first thing to note is that the polypropylene pipe is a complex technical product.

Currently, the industry produces three types of these products:

• for cold water supply;
• for hot water supply;
• for heating systems.

Compared with metal pipes, polypropylene products have a lower weight with equal strength. The connection of the elements to each other is accomplished by welding.

The apparatus for welding polypropylene pipes allows the installation of extensive communications.

The welding machine has a compact size, which allows you to work in hard-to-reach places.

On the inner surface of polypropylene pipes, rust, lime deposits, dirt do not form and corrosion does not occur. From the reinforced pipes lay heating pipes.

The video shows the process of connecting individual elements when the heating system is installed in a private house.

The technology of welding polypropylene pipes is simple and is available for use at home. The welding set for polypropylene pipes contains all the tools necessary for work.

In some cases, a soldering iron and a device such as an iron for welding polypropylene pipes are used. With pipes made of metal, such circulation is impossible.

Elementary calculations show that polypropylene parts are much more preferable to use than metal products. This applies to pipes of large diameter, and most running sizes.

In order to choose the appropriate type of product, you need to know their classification and labeling.

In the process of manufacturing, the symbol PN is marked on the pipe and the maximum pressure that the product withstands is indicated on the digital code.

You need to make a choice with knowledge of the subject, and immediately acquire a device for welding. To perform the installation of pipes yourself, you will need special equipment.

Welding tools

Before proceeding with the installation of the pipeline from polypropylene parts, it is necessary to properly prepare.

The welding device must be selected after the technical documentation for the pipeline system has been developed.

The choice is determined by technical parameters and economic considerations:

• the limiting size;
• ergonomics of the device;
• cost of the device.

Installation of small diameter products, up to 63 mm, can be successfully performed by a hand-held device. If you want to connect large diameter products, from 63 mm, then mechanical machines are used.

Such a set for welding polypropylene pipes is used for the laying of long lines.

The set of welding tools includes special scissors, which are designed for cutting polypropylene and nozzles of different diameters.

A special device for cleaning the surface of the product before welding. The surface of the parts must be degreased. For this purpose, ethyl or isobutyl alcohol is used.

Acetone can not be used because it loosens polypropylene. The warm-up temperature reaches almost three hundred degrees. Therefore, when working, use gloves.

The video presents a manual device for welding pipes and the sequence of operation during operation. The connection of elements in a private house is more convenient for carrying out with it.

Hand-held device

By its design, the device is a compact product that takes up little space. The main element of the device is a heating mirror on which the nozzle is attached.

In everyday life such a device is called a soldering iron or iron. In order to set a certain temperature level, the welding device is equipped with a control and adjustment unit.

On the panel there are LED indicators and on / off keys of the device. The working temperature for welding parts from polypropylene varies from 260 to 280 degrees.

The operating rules of the device are the same as for any other electrical device.

The main parameters for choosing a device when buying are:

• power;
• number of nozzles on the mirror;
• availability stand.

The more the power of the heat-heating element, the faster the nozzle warms up. This parameter determines the performance of the device.

One nozzle or several can be attached to the soldering iron. The amount varies depending on the design of the device and the dimensions of the soldering iron.

Practice shows that by performing a connection system in your home, it will be enough to have two baits. For such systems, pipes of 20 and 25 mm in diameter are used.

Connection and routing of the pipeline is carried out using connecting elements, which are called fittings. These products have different configurations - a corner, a tee, a cross.

Handle fittings as well as with polypropylene pipes.

When welding reinforced parts in hard-to-reach places, you must strictly maintain the set time for warming up and fixing the connection.

Especially for installers who work in their home, a table is made, and it shows the optimal modes for heating and connecting the two elements.

The video shows a fragment of connecting parts in an uncomfortable place for work.

Mechanical apparatus

Welding machines mechanical type  They are designed to ensure the connection of large diameter pipes.

The mechanical device has a more complex design than the manual version.

The welding unit is assembled from the following units:

• support skeleton;
• control block;
• grip for pipes;
• loose leaves;
• saw for pipe facing;
• heating mirror.

The device, despite its complex structure, has a compact design. Installation of the pipeline is carried out on the principle of butt welding.

The operating instructions prescribe a certain sequence of actions. First, the end faces of the parts to be joined are cleaned.

Then the pipes are heated, and their temperature should reach the melting threshold. At the final stage, the pipes are joined and tightly pressed against each other.

The pressing equipment is supplied together by the machine.

The welding unit, which has such a device, allows welding polypropylene pipes in the field during the laying of heating lines.

The video shows a device for welding large diameter pipes from polypropylene.

Welding technology

Equipment for welding and installation of heating or water supply systems should be prepared in advance. The welding technology is worked out to the smallest detail.

The whole process consists of three simple steps. First, you need to prepare the parts to be joined. Then heat them to melt. The melting point depends on the type of material.

And the third stage is the joining of two segments. The video shows how this is done. Practice shows that the larger the diameter of the tube, the longer it should be heated.

A soldering iron is used to connect products of small dimensions. The heating interval should be as specified in the instruction.

Before turning on the welding machine, pipe sections and fittings should be prepared. The device of the heating system needs to be displayed with marks on the walls in the attachment points.

The marker also marks the parts that will be welded. All the elements to be combined must be dried and degreased. Then they are inserted into the apparatus and heated.

The soldering iron should have an appropriate temperature. After heating, the parts are removed from the nozzles and connected by uniform movements. Without rotation.

Selection of the welded device

In preparation for the installation of the pipeline, the question arises, which welding unit to choose?

It is necessary to make a decision after evaluating the work front. It is important to calculate the power of the device and the number of nozzles that are attached to the soldering iron.

The welding time of polypropylene pipes is determined by the power.

It is necessary to take into account the cost of the welding machine. Superfluous overpay does not make sense.

But even with a low-power unit, the work can be unnecessarily prolonged.

Repair or replacement of communications made of polymer pipes is not without the procedure such as welding. How to properly weld polypropylene pipes with your own hands and what to consider when joining the elements, consider in the article.

One of the undeniable advantages of polymer pipes is the ease of assembly.

The installation of elements can be done almost everywhere: to lay openly on walls or to place hidden under the floor.

If welding water pipes  from polypropylene it is made correctly, the collected system regularly will serve without repair more than one ten years

Polymer pipes are available in diameters from 20 to 110 mm. For household purposes, the most commonly used products are sizes 20/25/32/40 mm. The area from the application determines the index of the nominal pressure of the material. In the marking it is denoted by the letters "PN":

• PN 10 - is chosen for the arrangement of cold water supply.
• PN 16 - is used for cold water, but with a higher head, as well as for the installation of a "warm floor" system.
• PN 20 - products, the only limit of which is the temperature regime of the liquids transported through them. It should not exceed 75 ° C.
• PN 25 - universal products used for the arrangement of both "cold" and "hot" systems, the temperature of which reaches 90 ° C.

On sale you can find polymer products, equipped with additional reinforcement.

Armored products are used for laying on long sections in conditions where it is necessary to reduce the linear expansion that occurs when temperature fluctuations

The main feature of polymer pipes is the impossibility of their bending. Therefore, all changes in the trajectory of the laid trunk are carried out only from straight sections connected by auxiliary hardware elements:

• crossings - to enable branching of the main flow;
• tees - breeders of streams;
• couplings - for connecting pipes in a straight section;
• bends - to change the direction of the pipeline.

Fittings can be equipped with a fused metal thread, which makes it possible to connect the polymer pipeline with metal elements.

To ensure that the seams are as tight and tight as possible, it is important to ensure an exact match between the diameters of the elements to be joined

When choosing auxiliary elements, two parameters should be taken as a basis: the internal section of the products and the thickness of their walls. These parameters must match technical specifications  used polypropylene pipes.

Methods of connecting polymer pipes

When the pipes made of polymeric materials are joined, depending on the installation conditions, one of two methods is used:

1. Soldering - involves heating and mating the molten ends of the elements.
2. Without soldering - involves joining pipes through compression fittings or by implementing so-called "cold" welding.

The second method of installation is convenient in the sense that for its implementation there is no need to use special equipment. All work can be done using a simple tool - a crimp key.

Connection Tools

The main tool used to connect plastic pipes  - an iron for welding. This is a kind of soldering iron, working from the network in 220V. The principle of the device is quite simple. The role of the heating element of the iron is performed by a welding heater, placed in a metal casing. He warms up to a given temperature a plate that heats the nozzles. The temperature regulator is responsible for maintaining the optimum temperature of the nozzles.

The iron is a compact and light welding device equipped with seats for placing sleeves for pipes and mandrel for shaped products

In the kit to the iron there are heating nozzles of standard sizes. Heat up to a certain temperature, they soften propylene to a viscosity that will ensure a tight joint of the elements. The nozzles are selected depending on the diameter of the pipes used:

• The 20-th size - for pipes in diameter in half an inch;
• 25th - for products with a diameter of 0.75 inches;
• 40th - for elements measuring 1.25 inches.

Since the cost of such a welding machine is quite high, and it is not so often necessary to use it, it makes no sense to purchase equipment. The tool is better to take a day or two for rent.

For high-quality cutting and preparation of welded areas, it is best to use a special tool for this purpose - a pipe cutter. With its help you can get a smooth, smooth and beautiful cut.

The role of the cutting element of the pipe cutter is made with a stainless steel blade; For ease of use, the tool is equipped with a rubber grip

In the absence of a pipe cutter, the work can be done by a Bulgarian or a hacksaw for metal. The only thing is that the fringe remains after the cutting tools. But it can not be removed easily by stripping off a strip of sandpaper.

In addition to the main tools for the work will also be required:

• gon;
• construction roulette;
• a simple pencil or marker.

When planning to join pipes by the method of "cold" welding, it is necessary to purchase in advance a thermoactive glue made on the basis of polyester or epoxy resin, or its thermoplastic analog, produced on the basis of rubber.

Basic stages of soldering technology

The key conditions for the successful installation of a plumbing system from polymers are the careful calculation of the required material and the competently welded elements.

Calculation of volumes of material and components

To simplify your work, minimizing the errors in the installation, the first thing you need to draw a scheme of the future system, indicating the number of turns and branches. When calculating the number of pipes for each length of the segment should be added to 25-40 mm, spent on "provar".

The price for polymer products and the shaped elements necessary for their installation is not large, and therefore, in the case of defective brazed pairs, which often occur at the beginning of work, it makes sense to make a small margin

If you have not yet had to weld polypropylene pipes, experienced specialists recommend that you purchase several pieces of pipes for preliminary training. Such costs and at a price will be inexpensive and will avoid major errors in the installation of the system.

A feature of polymer pipes is an increase in the coefficient of linear expansion under the influence of high temperatures. As a result: with heating or increasing pressure inside the system, the pipes become lengthened and eventually start sagging. To prevent this phenomenon, when laying sections longer than 4-5 meters, you will also need to use expansion joints.

Compensators are "P" -shaped connecting elements, outwardly resembling wrapped loops, which ensure the reliability of the system during its operation

Compensators are installed both on horizontal and vertical sections, mounting them between two fixed supports. If necessary, it is also possible to purchase special modification compensators, which can eliminate linear expansion at the angular folds of the pipeline.

We will find out how to properly weld polypropylene pipes, so that there are no leaks in the joints.

Soldering of pipeline components

Briefly, the essence of the technology for welding polypropylene pipes is that, under the influence of high temperature, the ends of the elements to be joined are heated and pressed tightly together to each other.

To create a strong connection when performing soldering, the pipe itself is warmed from the outside, and the auxiliary elements involved in its joining are internal

Before the beginning of the work, pieces of pipes cut off for the specified length relieve of unevenness and burrs. If a layer of internal or external foil is provided in the pipe, it must first be cleaned with a torch equipped with well sharpened and adjusted knives.

When performing stripping with the use of a face-piece, the pipe must be plunged into the tool until it stops.

The work on the welding of plastic pipes with their own hands is carried out in the following sequence:

1. Connect the soldering iron to the power supply in order to warm up the equipment to an optimum temperature of 260-270 ° C.
2. The pieces of pipe to be joined at the same time are put on the nozzles, ensuring the most even entry. This work should be done quickly and confidently.
3. After the specified time in the instructions, until the fittings and ends of the pipes melt, the elements from the heating nozzles are removed.
4. Dock the molten ends together, gently squeezing each other for 15-20 seconds.
5. The bonded parts are left in a static position so that the seam is completely cooled and the connection becomes monolithic.

Determine the duration of heating can be from the instructions attached to the equipment or using the table below.

The duration of heating to achieve complete polymerization of the joined elements depends on the diameter of the articles and the thickness of their walls

The requirements for the heating time specified in the table can not be ignored. Insufficient heating is not able to provide a reliable connection. Excessive overheating will result in the polypropylene "flowing" and the parts being deformed. As a result: protrusions are formed on the inner surface of the welded joints, which significantly reduces the diameter of the pipeline.

In order to be able to control the depth of occurrence of the segments in the heating element, thereby reducing the likelihood of a defect, it is desirable to pre-make the notches at their ends

After completion of the polymerization and freezing, which takes about 20 seconds, the joint is ready. By the same technology, all subsequent nodes are soldered to the finish, until the water supply is fully assembled.

Typical installation errors

The main mistakes that novice masters allow when working with polymer products:

1. Heating of parts. At the time of heating, the parts must be in the most flat position. The slightest displacement can negatively affect the operational parameters of the entire plumbing system.
2. Adhesion of polymerized ends. While pressing the molten ends of the elements, it is not possible to rotate the parts around their axis. This can lead to the fact that the seam is not strong enough.
3. Correction of alignment. When the elements are joined, only an easy adjustment of their alignment is allowed, the duration of the procedure being not more than 1-2 seconds.

Another important point: when carrying out the soldering of the cranes, it is necessary to take into account the location of the valves, providing them with a free full stroke.

Heated polypropylene cools so quickly that already an hour after the completion of installation in the system, you can safely serve water

If, after joining the elements as a seam, doubts arise, it is better to cut the joint site and re-make it again. Elimination of defects is better performed at the stage of installation of the structure, since it is much more problematic to replace the leaky joint in the running system.

Assembly of components without soldering

The use of compression fittings and modern adhesive compositions makes it possible to perform installation of polypropylene pipes qualitatively, quickly and with minimal material investment.

By installing a compression fitting

To implement this method of connection, you will need to purchase compression fittings and use a crimping wrench.

Compression fittings are equipped with sealing clamping rings, acting as dampers in the event of shock impulse loads (in contrast to simple union nuts)

Installation of the compression fitting includes three basic steps:

1. On the end of the tube cut off at a right angle and peeled off from the burrs, put on the blue nut. When placing the crimp ring of white color, it must be given such a position that the thickened part was directed towards the tail part of the pipe.
2. The pipe is inserted into the fitting until it stops, pushing the clamping ring to the maximum.
3. Twist the blue nut, "healing" it first manually, and then pressing with a key.

To assemble the compression fittings, no special knowledge and skills are required. Products are on sale fully ready for installation. Their installation can be performed under any temperature conditions.

By gluing together the elements

Adhesive method is used for the assembly of a water pipe, according to which it is planned to transport only cold water. To apply the method of "cold" welding, you will need to use the "aggressive" adhesive type LN-915.

The glue is able to dissolve the surfaces of the assembled parts by one third, thus creating conditions for cold diffusion welding

To protect the skin of the hands from accidental ingress of the composition and "corroding" it with the active ingredients, it is better to carry out gluing manipulations in protective gloves.

Sequence of actions for gluing products:

1. Verify the correspondence of the cutting angles of the joined areas and mark the pencil with the pencil for gluing.
2. Peel and degrease the pipe ends to be joined.
3. On the ends of pipes and the area of ​​the socket of the fittings, an adhesive layer is applied uniformly.
4. The pipe cuts are inserted into the holes of the fitting, being guided by the pencil marks. The structure is held in a fixed position for three minutes, after which excess waxes are removed with a napkin.
5. The combined elements are laid out on a flat surface and left for 5-6 hours until completely dry.

Running water to check the quality of bonding can only be done a day after the installation is completed.

When implementing this method, it is important to observe two basic conditions: temperature and humidity. All work should be performed at an air temperature of +5, + 35 ° C. When gluing in hot weather conditions, work should be done as quickly as possible so that the glue does not dry before the installation is completed.

On the subtleties of the processes of soldering and gluing pipes can be learned from the following videos:

How to solder pipes:

Assembly of plumbing without soldering:

Work on the self-matching of polypropylene pipes, even with a novice master, should not cause any special difficulties. It is only necessary to fulfill all technological standards in a clear and conscientious manner.

Soldering of pipes from polypropylene is carried out with the help of special apparatuses, which provide precise control over the time and temperature of melting of the parts. For cold water systems, cold (glue) welding is allowed.

How to choose the device?

In shape, all devices for welding polypropylene pipes are divided into:

• X-ray ("irons"): inexpensive devices designed for welding pipes with a diameter of up to 40 mm, with a plate-shaped heating element, in the holes of which are inserted paired nozzles - replaceable couplings and mandrels. Teflon coating protects plastic from adhesion to metal. Used mainly for periodic or one-time works. If the choice has stopped on this device, except its power and thermoregulation methods, it is necessary to check the stability of the structure.
• Cylindrical: semi-professional and professional units, the heating element in which has the form of a straight or lateral cylinder. Welding machine in the form of a letter "G" with a side cylinder can be used for soldering in hard-to-reach places.

The speed of the operations depends directly on the power of the device. For one-time work, it is better to purchase a medium power tool. Be guided by the diameter of the pipes. For example, if it is 40 mm, this figure is multiplied by 10, plus 20-40% of the stock is added. That is, 40 x 10 + 80 = 480 watts. Round the figure to 500 watts. For pipes of larger diameter (for example, 16-centimeter), a professional, expensive unit with a capacity of 1800-2000 W will be required.

The heating level, the information about which is displayed on the display, is set by the thermostat. The devices with electronic or microprocessor thermostats are considered more accurate, allowing to measure the temperature as accurately as possible. In capillary and bimetallic thermostats, the error in measurements increases.

Too many attachments to the building hair dryer, used in everyday life, do not need - it is enough to buy a device with nozzles 20, 25 and 32 mm in diameter. Moreover, a manual tool to weld pipes with a diameter of more than 40-60 mm is problematic. The set of the soldering iron can include additional tools: faskosnimatel, cutter, shyver for stripping reinforced plastic, calibrating device, face, etc. You can buy them separately.

Process technology

Depending on the type of connection, polypropylene pipes can be welded:

• Bell: in a similar way, pipes of small diameter (up to 40 mm) are connected in heating and water supply systems. Centering and compression are provided due to the calculated pipe dimensions and clutch or other shaped product (tee, adapter, etc.). In the ordinary state, the diameter of the pipe is slightly larger than the internal diameter of the coupling, after melting and applying a little physical effort, the pipe enters the coupling to a depth equal to the depth of the heating, forming a strong and reliable attachment. For polymerization, a certain time is maintained.
• Butt joint: for connecting parts of the same type and equal diameter. The ends of the pipes are located on one axis, that is, the end to the end. As a result of simultaneous heating and mechanical compression of parts, polypropylene interpenetrates. To achieve this effect requires the use of special machines. In domestic conditions the method is not applied, it is used for welding thick-walled pipes of large diameter in lines.

Pipes with a diameter of 4 cm to connect manually and center very difficult. For such operations, electric coupling units with alignment devices are used. Such devices operate in automatic mode and relate to high-tech, expensive equipment.

What is the temperature of heating?

To obtain a strong bond, it is important to determine the exact heating temperature. If it deviates in one direction or another, there is a risk of plastic damage during operation and leakage. At low temperatures, the plastic will not melt sufficiently, and the fastening will be unstable. With its excess, it is excessively deformed, and because of the formation of sags, the diameter of the hole will decrease. And insert the superheated and too softened pipe into the fitting will be problematic.

The temperature of the heating element is set by a mechanical (bimetallic) or electronic thermostat. If working with polyethylene requires a temperature regime within 220 ° C (± 5), then polypropylene is welded at a higher temperature of 260 ° C. Experts advise you to immediately set the desired temperature when purchasing a welding machine and then not to change it any further. On old "soldering irons" it is not regulated at all, but such devices are quite suitable for use.

The heating time of the pipes depends on their diameter. Observe it must be exactly:

• 20 mm: heating does not take more than 6 seconds;
• 25 mm: enough for soldering 7 seconds;
• 32 mm: processing time 8 seconds;
• 40 mm: heating 12 seconds.

Modern apparatus for welding polypropylene equipped with a system of light or sound warning. It is enough just to set the desired temperature and time.

Pay attention to the temperature of the surrounding air. In cold rooms, the heating time of the soldering iron is increased by 2-3 seconds. Although it is better to select this time by experience. At an air temperature below + 5 ° C, the heating time is increased by 50%.

Despite the apparent simplicity - heated, connected, cooled - in the welding of polypropylene there are many things that should not be missed:

• In the absence of experience at first it is better to practice on a piece of pipe, because the heated polypropylene retains plasticity for a short time, during this time it is necessary to have time to unite the elements without distortions, fix them firmly and, without changing their positions, wait for complete cooling.
• Pipes and fittings of different firms, even of the same diameter, should not be welded together - due to the difference in the chemical composition, it will be impossible to achieve a reliable connection.
• To obtain a smooth cut, exactly at 90 ° only a very sharp tool is used. All burrs are carefully cleaned.
• Buy only quality plastic - when choosing products from a dubious manufacturer, the pipeline can leak.
• To work on weight it is forbidden - the iron for welding should necessarily have a support. It is more convenient if it has a fastening to the table in the form of a screw clamp.
• Since the fitting warms up a little longer, it is put on the nozzle first.
• Too slow and tighten the interval between heating and installation should not be - welding will be fragile.
• The pipe must be inserted into the fitting until it stops, otherwise it will leak in the place of the resulting gap due to the reduction in the wall thickness.
• Plastic surpluses formed during the welding process should not be removed immediately - the non-heated joint is easily deformed. Although, of course, the experienced master of the swim appears very rarely.
• Rotate, screw in the details when connecting is prohibited, the movement must be done only in a straight line.
• Excessive force when connecting is also unacceptable - as a result, a large plastic influx can be formed in the pipe, preventing the passage of liquid.
• The accidentally damaged fitting should be replaced with a new one, but sealing it with a pipe is inadmissible.
• Some aggregates of Chinese and Turkish production are equipped with two heating elements with separate switches. But in order to avoid the risk of overheating of polypropylene, both should not be used immediately, let the second heater be only spare.
• The cooling time should be approximately equal to the heating time. Do not shorten this period, otherwise the connection will be fragile.
• The pipe joints must not be contaminated - welding dusty and dirty products can lead to loss of strength. Additional surfaces to be welded are degreased with acetone, gasoline or white spirit. Usual vodka for these purposes is prohibited, as it is capable of loosening plastic.
• Inadmissible and moisture ingress. When accumulating in water pipes, they are filled with salt or bread crumb, they should be washed thoroughly after welding.
• For systems with hot water  Polypropylene, reinforced with foil or glass fiber, is used. When cleaning foil, even a small remaining piece is sufficient to cause leakage during operation, it must be carefully removed for the entire length of the spike. Stripping of fiberglass is not required - this material solder very well.
• It is important not only the purity of the pipes, but also the soldering iron itself. After each operation, the plastic remains must be completely removed.

Cold welding

The bonding of polypropylene with a special glue (cold welding) is no less strong than fixing with a hot weld method. However, it is used only for pipes that supply cold water. Because the adhesive under the influence of high temperatures can soften.

The installation process is simple:

1. Pipes are cut precisely at an angle of 90 ° and cleaned from burrs, dust and dirt.
2. Fittings and pipes are marked in such a way that when they are connected between the fitting end and the pipe there is no gap more than 1 mm.
3. The glue is spread thinly on each of the parts.
4. They are held together.
5. The connection is fixed by hands in a fixed position for 15 seconds.
6. You can connect the water one hour after cold welding.