Water pipe welding machine. Types of welding of pvc pipes, advantages and disadvantages of the methods. Do-it-yourself plastic pipe welding: Video instruction

Plastic pipes have long gained popularity in the construction markets, not least due to their low cost and simple process of assembling the finished structure, which allowed them to stand out from other options. Plastic pipes are reliable and durable, they are not afraid of rust and are lightweight - which, together with other advantages, made them so popular. However, such pipes can also leak. This is mainly due to a violation of the pipe soldering process and errors made in this case. This, as well as the installation features, will be discussed later.

Varieties of welding PVC pipes

At the moment, there are two ways to solder PVC pipes. By itself, manual pipe welding is not technically difficult, but even the preparatory work should be done carefully and carefully to avoid future leaks. Experts identify the following work methods:

welding pipes using a special soldering iron and cutting shears (this welding technology is used in many jobs and, in fact, is the most widespread),
"Cold" welding (this method is simpler and allows you to work without the presence of a soldering device. To work on the connection of pipes, it is enough to work with aggressive adhesive for hard plastics).

The first two methods are primarily suitable for piping systems through which high pressure water is not expected to be pumped. If it is supposed to supply water or for heating systems under pressure, then welding involves several other methods:

socket welding. In this case, connecting elements (couplings, fittings, etc.) are additionally welded to the pipe,
electrofusion welding. In this type of welding, couplings contain special connecting elements that melt when voltage is applied to them, ensuring reliable soldering with pipe sections,
butt welding. A fairly simple process in its essence, used for welding large diameter pipes. In this case, the ends of the pipes are heated to the melting temperature (200-250 degrees) and simply connected together.

In fact, all the described methods are based on the same aspect: when exposed to high temperatures, the PVC material melts and forms a reliable connection due to the mutual penetration of particles into each other.

Each method has its own advantages and disadvantages. Simple welding allows you to work with different types of plastic pipes, but requires some skill. The use of an adhesive joint has high performance, practically not inferior to welding. But given the fact that polyvinyl chloride (PVC) pipes are not recommended for hot water (except for some varieties that can withstand high temperatures), this method of joining with glue is best used for communication systems that do not use high pressure.

Equipment used for welding

Welding of plastic pipes does not require a specific tool and allows you to carry out all the work alone. To do this, you will need scissors for cutting (it is only important to first make sure on the unnecessary section, how sharply they are sharpened in order to avoid possible deformation and burrs during cutting) and a special soldering iron with various nozzles for socket welding of pipes. A manual welding machine (soldering iron) must be selected taking into account the specifics of the work. For example, for welding plastic structures, the power of the soldering iron should be selected taking into account the diameter of the pipe. This will be discussed below.

When performing work, it is important to do all actions deliberately and slowly, since pipe welding is quite simple and can provide 15 years of trouble-free service of the water supply system, but only if the work is done correctly.

How PVC pipes are welded

Any welding process, whether it be the "cold" method or standard soldering using a special soldering iron, requires preparatory work first. They include the following steps:

cleaning pipes in places of future connections from any elements of contamination,
degreasing pipe joints by rubbing with alcohol,
preparation on the segments of the mark of entry into the fitting (non-removable connecting part of the pipeline, which is installed in those places where the pipes have branches or bends), while it should be remembered that the pipe is not inserted to the maximum stop, it is required to leave a gap of at least a millimeter,
chamfering from the ends of the pipes so that the pipe fits as tightly and without much effort into the connecting fitting.

After the preliminary work has been completed, proceed directly to the soldering process. Such a stage of work as pipe welding is not difficult to do with your own hands. Basically, the task is divided into four stages:

slicing,
heating to the desired temperature (250 degrees),
connection of pipe sections to each other,
cooling.

Pipe cutting is performed using a pipe cutter (well-sharpened special scissors, which will allow you to quickly and without defects accurately cut pipe sections of the required size (if this tool is not available, a hacksaw for metal will do).

Welding must be carried out in heat-resistant gloves and in compliance with safety regulations to avoid burns from the heating elements of the soldering iron. In fact, this is the most important stage of the work, since the actions must be carried out at such a speed that the alloyed elements do not have time to cool down, and it is important to avoid skewing when joining.

After connecting the pipe sections, it is important to securely fix the connection without applying any external loads to it. The last step is to let the finished compound cool (at least 20 minutes).

As you can see from the work process, at first glance it is quite simple. Its important feature is the correct calculation, since any negligence committed during work can already have an extremely negative effect on the reliability of the connections. Those plastic pipes, which were welded with skillful hands, will not need to be repaired for many years.

Common mistakes when welding pipes

Mistakes made at the initial stages will certainly show up in the future and therefore it is important to avoid negligence when performing work. The specialists identified typical problems that may arise at different stages of the work:

incorrect alignment of connecting elements,
excessive force when joining pipe sections,
insufficient heating of the connecting elements,
excessive overheating of the tool,
incorrectly selected heating device.

If, when combined with a PVC fitting, the pipe was not inserted up to the internal stop, then there will be a gap, which will have a lower pressure. In fact, such a section will have a smaller wall thickness and a larger inner diameter. Often, a similar error occurs if, during heating, the pipe itself was not tightly inserted into the base of the nozzle of the welding element of the soldering iron. From the outside, such a defect will not be noticeable, which complicates the process of identifying a defect during soldering.

On the other hand, the use of excessive force can also damage the soldering elements. In this case, a so-called "burr" will be squeezed out between the end of the plastic pipe and the internal stop of the connecting fitting, which, when melted, form rings that reduce the passable properties. In fact, there will be a noticeable obstruction to the fluid flow.

Insufficient heating of the connecting elements leads to defects in material joining, especially if we take into account the fact that the PVC pipe sections must be welded quickly, otherwise the quality of the connection will leave much to be desired.

During the connection work, the temperature of the working surface of the welding nozzle should not exceed 260 degrees, in increments of plus / minus 10 degrees. This is the optimum temperature for work, regardless of what pipe diameter the work is being done. This degree of heating allows you to create an internal stress in the material at the soldering point, which is necessary to perform the work. Therefore, all actions must be carried out quickly, until overheating is beyond the permissible range. With this in mind, the heating rate of the soldering iron must not be exceeded, even if it maintains higher temperatures.

The last common mistake is the wrong equipment for welding PVC pipes. There is a certain pattern that the power of the heater used in the work should correspond to ten times the diameter of the plastic pipe. In other words, to weld a pipe with a diameter of 50 millimeters, a heater with a capacity of 500 watts is required, and a heater of 1000 watts with a diameter of 100 millimeters.

Economy-class welding equipment (which is often produced by China or Turkey) is characterized by the use of additional components as part of an aluminum heater. This is done in order to provide an additional degree of heating of the heating element in the welding equipment, but this imposes an unnecessary load on the power supply and relay contacts. Such innovations are absent in equipment for soldering pipes from more famous manufacturers, therefore, in this case, the cost of purchasing good professional equipment will more than pay off with high-quality work.

PVC pipes and fittings must be from the same manufacturer. First of all, this concerns the desire to save money and purchase, for example, good quality components, but at the same time, having bought cheap Chinese pipes, do not expect the melting temperature to be the same. It is possible that at first during the check the defect will not be detected, but later it will most likely be able to manifest itself,
before buying, it is worth checking the temperature regime of the soldering iron or welding station. Since the price range of the cost of equipment is very wide, there may be a desire to save money. But in this case, it cannot be guaranteed that the required temperature of 260 degrees Celsius will be reached during operation of the heater. It is advisable to check its capabilities in terms of efficient soldering before purchasing equipment. This advice may look ridiculous, but it can prevent money loss on the purchase of equipment that is not able to maintain the correct temperature regime,
economy is the enemy of quality. There are known examples when a good thing is not expensive, but if it became necessary to use a soldering iron for frequent work with a large amount of material, then it is better to adhere to the opinion that the better and, accordingly, the more expensive the equipment, the longer it will live. The country of origin also matters. It is better to choose products from renowned manufacturers. The same applies to attachments and tools for work,
keep the connection area clean. The ingress of even a small amount of dust or dirt particles can disrupt the quality of the adhesion. Of course, this is not always possible, especially when replacing large-diameter pipes, which may not be at all in a clean environment, and yet it is necessary to try to follow this recommendation as well.
work at the appropriate temperature. If the weather outside or indoors leaves much to be desired, then it should be remembered that work cannot be carried out at temperatures below five degrees Celsius. Even at this temperature, the heating time increases and the joints become brittle.

Still, it's worth remembering the old hackneyed truth that quality work requires quality tools. It is necessary to pay attention to all the accompanying little things and then in the process of work you will be able to avoid possible mistakes and their consequences. If you still have questions about how pipes are welded, the video will clearly demonstrate the process and help to consolidate the acquired skills.

Useful information

Old rusted pipes of water supply and heating are certainly not a decoration of a modern apartment or a country house. For these purposes, plastic products are widely used today, which do not need painting and do not rust from the inside and outside.

Simple and safe

Installation or replacement with plastic analogs is a less laborious process than working with metal pipes, but all the same, when connecting, you cannot do without welding. And here you will need special welding machines for polyethylene, plastic, propylene and PVC pipes, the price of which is slightly more expensive than other inverters. You can buy them on our .

The welding process is carried out as follows: pipes are put on the nozzle, heated with a soldering iron and then manually connected. After the joint hardens (within about five minutes), they can be used in the house or apartment water and heat supply system.

Although we are talking about pipe welding, there is nothing to do with traditional electric welding of metal products, and it will not be necessary at alland welder's masks. Therefore, the user does not need any special training. The device itself consists of two parts:

special nozzle for the pipe diameter;
a soldering iron with which the parts to be joined are heated.

Specifications and equipment

A standard set of welding equipment for polyethylene, polymer, propylene and plastic pipes of any diameter includes a soldering iron and a nozzle or several nozzles of various standard sizes.

Depending on the performance, which is selected taking into account the intensity of the intended operation, the power of the soldering irons can vary from 650 to 1800 watts. At the same time, the melting temperature of all soldering irons is the same - 300 degrees Celsius.

The set can include up to seven nozzles: 16 mm, 20 mm, 25 mm, 32 mm, 40 mm, 50 mm, 63 mm. All of these dimensions correspond to the typical diameters of plastic pipes used for domestic purposes.

The set may additionally include

roulette;
scissors with which the ends of the blanks are cut;
stand for the convenience of using the equipment;
gloves to avoid burns while working.

All this is folded into a sturdy case, making the equipment easy to transport and store.

During the construction and repair of heating systems, hot and cold water supply, steel pipes are increasingly being replaced with plastic ones. This is understandable, for their installation does not require a high qualification of the welder, any person can handle the installation and connection.

The process is clean and fire safe compared to welding metal pipes. Among the plastic, polypropylene pipes are most popular for their consumer properties. For welding of such products, special devices are used.

Polypropylene pipes have a low cost, a large nomenclature, various connectors and locking devices are sold to them, which makes it possible to build engineering networks of any degree of complexity in the shortest possible time. This allows the use of a special plastic pipe welding machine.

Some of its types have a high cost, but they are designed mainly for large diameters. For the installation of internal engineering networks of most residential buildings, there is a pipe welding equipment for sale with a very attractive price.

Polypropylene is thermoplastic. When heated to its melting point, it passes into the liquid phase. After cooling, it hardens, while retaining all its strength characteristics.

If certain areas of polypropylene blanks are heated to the melting temperature, and then pressed against each other with melted areas, then diffusion of the melted layers will occur.

If you fix the parts and wait until they cool down, then the result will be a new monolithic product. On a cut, it is impossible to see the junction of the parts. These properties of plastic are successfully used in machines for welding polypropylene pipes.

The most common are:

devices for socket or socket welding;
butt welding devices;
equipment for electrofusion welding.

The last two varieties have a high cost, they are an order of magnitude more expensive than bell-shaped devices.

Butt joint

The peculiarity of the butt welding machine is as follows. Polypropylene products must be of the same diameter and thickness. The ends of the pipes must be perfectly cleaned and snug against each other.

They must be coaxial and be able to move along the axis under the influence of human muscular forces, electrical or hydraulic forces.

Technology

First, the ends of the polymer pipes to be connected are simultaneously heated to the melting point of the plastic, then they are tightly connected.

Molten plastic from different parts interpenetrates each other when compressed. In this position, the pipes are fixed until the molten polypropylene layer is completely polymerized. The result is a monolithic one-piece connection.

The process looks very simple, as it is when working with small diameter pipes. But when using polypropylene products of medium and large diameter, technological equipment is required.

Only with it it is possible to ensure the required cleanliness and accuracy of the ends, alignment, the required pressure for joining the joint.

Equipment

The butt welding machine is rarely used in private housing construction, except when laying external engineering networks.

Outwardly, it looks like a machine tool. It has guides along which clamps with pipes move. They have a screw or worm gear. For fixing polypropylene pipes of different diameters, sectional inserts are attached to the clamps.

In addition, the set of equipment includes an electromechanical trimmer, which is a double-sided circular knife. He simultaneously performs cleaning of the ends of the pipes to be connected.

The facer is usually mounted on a hinged hinge, but it can also be removable. There are two hinges, on the second there is a flat round heater. If he is alone, then there is a fixture. The hinges are also installed on the guides.

After the polypropylene pipes have been trimmed, the trimmer leans back and moves to the side along the guides.

In its place, the heater is shifted and installed between the joints. The pipes should press firmly against it, but without effort. Then the joints are heated to a predetermined temperature.

The last step is the compression process. The heater is removed, the products are shifted towards each other along the guides ensuring their alignment. The required pressure is created mechanically through a worm gear, or hydraulically.

Butt welding equipment is expensive, it is used in the construction of medium and large diameter main plastic pipelines.

Electrofusion equipment

Electrofusion welding technology is as follows. At the production stage, a heating element with two leads on its outer surface is inserted into each sleeve from the inner surface.

The pipes to be connected are inserted into the sleeve. A special cable connects the leads of the coupling and the welding machine. After that, the element inside the sleeve is heated.

Due to this, the section of the polypropylene pipe and the sleeve in the area of the heating element melts. When the device is turned off, reverse polymerization of the connected parts of the product occurs. As a result, a monolithic connection is formed.

They can work with products of almost any diameter. They can weld polypropylene pipes as well as low-density polyethylene (HDPE) products.

The main element is a microprocessor unit with a regulated power supply. It saves the welding protocol to control the operation and generates the necessary current to obtain the required heating temperature.

At a specified time, depending on the diameter of the product and other conditions, he turns off the device. The device can operate in open areas in the temperature range -20 ... + 60 ° C.

For example, the Rothenberger ROWELD ROFUSE PRINT apparatus, with its low weight and dimensions (a small box weighing about 20 kg), allows you to connect HDPE and polypropylene pipes with a diameter of up to 1200 mm.

Data on them can be entered manually or read from a barcode installed on the pipe by the manufacturer. The device is easy to use and comes with detailed instructions.

Bell and coupling technology

The technology of socket or socket welding is most widespread when fusing small-diameter polypropylene pipes, which are mainly used in housing construction.

The essence of the welding process is to heat the outer side of the pipe and the inner part of the sleeve to the melting temperature and then insert the product into the sleeve.

Upon cooling, polymerization occurs and an integral connection is obtained. The outer diameter of the pipe is slightly larger than the inner diameter of the coupling; it is impossible to connect them in the cold state.

When they are warmed up to the required temperature, then enough human effort. The apparatus turns out to be very simple. It is an electric heater with nozzles and a temperature controller.

The most widespread are devices with a xiphoid and cylindrical heater.... The set of equipment usually includes a set of attachments, a cutting tool and a device for installing a heater.

The device has a knob with temperature control and heating indicator. The network cable is usually connected via a handle. On a cylindrical heater, nozzles are mounted in pairs and can be installed at any angle.

There is a heater in the cylinder, which makes it possible to evenly warm up all the nozzles mounted on it. On the xiphoid heater, the nozzles are mounted on both sides.

Choosing a welding device

Due to the abundance of equipment offered, the question arises, which welding machine for the installation of polypropylene pipes to choose?

There is no need to chase power or versatility here. You need to determine for yourself what diameters you will have to work with in the foreseeable future. In the vast majority of cases, these are products from 16 mm to 50 mm.

Based on this, nozzles for welding polypropylene pipes are also chosen. The choice of the power of the device is made at the rate of 10 W per 1 mm of pipe diameter, it is enough to have 500-800 W, it is enough to work with any products used in individual construction.

Sometimes you want to connect something from a sheet of polymer, such as polyvinyl chloride. In this case, a special one is used, if not, then an ordinary electric soldering iron.

For welding products of complex design and thin-walled pipes of large diameter, hot air guns and are used. They are indispensable in hard-to-reach places where it is impossible to locate traditional pipe welding machines.

July 28, 2016
Specialization: Capital construction works (laying of foundations, erection of walls, construction of a roof, etc.). Internal construction work (laying of internal communications, rough and final finishing). Hobbies: mobile communications, high technologies, computer technology, programming.

I have a neighbor (regular readers are already familiar with him in absentia), who began to make repairs in his bathroom and toilet. And since he had little money, he decided to install the pipes on his own. And if he succeeded with the sewage system the first time, then the welding of plastic pipes for the water supply caused some problems.

It seems that he also has instructions, and the device he bought (and did not rent) is far from the cheapest, and for some reason the connections are not airtight.

After spending some time, he again came to me for advice (by the way, we had a good time with a glass of tea last time). Well, why should I refuse a good person? We sat down in the kitchen with him, and I laid out the whole process for him on the shelves.

By the way, in this regard, there was a reason to tell you, readers, about how to choose an apparatus for welding plastic pipes and how to use it correctly.

General rules

As a practitioner, I know two ways to weld plastic piping parts:

with the help of sockets;
end-to-end.

Below I will talk about both technologies, but before that I would like to mention some general rules that will help you follow the recommendations below and achieve the best connection quality:

I always weld pipes only at positive air temperatures... Otherwise, the technological process requires serious changes, which negatively affects the tightness and durability of the connection.

For piping installation using the welding method, I always buy parts from one manufacturer and one variety to ensure the uniformity of the chemical composition of the plastic.

In this case, when heated at the same temperature and for a strictly fixed amount of time, the polymer acquires the same mobility, which ensures a reliable and waterproof connection.

It is about the same chemical composition of the pipes, and not about their color. Tinting is done by adding a small amount of dye to the raw material, which has no effect on the melting time of the plastic.

And never take pipes for work, the price of which is too low in comparison with similar parts. Most likely, this is a fake and you will not be able to hermetically join the pipes into a reliable water supply system.

The parts to be connected must be thoroughly cleaned of dust, dirt and grease stains.... It is the latter that greatly affect the quality of the welded. I always wipe down the ends of parts before welding with alcohol, white spirit, or other suitable solvent.

Also, make sure that the cloth you are using does not leave fibers (such as bandages) on the pipe.

Damaged polymer is also a factor affecting quality.... Sometimes pipes lie in the sun for a long time, and ultraviolet light destroys plastic. In this case, the damaged layer must be removed with a special tool or another part that has been stored correctly must be taken.
It is equally important to ensure that the pipes are dry.... Condensation sometimes forms on them, which will not allow welding products at the molecular level.

And the last point that I wanted to mention at the very beginning. Cooling of the joint after joining should take place in natural conditions. If you pour cold water on it or speed up the process with chilled air, you can achieve the opposite.

On the contrary, in some cases (for example, if the air temperature in the room is too low), it is necessary to slow down the process by insulating the fitting with a pipe with a cloth or heat-insulating material.

Socket welding

Welding plastic pipes is the most common way to join plumbing parts. It is used for joining products of small diameter, which are sufficient for the design of intra-apartment engineering systems.

General information

To connect polypropylene parts, so-called fittings are used - products in the form of corners, tees, bends, taps, and so on. They are made from the same type of plastic as the pipes themselves.

Previously, it was believed that additional fittings were a disadvantage of the technology for welding water pipes, but practice shows that this is how an effective engineering system can be designed without much expense and difficulty. For example, the corners allow you to rotate the pipe 90 degrees, absolutely without fear of reducing the diameter of the inner section of the product.

Briefly, I can describe the whole process as follows: when pipes are welded using the socket method, the surfaces of the elements to be joined are melted (for this, special equipment is used), after which they are connected, forming a strong connection with the mutual penetration of molecules.

Compared to butt welding, I think this connection is more reliable. The very fact that you insert one part into another during operation provides additional strength. In addition, in this way there is practically no need to worry about the correct alignment of the longitudinal axes of the pipeline.

But what can I say, several times, for the sake of interest, my wife tried to weld plastic pipes. And after a short training, everything turned out quite easily and quite reliably.

Required tools

For work, you definitely need a soldering iron for welding plastic pipes. This wonderful machine can also be called an iron or a welding machine.

Structurally, the tool is a heater with a special head on which replaceable elements with couplings and mandrels are put on. The latter are just needed for the simultaneous heating of the pipe, which is inserted into the sleeve, and the fitting, which is put on the mandrel.

As a result, the parts are heated evenly, which provides a reliable and completely waterproof connection.

My iron is equipped with heating elements made in the shape of an elongated triangle. However, the store sells many other models. The appearance of the soldering iron does not play any practical role.

When buying, pay attention to which pipes of which (maximum) diameter can be welded using the device model you like.
And also ask how many heating pairs (couplings and mandrels) can be installed at the same time.

I will give you a few more tips for free, which, I hope, will help you choose a high-quality and reliable tool that will be a pleasure to work with:

The larger the area of the heating element, the larger the pipe diameter can be soldered. The fact is that the couplings must be screwed so that their lower part completely touches the heater, and does not protrude beyond its borders.

The power of the soldering iron does not matter. If the working elements are installed correctly, the required temperature will be reached in any case. And the power only affects how long you have to wait for this moment.
In some soldering irons, the heating element is designed as a cylinder. Such devices take up less space than classic ones. As for other technical characteristics, I personally do not see any differences.

The type of temperature sensor installed in the device is important for operation. The more accurately it reads the metrics, the better the connection will be. That is, the higher quality welding machine you get.

It is best to choose a device with electronic control units, which read the indicators most accurately and in the maximum proximity to the working heating elements. Welding machines equipped with such sensors have less thermal inertia (they react more quickly to changes in device settings).

Capillary thermostats and bimetallic relays are not as accurate. They have a very large runaway between the value indicated on the scale of the device and the actual temperature of the heater.

Regardless of the type of relay used, I recommend that after the light comes on, indicating the heating of the device, wait a couple more minutes so that the working element is certainly brought into working condition.

In addition to the welding machine with the required number and mandrels, you need to stock up on other devices, without which pipe welding, although possible, is very difficult.

I advise you to have:

a device for chamfering from plastic pipes;
calibrator;
trimmer;
special scissors for cutting parts;
liquid degreasing the plastic surface.

Sometimes these devices are included with the soldering iron, but often they have to be purchased additionally.

Welding technology

If you have accurate measuring instruments, then you can experimentally make sure that the actual pipe diameter is slightly larger than the value indicated in the technical documentation. Accordingly, the actual inner diameter of the fitting is slightly smaller than necessary.

For example, if you buy polypropylene water pipes with a diameter of 20 mm, then their actual size will be 0.5 mm larger. Accordingly, the fitting will be smaller by 0.5 mm.

The rods and couplings of the heating device have a conical surface and exactly in the middle, if measured from the edge, their diameter becomes equal to the nominal one.

That is what I want to say. If you try to insert pipes into a fitting without heating, or slide them over a cold soldering iron, you will fail. This was done in order to ensure, after the end of all procedures, the most tight, tight and durable connection.

So, in the process of joining parts with the molten outer layer, a small part of the plastic is squeezed out, forming the so-called burr (low roller). And the inner layers of the pipe are compressed slightly to enter the fitting.

As a result, it turns out that the heated surfaces of the fitting and the pipe press a little against each other, displacing the air inside and ensuring the mutual diffusion of plastic molecules.

This I got a little lost in the direction of theory, which, however, you will need to understand the internal processes occurring during welding. As for the practical part, a short list will be given in the diagram, and I will tell you in detail about each stage further.

Pipe preparation

So, I'll start by preparing the pipes. First you need to cut them into pieces of the desired length. To do this, it is best to use special scissors, thanks to which the cut will be located strictly at an angle of 90 degrees.

There are mechanical devices on sale, but if you have a huge amount of work, you can also find units that operate on the electrical network. Although I have used a hand cutter all my life and hands, believe me, did not fall off.

After that, you need to prepare the cut pipes for the welding process. If you bought ordinary pipes, you just need to clean the end of dirt and debris, and then degrease the plastic surface using special solutions.

But often reinforced polypropylene pipes are used to design domestic water supply systems. For this, either aluminum foil or fiberglass is used. Such an engineering solution helps to reduce the coefficient of thermal expansion of plastic, as a result of which you do not need to install special expansion joints in the water supply and heating system.

Aluminum, among other things, excludes the penetration of oxygen into the water, which is very important for closed-cycle climate systems (airing of heating mains is excluded).

So, if you have to weld metal-plastic pipes, that is, parts with an aluminum reinforcing layer, you need to carefully clean off the entire foil layer with a shaver - a specially designed tool for this. If this is not done, you should not even dream of a tight connection between the fitting and the plastic pipe.

Fiberglass parts do not require special handling and can be prepared for welding in the usual way.

I met pipes on sale where the reinforcing metallized layer was located not next to the surface, but in the thickness of the plastic wall. Then, instead of a shaver, you need a special facing tool that removes metal from that part of the part that needs to be joined. Otherwise, water can penetrate through the reinforcement gap and cause swelling of the plastic.

To achieve the best result, couplings can be purchased that have a special design and are designed for reinforced pipes. During the soldering process, the plastic seals the hole with foil, completely eliminating water leakage.

To be 100% sure of the end result, I advise you to always calibrate the pipe from the outside and chamfer the end of the part. Sometimes the product may have a slightly elliptical shape, which is leveled by calibration. A small bevel will make it easier for you to install heated parts.

But this is my personal advice and such an operation is not provided for by the rules for installing plastic pipes.

Soldering iron preparation

So, we sort of figured out the preparation of the pipes, now I’ll tell you about how to properly prepare the welding machine for work, or, in other words, the soldering iron.

First of all, the device must be firmly fixed on special legs, in a bracket or on a suitable base. When you insert cold plastic parts to warm up, you need to apply some force. Therefore, in order to avoid deformation of the polymer, it is necessary that the sleeve and mandrel be absolutely motionless.

After fixing the entire soldering iron to its heating element, you need to screw the so-called pair - a coupling and a mandrel - the size of which will correspond to the diameter of the pipes currently being mounted.

Then you can turn on the appliance to warm up. After a while, it will heat up to a temperature of about 260 degrees Celsius. This far exceeds the point at which plastic becomes fluid. As a result, you can quickly melt the surface of the pipe and fitting without compromising the integrity of the depth layers of the part.

The end of the heating process is signaled by a light on the handle of the device (at least for me, but I don’t think that the device you bought is anything significantly different).

Warming up parts

As soon as the soldering iron has entered the operating mode, you can proceed to heating the parts. To do this, you must simultaneously put on the mandrel and insert the fitting and the pipe into the coupling, respectively. If you cannot do this at one time (you lack dexterity), first push the fitting, it is more massive because it can warm up for 1-2 seconds longer.

All products for the installation of a water supply system, as I said, have a special allowance. Therefore, when putting them on the heating element, you need to apply a little effort. However, it is important not to overdo it, acting gradually.

As the parts are put on, excess polymer will be squeezed out, forming a small sag (burr). If the parts for heating are installed too freely, I consider this a sign of marriage, I throw out the prepared pipe and fitting, starting the operation over again. Believe my experience, in this case, a high-quality connection will still not work.

It is important to feel the depth of installation of products on the heating element. As soon as the pipe rests against the bottom of the coupling, and the fitting against the edge of the mandrel, no more pressure is needed. Otherwise, you can jam the end of one part and the limiter of another, that is, everything will have to be redone again.

Some people make marks on the pipe with a pencil to understand how deep it should be inserted into the heater. However, I can tell you with confidence that you will feel everything in the process of work yourself, do not bother with the marks.

After installing the parts, you need to hold them on the soldering iron for some time so that the plastic surface has time to melt a little. It is very, very important here to maintain a specific period of time. If you overexpose - the pipe is deformed, underexposed - diffusion will be incomplete, the connection will be leaky.

Each manufacturer of plastic pipes provides tables by which you need to navigate. As an example, I will give the approximate parameters for polypropylene pipes of the PN20 brand.

You need to timed the time from the second you pushed the parts all the way. As soon as the required amount of time has passed, the products must be removed at the same time, also applying a certain, but not excessive force to this.

Assembling parts

After warming up, without hesitation for a second, you need to start welding. To do this, the pipe must be inserted into the fitting. Moreover, do this no later than 5 seconds after the end of the heating process. Otherwise, the plastic will cool too much. Either you will not be able to assemble the pipes at all, or the end result will be very far from ideal.

It is very important not to rotate the parts about the longitudinal axis during assembly. The maximum offset should not exceed 5 degrees. Otherwise, the tightness and strength of the assembly will also be violated.

Correctly done work will be evidenced by the influx of plastic (burr), which forms near the joint. It should be the same height around the entire circumference of the part.

Cooling of parts

After connecting the parts, they must be left for a while so that the polymer hardens. This only takes a few seconds, during which they must not be touched.

However, I advise you to allow about 2 minutes to cool down. During this time, the diffusion process will be completely completed and there is no need to worry about the strength of the knot.

Butt welding

In addition to socket welding of plastic pipes, which I described in detail above, the so-called butt welding is used in construction. Its essence lies in heating the sections of polymer parts with a special device (mirror) until melting, followed by joining under pressure until a sealed seam is formed.

The work technology is quite simple. The result is a very strong, tight and durable seam.

However, this is only at first glance, since I, as a person who understands this matter, can point out several features.

It is necessary to ensure very accurate alignment of adjacent parts along the longitudinal axis. After the end of the process, the walls of the pipes must coincide with each other by at least 90%.
When welding, a certain force must be applied to the products, pressing the part against the welding mirror. Then, exactly this should be done during the hardening of the seam.
When cutting parts and machining the end, you must carefully ensure that the cut is located at an angle of 90 degrees to the wall.

Everything here is quite simple, but only if you use a special device in your work - a centralizer, which is equipped with a special drive that provides the clamping force. You also need a pipe cutter and a trimmer.

Therefore, for the installation of domestic plumbing systems, where pipes of a small diameter are used, and the volume of work carried out is small, socket welding is used. Moreover, I will tell you, the resulting connections are almost stronger and more durable. In the latter case, a kind of castle is formed, which in no case will allow water to pass through.

Butt welding is more often used in the design of large trunk systems.

Typical mistakes when working

Now you know everything I could tell you about welding plastic pipes. I just want to dwell a little on the typical mistakes that beginner craftsmen make when welding pipes. They were the ones who prevented my neighbor from doing the job well the first time.

Dirty and wet parts

Any experienced craftsman, among whom I dare include myself, always wipes the end of the pipe and the inside of the fitting before starting soldering. This is done already at the reflex level. The fact is that during repairs, all parts are usually piled on the floor, which is hardly clean. Sometimes I had to dismantle improperly assembled pipes, and so, there usually was always a strip of dirt or dust.

Another worst enemy is moisture. Even a drop of condensed water evaporates when heated, which causes deformation of the joint. By the way, I have come across cases when such a "wet" connection withstood even preliminary tests, but during operation, cracks still appeared (in my case, after 5 months).

And once again, let me remind you about the foil. Not a single piece of the metallized layer should get into the joint, since you can completely forget about reliability.

And further, not only pipes need to be cleaned of dirt, but also the working element of the soldering iron... Sometimes traces of polypropylene remain on the sleeve or mandrel. They also need to be cleaned off with a rag before you solder the next node.

Incorrect placement

Once you have finished heating the pipes, you need to connect them immediately. And not just stick the part into the fitting, but position it correctly in relation to each other. This is where novice welders have problems.

Often, after the joint, beginners begin to rotate the products or move them relative to each other, which in no case should be done.

One more point. There is no need to remove plastic spills near the fitting before the connection has cooled down... Otherwise, you can easily deform the assembly, which will lead to depressurization. By the way, if you have warmed up the pipe exactly as much as indicated in the accompanying table, you will not have any sagging.

Poor quality material

Very often, a welded joint does not work if you saved money and bought low quality polypropylene pipes from an unknown manufacturer. I faced similar situations. So, even my experience did not help me weld such parts normally.

That's why you need to purchase materials only in a trusted store.

Some more "smart people" are trying to solder pipes from different manufacturers. I have already mentioned this. The unequal chemical composition does not allow the plastic to warm up properly, which leads to technology violations.

Violation of assembly rules

Here I will cite those violations that I most often met in my practice:

When assembling the unit, the pipe is not pushed into the fitting until it stops, as a result of which a gap forms inside. That is, the wall of the pipe will be thinner than it is provided by the technical conditions and when a force is applied (for example, water pressure) in this section, the part may burst.

During assembly, excessive force is applied to the pipe being inserted into the fitting. As a result, plastic sloshing at the cut, which reduces the internal section of the pipe or completely melts the hole. Both that, and another adversely affect the operation of the water supply system.
Use when assembling damaged fittings. For example, you are assembling a piping and you have only one elbow fitting and a crack is found in it. Instead of going to the store and replacing it, careless foremen install it in the system. I will not describe the consequences.

Output

As you can see, welding plastic pipes with your own hands is not as difficult as my neighbor imagined it to be. If you want to take a closer look at the process itself, you can watch the video in this article. I will also be glad if you share your own tips and stories about how you soldered plastic pipes. You can do this in the comments to this article.

July 28, 2016

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