Modern technology of welding of polyethylene pipes

The technology of welding of polyethylene pipes may be different. Such pipes are now found everywhere, so the question of working with them is relevant. Today, there are several technologies for welding of polyethylene pipes.

Soldering iron for welding of polyethylene pipes

Soldering iron for welding of polyethylene pipes.

Diffusion welding of polyethylene pipes

At first glance it may seem that polyethylene is not a serious material. But it is not. Modern production technologies provide not only its high quality, but also good reliability.

Welding of polypropylene pipes

Welding of polypropylene pipes sober.

One of the easiest ways of welding is considered diffusion. It does not require special equipment, which will greatly facilitate the work of a beginner.

High and low pressure polyethylene is one of the types of thermoplastic polymers. In the process of heating, this material first of all becomes soft, and then under the influence of temperature it melts completely, since the molecules cease to be in the same chain with each other. But as soon as the heat ceases to act, everything returns, that is, the polyethylene becomes rigid again. And this moment is suitable for mixing two plastic parts. After performing such an operation, a welding seam is obtained, which is a restraint between two blanks.

The convenience of polyethylene lies in the fact that for the implementation of melting it does not require too high temperature, enough and 270 °. Moreover, the time spent on this is very little, it depends on the thickness of the working material. Therefore, this type of work does not require a powerful installation at hand.

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Equipment for welding of polyethylene pipes in the diffusion method

As already noted, this type of work is elementary in the implementation and application of special equipment.

Cold welding scheme for PVC pipes

The scheme of "cold welding" of PVC pipes.

The standard set of tools in this case will not be able to do without:

  1. Truboreza. Special installation in the form of a guillotine, which is designed to divide the whole pipe into separate components of the required size.
  2. Calibrator. With this tool, you can restore the shape of the diameter of polyethylene pipes after they are trimmed.
  3. The pickup. As the name implies, this tool works with end bevels of pipes, giving them the necessary shapes.
  4. Welding installation. With the help of this apparatus, high temperatures are produced, which melt the material. If you objectively evaluate, then such a welding machine is an analogue of a soldering iron.
  5. A set of nozzles with a specific caliber. They are needed in order to conduct the required temperature at the desired points of welding, and their diameter corresponds to the cross section of the pipe with which the work is performed.

Of course, one cannot do without measuring roulettes and rulers in this matter. To work with clean surfaces, you need to stock up with unnecessary rags to clean off all the dust and dirt. You may also need keys to install nozzles on the heating rail, screwdrivers for working with the contacts of the electric coupling. In general, all these tools are in the household of any man, or you can ask them from a neighbor.

If you still have to buy them, the cost is not so high.

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Requirements for welding of polyethylene pipes

There are three types of joining polyethylene pipes:

  • in the butt;
  • into the socket;
  • into the clutch.

Each of these options has its own technology. However, there are general requirements for the welding process.

Pipe welding time

Pipe welding time.

In order for the work to be performed to have the appropriate quality, all polyethylene pipes must be from the same batch of the same manufacturer. The difference may not be visible, but the factory production is also not insured against marriage. Even if in millimeters, but the same diameter may differ in different batches.

One batch guarantees a uniform chemical composition of the material and its thickness. These indicators in many respects influence the duration of welding, namely, the heating. If the work will be carried out with different pipes, then one element may not melt, and the second, on the contrary, may be melted. As a result, it turns out defective seam, which is not subject to high-quality operation.

The quality of the alloy depends on the purity of the material. At the ends of the pipes should not be any pollution. Any particles of sand, dust or dirt will prevent the creation of an airtight joint.

A very important point - the weather conditions. It is very detrimental to the welding of polyethylene affect rain, sun and frost. Such negative factors make it difficult to create a reliable connection.

As already mentioned, the process of polymer welding involves the melting of the material, and then its freezing. Until the new seam completely hardens, it cannot be touched, so as not to deform. Such amendments simply violate diffusion.

So, we consider each type of welding separately.

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Butt welding of polyethylene pipes

This method is suitable for pipes with wall thicknesses from 5 to 50 mm. This type of connection is made by heating the ends of the pipes, after which their joints are pressed.

Scheme of butt welding of polyethylene pipes

The scheme of butt welding of polyethylene pipes.

To make butt welds, you must act as follows:

  1. Each pipe end to be welded is placed in a special machine that is designed for welding. There are special clamps that secure the segments.
  2. After fixing, the edges of the pipes are leveled, that is, all excess material is removed with a cutter. After that, the pipeline is aligned until the longitudinal axes of both segments coincide.
  3. After alignment, a heating plate is inserted between the ends to soften the material.
  4. Once the polyethylene is ready, the plate is removed. The ends are reduced to each other and compressed with the application of precisely calibrated force.

As a result, you can see at the junction of the annular seam.

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How to weld polyethylene pipes in the socket

The split is the expanded part of the product.

This type of welding is carried out by entering a narrower part of the pipe into a wide one. It should be noted that the sockets can be on the pipes initially or they can be welded separately. If the second option is used, then a smooth-wall coupling is used for this. And later on, the ends of both pipes are attached to it by welding.

Butt-Weld Pipe Errors

Butt-welding errors.

This type of welding is financially more expensive than the previous equivalent. This is influenced by the number of stitches, and the purchase of an additional element - the clutch.

The stages of welding of polyethylene pipes in the socket:

  1. The first step is to trim the edges of the pipes, observing a right angle. After that, they are given the necessary shapes with the help of a calibrator and a pick-up unit.
  2. All working materials are put in order, cleaned of contamination. It is also necessary to prepare the welding machine, having established on it a nozzle of the corresponding caliber.
  3. The soldering iron itself is connected to the mains and heated to the required temperature indicators. After the tool is ready for operation, the coupling is put on the body of the first caliber, and the tube itself is inserted into the bowl of another caliber. After a certain time, a soldering iron will soften the material from the inside of the coupling and from the outside of the pipe.
  4. As soon as this happens, the blanks are removed, the pipe is inserted into the sleeve. In this position, the joint is fixed for 20 seconds, after which it can be released.

Each subsequent seam is created in the same way.

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Welding of polyethylene pipes using an electric type coupling

This type of welding requires an ordinary transformer, because the electric coupling keeps all the heating elements inside. The welding process itself is carried out by connecting its terminals to the wires and timely switching on the current.

Preparation of pipes for brazing and direct welding

Preparation of pipes for brazing and direct welding.

The welding process is as follows:

  1. Initially, it is necessary to cut the end of the pipe at an angle of 90 °, after which the chamfer is removed. The other end of the pipe being joined is processed in the same way.
  2. Next, the material is cleaned up, after which the pipes must be inserted into the electric coupling. Then the clutch terminals and transformer wires are connected.
  3. After the transformer is connected to the mains, it will begin to activate the hidden plates. It is necessary to wait until they soften the inner part of the coupling. After this has happened, the equipment is turned off.
  4. After a short time, the wires and terminals disconnect.

This method of welding is convenient because it does not require experience or any specific knowledge in this area. But as a drawback it is worth noting the cost of such work. Electrical clutches are quite expensive.

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Low-pressure polyethylene

Pipes made of low pressure polyethylene (HDPE) are widely used in the replacement of iron, cast iron and plastic pipes. And all this is due to the fact that such a product has a rather long lifespan, especially if we compare it with steel, asbestos-cement or reinforced concrete analogues. The process of their installation is nothing complicated, although in many respects this merit belongs to modern welding machines.

Scheme of connection of pipes by coupling with inset heater

Pipe connection scheme with a coupling with a mortgage heater: 1 - a pipe, 2 - a label for the fit of the coupling and machining of the pipe surface, 3 - a coupling, 4 - a mortgage heater, 5 - a current-carrying (welding) cable.

But before you start welding, you need to complete a few points:

  1. Prepare a workplace. There should be no foreign objects on the site. If there is any garbage, it should be eliminated. Only after this, all necessary welding equipment and tools are installed on the site.
  2. All elements (pipes, fittings, etc.) that will be involved in welding must be clean. Therefore, they are pre-wiped with rags.
  3. Next, connect the pipe with fittings.
  4. We must not forget that all edges must be properly prepared.

Often, each manufacturer equips their product care instructions. This is correct, because good care is a guarantee of high-quality material and long service life. It is necessary first to make sure that all the structural elements are intact.

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Little about the preliminary work

Since the welding machine is far from cheap and not safe equipment, it requires preliminary work, namely:

Diagram of the change in pressure during the butt welding process

Diagram of the change in pressure value during the butt-welding process.

  1. First of all, all parts of the welding machine should be subject to mandatory inspection.
  2. The insulation of earthing and all electrical wires is checked.
  3. Do not forget about the fuel. Therefore, if it is not, then it refuels. But here you should know that if the device has not been used for a month or more, the old fuel is better to be drained and refilled fresh.
  4. Checks the performance of the device. To do this, use the control inclusion.
  5. Each welding machine has oil in its hydraulic system. Its level should be controlled, and in the same way as fuel.
  6. Many welding machines are mobile. Their movement must occur freely, otherwise, during welding, situations may arise where the welder does not help, but only hurts.
  7. Examine the extent to which the sharpening process of the butt-end knives occurs.
  8. All control and measuring mechanisms must be fully operational.
  9. During the work with pipes of low pressure special clips and reducing inserts are applied. Therefore, it is necessary to take care of this in advance so that their diameter matches the pipes.

We should not forget that all friction parts must be lubricated. But before you carry out the lubrication, it is necessary to know the requirements of manufacturers, which indicate all permissible lubricating compositions.

If the device was previously used, it must be cleaned, since there may be any contamination on the surface of the heaters, the scraper and the end sealer. Including the remains of polyethylene. To do this, use a cloth moistened with a solvent.

All the above requirements are a guarantee of high-quality and reliable operation of polyethylene pipes.

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