How to weld a pipe to a pipe? Types of pipes, welding equipment

The need for making connections between the engineering contours of the pipeline occurs when both the first gasket and during the repair operations are performed. A feature of pipe welding in communication systems is the mandatory provision of tightness. Only in rare cases this aspect has no special significance, and it can be neglected. In search of an answer to the question of how to weld a pipe to a pipe, one can not do without the description of modern technologies. First of all, this applies to plastic materials, which not so long ago became widespread in the market and quickly introduced a new soldering method into the assembly work. But traditional metal pipes are welded on a modern and more technological level, rather than 10-15 years ago.

What kinds of pipes can be welded?

The entire range of pipe material used in water, gas and heating systems can be divided into two types of material: metal and plastic products. In both cases, the pipes can be welded, otherwise installation work with them would be impossible. Of course, as an alternative, we can recall the threaded connection method, which used to be applied to complex steel structures, but this technique has long been obsolete and is not used. Nowadays, steel pipes are welded by means of electric arc devices, which make it possible to provide strong joints. The technology of working with plastic pipes differs somewhat. In this case, the problem of using classical welding is due to the softness and viscosity of the material structure. Therefore, soldering and melting methods are used, which are also included in the general group of welding technologies. At the same time, the technical means for implementing such types of connection are significantly different from traditional welding equipment.

Equipment for welding

The most popular device for electric arc welding of metal pipes is a semiautomatic inverter type. In the process of working to protect the working area from external influences, a special gas is used, which allows achieving a high degree of accuracy and tightness in the seam. The popularity of machines for manual arc welding of MMA is declining. This is an affordable and easy way to get a seam with high mobility of equipment, but it has significant drawbacks, among which low productivity and the formation of slag on the surface of the seam that has to be removed. As for the technique for welding plastic materials, the most commonly used are pressing complexes for soldering. Both modern polypropylene pipes and PVC models are welded in a machine that has a face, gripping vise, a cutting plate (heating element) and a device for sealing seams in the design.

Preparation of metal pipes for welding

Pipes are carefully cleaned in order to maximize fit to each other. Both docking sides must have a chamfer located at a 45-degree angle relative to the axis of the pipe. In this case, a flat butt with a width of at least 2 mm should remain. However, the specific parameters may differ depending on the pipe diameters. No less important in the question of how to weld the pipe to the pipe, correct alignment. Immediately before the operation it is necessary to assemble - so that the maximum accuracy in cutting the edges of the two welded components is ensured. In some cases, a tack is performed, that is, a short seam is formed, which during the assembly process acts as a patch in the structure.

Electrowelding of metal pipes

First of all, the "grounding" clamp should be made. The cable must be isolated and fixed in a special holder. On the welding machine, the optimum current power rating required for a particular material is set - the average values are required for soft alloys, and the higher values are suitable for alloy steels. Then the arc is clamped, and the electrode is placed at a 60-degree angle relative to the workpiece. From this moment, by touching the arc of the working surfaces, welding of metal pipes begins, which can be accompanied by the formation of sparks. The electrode must move slowly, but so that no sticking occurs. If there is a delay in one place, there is also a risk of excessive deformation. Avoid this will allow a uniform arc over the entire surface. As a result, a strong wavy seam should form.

Preparation of plastic pipes for welding

First, the pipes are cut to size in accordance with the sufficient length of the planned structure. That is, it is desirable to organize a general installation process in such a way that welding was the final stroke. This is not always feasible, but if possible, all technical work with the pipeline should be carried out before welding activities. Also, it will not be superfluous to leave a small stock, so that part of the product could be introduced into the fitting. Then, as in the case of metal analogs, polyvinylchloride and polypropylene pipes are cleaned. The main task at this stage is to get smooth, clean and tidy edges. The reliability of the future seam depends on the quality of the edges of the pipe. This is especially true for plastic products, since in a soft structure the smallest burrs and irregularities are of great importance in the soldering process.

Connection of plastic pipes

Large complexes for welding plastic pipes usually have a fixed installation and allow in-line production of joints. The processes of single soldering operations are a little more complicated. For such purposes, manual devices are used that work with heating elements in the form of nozzles. Before work it is necessary to install the device on a flat surface, and also to set the optimum temperature regime. For example, welding of PVC pipes is usually carried out at 260 ° C. In 10-15 minutes. After switching on the device will gain the optimum temperature regime, it will be possible to start the operation.

On the nozzles are installed workpieces for connection - on the mandrel fix the fitting, and on the sleeve is installed the pipe. The operation itself takes several minutes, as the plastic melts quickly. Therefore, after the device is turned on, prepare to complete the process. Direct welding of PVC pipes with the subsequent connection is made from the first time by one action. The resulting joint in the first seconds can not be turned and try to adjust, since any changes after welding will affect the strength for the worse.

How long does it take to cool the material?

In the case of metal pipes, the process takes longer and, as a rule, the formation of the joint is done layer by layer. Therefore, the structure is gaining strength already in the course of working events. After work, it is sufficient to wait until the junction site has cooled naturally. It takes a few minutes to wait, if welding the joints of plastic pipes. Depending on the thickness of the product and the depth of welding, this interval can vary from 3 to 20 minutes. It is important to note that in the work with metal, and during the adhesion of plastic elements, it is impossible to use means that accelerate the cooling process.

How to weld a pipe to a pipe at different cross-sections?

Sometimes due to certain reasons, caused by non-standard design execution of the pipeline, one has to deal with different sections. For example, there may be a need for joining a classical circular pipe and a workpiece with an expanded cross-section. In this case, an angle is welded to the ordinary pipe, in which the width of the shelf corresponds to the radius of the circle. The operation is performed only on one shelf. Further, the technology of welding pipes with different cross sections provides for ignition of the arc on a thicker material. By redistribution of the formed weld metal, it is necessary to make a joint over the entire joint area - it is obvious that in this case it will be larger than in the standard welding.

Conclusion

New technologies have made it possible to simplify the welding processes of different materials, greatly expanding the installation possibilities. Today, in questions as to how to weld a pipe to a pipe, there are practically no technical limitations. Arc welding, for example, allows you to work with all materials that are used not only in domestic, but also in the industrial economy. There are no barriers for the installation of plastic pipes, which are easily connected by soldering equipment.