The advantages of flexible plastic pipes cause the replacement of obsolete metal counterparts. This process is especially evident in sanitary structures. Polymeric materials are easy to use and at the same time are almost as good as metal in terms of technical and operational qualities. But along with the replacement of the material, the methods of its processing also change. A rather specific operation in terms of technical support is the welding of polyethylene pipes, during which it is necessary to use special fixing and heating devices. With the qualitative implementation of this procedure, it is possible to obtain a sealed and resistant to external influences place for splicing two elements.
Technology overview
To connect two plastic pipes, the method of joining their surfaces under the influence of heating, which is performed by a metal tool, is used. As a result of direct contact with heated surfaces, intensive heat transfer is ensured. This property distinguishes the technology from air heating. This way of distributing heat in plasticmass has a positive effect in terms of the formation of a reliable structure and does not imply thermal stress with subsequent deformation of the joints. In addition, butt welding of polyethylene pipes allows you to form joints that are as strong as a solid structure. The process itself involves heating the end surfaces of two elements to a molten state and their further reduction into one segment. But with all the outward simplicity, this technology requires accuracy in execution, which largely depends on the tools used. It should be noted that modern high-tech machines for plastic welding minimize the influence of the human factor, but do not completely exclude it.
PE pipe welding equipment
Even small-scale welding events of this kind involve the use of a whole group of technical means. The basis of such equipment is the centralizer, which provides clamping of two pipes for further assembly operations. Also, a special frame is used to fix the centralizer itself. To activate the work of the movable clamps, a hydraulic system is used, which operates due to a mechanical drive. However, there are different types of equipment that perform this function. On the market you can also find a universal apparatus for butt welding of polyethylene pipes of various sizes. As part of such devices, kits with nozzles with a diameter of 20 to 75 mm are usually provided. This is the best option ifit is planned to perform installation actions in domestic conditions. For more complex tasks, you will need a set of several functional parts that form a single welding complex.
Centralizers for pipe welding
At first, this technology was used exclusively in working with pipes, one of which was stationary, that is, it was already part of the communication network. This made the task easier, as the accuracy of the connection increased. Problems arose in working with two movable pipe ends, for which the base centralizer was introduced. This is a device due to which the welding machine for welding polyethylene pipes provides high accuracy in the formation of the joint. It is required first to achieve the alignment of the ends, and after that the operator performs their reduction. By design, the centralizer resembles a massive clamp system made of two metal parts. Although such units are somewhat universal equipment, they should still be selected for pipes with target range sizes.
Hydraulic units for welding
In the process of welding, mechanical action is provided on the pipes in order to move them along the axes or towards each other. To perform this function, the mentioned hydraulic unit is used. Usually it forms a single complex with the centralizer, providing its control. In the simplest configurations, equipment for welding polyethylene pipes performs only fixation and soldering of elements. Morecomplex systems require the user to control the pressure applied to the hydraulic machine, to accurately fit pipe ends, and to directly control the clamps of the centralizer. All these functions can fall on the hydraulic unit. Especially to simplify these operations, manufacturers supply equipment with ergonomic control panels, including those with automatic systems.
Flat cutters and heaters
The welding operation is foreshadowed by the preparation of pipes. In particular, with the help of a trimmer, the edges and planes of the elements are somewhat polished in order to ensure their tight fit. As for the heaters, they are integrated into a complex consisting of a hydraulic machine and a centralizer. By design, this component resembles a large pancake, which is placed between the ends of two pipes, ensuring their heating. This part is also controlled through a special remote control. If this unit for welding polyethylene pipes is used on a regular basis, then it is included in a single design with a centralizer. It usually acts as a flip-up accessory despite the importance of the heating function. It is also worth noting that the heaters must have special Teflon coatings, which allows them to be easily removed after the pipes are melted.
Preparation for welding
Work begins with immersion of pipes in the centralizer and their subsequent fixation. Pipes should be securely fastened so that they can also be moved smoothly. howAs a rule, one part is fixed rigidly, while the other moves due to the force of a hydraulic machine. If necessary, do-it-yourself welding of polyethylene pipes can be performed without a trimmer. In this case, the mating surfaces must first be cleaned with a grinding tool. If there is a trimmer available, then cleaning is carried out directly on the centralizer, after which the resulting chips are removed from the outside and from the inside. Next, you can proceed to the control fit. It is important that the pipes fit together with a minimum clearance and deviations in planes. Small errors are compensated by welding, but even in this case, the unevenness of the plastic mass in the joint zone will be ensured.
Heating pipes
Perhaps this is the most important stage, since it involves heating the plastic. First of all, the heated disk must reach a sufficient temperature. After that, it is located between two ends, which are pressed to ensure preheating. The force should be small, but sufficient so that the material of the two pipes is melted and tightly converged. In order to obtain high-quality welding of polyethylene pipes, it is necessary to control the thermal effect. It can be monitored visually - the optimal mode provides for the melting of the ends, but subject to the preservation of the viscosity of the structure. The result of this stage should be the formation of a small roller of the molten mass, which will slightly go beyond the edges of the ends.
Swap
After heating the ends, it is very important to remove the hot tool in a timely manner and re-combine the surfaces to be welded. It is important that the pipes maintain the overall integrity of their edges at future joints. The maximum time period during which this action must be performed is 25 seconds. But this is true for large pipes, the diameter of which is 60-75 mm. For a household PVC plumbing pipe, this figure is about 5-10 seconds. A high transfer rate is required because the material cools quickly without the support of a heater. As a result, butt welding of polyethylene pipes may lose quality due to loose adhesion of the ends. On the other hand, haste is not always good either. Violations in the accuracy of mixing elements are no less dangerous from the point of view of the formation of a high-quality seam.
Draft pipe
The essence of the draft lies in the correct formation of the seam and bringing its grant to an optimal state. After the joining of the ends without a heater is completed, the stage of complete cooling of the material begins. During this period, it is also possible for the plastic mass to go beyond the edges - this will be the creation of a quality grant. It is desirable that the formation of a new layer of outgoing plastic occurs against the background of its mixing with the burr obtained before the rearrangement. In this way, deeper welding of polyethylene pipes with optimally mixed structures of the two materials will be obtained. Usually, in order to achieve a good result after repositioning, operators increase the clamping force, which tightensend faces.
Material cooling
The final formation of the weld with the fixing of its structure occurs in the cooling stage. The acquisition of strength in the joint zone occurs due to the fact that the places of the pipe walls adjacent to the resulting seam increase in thickness. By the way, this means not just the formation of a reliable joint - such sections, as a rule, turn out to be mechanically stronger than the original structure of the material. This indicator can be artificially increased due to more intense heating, which allows welding of polyethylene pipes within the limits of technological limitations. The very same cooling should occur naturally and at room temperature. That is, it should not be helped to accelerate cooling, as this may adversely affect the future qualities of the seam. After complete cooling, the pipe should be removed from the welding unit, after loosening the clamping force.
Conclusion
Technologically, the process of connecting plastic pipes is much simpler than welding metal counterparts. However, PVC materials that are popular in our time have appeared recently, and therefore the methods for processing them are not so common among home craftsmen. In fact, welding of polyethylene pipes is carried out easily and with little or no investment in consumables. The main thing is to purchase the appropriate equipment. For work with small diameter pipes, compactdevices in which all the main functional parts are already provided. Another thing is that in everyday life the need to perform such operations occurs quite rarely, although the quality of the result of such welding cannot be repeated in any popular way.
