Every year more and more often the design of plumbing and heating systems in apartments and private houses is carried out with the help of polypropylene pipes. Modern manufacturing techniques allow you to create durable communications that do not corrode. At the same time, the main task facing the builder is to create a high-quality connection of the pipes to each other, since the reliability of communication systems will depend on this. Therefore, the main methods of joining polypropylene products will be discussed below.
Figure 1. Special fittings have threaded threads on one side and a solder coupling on the other.
Methods for joining polypropylene pipes
Installation of plastic pipes is made fairly quickly and easily, so that even a person without special training can cope with this work. Connections can be detachable (threaded) and one-piece. In the first case, special threaded fittings are used, and it will not be possible to cut the threads yourself. Therefore, a sealant or Teflon tape is used to create a reliable fit.
Figure 2. Installation of polypropylene pipes using compression fittings.
Welding joints are more durable and reliable, but their creation requires special equipment - a device for welding polypropylene. In turn, welding can be socket-mounted or butt-welded. Each method has its positive and negative sides.
In most cases, thin-walled products are connected collapsible way. PN 10 pipes are widely used to construct warm floors, as well as to supply cold water. In a low-pressure and high-pressure heating system, PN 16 products are used to supply water. It is recommended to join pipes with a diameter of PN 20 and PN 25 using welding.Back to table of contents
Folding connection of polypropylene products
For fitting plastic products with metal elements (mixers, counters, etc.) special fittings are used, on one side of which there is a cut thread, and on the other side there is a coupling for soldering (Fig. 1). In this case, the thread can be both external and internal.
Installation of polypropylene pipes with steel using fittings as follows:
Figure 3. Diagram of flange connection.
- The end of a metal product is lubricated with oil or grease, and then threading is done (internal or external). If the fitting has an internal thread, the pipe must have an external one and vice versa.
- The thread is wound tow and processed with silicone.
- The fitting is screwed and clamped with a key, but without application of excessive force, as otherwise it may crack.
- A polypropylene pipe is inserted into the other end of the fitting, after which it is soldered.
Using such fittings, it is very convenient to create various twists and turns of communication systems. If you need to slightly change the configuration of the fitting, it should be heated to a temperature of about 135 ° C.
Another type of collapsible installation of polypropylene pipes is their joining using compression fittings. They are convenient in work and can be used to construct both cold and hot water supply. There is no need to use welding equipment. It is enough to have on hand scissors, shears and a set of wrenches.
Installation of polypropylene pipes using compression fittings is as follows (Fig. 2):
- a crimp nut is installed at the end of the pipe;
- a ring-type ring is installed on top of the nut so that its edge is at a distance of 1 mm relative to the cut of the pipe;
- the plastic pipe is put on up to the stop and fixed on the choke;
- a wrench nut is installed with wrenches.
Figure 4. The welding machine has nozzles in the form of a sleeve for heating the external surface of the pipe and a mandrel for heating the internal surface.
Flange joining is used for polypropylene products with a large cross-section. Such a connection allows, if necessary, to easily disassemble any part of the pipeline and eliminate the malfunctions that have occurred (Fig. 3). Also quite often the flange joint is used for the installation of plastic products with metal.
Installation of flanges is quick and easy. First, the end of the pipe is cut off smoothly, after which a flange and a rubber gasket are put on it. The same operation is performed with the other end of the pipe. After that, both flanges are connected to each other with bolts.Back to table of contents
Welding joint of polypropylene pipes
For welding products with a cross section of up to 6.3 cm, the predominant type is socket or socket welding. In this case, the joining of pipes is carried out with the help of the 3rd part - the coupling.
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To connect polypropylene pipes with a diameter of more than 6.3 cm, it is recommended to use a butt welding method.
Coupling welding of polypropylene pipes
Figure 5. Table welding time of polypropylene pipes.
A special welding machine with nozzles (Fig. 4) is used for welding plastic products. The heating elements are made in the form of a sleeve for heating the outer surface of the pipe and the mandrel for heating the inner surface. Standard nozzles are equipped with a teflon layer and have a diameter of 1.6 to 4 cm.
The welding machine is installed on the table or another horizontal base, with the help of special keys replaceable heating elements are fixed. After that, the required temperature is established at which the apparatus warms up for 10 minutes. The welding time of polypropylene pipes depends on their diameter (Fig. 5).
Coupling welding is performed as follows:
- the ends of the connected elements are placed on the nozzles;
- according to the table, the required melting time is maintained;
- plastic products are removed from the nozzles and connected to each other;
- The required cooling time is maintained.
Butt welding of polypropylene pipes
This type of welding can be performed between products with a wall thickness of at least 4 mm. If their diameter exceeds 5 cm, then a special stationary welding machine is used for work. Such a device is also used in the case when it is necessary to obtain a high-precision welding seam.
Before starting the installation work, the connecting ends should be cut off, which will ensure their parallelism. After that they are amenable to heat treatment using a special heating disc. In the course of work it is recommended to use centering equipment. The sequence of connecting works is similar to the socket welding.
There is nothing difficult about joining polypropylene pipes. As with most building technologies, proper implementation of all established standards is required. In this case, the process will be carried out not only quickly, but also will allow to achieve high-quality results.