Overhaul of any building and premises involves the replacement and repair of many communications of the heating system, water supply and sewage. But most often, a complete replacement of communications fails. So, repair in one of the apartments of an apartment building does not mean replacing pipes in neighboring rooms. That is why there is a need to dock metal pipes with modern polypropylene products.
Correct adherence to the technology of transition from metal to propylene is a guarantee of the reliability and durability of operating communications. In this case, it is necessary to know well the features and characteristics of the materials used, and to be able to prepare the blanks for joining.
Features of metal pipes
It is worth noting immediately that the transition from metal to polypropylene using copper or aluminum pipes is extremely rare. This is due to the small use of such pipelines in communication systems, except in the distribution circuits of the elevator node of the heating circuit of a private house.
Most often, the transition from metal to polypropylene without thread is necessary during the long-term operation of solid pipes of increased strength, which were connected using threaded inserts. During 15–20 years of operation, metal products retain their practical properties, while welded and threaded sections become completely unsuitable for the further performance of their functions. It is in the joints that the effect of metal corrosion is most pronounced. Therefore, there is a need to replace an unreliable site.
Types of metal pipes
In the water supply and sewage system, the following types of metal pipes are most often used:
- The most widely used steel products. But due to susceptibility to corrosion and a decrease in diameter inside the pipe, due to overgrowing with scale, there is a deterioration in performance.
- Galvanized steel pipes are less susceptible to corrosion, but their use is limited due to the complexity of assembly work.
- Big problems also arise when processing stainless steel pipes. The high cost of this material significantly reduces its use.
- Cast iron products are widely used in sewers. This metal has great strength, but has a fragile structure, which is also the reason for the failure of cast iron products.
Therefore, in modern heating systems, the transition from metal to polypropylene is the most common, due to the characteristic properties of the latter.
Properties of plastic pipes
The modern materials from which pipes are made are popularly called plastic, but this means a fairly wide range of different products.
There are several types of pipes made from materials that have their own special properties and characteristics. The main types of plastic pipes most commonly used in water supply, sewage or heating systems are:
- Products made of polyvinyl chloride are most often used in the construction and repair of sewer networks of various industrial and domestic facilities. In heating systems, such pipes are not used.
- Polyethylene pipes have high ductility. They are used for cold water supply, as they are able to withstand fluid temperatures up to 80 .
- Polypropylene products are widely used for heating and hot water, as this material is characterized by increased hardness and the ability to withstand higher temperatures. Such pipes can be used even without a metal reinforcing mesh.
The main joints of pipes
The main places of transition from metal to polypropylene are:
- Overhaul in a separate apartment of an apartment building implies the replacement and modernization of some communication systems, which creates the need for joining metal and plastic products.
- In heating systems, connecting a heating boiler to distribution circuits also involves joining two different pipes.
- You also have to connect the plastic wiring of any house with the places of connection to a common water supply and sewage line.
These are only the three main, most common places for joining products from heterogeneous material. There are other situations when you need to make the transition from metal to polypropylene. The laying of pipes under the roads is carried out only by metal products, which is also the need to create special places for connecting pipes from various materials.
The main ways to make the transition
When choosing the method of transition from metal to polypropylene, it is necessary to take into account the properties and purpose of the trunk system, as well as the diameter of the pipes used.
Most often, two transition methods are used to create a high-quality connection of dissimilar parts:
- Using special flanges.
- Docking is carried out using a special device - a fitting.
The question of how to connect the pipes is decided depending on the availability of docking.
Flange device
The flange transition from metal to polypropylene is mainly used for reliable connection of large diameter pipes. The place of joining of pipes using flanges is quite durable and tight. At the same time, there is the possibility of dismantling the connection, i.e., the docking is collapsible. This method allows you to make the necessary repairs of the installed equipment, followed by the connection of sites.
The flange consists of the following parts:
- the body of the product, which is made of steel or cast iron;
- a special metal ring is installed between the two flanges;
- inside the housing there are O-rings, which create a good tight connection;
- between each other two flanges are fastened with special fixing bolts.
Flange connection method
The technological process of transition from metal to polypropylene without thread, using flanges, is as follows:
- A neat cut is made at the junction, without end facet. The cut is made strictly perpendicularly, without burrs.
- Then, a flange is put on the cut.
- A special rubber gasket is put on the pipe. At the same time, it should be located 10 cm from the edge of the pipe.
- A flange is pushed onto this seal, and it is fastened to the counterpart of the flange, which is worn on the second pipe.
- Tighten the bolts evenly, without much effort.
Coupling connection
Installation of the transition from metal to polypropylene with a sleeve is performed according to the following scheme:
- Strictly perpendicularly performed cut at the end sections of the parts.
- Then apply the coupling so that its center is located exactly at the place of docking.
- The position of the connecting element is marked with a marker.
- Then the connected ends of the parts are coated with special silicone grease.
- According to the label, one end of the parts to be joined is inserted, and then the other pipe. In this case, it is necessary to strictly monitor the correct installation on the axial line of both parts. The previously made markings will serve as a guideline for the installation of the coupling.
This method of connection is characterized by good tightness and durability of the joint. When switching from metal to polypropylene, the pipe diameters should be the same.
Docking dissimilar pipes with fittings
A fitting is a special device with which you can connect parts made from different materials. There is a thread on one side of the fitting with which the element is attached to a metal pipe. The other end of the fitting is smooth for secure attachment of plastic products.
The process of using fittings for the transition from metal to polypropylene is as follows:
- The end of the metal pipe is stripped, and thread cutting is performed using a thread cutter. You can also weld a special squeegee, but this will require a welding machine.
- After threading, it is necessary to thoroughly clean the joining point of burrs and chips.
- Then a special tape is wound clockwise, which gives the connection a high tightness. In this case, the tape is lubricated with silicone sealant, the number of turns is selected empirically.
- Next, the fitting is screwed onto a metal pipe without much effort so as not to damage the housing of the element.
- The next step is to connect the polypropylene pipe to the other end of the fitting.
GEBO Fittings
This name was given to special devices for connecting pipes. They are named after the company GEBO, which was the first to develop and master the production of compression fittings. The transition from metal to polypropylene without Gebo threads can be used at liquid temperatures up to 90 ℃, which makes it possible to use them both in hot water supply and in heating systems.
Devices can be of two types:
- one-sided, which have on one side a threaded part for connection to a metal pipe, and the other side are connected through a compression ring to a polypropylene product;
- double-sided fittings are equipped with compression rings on both sides.
Device and installation of compression fitting
The compression type fitting housing has a special conical recess in which a conical rubber ring is inserted for sealing. Then a clamping ring is installed, and then a special crimping device, which is cut into several teeth.
The tightness of the connection is created by indenting the gasket while tightening the special nut. At this time, the teeth of the crimp ring are pressed into the end of the part, creating a tight connection.
To obtain a strong and tight connection, it is necessary to pre-clean the ends of the joined products.
American fittings
Such modern devices were developed in the United States, hence the name came from. "American" appeared on the domestic market of plumbing materials relatively recently, but quickly gained wide popularity during the installation and repair of many systems. Such popularity was ensured by the possibility of creating reliable and quick pipe connections in hard-to-reach places.
The transition from metal to polypropylene "American" can not be called a specific method of connection, this principle of operation of the device combines various fittings. The main element that significantly distinguishes this type of connection is the union nut.
Of the advantages of this design, we can distinguish:
- A device for the durable connection of dissimilar materials, in which the pipes do not rotate, but remain stationary. This property is important when working in hard to reach places.
- Creating a reliable connection of pipeline sections from various materials.
- Obtaining a detachable connection, which is important when carrying out repairs on various plumbing systems.
- High tightness of the joint, which is achieved by the presence of a special gasket.
The tightness of the connection is achieved by clamping the gasket while screwing the union nut. The use of this design allows you to connect pipes of various diameters. The transition from metal to polypropylene of the 32nd pipe diameter, which is most often used in water supply systems, is quick and easy.
Remember that, if necessary, to repair certain sections of sewage, heating and water supply systems, the use of modern flanges, fittings and couplings will completely eliminate welding from the process. To carry out such repairs is within the power of any home owner on their own, without the use of expensive equipment.