The overhaul of any building and premises involves the replacement and repair of many communications of the heating system, plumbing and sewerage. But most often it is not possible to make a complete replacement of communications. So, repair in one of the apartments of an apartment building does not imply the replacement of pipes in neighboring rooms. That is why it becomes necessary to join metal pipes with modern polypropylene products.
Proper adherence to the technology of transition from metal to propylene is a guarantee of reliability and durability of operated communications. At the same time, it is necessary to know well the features and characteristics of the materials used, and be able to prepare blanks for joining.
Features of metal pipes
It should be noted right away that the transition from metal to polypropylene using copper or aluminum pipes is extremely rare. This is due to the low use of such pipelines incommunication systems, except perhaps in the distribution circuits of the elevator unit of the heating circuit of a private house.
Most often, the transition from metal to non-threaded polypropylene is necessary during long-term operation of hard pipes of increased strength, which were connected using threaded inserts. Metal products during 15–20 years of operation retain their practical properties, while welded and threaded areas become completely unsuitable for further performance of their functions. It is in the places of docking that the effect of metal corrosion is felt most pronounced. Therefore, it becomes necessary to replace an unreliable section.
Types of metal pipes
The following types of metal pipes are most often used in the water supply and sewerage system:
- The most widely used steel products. But due to susceptibility to corrosion and reduction of the diameter inside the pipe, due to overgrowth of 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.
- Also big problems 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 brittle structure, which is also the reason for the failure of cast iron products.
Therefore, in modern heating systems, the transition frommetal to polypropylene is the most common, due to the characteristic properties of the latter.
Properties of plastic pipes
Modern materials from which pipes are made are popularly called plastic, but this implies a fairly wide range of different products.
There are several types of pipes made from materials with their own special properties and characteristics. The main types of plastic pipes most often used in water supply, sewerage or heating systems are:
- Products made of polyvinyl chloride are most often used in the installation and repair of sewer networks of various industrial and domestic facilities. Such pipes are not used in heating systems.
- Polyethylene pipes have high plasticity. Used for cold water supply, as they are able to withstand liquid temperatures up to 80 ℃.
- Polypropylene products are widely used for heating and hot water supply, as this material is characterized by increased hardness and the ability to withstand higher temperatures. Such pipes can be used even without metal reinforcing mesh.
Main pipe joints
The main transition points from metal to polypropylene are:
- Major overhaul in a separate apartment of an apartment building involves the replacement and modernization of some communication systems, which creates the need for joining metal and plastic products.
- In heating systems, connectionheating boiler to distribution circuits also involves joining two different pipes.
- You also have to connect the plastic wiring of any house with the connection points to the general water supply and sewerage line.
These are only the three main, most common places for joining products from dissimilar materials. There are other situations when it is necessary to make the transition from metal to polypropylene. The laying of pipes under the roads is carried out only with metal products, which also necessitates the creation of special joints for pipes made of various materials.
Basic ways to make a transition
When choosing a method of transition from metal to polypropylene, it is necessary to take into account the properties and purpose of the main 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 which method to connect the pipes is decided depending on the availability of docking.
Flange arrangement
Flange transition from metal to polypropylene is mainly used for reliable connection of large diameter pipes. The place where pipes are joined using flanges is quite strong and tight. In this case, it is possible to dismantle the connection, i.e.docking is collapsible. This method allows you to make the necessary repairs to the installed equipment, with the subsequent connection of the sections.
The flange consists of the following parts:
- body of the product, which is made of steel or cast iron;
- a special metal ring is installed between the two flanges;
- there are o-rings inside the case, which create a good tightness of the connection;
- two flanges are attached to each other with special mounting bolts.
Flanged connection method
Technological process of transition from metal to polypropylene without thread, using flanges, is as follows:
- A neat cut is made at the junction, without an end chamfer. The cut is strictly perpendicular, without burrs.
- Then a flange is put on the cut made.
- 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 with the mating part of the flange, which is put on the second pipe.
- Tighten the bolts evenly, without much effort.
Coupling
Installation of the transition from metal to polypropylene with a coupling is carried out according to the following scheme:
- A strictly perpendicular cut is made at the end sections of the parts.
- Then apply the clutch so thatso that its center is located exactly at the docking site.
- The position of the connecting element is marked with a marker.
- Then the ends of the parts to be joined are coated with special silicone grease.
- According to the mark, one end of the parts to be connected is inserted, and then the other pipe. In this case, it is necessary to strictly monitor the correct installation along the center line of both parts. The markings made earlier will serve as a guide for installing the coupling.
This method of connection is characterized by good tightness and strength of the joint. When switching from metal to polypropylene, the pipe diameters must be the same.
Connecting dissimilar pipes with fittings
A fitting is a special device with which you can connect parts made of different materials. On one side of the fitting there is a thread with which the element is attached to the metal pipe. The other end of the fitting is smooth, for securely attaching plastic products.
The process of using fittings to change from metal to polypropylene is as follows:
- The end of the metal pipe is cleaned, and threading is carried out using a thread cutter. You can also weld a special sling, but this will require a welding machine.
- After threading, it is necessary to clean the joint well from burrs and chips.
- Then, a special tape is wound clockwise, which gives the connection a high tightness. Tape at the same timelubricated 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 element body.
- The next step is to connect the polypropylene pipe to the other end of the fitting.
GEBO fittings
This is the name given to special devices for connecting pipes. They are named after the GEBO company, which was the first to develop and master the production of compression fittings. The transition from metal to polypropylene without Gebo thread 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 a threaded part on one side for connection to a metal pipe, and the other side is connected through a compression ring to a polypropylene product;
Double end fittings are equipped with compression rings on both sides
Arrangement and installation of a compression fitting
The body of the compression type fitting has a special cone recess into which a cone-shaped 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 pressing the sealing gasket when tightening the specialnuts. At this time, the teeth of the ferrule dig 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
These modern devices were developed in the USA, hence their name. In the domestic market of sanitary materials, "American" appeared relatively recently, but quickly gained wide popularity in the installation and repair of many systems. Such popularity was ensured by the ability to create a reliable and quick connection of pipes in hard-to-reach places.
The transition from metal to polypropylene "American" cannot be called a specific connection method, this principle of operation of the device combines various fittings. The main element that significantly distinguishes this type of connection is the union nut.
From the advantages of this design, we can distinguish:
- Device for a strong connection of dissimilar materials, in which the pipes do not rotate, but remain motionless. This property is important when working in hard-to-reach places.
- Creating a reliable connection between pipeline sections from various materials.
- Obtaining a detachable connection, which is important when carrying out repair work on various plumbing systems.
- High tightness of the joint, which is achieved by the presence of a special sealing gasket.
The tightness of the connection is achieved by pressing the sealing gasket when screwing on the union nut. The use of this design allows you to connect pipes of various diameters. The transition from metal to polypropylene of the 32-diameter pipe, which is most often used in water systems, is carried out easily and quickly.
Remember that if necessary, repair certain sections of sewerage, heating and water supply systems, the use of modern flanges, fittings and couplings will completely exclude welding work from the technological process. Any home owner can carry out such repairs on their own, without the use of expensive equipment.
