Carrying out electrical work almost always involves the installation of appropriate wiring. Laying the cable with its subsequent fixation allows you to organize the connection of lighting, household appliances and various equipment in the house or at the industrial enterprise. However, it is often necessary to use additional means of protection of wiring from various types of damage. Among them are corrugated metal pipes.
Corrugated steel pipes are used to protect electrical cables in the home and industry
The principle of operation of the protective product
One of the main characteristics of all pipe products is resistance to external mechanical loads of any origin. To such, at the first place, refers to the weight of the soil. If you compare corrugated and smooth metal pipe, will become obvious, that with equal conditional passage, the surface area of the first is much larger. And from the course of high school physics it is known, what
P=F/S,
where P is the pressure, F - force, acting perpendicular to the plane, S is the surface area.
Analysis of this formula shows, what, the larger the surface area, the lower the pressure per square centimeter of corrugated metal pipe. This factor provides a significant load-bearing capacity of this product.
Useful Information! The walls of the pipes transmit part of the vertical load of the surrounding soil. Therefore, the primary role is played by that, how well the soil or concrete mixture adheres to the surface of the corrugated pipe throughout the cross section.
If voids are left on the sides when stacking these products, the probability of deformation of these structural elements is nonzero.
The strength of corrugated pipes is higher, than in smooth, therefore they are used for underground highways
Features and types
There is a feature in the metal corrugated pipe, due to the technology of its production. The manufacturing process of this material is performed by forming a surface under pressure of rollers of different diameters and configurations. Segments with a smaller diameter are characterized by a smaller thickness of the metal. This design solution gives the pipe some flexibility, thanks to which it is not necessary to apply fittings for bending of the line in case of obstacles in the way of laying of the pipeline.
On sale you can find metal corrugation for wiring of the following types:
- light flexible sleeves, characterized by a low level of mechanical stability. Their installation is allowed only on top of stretch ceilings and under plasterboard structures, that is, in those places, where high pressure will not apply to the wiring cable. The reason for this requirement is, that this device can not withstand heavy and sharp loads, therefore, the power line cannot be considered completely secure;
- heavy products of medium strength. Such a spiral corrugated metal pipe can be used to lay a cable in concrete, earth and plaster;
- heavy corrugations. Pipes of this type can withstand high loads. It is recommended to apply them in places, requiring special attention to safety. These include health facilities, education, as well as other organizations, including public, with high attendance.
An important feature of metal corrugated pipe is its high flexibility
Where metal corrugated pipes are used
The production of these products was first mastered in Russia. It happened in the distance 1875 year at a metal factory in St. Petersburg. Then, already in 1896 year, their production was established in the United States. And only then did metal corrugated pipes appear in Japan, Korea and the African continent. In the USSR, their production was given serious attention. The older generation remembers the "construction of the century" - Transsib BAM and others. The important role of corrugated metal culverts in this case is undeniable.
In general, present on the modern market, such products differ in diameter and cross-sectional shape. Actually, these parameters determine the scope of their application.
Importantly! Buying a corrugated metal pipe for wiring, remember, that in the catalog, usually, the outer diameter is specified. It differs from the inner diameter by a few millimeters.
Corrugated pipe products are available with the following cross sections:
- round. This section is characterized by a corrugated metal pipe, used to create a culvert height 1,5-7 meters. The same cross section, but only smaller, has a corrugated pipe to protect the wiring;
- square. Corrugated pipes with this cross section are used to create culverts and in the construction of tunnels (3-8 meters);
- pear-shaped. Tunnels, culverts (1,5-8 meters);
- arch. For small bridges, auto - and railway tunnels (height from 2 to 13 meters). Corrugations of this type can be installed in existing embankments by puncturing them;
- pipe arch. Tunnels under highways and railways (height from 2 to 13 meters);
- vertical ellipse. This section is suitable for telecommunication tunnels, created on the basis of corrugated metal culverts;
- transition. Pedestrian crossings are built with their use (height 1,8-9 meters);
- horizontal ellipse. This cross section is inherent in a corrugated metal culvert;
- arch with high or low profile. Small bridges, railway and automobile tunnels (height 6-15 meters).
Corrugated metal pipes come in different diameters and configurations
Manufacturing and benefits
The strength of the metal corrugated pipe for wiring is due to the variable cross section. Assembly is performed from standard elements in the factory. Corrugated metal sheets are used for this purpose. Their connection is carried out by flat-curved and flat-convex washers using bolts. The standard size of all these elements is determined by the dimensions of the structure. Hot-dip galvanizing provides high corrosion resistance. A metal corner is used for the border. In the process of manufacturing the structure, a grade of steel is used, which is optimally suited to the intended operating conditions:
- 15JV - from minus 40?C and above;
- 09G2D - at minus 40?C and below.
The production of corrugated stainless steel pipe has its own characteristics. This material was first used for this purpose in the beginning 80 years of the last century in Japan. Thick steel tape is used in the manufacturing process 0,25-0,3 millimeters. The formation of the tape from the pipe is carried out by argon welding on an automatic line. The reliability of the weld is monitored using a laser installation. Its width should not exceed the wall thickness more, than in 1,6 times. The formation of corrugations is the final stage of production of products of this type.
Useful Information! Before sending the finished product to the warehouse, the corrugated pipes must be checked for leaks by immersion in a container with ordinary water.. Compressed air, passing through the product, locates defective areas.
In addition to performing the functions of protection of wiring from adverse effects, corrugated metal pipes are widely used in heating and water supply systems.
The production of pipes includes several stages, corrugation formation is the final part of the process
The advantages of stainless steel products include:
- ease of installation and operation;
- increased heat transfer (compared to copper);
- impossibility of formation of sediments on the walls;
- high corrosion resistance;
- possibility of use in the temperature range 0? T? +100?C.
- ability to withstand pressure up to 65 there is (64,15 atmosphere). If welding is performed at a temperature of about +1150?WITH, the seam is able to withstand 210 atmospheres.
Specifications
As mentioned above, the main parameter of a corrugated pipe for carrying out is its diameter. In order not to waste time searching for a suitable version of the pipe product, you can use the data, presented in the table.
Table 1
| Conductor cross section, square millimeters | Cable type and voltage | ||||||
| 4-x vein to 1 kV | Three-core voltage, kV | 2-x vein voltage to 1 kV | Single-core to 1 kV | ||||
| Ten | Six | To 3 | |||||
| Eight hundred | ______ | ______ | ______ | ______ | ______ | One thousand seven hundred | |
| Six hundred and twenty-five | ______ | ______ | ______ | ______ | ______ | One thousand five hundred and twenty | |
| Pyatsot | ______ | ______ | ______ | ______ | ______ | One thousand four hundred | |
| Four hundred | ______ | ______ | ______ | ______ | ______ | One thousand two hundred and twenty | |
| Three hundred | ______ | ______ | ______ | ______ | ______ | One thousand | |
| Two hundred fourty | ______ | Four hundred and sixty | Five hundred and ten | Five hundred and seventy | ______ | Eight hundred and eighty | |
| One hundred and eighty-five | Four hundred and fifty | Four hundred | Four hundred and forty | Four hundred and ninety | ______ | Seven hundred and fifty-five | |
| Hundred and fifty | Three hundred and ninety-five | Three hundred and fifty-five | Three hundred ninety | Four hundred and thirty-five | Pyatsot | Six hundred and seventy-five | |
| One hundred twenty | Three hundred and fifty | Three hundred and ten | Three hundred fourty | Three hundred ninety | Four hundred and thirty-five | Five hundred and ninety-five | |
| Ninety-five | Three hundred and ten | Two hundred and sixty-five | Two hundred and ninety-five | Three hundred fourty | Three hundred and eighty | Five hundred and twenty | |
| Seventy | Two hundred and sixty-five | Two hundred and fifteen | Two hundred and forty-five | Two hundred and eighty-five | Three hundred and twenty-five | Four hundred and forty | |
| Fifty | Two hundred and fifteen | One hundred and eighty | Two hundred | Two hundred and thirty-five | Two hundred and seventy | Three hundred and sixty | |
| Thirty-five | One hundred and seventy-five | Hundred and fifty | One hundred and sixty | One hundred ninety | Two hundred and twenty-five | Two hundred and eighty-five | |
| Twenty five | Hundred and fifty | One hundred twenty | One hundred and thirty-five | One hundred and sixty | One hundred and eighty-five | Two hundred and thirty-five | |
| Sixteen | One hundred and fifteen | Ninety-five | One hundred and five | One hundred twenty | One hundred forty | One hundred and seventy-five | |
| Ten | Eighty-five | ______ | Eighty | Ninety-five | One hundred and five | One hundred forty | |
| Six | ______ | ______ | ______ | Seventy | Eighty | ______ | |
There are other technical characteristics of these products. The following deserve special attention:
- the surface roughness coefficient is equal to 0,008;
- the thermal conductivity of corrugated stainless steel pipe is equal to 17 W / m * K;
- the bending radius of the product depending on its diameter varies in the range 25?R?150 mm;
- service life over 30 years.
The choice of the diameter of the corrugated pipe depends on the parameters of the cable, which will take place in it
Installation of wiring in the corrugated pipe
This procedure involves several stages.
Preparation of materials. First, cut the required piece of corrugated metal pipe for the cable. It is very important not to let the steel wire broach go inside the tubular product, because it is always slightly stretched. If you miss, it rests on the fold of the pipe. And to get the cable, you will have to make an incision in another part of it. To avoid such an unpleasant situation, cut the broach, hold it with your fingers, and at the end of this operation, pull it out a little and bend along the pipe.
Preparation of wiring harness is to fasten wires or cables with insulating tape at regular intervals.
Wrinkle! It is better to use PVC insulating tape, and not cotton, because it is very smooth and does not create additional friction when pulling the wiring.
Pay special attention to the quality of fastening the harness to the broach rope. It must be extremely reliable, otherwise in case of breakage you will have to do the work again. Electricians do this in two ways: the harness is wrapped with steel wire, collecting it with trade winds. More effective fastening is a puncture by a cable of a broach of spring isolation of cables of a plait with the subsequent winding of places of punctures by an insulating tape.. It is necessary to do this, so that the ends of the wiring cables do not rest on the corrugations when pulling. The longer the joint between the harness and the broach rope, the longer it will be, the more reliable it will be.
Tightening the harness in a corrugated metal pipe. It is easier to do this work together. One partner holds the rope firmly, and the second pulls on the burning corrugation. However, securely fixing the broach, you can handle yourself. But, anyhow, without strong hands, able to continuously pull the corrugation with considerable effort, will be very difficult to manage. in addition, free space is required to perform this operation. And remember, Extreme care must be taken when handling the harness and corrugation, to prevent breakage of the broach.
That process of a cable drawing in corrugations was fast and without problems, choose sleeves, equipped with a probe
Fastening of a metal corrugated pipe for wiring. After tightening the harness, the resulting structure should be fixed to the wall or ceiling. As fastening elements it is possible to apply a mounting aluminum strip or special clips, which should be selected according to the diameter of the pipe. In trade enterprises they can be bought individually. Position the fasteners at approximately equal intervals. So you do not allow sagging corrugations, the weight of which will add a wiring harness stretched inside it.
Connecting switches and sockets, as well as inserting harnesses into the junction boxes, the end of the corrugations is also better to hide inside, so that there are no bare areas of wiring. Buy boxes for this purpose, sockets and switches with rubber seals, which are cut to the diameter of the corrugations. This is especially true when laying external communications.
Recommendations for selection and installation
Corrugated spiral metal pipes meet the requirements of fire safety in terms of laying networks in wooden housing in the open way. Of course, when a corrugated pipe with a wiring cable is laid on a wooden wall, it is necessary to do it with use of other fire-resistant material, as which can be used, example, asbestos.
Useful to know! This approach will prevent outbreaks, if there is a short circuit when the automation system is not working.
And another very important point: the quality of fastening clips should not concede to quality of corrugated pipes. Select these fixing elements based on their ability to withstand the appropriate load. It is also important to keep in mind, that on sale in the domestic market you can find defective metal corrugation for wiring, not equipped with a steel cable, employees for cable routing. That there were no problems, buying, find out if you have this accessory.
Fasteners should be selected according to the diameter of the corrugated pipe, then it will be reliable
When buying, prefer products from well-known brands. Although its cost is relatively high, it fully meets the quality of the corrugation for wiring. Today in this segment of the domestic and world market products of such companies are especially popular, as:
- Legrand (France). In the USSR, the products of this brand first appeared in the not so distant 1980 year;
- IEK Group of Companies (Russia). Its branches are open in the Baltic States, Mongolia, Kazakhstan, Moldova and Ukraine;
- Franconian (Germany). The fact speaks eloquently about the demand and the highest quality of products of this brand, that in this segment of the world market it works more 100 years. Frankische was founded in 1906 year.
It should be noted, what, according to some homeowners, the use of corrugations for wiring from an aesthetic point of view is unacceptable. However, if you put it evenly and neatly, then you will get a normal appearance, which does not spoil the interior design of the living space.