Plastic has long ceased to be perceived as fragile, literally disposable material, suitable only for the production of toys and other small items. Now the modified plastic has not the worst properties, than metal, and sometimes more attractive. Large diameter polymer pipes are used even in spheres, requiring increased responsibility, - when laying oil- and gas pipelines, heating and sewerage systems.
Pipes of big diameter from polymeric materials are capable to compete with steel at the device of highways of various complexity
Where large diameter plastic pipes are used?
The category of large diameter pipes includes products with the following dimensions: their diameter is from 500 to 1200 mm (there are also products with a diameter of up to 2000 mm). These types of plastic products have become very popular due to their good technical characteristics, durability and low market value. The use of large diameter pipes has become relevant in the following areas of industry and supply:
- replacement of domestic water supply systems, which were previously used exclusively concrete (or asbestos cement);
- replacement and reconstruction of old cast iron or steel water and sewage communications: in this case polypropylene plastic pipes of big diameters are most often applied, as this material guarantees absence of deposits on walls of system thanks to the smoothness;
- supply and transportation of media, which are under high pressure - as in household use (pressure systems), and in industry. Plastic pipes are widely used for transportation from oil and gas fields, even by sea: in this case, the pipeline is assembled on land, and then flooded;
- laying of underground communications - thick-walled plastic is extremely strong (in this respect, plastic is much superior to brittle concrete), therefore, it is able to withstand the load of the soil;
It is interesting! Depending on that, to which stiffness class the product belongs, the pipeline can be immersed to a depth of 2 to 16 meters.
- installation of stormwater, household or drainage sewers in areas with high-rise buildings or private buildings, in industrial areas.
High-capacity high-capacity high-capacity pipes are mounted
Large diameter pipelines are used equally successfully in all areas, where the transportation of liquids and other media in large volumes is required.
Varieties of large plastic pipes
Classification of plastic pipes is based on the type of plastic. There are three types of materials, from which products for plastic pipelines are made:
- PVC pipes. This category of plastic products is used only in two cases - as a basis for sewer systems and as an outer layer for plumbing structures. Restrictions on the use of PVC pipes are due to this, that this material eventually begins to emit toxic substances.
- Polypropylene pipes. Products with fairly rigid walls, resistant to temperature changes, thanks to which they became widespread even when installing heating systems. They have soundproofing properties, as well as chemically inert to aggressive substances and acids. This quality makes them suitable for operation in large-scale sewer systems.
- Polyethylene pipes. Plastic pipe made of polyethylene perfectly tolerates low temperatures, which is why it is often used in the northern regions. When interacting with hot media, the structure of polyethylene changes irreversibly. For heating and other areas, associated with high temperatures of transported media, used a modified type of polyethylene - PE-C, or cross-linked polyethylene.
Polypropylene pipes are considered universal, they can withstand heavy loads and do not require special operating conditions
The highest quality, Polypropylene products are considered to be a reliable and universal option among large plastic pipes. Sometimes polypropylene systems are reinforced, which increases their service life.
Advantages of large diameter plastic pipes
The prevalence of large diameter polymer pipes can be explained by the presence of the following positive qualities:
Plastic does not lose its properties with constant interaction with humid environments, at the same time, that the main problem of metal products is their susceptibility to corrosion.
- the plastic pipe can be operated without any problems for no less time, than concrete or metal. Some manufacturers provide a guarantee for polymer products, component about 50 years. For comparison, the warranty period of the metal pipeline is only 20-25 years;
- the thermal conductivity of large diameter plastic pipes is much lower, than products made of other materials, so, and heat loss will be less;
- prices for plastic pipes are more than acceptable: depending on the diameter, class of rigidity and wall thickness the cost of one running meter of plastic pipe can be from 20 rubles to 800 rubles;
- toxic substances are not used in the production of plastics. In general, plastic pipes can be called environmentally friendly products (exception - PVC products, recognized as toxic);
- almost perfectly smooth plastic surface, not prone to overgrowth and the formation of salt deposits and plaques. This means, that the lumen of the pipe will not decrease over time, and bacteria and other harmful microorganisms will not multiply in the pipelines;
- plastic has low weight, which simplifies and reduces the cost of transporting large batches of large diameter pipes.
Plastic piping can be laid underground, and underwater, it is able to function smoothly for decades
Along with the many advantages of any plastic pipe, there are disadvantages. Among them is insufficient resistance to work in high temperatures. However, Recently, many improved versions of plastics are available, capable of operation in hot water supply and heating systems.
Another difficulty is that, that different types of plastic require a special type of fastening (different melting points, fitting fasteners). This must take into account the use of several types of plastic pipes in one line.
Also keep this in mind when laying plastic pipes on the ground, that some types of plastics are gradually destroyed under the influence of ultraviolet rays. Insulation is required to better preserve the pipelines.
Diameters and stiffness classes of large plastic pipes
One of the main indicators, which should be relied on when choosing large diameter plastic pipes - this is their stiffness class. This concept is based on information about the allowable depth of laying the pipeline in the ground. The inner diameter of the product also depends on the stiffness class.
The range of large pipes includes items, are given in the table.
Table 1
| Hardness class of plastic pipe | The maximum possible depth of laying in the ground, not more | diameters of products |
| Products for overhead pipelines | — | 500 mm, 880 mm, 1400 mm |
| SN2 | 2 m | 600 mm, 900 mm, 1500 mm |
| SN4 | 2-4 m | 680 mm, 970 mm, 1600 mm |
| SN6 | 4-6 m | 700 mm, 1000 mm, 1800 mm |
| SN8 | 6-8 m | 780 mm, 1170 mm, 2000 mm |
| SN12 | 8-12 m | 800 mm, 1200 mm, 2200 mm |
| SN14 | 16 m | 850 mm, 1300 mm, 2400 mm |
The choice of plastic pipes depends on the characteristics of the system. The main task of a large pipe is to withstand the maximum pressure of the medium, transported. When choosing a product of optimal diameter, important information is important, how much medium should be transferred to the system over a period of time. Using a pipe that is too small in diameter can cause the product walls to rupture, and too large - a decrease in pressure in the overall system.
Pipe diameter is an important parameter, on which the efficiency of the highway built of them depends
Another factor, which affects the choice of plastic pipe, there is a constant temperature in the system, since all types of plastic have different temperature limits.
How to install large diameter pipes?
Large pipes require increased joint strength, which is quite difficult given the large diameter of the products.
Methods of connecting pipes are divided into detachable and non-detachable. The first method involves dismantling the connection if necessary and reassembling it. With the non-removable method, it becomes impossible to reuse the parts, the joint reaches the strength of the monolith (deviation in strength and at the joint is not more 10%). A one-piece connection often involves welding, which is carried out with the help of special industrial welding equipment and electric couplings.
Importantly! One-piece connections are then used, when the maximum strength of the pipeline and minimization of any probability of leakage is required. Example, it is planned to use the system under high pressure.
Butt welding is performed according to this technology:
- The ends of the pipes are securely fastened in the welding machine.
- Sections of segments are being prepared for welding, are heated by means of a special heating plate.
- The segments are connected, the place of a seam is leveled and becomes absolutely imperceptible.
One of the options for detachable connection of large pipes is the bell method
Electric coupling welding is performed using connecting parts, having in the design the built-in heating element. Thanks to this part uniform melting of plastic from within is carried out, which ensures complete tightness of the connection.
In some cases, all system requirements can be met by detachable connections. They will also have a sufficient level of reliability. Detachable installation is carried out using flanges or bell parts.
The bell and flange connection method is appropriate in those cases, if a pressureless sewer or sewage pipeline is installed.
Such a product, as a large diameter plastic pipe, can be deservedly considered the material of the future. Plastic products are becoming increasingly popular in various fields of consumer services and industry. The properties of polymers are improved annually, so, perhaps, plastic will be available in a short time, able to become a full-fledged replacement for heavy metals.