Today, polyethylene pipes are widely used in the repair and construction of pipelines, in automatic irrigation systems, in the arrangement of pools and the construction of artesian wells. In the latter case, we are talking about the transportation of groundwater.
However, before buying such products, it is important to familiarize yourself with some parameters, among them it is necessary to highlight the purpose, internal and external diameters, as well as characteristics and operating conditions. In polyethylene, as in any other material, the scope is due to physical properties. Today polyethylene of low, high and medium pressure is known, which depends on the production method.
Areas of use
The least mechanical strength is possessed by high-pressure polyethylene. It is used in the production of sewer pipes and as a protective sheath for cable lines. Low pressure material is very durable. It is also called high density materials. He goes on to manufacture pipes for pressure pipelines. They are able to withstand high mechanical loads and pressures. The limitation of all types of polyethylene is fusibility. At 80 ° C, the material begins to soften, and melts already at 105 ° C. This property is decisive when using such pipes.
Scope is limited to high temperatures. But the described pipes are used in various fields, namely:
- with a sewage device;
- when digging wells;
- when laying cold water supply;
- when arranging irrigation systems;
- when laying gas supply systems;
- in electrical work.
What is the limited use
Polyethylene products are deformed when exposed to high temperatures, so when installing heating systems, you should use another type of polymer pipeline - polypropylene reinforced pipes. An exception is the pipeline, during the installation of which molecular cross-linked polyethylene is used. If we compare it with the usual one, it is not afraid of exposure to high temperature, which circulates inside and has the following advantages:
- lack of corrosion;
- low cost;
- long term of operation;
- light weight;
- low roughness coefficient;
- different diameters;
- lack of need for coloring and isolation.
Outer and inner diameters
The diameter of polyethylene pipes is one of the important characteristics that should be considered when choosing such products. This value can be indicated in several variants. Depending on the measurement method, the diameter may be:
- nominal;
- conditional;
- internal;
- external;
- outside.
Rated is most often applied. It displays the diameter of the circle in contact with the fittings of the fittings. The nominal diameter may be external or internal. The nominal diameter of polyethylene pipes is prescribed in the state standard. This value is the nominal value, rounded to 0, 1 mm up.
Outer or outer diameter is a circle that is formed by the plane of the outer surface. The inner diameter of polyethylene pipes is measured around the circumference of the inner surface.
On sale today you can find pipes that are able to withstand different atmospheric pressures during operation. Among the most common should be highlighted: SDR 17; SDR 13.6 and SDR 11. The first pipe has a pressure of 10, the second - 12.5, the third - 16 atmospheres. These products have different outer and inner diameters, as well as wall thickness.
The outer diameter of the pipe with lower pressure varies from 25 to 630 mm. The inner diameter may be equal to the limit of 21.2 to 547, 4 mm. The wall thickness in this case is equal to a figure from 2 to 37, 4 mm. One linear meter of such a pipe weighs 69.9 kg maximum. The minimum value is 0.152 kg.
More about diameters
The diameters of the polyethylene pipe will be different if you have an SDR 13.6 product in front of you. In this case, the outer diameter remains the same, but the inner diameter will vary from 21.2 to 527.8 mm. The wall thickness is 2.1 mm minimum and 46.3 mm maximum. One linear meter of the pipe weighs 0.154 - 84.8 kg.
Before buying, you should be aware of the diameters of the SDR 11 polyethylene pipe, which is capable of undergoing 16 atmospheres. The outer diameter remains the same, but the inner diameter varies from 20.4 to 503.8 mm. The wall thickness is equal to the limit of 2.3 to 57.2 mm.
When choosing a pipe, you should be careful, because Russian manufacturers indicate external diameters, while foreign ones indicate internal. Polyethylene pipes of large diameter are more demanded today. The main areas of their use are:
- pressure pipelines;
- drainage systems for storm sewers;
- sewer collectors.
Pluses of big pipes
Polyethylene pipes, the outer diameter of which is quite large, have an advantage, among them are:
- low cost;
- small mass;
- environmental friendliness;
- tightness strength;
- resistance to shock and tension.
If water suddenly freezes in such pipes, then it will not damage the material. The length also depends on the diameter. For example, products with a diameter of more than 160 mm can be purchased in segments from 3 to 12 m. If you need products with a smaller diameter, they can be of any length, sold in coils or bays.
The purpose of the pipe 110 mm
A polyethylene pipe with a diameter of 110 mm is made of low-pressure material by extrusion. Products are easy to install and low cost, and you can use them in many areas. The main field of application is the protection of low-current and power electric wires from damage during hidden installation.
You can buy such a pipe by paying 149 rubles. per linear meter. If we compare this product with a plumbing one, the first is pressure-free, which means that it can be used for storm sewer or cable laying. It is realized in segments of 12 and 13 m. If desired, you can place an order for segments of any length that will be convenient for installation and delivery.
What else to look for
The pipe is not capable of undergoing tensile pressure, therefore it cannot be laid using the HDD method. The product is available in several versions, each of which differs in wall thickness. This parameter can vary from 4, 2 to 10 mm. Butt welding is most commonly used to join pipe sections. Although not recommended, a sleeve connection may be used. Compression fittings are also great. You can use special fittings to connect the elements.
Welding Features
What diameters do polyethylene pipes have, you now know. However, for the installation of these products, it is necessary to familiarize yourself with the features of the docking. Connections can be detachable and not detachable. The first provides for the possibility of disassembling the system during operation. To create such a connection, steel flanges are used. During operation, disassembly cannot be carried out if the connection is one-piece.
The latter view can be implemented in one of two ways. The first involves the use of butt welding technology, while the second method is the welding of pipes with couplings. Welding of large diameter polyethylene pipes is carried out using thermoresistive fittings and butt welding method. The compound is monolithic in both cases and very reliable.
Features of butt welding and installation
Butt welding requires the use of welding equipment. Simplification of the installation process leads to the absence of the need for additional parts. This technology is relevant only for HDPE pipes of the same diameter. Butt welding can be obtained only when it is performed with one seam. This ensures equal contact strength of the parts.
Butt assembly is the most efficient and versatile. Using this technique, the flexibility of the material along the length of the pipeline is maintained. This process is not accompanied by difficulties, regardless of the type of pipeline laying, which can be traditional, open or trenchless.
If you decide to perform butt welding, then you should use a heating tool. For this, the ends of the elements to be welded are installed in the center of the welding unit. After alignment and reliable fixation, the ends of the pipes must be cleaned of dirt and dust with a napkin. The surfaces to be welded are machined by a mechanical end device. As soon as you get uniform chips, the thickness of which is not more than 0.5 mm, the manipulations must be stopped, remove the device and check the mutual parallelism by hand. If there is a gap between the surfaces to be welded that is greater than the permissible value, the trimming manipulations must be repeated.
Using a non-stick coated heating tool, the pipe ends must be heated. When the reflow reaches the highest phase, the surfaces must be parted and the heating element removed from the welding zone. The welded surfaces then close. After this, the pressure must be uniformly raised until the value reaches the desired value. The seam should be kept under a certain pressure for a while.