Features of low-pressure polyethylene
Almost everyone knows that with the polymerization of organic gas, ethylene is made of classic polyethylene. Under certain conditions, the molecules of a given gas create polymer chains, thus forming a unique product. HDPE is produced in almost the same way, only the exact pressure and temperature values that the pressure chamber is maintained are set. At the same time, the pressure is 20 atmospheres, and the temperature is 150 degrees.
In such conditions, a special product is produced, with its advantages and disadvantages. Let's consider them, based on the use of the HDPE pipeline type:
- Can withstand a pressure of several dozen atmospheres. The maximum limit is 5Mpa.
- The running meter of the HDPE pipeline has a low weight. Thus, the cubic meter is 900kg.
- At negative temperatures HDPE glassy, and at a temperature above 40 degrees, the pipe will lose its ring cruelty.
- When heated to 70 degrees, the HDPE pipe increases by only 3%.
As you can see, due to the temperature limitation, the HDPE pipeline is used for laying water conduits with cold or drinking water. Installation is carried out inside the building or in a trench, at a depth below the freezing point.
Technical characteristics and operation parameters of HDPE pipes
- For transporting water up to forty degrees Celsius( cold, drinking, technical water);
- For transportation of gaseous or liquid medium, in the same temperature regime;
- Served as a duct or insulation for an electrical cable.
The most important disadvantage of low pressure polyethylene is the limitation of the operating temperature of 40 degrees Celsius. If you adhere to this temperature regime, the life of this pipe will not be less than 50 years.
The operating conditions are also affected by the grade of HDPE.To date, the following grades are used:
- PE 100, resistance limit = 10MPa.
- PE 80, the limit of durability = 7.5MPa.
- PE 63, the limit of stability = 6.3 MPa.
- PE 33, resistance limit = 3.3 MPa.
For each of them a certain number of pipe sizes are manufactured, thus:
- of PE 33 are manufactured in 15 sizes;
- from PE 63 are manufactured in 30 sizes;
- from PE 80 is produced in 34 standard sizes;
- from PE 100 is produced in 26 sizes.
In addition, the HDPE pipeline is divided into 11 groups, according to the SDR coefficient. It is equal to the ratio of the outer diameter to the wall thickness.
Low pressure polyethylene pipe assortment, their diameters
Parameters of the assortment can be viewed in GOST at number 18599, 2001.Based on this regulatory document, the key parameters are the pipe diameter and wall thickness. These two indicators are closely related to the type of polymer.
For PE 33, the diameter of the HDPE pipe is from 10 to 160 mm, and the wall thickness is from 2 to 12 mm.
For PE 100, the diameter of the HDPE pipe is 32 mm to 1 m, and the wall thickness = 1 to 59 mm.
For PE 63 and PE 80, the pipe diameter HDPE = from 16 to 1600mm, and the wall thickness = from 2 to 67 mm.
Labeling of low pressure polyethylene pipes
The communication data marking is located on the outside and includes the following data:
- The name of the company that issued this product, indicating the product standard.
- Material name with polyethylene grade.
- Digit with outer diameter, in mm.
- Value with nominal pressure( also the maximum permissible pressure in MPa can be specified).
- Date of manufacture and batch number.
A distinctive feature of this pipeline is a colored strip, blue or yellow.
Blue - means that the pipeline needs to be used for transporting water;
Yellow - means that the pipeline is designed to transport gas.
