GOST 18599-2001, which has the name “Polyethylene Pressure Tubes”, regulates the quality of the pipes and describes their main technical parameters, including the diameters of polyethylene pipes. PE pipes are widely used in the construction and repair of pipelines, the arrangement of pools, in automatic irrigation systems for plantings, and in the construction of artesian wells (for transporting groundwater).

Requirements GOST

According to the requirements of GOST, the inner and outer walls of polyethylene pipes used in plumbing systems should be smooth, without foreign inclusions, cracks, air bubbles, and sinks. A small waviness or longitudinal stripes on the surface of the pipes is possible, but only if these defects do not affect the wall thickness and do not exceed the maximum permissible deviations. They are available in black or blue. Sometimes you can find black plastic pipes with three blue longitudinal stripes, which are distributed evenly around the circumference and represent a marking. Gas pipes from plumbing distinguish yellow stripes on the same black background.

Advice from a professional: Coloring polyethylene pipes in blue or black is necessary for the rapid visual distinction of PE pipes from other products.

Main characteristics

Polyethylene pipes can be used in various areas of water supply. Classification of PE pipes occurs according to the following characteristics:

brand of polyethylene used in the manufacture of pipes;
indicator of pipe resistance to internal pressure SDR;
pipe diameter

Grades of polyethylene

The grades of polyethylene pipes into which the entire range of pipes made of PE is subdivided are as follows:

PE 63 (was invented first and in our time is practically not used);
PE 80;
PE 100.

Each brand has its own characteristics:

Polyethylene brand PE 63 is a linear homopolymer, completely consisting of ethylene molecules. It is characterized by high short-term strength, but low resistance to cracking and destruction. The MRS indicator, which reflects the duration of the maintenance of strength and is used in the calculation of the working pressure, is 6.3 MPa. During prolonged operation, the polyethylene pipe PE 63 begins to break down, because the properties of strength at a certain point sharply decrease.

PE 80 water pipes have excellent consumer properties and withstand the substantial internal pressures of the fluids they transport. If it is necessary to build a plumbing system of small diameter (no more than 90 mm), PE 80 polyethylene pipe is optimally suited for this purpose.

The construction of cold water mains involves the use of polyethylene pipes of large diameters. To save raw materials and materials in the construction of large-scale structures, it is advisable to operate polyethylene pipes PE 100.

 

 

 

 

 

 

 

 

 

 

 

SDR polymer tubes

One of the important indicators that characterize polyethylene pipes is the standard aspect ratio or SDR (StandartDimensionRatio). This parameter is the ratio of the outer diameter (nominal) to the wall thickness (also nominal):

Obviously, with increasing SDR, the wall thickness of the pipe decreases, and vice versa, the wall thickness of the PE-pipe is larger, the smaller the SDR value. Although in practice the SDR indicator is a standard parameter taking values ​​according to the table.

Calculate the nominal wall thickness of a PE pipe using the following formula:

SDR depends on the series of polyethylene pipe (S):

where S is the value corresponding to the standard size of the existing polyethylene pipe, which is selected according to GOST 8032 from the R10 series and is equal to 2.5; 3.2; four; five; 6.3 and 8; 8.3; ten; 12.5 or 16.

A series of polyethylene pipe shows how many times the voltage that occurs in the pipe wall under the action of the maximum working pressure (MaximumOperationPressure, MOP) is stronger than this pressure. However, the definition of “pipe series” is irrelevant in practice, since it is an ephemeral characteristic that is not endowed with physical meaning.

The maximum working pressure is the pressure at which the service life of the pipeline is at least 50 years, if all the operating conditions of the pipes (as well as their transportation and storage) are met. MOR is calculated as follows:

 

 

where MRS is the minimum value of the strength of polyethylene;
C is the pipeline laying factor (it is also called the “safety factor”), which depends on the pipe laying conditions and takes on different values ​​(1.25 for polyethylene pipes responsible for cold water supply, as well as 2 ÷ 3.15 for pipes transporting flammable gases).
Advice from a professional: In order not to make a mistake in choosing a polyethylene pipe that is suitable in each specific case, it is enough to know MRS (pipe raw material characteristics) and SDR (main pipe design index).

Diameter of polymer pipes

The main competitor of polyethylene pipes are welded water and gas pipe steel pipes of small diameters (DN 10 DN 50, with a diameter of 57-210 mm). In the meantime, the majority of plants producing pipes made of polyethylene have mastered the production of PE pipes of large diameters, which favors the fact that in the near future polyethylene pipes will permanently remove their metal counterparts from the market.

PE pipes are made of various diameters (diameters range from 20 to 1,200 mm), as well as different pressures – 5-16 MPa. The length of the pipe depends on the diameter:

with a diameter of 20-110 mm, it is 50 m;
polyethylene pipe 110 mm and more has a length of 12 m.
In more detail with the assortment can be found in the table of interdependence of the diameter of the pipe wall.

 

 

 

 

 

 

 

 

 

 

Polyethylene pipes of large diameters are in particular demand: they are used in the construction of drainage systems, pressure pipelines, storm sewers and sewers. The main advantages of pipes with a large working diameter are:

acceptable cost of production, installation and operation compared to metal pipes;
low weight, which greatly facilitates transportation and installation;
at freezing of water inside the pipe, no negative processes occur;

polyethylene pipes are toxicologically and environmentally friendly;
they are not dangerous goods, which is very important during transportation;
possess high resistance to stretching and shocks;
when welding butt-butt weld welded joint turns out reliable and durable, it does not affect the service life of the pipeline;
butt welding of pipes – an easy and inexpensive way to connect elements of the pipeline.

Polymer pipe marking

 

 

 

 

 

In order to identify products by the manufacturer, the polyethylene pipes are marked. It is applied on their outer surface with an interval of 1 m (sometimes less) and includes data:

the name of the manufacturer (can be replaced by the application of a trademark);
symbol of the product;
Date of issue.
Additionally, the manufacturer can specify the number of the party or line.

Advice from a professional:

The ability to read the labeling of pipes made of low pressure polyethylene simplifies the selection of suitable materials.

The symbol of polyethylene pipes contains all the main characteristics and is as follows:

the word “pipe”;
the grade of polyethylene from which the product is manufactured;
SDR (from the assortment table);
dash sign;
nominal diameter of the product;
pipe wall thickness;
appointment (“technical” pipe or “drinking”);
name used in the manufacture of GOST.

For example, we analyze the label “PE 80 SDR 11 – 50 x 4.6 technical GOST 18599-2001.”

Interpretation: polyethylene pipe – diameter 50 mm with a wall thickness of 4.6 mm, intended for technical needs and manufactured according to GOST 18599-2001. In its production, polyethylene of low pressure PE 80 was used.