What does sdr. SDR polyethylene pipes - marking and application. Benefits of using PE pipes

How to find out the SDR of polyethylene pipes, for which pipes with different indicators are used

When choosing polyethylene pipes for household or industrial communications, pay attention to the labeling of the product. It contains the following designations:

• manufacturer's name;
• GOST number, which regulates the characteristics of the product;
• the abbreviation PE, which indicates the material of manufacture - polyethylene, which is a thermoplastic polymer;
• grade of polyethylene indicated by the number next to the PE designation;
• pipe diameter, wall thickness;
• SDR designation with a number.

If the purpose of most of the designations is clear, then sometimes there are difficulties with SDR. If you are planning polyethylene products in Moscow and do not know how to choose according to SDR, today we will tell you more about this designation.

How SDR is calculated

The abbreviation SDR means a standard dimensional coefficient that characterizes the ratio between the outer diameter and the wall thickness of the product. That is, the indicator is calculated by the formula:

SDR = outside diameter / wall thickness

If you see a pipe with a large SDR, it means that it is thin-walled, and vice versa: the smaller the designation, the thicker the wall. The performance characteristics of the product depend on the wall thickness. The larger it is, the greater the load will withstand the product. This applies to all types of loads:

• internal pressure;
• external compression for pipes that run underground and are covered with a layer of soil;
• external mechanical influences, for example, during soil shifts, subsidence due to rains, and so on.

What pressure and operating conditions are rated for different SDRs

Manufacturers produce products whose SDR ranges from 6 to 41. Pipes with the lowest indicator are designed for a pressure of 25 atm, with the highest they can withstand 4 atm.

According to the dimensional coefficient, pipes can be classified into several groups, which are designed for different operating conditions:

• SDR 26-41 - the least durable products, suitable only for gravity sewer outlets, in which there is no additional pressure;
• SDR 21-26 - suitable for low-pressure water supply, for example, they are used for laying house communications in low-rise construction;
• SDR 11-17 - pipes suitable for low-pressure water pipes, as well as irrigation systems;
• SDR 9 and less - products are suitable for pressurized water supply systems, pressurized sewers, as well as gas pipelines.

To ensure the smooth functioning of the pipeline, it is important to connect the pipes with appropriate fittings. not suitable for them, clamping transitional structures are needed.

Practical examples

Here are a few examples of how products of the popular brand of PE-80 polyethylene can be used:

• SDR 13.6 are suitable for long-term plumbing systems;
• SDR 17 are medium-strength products, they are lightweight and cheap, which makes them suitable for water supply systems in low-rise buildings;
• SDR 21 is suitable only for outdoor installation, designed for non-pressure systems, as it does not withstand internal pressure and compression by the soil layer.

Note! The strength of the pipe depends on the SDR, as well as the brand of polyethylene. With the same dimensional coefficients, a product made of durable polyethylene will be more resistant to mechanical stress, and therefore suitable for difficult operating conditions.

You can buy polyethylene pipes of all SDR values ​​​​in our heating hypermarket - website
Also, if you already have polyethylene pipes in stock, but you need to buy fittings for polypropylene pipes, you will find everything you need from us!

When purchasing polyethylene pipes for arranging communication systems for domestic or industrial purposes, you can see the markings applied to them with a set of various data about a particular product. It contains:

• information about the pipe manufacturer,
• numbers of GOST standards, in accordance with which it was manufactured,
• the abbreviation "PE", meaning that the pipes are made of polyethylene - a thermoplastic polymer of the hydrocarbon "ethylene", and its brand (PE-100, PE-80, etc.),
• the diameter of the product and the thickness of the material of its walls,
• as well as the abbreviation SDR with a specific index.

In this case, the SDR of polyethylene pipes is a strength value that can be used to most accurately determine the capabilities of pipe products.

What makes up SDR

SDR (from English Standard Dimension Ratio - standard dimensional coefficient) is a dimensional characteristic of a polymer pipe, which is the result of the ratio of the outer diameter to the thickness of the polyethylene wall. This value is inversely proportional to the pipe wall thickness, that is, products with a large SDR index have thinner walls, and vice versa - a thick-walled pipe is indicated by a smaller SDR.

Pipes of the same diameter with thicker walls can withstand much greater loads, which are caused during operation by the following technical and natural factors:

• internal pressure of the content,
• external compressions, for example, when the pipe is covered with earth,
• external mechanical influences, such as seasonal ground shifts, etc.

That is, the SDR indicator, along with the thickness of the polyethylene layer, indicates the load or pressure possible for a given pipe, or pressure (internal and external).

What is the difference between pipes with different SDR index

General differences

At the moment, polyethylene pipes with SDR from 6 to 41 are produced, for which the loads presented in the following table by “pressure classes” are possible:

Thus, the standard dimensional coefficient can be used in determining the purpose of the pipe for specific systems - pressure and non-pressure, namely:

• Pipes with the index SDR 26-41 are used for non-pressure (gravity-flowing) sewer outlets;
• With indicators of 21-26, they can already be used for intra-house low-pressure water supply of low-rise buildings;
• Products indexed by an indicator from 11 to 17 can be used for the construction of low-pressure water supply and irrigation systems;
• Pipes with SDRs above less than 9 are suitable for pressure systems designed for water supply, the installation of pressure sewers and even gas pipelines.

Examples

Polyethylene pipes of the same brand with different SDRs can have significant differences. So, for the most popular brand of polyethylene PE-80, this is:

1. PE 80 SDR 13.6 - very durable, can be used for the construction of long-term water supply systems;
2. PE 80 SDR 17 are considered products with average performance and are recommended for installation in plumbing systems of low-rise buildings, where their strength is quite sufficient, and low weight and low cost will save on installation work;
3. PE 80 SDR 21 is not recommended for pressurized systems, buried in the ground and gas pipelines, as they have low compressive strength and internal pressure.

IMPORTANT! When choosing a pipe according to SDR, be sure to consider the grade of polyethylene from which it is made. Even for the same dimensional coefficients, a pipe of a higher grade will be stronger and more resistant to mechanical stress. For example, PE 100 SDR 17, unlike PE 80 with the same index, can be used for pressure water and gas pipelines.

When buying a polyethylene pipe, it is important not only to guess the price, but also to correctly decipher the marking. The most difficult thing is the interpretation of SDR. In this article, we will talk about the features of the SDR in more detail, as well as consider other characteristics that must be considered when choosing a pipe.

Diameter and thickness

When wondering what SDR is, many customers forget about the other two parameters: diameter and wall thickness. The value of SDR depends on them. To make it easier for you to remember, we suggest taking a look at the formula

It follows from it that SDR shows the ratio of the outer diameter of the pipe to the wall thickness. It turns out that the thicker the pipe, the smaller the SDR.

Now manufacturers produce pipes with an SDR range of 7.4 to 33. Each category has its own pressure level.

Table. Maximum pressure of PE pipe 100 in various SDRs

Thus, knowing the SDR, you will be able to select a pipe for a specific pressure, which will allow you to perform installation work faster and better in the future.

What other characteristics should be taken into account

In addition to SDR, it will not be superfluous to find out weight of 1 running meter. So you can calculate the volume of the pipe, which will help you order a vehicle of the desired cubic capacity.

Polyethylene. Please note that when choosing a pipe according to the SDR, you must know the brand of polyethylene from which the pipe is made. Today, most manufacturers use PE 100. The latest raw materials have an improved structure and increased density, which ensures long-term operation of the finished product.

GOSTs and TU. PE pipes are manufactured in accordance with GOST if they are used in pressure networks transporting drinking and utility water. You can distinguish such a pipe by the blue stripes applied along the body. By the way, yellow stripes are used to mark PE gas pipes. generally accepted GOST for water pipes is 18599-2001 . As for TU (technical conditions), the situation is different here. There is no single prescriptive document, each manufacturer creates it independently. Of course, not from "air", but guided by the tolerances of the same GOST.

Release form. Traditionally, polyethylene pipes are made in segments and coils. The first is whips 6, 16 meters long. Bays are pipes of small diameters wound into a roll (from 10 to 63 mm). The rest of the sizes are supplied in pieces. Information about this is usually contained in the description, or it is reported by the manager during a telephone conversation.

How to buy a plastic pipe and save

Our company has been selling HDPE and PE pipes for over 10 years. During this time, we have helped thousands of customers across the country to find a quality pipe at a low price. Especially for our readers, we will reveal a couple of secrets of a successful purchase.

1. Provider. A good supplier is half the success. Find someone who will supply you with a pipe at quite divine prices, you can exhale. It is most advantageous to cooperate with representative offices of large factories and direct manufacturers.
2. Range. The more offers, the more chances to get a discount. Seasonal sales, liquidation of warehouse balances can significantly reduce the cost of pipes. However, there is another danger here: to buy low-grade illiquid assets. Therefore, when purchasing PE pipes at low prices, do not forget about quality.
3. Delivery. Many companies include delivery to the client in the cost of the pipe. Others offer this service for free, which is not true in all cases. In order not to be deceived, ask the manager to calculate the cost without delivery. If the warehouse is nearby, then you can hire a car yourself.

And, of course, the main secret of "pipe economy" is not to be a miser in everything. The slogan "cheap and cheerful" in the case of pipes can only do harm. You will still have to pay, perhaps a much larger amount than planned. Without fanaticism: save a pretty penny where it's safe. Happy shopping and good mood!

Polyethylene pipes, like any others, have a marking system. It can be difficult for novice builders to understand what a SDR 11 polyethylene pipe is or what is encrypted in the marking “PE 80 SDR 21”.

Our article will explain the meaning of the required parameters, in addition, it presents a brief technological characteristic and the main areas of application of the most popular types of polyethylene pipes.

What is SDR and PE?

SDR is the ratio of the outer diameter of a polyethylene (or any other) pipe to the thickness of its wall. Thus, with an increase in the SDR index, the pipe wall becomes thinner, and vice versa, the wall thickness increases with a decrease in the index.

After the prefix PE (“polyethylene”), manufacturers indicate the brand of polyethylene. Nowadays, PE-80 and PE-100 are most common.

The materials have some differences:

1. PE 100 has a more ordered structure of the crystal lattice, due to which, after welding, a stronger and more uniform weld can be obtained.
2. However, due to the first difference, PE 80 requires a lower temperature for soldering.
3. The PE 100 material is generally denser and more durable, which means it can be used in more severe operating conditions.
4. The production of pipes of the required diameter will require a larger amount of PE 80 polyethylene (compared to analogues), which increases the cost of the final product, as well as the price of its delivery to the construction site

In the article "" you can get acquainted with these indicators in more detail.

Pro tip: There may be an opinion that since polyethylene of the 100th brand is more reliable, resistant and cheap, it is better to use only it. However, in practice, each type of pipe has found its optimal application. Let's consider them in more detail.

Characteristics of products made of PE 80

PE 80 SDR 21

These are low-pressure pipes that are intended for use in the installation of non-pressure, as well as low-pressure sewage systems created in small apartment buildings. It is possible to create a pressure water supply for small areas of open areas. This type of pipe is fully certified for the use of pipelines providing cold water supply and sewerage operation. Experts do not recommend the use of such pipes in such cases:

• installation of gas pipelines due to insufficient thickness of the pipe wall,
• laying main pipelines, as excessive squeezing can lead to physical destruction of the pipe.

PE 80 SDR 17

The polyethylene pipe SDR 17 is distinguished by the average value of the ratio of the outer diameter of the pipes produced today to the thickness of their wall. Pipes PE 80 SDR 17 are recommended for use in a very wide range. They are used:

• for plumbing systems designed to supply drinking water;
• for household water pipelines from facilities where water treatment is carried out to the consumer;
• for installation of irrigation systems.

The choice of these pipes for the installation of communications in a low-rise building is considered optimal, since their installation will ensure high strength, lightness of pipelines, and the cost of purchasing the material will be relatively low.

PE 80 SDR 13.6

Pipes PE 80 SDR 13.6 are low pressure pipes and are recommended for use in the installation of pipelines transporting cold drinking water.

High technical qualities and consumer characteristics of this type of pipes are due to the use of an improved grade of polyethylene (PE80) and the use of a new method in the process of cleaning raw materials.

Pro tip: Due to the long warranty period (up to 70 years), such pipes are widely used in the creation of long-term water supply systems.

Characteristics of products made of PE 100

PE 100 SDR 26

These are pipes for transporting household and drinking water in urban areas and outside the city. For their production, polyethylene PE100 is used, the distinctive qualities of which are high density, due to which pipes made of this material are superior to products made of PE80 in terms of long-term strength and resistance to cracking.

In addition, the quality indicators of the material made it possible to significantly reduce the wall thickness of the product, which lightened its weight. PE100 pipes are recommended for wide application in such cases:

• for the installation of water pipes;
• for pipelines intended for the transport of liquid food products, for example, in the production of milk, juice, brewing and winemaking.

PE 100 SDR 21

Pipes PE 100 SDR 21 are used for the construction of water pipelines. Passing through pipes of this type, water retains its taste and is characterized by the absence of foreign odors.

This type of pipe can be successfully used if it is necessary to use it jointly with steel pipes, since special detachable and one-piece adapters that equip the ends of each pipe of this type (plastic at one end, metal at the other) provide the ability to connect both with plastic as well as steel pipes. Corrosion processes, other types of destruction and blockages are not terrible for such pipes.

PE 100 SDR 17

Products marked PE 100 SDR 17 are pipes of a new generation due to the use of advanced technologies used in the production of PE100 polyethylene. A feature of these products is uniquely high strength indicators, which has a significant impact on enhancing the performance of polyethylene pipes.

Pipes of this type are recommended for use in pressure water supply systems and gas pipelines. At the same time, such pipes are considered ideal for the installation of pipelines with a large cross section. In the manufacture of pipes of this type, it turns out to be very significant material savings due to the possibility of reducing the wall thickness while maintaining the high strength of the product. The technical characteristics of such pipes allow their widespread use in the construction of long pipelines.

PE 100 SDR 11

The pipe polyethylene SDR 11 is made of the polyethylene received at a low pressure. At the same time, the high density of the PE 100 SDR 11 pipe material makes it possible to use them for high-pressure water pipes. The material used for the manufacture of pipes ensures high quality and environmental safety of drinking water.

Pipes of this type are suitable for the operation of systems with advanced water supply capabilities. It is possible to use such pipes for the installation of sewer collectors - the chemical resistance of the material used in the production ensures high strength and durability of the pipes. Laying of such pipes is possible with any type of soil.

This is the characteristic of the most used types of polyethylene products for pipelines. It should be noted that the quality of the finished product is largely influenced by the brand of polyethylene pipes, and this factor must be taken into account when buying.

Standard dimensional ratio or Standard Dimension Ratio, the combination that gave rise to this abbreviation. We are talking about SDR for polyethylene pipes, and the simplest formula for its definition is:

Where dn is the outer diameter, en is the pipe wall thickness. So, we understand that the thinner the pipe, the more SDR and vice versa. In fact, it is possible to calculate just the wall thickness using the SDR indicated in the marking, because this indicator is standard: 41, 33, 26, 21, 17.6 and below, up to 9 - all these are SDRs of different pipe thicknesses. In addition, the standard dimensional ratio depends on another indicator, namely, the pipe series:

where S is the series.

What is a series?

For domestic pipes produced in accordance with GOST 8032 and foreign pipes corresponding to it, S is a normalized value and depends on the size of the product. It will help to determine how many times the stress in the pipe wall from the applied working pressure MOP exceeds this working pressure. For example, series 2.5 says - two and a half times the allowable voltage is higher than the MOP.

The maximum working pressure itself, at which (in a constant value) the service life of the pipe reaches the 50 or 100 years declared by the manufacturer, is calculated as follows:

MOP=2 MRS/

Where MRS is the minimum strength of PE in long-term operation, and C is the safety factor. We are already familiar with SDR. C can take values ​​of 1.25 (for cold pipes), 2 or 3.15 for hot pipes or transporting explosive gases. When choosing a series, they don’t pay much attention. It is enough to select pipes according to MRS and SDR, if the operating conditions are already known.