When purchasing polyethylene pipes for installing communication systems for home or industrial purposes, you can see markings applied to them with a set of various data about a specific product. It contains:
- information about the pipe manufacturer,
- numbers of GOST standards in accordance with which it was manufactured,
- 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.),
- diameter of the product and thickness of the material of its walls,
- as well as the abbreviation SDR with a certain index.
In this case, the SDR of polyethylene pipes is a strength value by which the capabilities of pipe products can be most accurately determined.
What does SDR consist of?
SDR (from English Standard Dimension Ratio - standard dimensional ratio) 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 thickness of the pipe walls, that is, products with a higher SDR index have thinner walls, and vice versa - a thick-walled pipe is indicated by a lower 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 contents,
- external compression, for example when the pipe is covered with earth,
- external mechanical influences, such as seasonal soil movements, etc.
That is, the SDR indicator, along with the thickness of the polyethylene layer, indicates the possible load or pressure (internal and external) for a given pipe.
What is the difference between pipes with different SDR indexes?
General differences
At the moment, polyethylene pipes are produced with SDR from 6 to 41, for which the possible loads are presented in the following table by “pressure classes”:
| SDR 6 | SDR 7.4 | SDR 9 | SDR 11 | SDR 13.6 | SDR 17 | SDR 17.6 | SDR 21 | SDR 26 | SDR 33 | SDR 41 |
| 25 atm | 20 atm | 16 atm | 12 atm | 10 atm | 8 atm | 7 atm | 6 atm | 5 atm | 4 atm | 4 atm |
Thus, the standard dimensional coefficient can be used when determining the purpose of the pipe for specific systems - pressure and non-pressure, namely:
- Pipes with index SDR 26-41 are used for free-flow (gravity) sewer outlets;
- With indicators of 21-26 they can already be used for intra-house low-pressure water supply to low-rise buildings;
- Products indexed with an index from 11 to 17 can be used for the construction of low-pressure water supply and irrigation systems;
- Pipes with an SDR greater than or equal to 9 are suitable for pressure systems intended for water supply, construction of pressure sewer collectors 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 it is:
- PE 80 SDR 13.6 – very durable, can be used for the construction of long-term water supply systems;
- PE 80 SDR 17 are considered products with average performance and are recommended for installation in water supply systems of low-rise buildings, where their strength is sufficient, and their low weight and low cost will save on installation work;
- PE 80 SDR 21 are not recommended for pressure systems, burial in the ground and gas pipeline construction, as they have low compressive strength and internal pressure.
IMPORTANT! When choosing an SDR pipe, 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.
You have built your own country house, dacha, or even bought yourself a new wonderful apartment. The time has come to lay utilities, such as heating systems, cold and hot water supply. The modern market allows buyers a huge selection of pipeline fittings, and of course modern plastic pipes. They all look the same, and it is almost impossible for a non-specialist to understand them. But how not to make a mistake and buy a truly reliable polypropylene, polyethylene, plastic pipe. How to guarantee to protect yourself from possible ruptures and leaking pipes. The answer lies in a very important parameter that you must know before purchasing a pipe.
Pipe SDR is the main digital indicator of pipe reliability, and the lower it is, the more reliable the pipe.
What is SDR? This is the ratio of the diameter of the pipe to the thickness of its walls. The thicker the walls of a plastic pipe, the more reliable it is. Accordingly, if the diameter is divided by a larger number, the result obtained is smaller.
Let's look at several SDR values using polypropylene pipes as an example.
Polypropylene pipe SDR 11
- operating pressure no more than 10 atm
- as a rule, this is not a reinforced pipe that is used only for cold water supply. This pipe is not suitable for heating systems.
- can be used to supply cold water both in a private house and in urban areas. In both cases, the water pressure in the mains will not exceed 3-5 Atm.
Polypropylene pipe SDR 7.4, specifications:
- working pressure no more than 20 atm
- can be used to supply cold and hot water both in a private home and in urban areas. But if we consider this SDR value for the supply to heating radiators in a city multi-storey building, you can play it safe by taking a pipe with a lower SDR value.
Polypropylene pipe SDR 6, specifications:
- working pressure no more than 25 atm
- as a rule, this is a pipe reinforced with aluminum foil and fiberglass, which is used for both cold and hot water supply and heating.
- can be used to supply cold and hot water both in a private home and in urban areas. Technical parameters allow polypropylene pipes with this SDR value to be used even in heating systems of multi-storey buildings. This is a polypropylene pipe with a high safety margin.
Polyethylene pipes, like other building materials, have a marking system. This approach allows the buyer to understand the technical and quality characteristics of the product, determine the purpose of a particular pipe and its ability to cope with loads.
It is allowed to add additional information to the GOST-approved marking of PE pipes () - for example, some manufacturers indicate the company logo and address on the product. But there is information that the manufacturer must include. One of them is SDR.
Marking of polyethylene pipes
The procedure for marking pipes is approved by GOST. Information is applied in one line, with the same font size using color printing or thermal embossing with a certain depth. The marking system for polyethylene pipes must display the following indicators:
- information about the manufacturer (name or trademark);
- symbol of the pipe material - PE (polyethylene);
- numbers indicating the brand of raw material granules from which the pipe is made - 32, 63, 80,100 (the higher the number, the greater the wall density);
- the quality standard according to which the product is manufactured - GOST or DU;
- outer diameter of the pipe (from 16 to 1200 mm) and thickness of its wall;
- pipe SDR coefficient, indicating the permissible load limit;
- purpose of the pipe (technical or drinking).
Additionally, the production line or batch number may be indicated, as well as the date of manufacture of polyethylene pipes. Color marking is also used: a yellow longitudinal strip along the entire length indicates that the pipe is intended for a gas pipeline, blue - for a water supply.
What does SDR mean?
One of the main indicators of the strength characteristics of a polyethylene pipe, which is provided for by GOST and must be indicated during labeling, is SDR. This parameter allows you to determine the capabilities of products. Explanation of this designation in English (Standard Dimension Ratio) - standard dimensional ratio.
The SDR coefficient of a pipe shows the ratio of its outer diameter to the wall thickness; the following formula is used to calculate the indicator:
SDR = D: S, where D is the outer diameter (in mm) and S is the pipe wall thickness (in mm).
The higher the SDR coefficient, the thinner the pipe wall, and vice versa - for a pipe with thick walls this indicator is lower. Thus, a pipe with a low SDR will have greater capabilities and ability to withstand severe loads than a product with a high ratio.
Important! If you choose a product with the best performance characteristics from pipes of the same diameter and with different SDR values (for example, 17 and 21), you should give preference to a smaller coefficient - 17. However, you need to take into account: the greater the wall thickness, the lower the throughput of the pipe due to its reduction internal section.
Difference between pipes with different SDR
Modern industry produces PE pipes with SDR indices from 6 to 41 with loads corresponding to the pressure classes presented in this table:
The SDR index is thus used to determine the purpose of pipes for pressure and non-pressure systems. Most often, products with indicators 11, 17,21 are used. General differences between pipes with different SDR indexes determine the conditions for their use:
- HDPE products with a coefficient below 9 are used for the construction of water pressure systems, sewerage and gas pipelines;
- pipes with characteristics SDR 11-17 are used for the manufacture of irrigation systems and low-pressure water supply;
- indicators 21-26 are suitable for creating water supply systems for one- and two-story buildings;
- pipes with index SDR 26-41 are used for non-pressure sewer communications.
Note! When choosing a pipe according to SDR, you must also take into account the grade of polyethylene. With the same dimensional coefficients, pipes with a higher PE grade will be much stronger. For example, PE 100 SDR 17 can be used to create pressure water and gas pipelines, but PE 80 pipes with the same SDR rating are less resistant to mechanical stress, and therefore are not suitable for these purposes. You can read more about polyethylene pipes in our article "Polyethylene (HDPE) pipes PE-100"
Let's look at the operating characteristics of some of the most popular pipes, based on the standard dimensional coefficient.
PE 80 SDR 13.6
These HDPE pipes are best suited for installing home plumbing systems, transporting liquids and chemicals. The most durable products of this brand with a prescribed pressure of 10 atmospheres. The wall of such pipes can withstand temperature changes, so they can be used even in the North.
PE 80 SDR 17
Pipes SDR 17 grade PE 80 have an average coefficient. The scope of application of this option is quite wide. Supply of drinking water for technical purposes, creation of irrigation systems. The use of such pipes for water supply to low-rise buildings is especially important: they are highly durable, lightweight and relatively inexpensive. Withstands pressure of 8 atmospheres at a permissible temperature of 200⁰C. However, PE 80 SDR 17 pipes are not used for the installation of water supply systems in high-rise buildings.
PE 80 SDR 21
These HDPE pipes are also used for transporting drinking water in country and urban one-story houses and for installing free-flow sewerage. The small thickness of the walls does not make it possible to use them for installing water supply systems in high-rise buildings, and PE 80 SDR 21 pipes cannot be installed underground: the pipeline will not withstand the loads. At temperatures not exceeding 200⁰C, the system will withstand up to 50 years of operation. When reaching 400⁰C, the pipe begins to experience deformation.
PE 100 SDR 26
These products are used for the installation of domestic wastewater and drinking water in urban areas and outside the metropolis. Pipes are used for sewer systems and laying artesian wells. They are used for transporting food industry liquids - juices, wine. Low wall thickness contributes to light weight and increased throughput by 10% at a pressure of 10 atmospheres.
PE 100 SDR 21
An ideal option for installing drainage systems not only in small country houses, but also in multi-storey buildings, since pipes with PE 100 SDR 21 ratings can withstand high loads, including pressure. In addition, the water transported in them does not change its taste and does not absorb foreign odors. They are also used for reclamation and irrigation works. Using adapters, you can combine PE products with metal pipes.
PE 100 SDR 17
Modern generation pipes with excellent strength and damage resistance. Products that can withstand a load of 10 atmospheres are optimal for the construction of pressure water pipelines and gas supply systems. They are considered the most suitable option for installing large cross-section systems and are successfully used for the construction of long pipelines. Therefore, PE 100 pipes with SDR 17 are perfect for cold water supply
PE 100 SDR 11
The high density of HDPE from which these pipes are made, reliability and strength, allow the products to be used for all types of communications: hot and cold water supply, construction of gas mains, sewer collectors. They are resistant to chemical attack, so they can be laid in any soil. At a pressure of 16 atmospheres, PE 100 SDR 11 pipes will last up to half a century. For example, polyethylene gas pipes PE 100 with SDR 11 have proven themselves well. However, lifting mechanisms are required for installation due to the large weight of the products.
Thus, the index of the standard pipe dimensional coefficient SDR is one of the first indicators that you need to pay attention to when choosing. Together with the brand, this indicator determines the quality and conditions for further operation of the pipe.
When purchasing from the SantekhnikUM company for the installation of communication systems for home or industrial purposes, you can see markings applied to them with a set of various data about a specific product. It contains:
- information about the pipe manufacturer,
- numbers of GOST standards in accordance with which it was manufactured,
- The abbreviation "PPR" means that the pipes are made of polypropylene - a thermoplastic polymer of the hydrocarbon "polypropylene".
- diameter of the product and thickness of the material of its walls,
- as well as the abbreviation SDR with a certain index.
In this case, the SDR of polypropylene pipes is a strength value by which the capabilities of pipe products can be most accurately determined.
What does SDR consist of?
SDR (from English Standard Dimension Ratio - standard dimensional ratio) is a dimensional characteristic of a polymer pipe, which is the result of the ratio of the outer diameter to the thickness of the polypropylene wall. This value is inversely proportional to the thickness of the pipe walls, that is, products with a higher SDR index have thinner walls, and vice versa - a thick-walled pipe is indicated by a lower 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 contents,
- external compression, for example when the pipe is covered with earth,
- external mechanical influences, such as seasonal soil movements, etc.
That is, the SDR indicator, along with the thickness of the polypropylene layer, indicates the possible load or pressure (internal and external) for a given pipe.
What is the difference between pipes with different SDR indexes?
General differences
At the moment, polypropylene pipes are produced with SDR from 6 to 41, for which the possible loads are presented in the following table by “pressure classes”:
| SDR 6 | SDR 7.4 | SDR 9 | SDR 11 | SDR 13.6 | SDR 17 | SDR 17.6 | SDR 21 | SDR 26 | SDR 33 | SDR 41 |
| 25 atm | 20 atm | 16 atm | 12 atm | 10 atm | 8 atm | 7 atm | 6 atm | 5 atm | 4 atm | 4 atm |
Thus, the standard dimensional coefficient can be used when determining the purpose of the pipe for specific systems - pressure and non-pressure, namely:
- Pipes with index SDR 26-41 are used for free-flow (gravity) sewer outlets;
- With indicators of 21-26 they can already be used for intra-house low-pressure water supply to low-rise buildings;
- Products indexed with an index from 11 to 17 can be used for the construction of low-pressure water supply and irrigation systems;
- Pipes with an SDR greater than or equal to 9 are suitable for pressure systems intended for water supply, construction of pressure sewer collectors and even gas pipelines.
Examples
Polypropylene pipes of the same brand with different SDRs can have significant differences. So, for the most popular brand of polypropylene SDR 11 (PN 10) VALFEX
- Polypropylene pipe SDR 11 (PN 10) VALFEX– Polypropylene pipe PPR-C SDR 11 (PN 10) complies with GOST 32415-2013, suitable for drinking and domestic cold water supply systems, hot water supply, as well as process pipelines transporting liquids and gases that are non-aggressive to pipe materials. The pipes have good thermal insulation properties, chemical resistance to more than 300 substances and solutions, as well as noise-absorbing properties. Maximum operating temperature: +60 °C. Pipeline installation technology – polyfusion welding;
Polypropylene pipe SDR 6 (PN 20) VALFEX-Pipe made of polypropylene PPR-C SDR 6 (PN 20) complies with GOST 32415-2013, suitable for drinking and domestic cold water supply systems, hot water supply, as well as process pipelines transporting liquids and gases that are non-aggressive to pipe materials. The pipes have good thermal insulation properties, chemical resistance to more than 300 substances and solutions, as well as noise-absorbing properties. Maximum operating temperature: +95 °C, briefly up to +100 °C. Pipeline installation technology – polyfusion welding;
Glass fiber reinforced polypropylene pipe SDR 7.4 (PN 20) VALFEX-Polypropylene pipe PP-R, reinforced with glass fiber, SDR 7.4 (PN 20), complies with GOST 32415-2013 and is used for radiator heating systems, drinking hot and cold water supply systems, air conditioning, industrial pipeline networks. The pipe has an increased service life in heating and cooling systems, because The glass fiber layer ensures the strength of the pipes with a smaller wall thickness, while the conductivity of the carrier is increased by 20%. Pipeline installation technology is polyfusion welding. Maximum operating temperature: +95°C.
Glass fiber reinforced polypropylene pipe SDR 6 (PN 25) VALFEX — Polypropylene pipe PP-R, reinforced with glass fiber, SDR 6 (PN 25), complies with GOST 32415-2013 and is used for radiator heating systems, drinking hot and cold water supply systems, air conditioning, industrial pipeline networks. The pipe has an increased service life in heating and cooling systems, because The glass fiber layer ensures the strength of the pipes with a smaller wall thickness, while the conductivity of the carrier is increased by 20%. Pipeline installation technology is polyfusion welding. Maximum operating temperature: +95°C.
Polypropylene pipe reinforced with aluminum SDR 6 (PN 25) VALFEX — Polypropylene pipe reinforced with aluminum PP-R PN 25 SDR 6 (PN 25) complies with GOST 32415-2013. It is used in cold and hot water supply, low- and high-temperature heating, when laying pneumatic pipelines, process pipelines, and in integrated fire-fighting water supply systems. The inner aluminum layer has absolute oxygen impermeability, reduces the thermal expansion of the pipeline, and also increases the strength of the pipe due to the presence of a continuous longitudinal weld. The special design of the pipes does not require stripping before welding. Nominal pressure (cold water transportation) – 25 bar. The maximum operating temperature is 90 °C. The range of outer diameters of the proposed polypropylene pipes is 20–110 mm.
IMPORTANT! When choosing an SDR pipe, be sure to consider the grade of polypropylene 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, SDR 6 (PN 25) VALFEX, Unlike SDR 6 (PN 20) VALFEX with the same index, can be used for pressure water and gas pipelines.
In recent years, polyethylene pipes (PE) have become widely used, especially in the construction industry. PE pipes are used in the construction of gas pipelines and water pipelines, they are used to equip swimming pools, automate irrigation, and are widely used in other industries. Polyethylene itself is a thermoplastic material; it is obtained by polymerization of an oil refinery product. In this article we will look at the characteristics of various types of products and understand what the marking “PE SDR pipe” means.
The equipment used for the production of such pipes is not bulky or particularly complex. and are manufactured in various diameters in accordance with GOST, and are marked accordingly. Depending on the purpose, they differ in characteristics; each type of PE pipe has a corresponding brand.
Polyethylene grades
Grade PE 80, PE 63, PE 100 corresponds to the strength index MRS 8; 6.3 and 10, i.e., means the minimum long-term strength of the polyethylene from which these pipes are made. Pipe polyethylene of these grades is obtained from a rigid polymer with a linear structure and a high degree of crystallinity. These products have good resistance to most inorganic and organic acids, petroleum carbons, alkalis, salts, etc.
Polyethylene grades PE 100, PE 80 and PE 63 are widely used nowadays; its main distinguishing feature is density, strength and, of course, cost.
PE 32 SDR pipe is also produced, its quality is regulated, its scope of use is water supply (at a nominal pressure of 2.5 atm.) and sewerage.
It seems that PE 100 is the most reliable, durable and cheaper grade of polyethylene; in fact, each of these grades has its own individual application.
In addition, such pipes have a visual difference depending on their purpose. For example, pipes with a blue stripe are used to install a drinking water supply system, and products with a yellow stripe are used to lay a gas pipeline.
PE 100 pipe
It is characterized by high working pressure, maximum tensile strength and resistance to mechanical stress. Certified raw materials are used for its production. Qualitative characteristics made it possible to reduce the wall thickness of this product and reduce its weight. Pipes of this brand are most often used for the following purposes:
- water and gas pipelines;
- installation of pipelines for supplying food products in liquid form (juices, milk, wine, beer, etc.).
These products are wear-resistant, quite lightweight, and medium-pressure plastic is used for their manufacture. Pipes of this brand belong to low-pressure pipes, the main purpose of which is the installation of low-pressure and non-pressure pipes in multi-apartment residential buildings. In addition, they can be used to install small-diameter pressure water supply in a small area.
The products are certified and can be used for their intended purpose.
At the same time, experts do not recommend using them in some cases. Due to the small thickness of the wall, it is not recommended to install gas pipelines and main pipelines from such products.
PE 63 pipe
This grade of polyethylene contains mainly ethylene molecules; it is characterized by short-term strength, but at the same time it is prone to cracking and destruction. Due to these characteristics, it is less often used in civil and industrial construction for the construction of drainage systems of road communications, basements of buildings, foundations and sites.
These pipes are used in the laying of fiber optic lines, where they are used as a casing for utility lines. Sometimes these pipes are used in agriculture; with their help, moisture is drained from waterlogged areas and swamps.
Polyethylene pipe and its SDR
What is SDR
One of the main indicators characterizing a PE pipe is SDR. It displays the ratio of the outer diameter of a polyethylene pipe and the thickness of its wall; it is calculated using a table or formula:
SDR = D/s Where
- D = outer diameter of PE pipe (mm);
- s = pipe wall thickness (mm).
This indicator characterizes the strength of the pipe: the higher it is, the weaker the pipe and vice versa.
Accordingly, a product with a small SDR can withstand greater pressure compared to the same product, but having a higher value. Thus, polyethylene pipes whose wall thickness is more capable of withstanding quite noticeable pressure.
The ability of polyethylene to be stable and neutral to gaseous and liquid substances determined the scope of its application. In addition to gas and water mains, PE pipes are used for transporting gaseous and liquid materials and other purposes.
Polyethylene pipes with different SDR
Each type of pipe has its own characteristics, let’s consider them:
- Polyethylene grade 100:
- The PE 100 SDR 17 pipe is indispensable in gas pipelines and pressure water supply systems, especially in pipelines with a large cross-section. Its technical characteristics allow the use of such pipes for the installation of long-distance pipelines. This polyethylene pipe SDR 17 belongs to a new generation of products, which was obtained by using modern technologies used in the manufacture of PE 100. Excellent performance characteristics of pipes made from this material are achieved due to the high strength properties of polyethylene.
- Polyethylene pipe SDR 11 is made from polyethylene obtained at low pressure. Moreover, its high density makes it possible to use these products on high-pressure water pipelines. In addition, this type can be used for the installation of sewer collectors due to its resistance to aggressive environments. Laying can be done in almost any soil.
- Products made from PE 100 polyethylene, such as the PE SDR 26 pipe, can withstand pressures of up to 6.3 atm, and are used mainly in non-critical water supply systems, in gravity sewers and for protecting communications.
- PE pipe SDR 21 grade 100 - its main purpose is to install water pipes; according to experts, the water in this product does not have any foreign taste and retains its taste well.
- Polyethylene grade 80:
- A product such as the PE 80 SDR 11 pipe belongs to a new generation of products, the characteristics are much higher than those of PE 63. Its main purpose is to supply cold water; in addition, if necessary, it can be used for sewerage and gasification.
- The PE 80 SDR 13.6 pipe is used for installation and repair of water pipes and pipes for liquid chemicals, to which polyethylene is neutral.
- PE 80 SDR 17 pipes are the optimal choice for low-rise construction, as they have sufficient strength for it and at the same time an affordable cost.
- The PE 63 SDR 11 pipe is made from various types of polymers. Can be used for supply lines in water supply systems, like sewer pipes, and also as a protective case for communications and power supplies.
Advantages of using PE pipes
The wide range of applications of these products is explained by many advantages over their analogues made of metal, such as:
- products made of polyethylene have a warranty period of about 50 years;
- they are not exposed to moisture, aggressive environments, corrosion, stray currents, and do not require cathodic protection;
- are light in weight;
- installation is simple, while maximum tightness is achieved, and there is no need for professional equipment;
- the pipes are frost-resistant and do not burst even when the water in them freezes;
- due to the ideal inner surface of the pipe, no deposits form on the walls;
- prices for the purchase and installation of pipes are reasonable.
