Standard dimensional ratio or Standart Dimension Ratio, a combination that has gone to this abbreviation. It is about SDR for pipes from polyethylene, and the simplest formula looks like:
Where Dn is the outer diameter, en - the thickness of the pipe wall. So, we understand the thinner the pipe, the more SDR and vice versa. In fact, it is possible to calculate the wall thickness specified in the marking of the SDR, because the indicator is standard: 41, 33, 26, 21, 17.6 and lower, to 9 - all this SDR is different in the thickness of the pipes. In addition, the standard dimensional relation from another indicator depends, namely - the pipe series:
| SDR 41. | SDR 33. | SDR 26. | SDR 21. | SDR 17,6 | SDR 17. | SDR 13,6 | SDR 11. | SDR 9. | SDR 7,4. | SDR 6. |
where S is the series.
What is a series?
For produced according to GOST 8032 domestic and corresponding foreign pipes S - the value is normalized and dependent on the product size. It will help determine how many times the voltage in the wall of the pipe from the working pressure rendered by the working pressure exceeds this working pressure. For example, a series of 2.5 speaks two and a half times the allowable voltage above the MOR.
The maximum working pressure at which (in constant meaning), the service life of the pipe reaches the manufacturer's declared 50 or 100 years, is calculated so:
Mor \u003d 2 mrs /
Where MRS is the minimum PE strength in long-term operation, and C is the safety reserve coefficient. With SDR, we are already familiar. C can take 1.25 values \u200b\u200b(for cold pipes), 2 or 3.15 - for hot pipes or transporting explosive gases. A series of attention when choosing is not particularly paying. It is enough to pick up pipes on MRS and SDR, if the operating conditions are already known.
Published: September 22, 2015By purchasing polyethylene pipes for the device of communication systems in domestic or production purposes, you can see the labeling with a set of different data on a particular product. It contains:
- information about the pipe manufacturer,
- rooms of GOST standards, according to which it has been manufactured,
- reduction "PE", meaning that pipes are made of polyethylene - thermoplastic hydrocarbon polymer "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 an SDR abbreviation with a specific index.
In this case, the SDR of polyethylene pipes is the strength value in which you can most accurately determine the capabilities of pipe products.
What makes a SDR
SDR (from English Standart Dimension Ratio - standard dimensional coefficient) is the dimensional characteristic of the polymer pipe, which is the result of the ratio of the external 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 large SDR index have thinner walls, and vice versa - a thick-walled pipe is denoted by a smaller SDR.
The pipes of the same diameter with thicker walls can withstand much greater loads, which are caused during operation with the following technical and natural factors:
- internal pressure pressure,
- external compression, for example, when popping up the ground,
- external mechanical stress, such as seasonal shifts of soil, etc.
That is, the SDR indicator simultaneously with the thickness of the polyethylene layer indicates the load possible for this pipe, or pressure (internal and external).
What is the difference between pipes with different SDR index
General differences
Currently produced polyethylene pipes with SDR from 6 to 41, for which the loads presented in the following table according to the "pressure classes" are possible:
| 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 in determining the purpose of the pipe for specific systems - pressure and non-pressure, namely:
- Pipes with the SDR 26-41 index are used for non-pressure (samotane) sewer taps;
- With indicators 21-26 can already be used for the domestic slothing water supply of low-rise buildings;
- Products, indexed by an indicator from 11 to 17, can serve as for the construction of slightly water and irrigation systems;
- The pipes with SDR are above less than 9-ta are suitable for pressure systems designed to supply water, a device for pressure sewer collectors and even gas pipelines.
Examples
Polyethylene pipes of one brand with different SDRs may have significant differences. So, for the most popular polyethylene brand PE-80 is:
- PE 80 SDR 13.6 - very durable, can be used to build long-term water supply systems;
- PE 80 SDR 17 is considered to be products with average indicators and are recommended for installation in low-rise storage systems, where their strength is quite enough, and low weight and low cost will allow saving on installation work;
- PE 80 SDR 21 is not recommended for pressure systems, instillations in the ground and gas pipeline device, as they have low strength to squeezing and internal pressure.
IMPORTANT! When choosing a pipe on SDR, be sure to take into account the polyethylene brand from which it is made. Even for the same dimensional coefficients, a higher brand tube will be stronger and more resistant to mechanical stress. For example, PE 100 SDR 17, in contrast to PE 80 with the same index, can be used for pressure water and gas pipelines.
By purchasing in the company "Plumbing", for the device of communication systems in domestic or production purposes, you can see the labeling applied to them with a set of different data on a particular product. It contains:
- information about the pipe manufacturer,
- rooms of GOST standards, according to which it has been manufactured,
- reduction "PPR", meaning that pipes are made of polypropylene - thermoplastic polymer of hydrocarbon "Polypropylene".
- the diameter of the product and the thickness of the material of its walls,
- as well as an SDR abbreviation with a specific index.
In this case, SDR polypropylene pipes is a strength value at which it is possible to most accurately determine the capabilities of pipe products.
What makes a SDR
SDR (from English Standart Dimension Ratio - standard dimensional coefficient) is the dimensional characteristic of the 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 large SDR index have thinner walls, and vice versa - a thick-walled pipe is denoted by a smaller SDR.
The pipes of the same diameter with thicker walls can withstand much greater loads, which are caused during operation with the following technical and natural factors:
- internal pressure pressure,
- external compression, for example, when popping up the ground,
- external mechanical stress, such as seasonal shifts of soil, etc.
That is, the SDR indicator simultaneously with the thickness of the polypropylene layer indicates the load possible for this pipe, or pressure (internal and external).
What is the difference between pipes with different SDR index
General differences
At the moment, polypropylene tubes with SDR from 6 to 41 are available, for which the loads presented in the following table according to the "pressure classes" are possible:
| 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 in determining the purpose of the pipe for specific systems - pressure and non-pressure, namely:
- Pipes with the SDR 26-41 index are used for non-pressure (samotane) sewer taps;
- With indicators 21-26 can already be used for the domestic slothing water supply of low-rise buildings;
- Products, indexed by an indicator from 11 to 17, can serve as for the construction of slightly water and irrigation systems;
- The pipes with SDR are above less than 9-ta are suitable for pressure systems designed to supply water, a device for pressure sewer collectors and even gas pipelines.
Examples
Polypropylene pipes of one brand with different SDRs may 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 drinking cold water supply systems, hot water supply, as well as process pipelines, transporting fluids and gases, non-aggressive pipes. Pipes have good thermal insulation properties, chemical resistance of more than 300 substances and solutions, as well as noise-absorbing property. Maximum operating temperature: +60 ° C. Technology installation of pipelines - polyfusion welding.;
Polypropylene Pipe SDR 6 (PN 20) Valfex - Polypropylene PPR-C SDR 6 (PN 20) complies with GOST 32415-2013, suitable for systems of drinking and drinking cold water supply, hot water supply, as well as tubing pipelines, transporting liquids and gases, non-aggressive pipes. Pipes have good thermal insulation properties, chemical resistance of more than 300 substances and solutions, as well as noise-absorbing property. Maximum operating temperature: +95 ° C, briefly up to +100 ° C. Pipeline mounting technology - polyfusion welding;
Polypropylene fiberglass reinforced tube SDR 7.4 (PN 20) Valfex -Polipropylene PP-R pipe reinforced with fiberglass, SDR 7.4 (PN 20), corresponds to GOST 32415-2013 and serves for radiator heating systems, drinking hot and cold water supply systems, air conditioning, industrial pipelines. The pipe has an increased service life in heating and cooling systems, because The fiberglass layer ensures the strength of the pipes with a smaller wall thickness, while the carrier conductivity is increased by 20%. Pipeline mounting technology - polyfusion welding. Maximum operating temperature: + 95 ° C.
Polypropylene fiberglass reinforced pipe SDR 6 (PN 25) Valfex - Polypropylene PP-R pipe reinforced with fiberglass, SDR 6 (PN 25) corresponds to GOST 32415-2013 and serves 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 fiberglass layer ensures the strength of the pipes with a smaller wall thickness, while the carrier conductivity is increased by 20%. Pipeline mounting technology - polyfusion welding. Maximum operating temperature: + 95 ° C.
Polypropylene pipe reinforced with aluminum SDR 6 (PN 25) Valfex -Polypropylene reinforced with aluminum PP-R PN 25 SDR 6 (PN 25) corresponds to GOST 32415-2013. It is used in cold, hot water supply, low, high-temperature heating, when laying pneumatic pipelines, technological pipelines, in combined firewood systems. The inner aluminum layer has absolute oxygen-resistance, reduces the temperature elongation of the pipeline, and also increases the strength of the pipe, due to the presence of a solid longitudinal weld. The special design of the pipes does not require stripping before performing welding. Rated pressure (cold water transportation) - 25 bar. Maximum operating temperature - 90 ° C. The range of external diameters of the proposed polypropylene pipes - 20-110 mm.
IMPORTANT! When choosing a pipe on SDR, be sure to take into account the polypropylene brand from which it is made. Even for the same dimensional coefficients, a higher brand tube will be stronger and more resistant to mechanical stress. For instance, SDR 6 (PN 25) Valfex, Unlike SDR 6 (PN 20) Valfex With the same index, it can be used for pressure water and gas pipelines.
How to find out SDR pipes from polyethylene, for which the pipes are used with different indicators
When choosing polyethylene pipes for household or production communications, pay attention to the product labeling. It contains the following notation:
- manufacturer's name;
- gOST number, which regulates product characteristics;
- pE reduction, which indicates the material of the manufacture - polyethylene, which is a thermoplastic polymer;
- the brand of polyethylene, indicated by the number next to the designation of PE;
- pipe diameter, wall thickness;
- designation SDR with digit.
If with the assignment of most designations is understandable, then with SDR sometimes there are difficulties. If you are planning in Moscow and polyethylene products and do not know how to choose from SDR, today we will tell more about this designation.
How to count SDR
Under the abbreviation SDR implies a standard dimensional coefficient that characterizes the ratio between the outer diameter and the thickness of the product wall. That is, the indicator is calculated by the formula:
SDR \u003d outer diameter / wall thickness
If you see a pipe with a large SDR, then it is thin-walled, and vice versa: the less the designation, the time the wall. The operational characteristics of the product depend on the wall thickness. What it is more, the greater the product will withstand the product. This applies to all types of loads:
- internal pressure;
- external compression for pipes that pass under the ground and falling asleep with a layer of soil;
- external mechanical impacts, for example, during soil shifts, sediments due to rain and so on.
For what pressure and operating conditions are designed for various SDRs
Manufacturers produce products that SDR ranges from 6 to 41. Pipes with the smallest indicator are designed for pressure 25 atm, with the largest - capable of withstanding 4 atm.
According to the dimensional coefficient of the pipe, you can classify into several groups that are designed for different operating conditions:
- SDR 26-41 - the least durable products suitable only for samotane sewage taps, in which an additional pressure does not occur;
- SDR 21-26 - suitable for slightlyphant water supply, for example, they are used for laying in-house communications in low-rise construction;
- SDR 11-17 - pipes suitable for slightly water pipes, as well as irrigation systems;
- SDR 9 and less - products are suitable for pressure systems of water supply, pressure sewers, as well as gas pipelines.
To ensure the uninterrupted functioning of the pipeline, it is important to connect the pipes with the corresponding fittings. It is not suitable for them, we need clamping transitional structures.
Practical examples
Here are some examples of how to operate the products of the popular brand of polyethylene PE-80:
- SDR 13.6 are suitable for long-term water supply systems;
- SDR 17 belongs to medium-strength products, differ insignificant weight and low cost, due to which they are suitable for water supply systems in low-rise buildings;
- SDR 21 is suitable for outdoor gaskets, designed for non-pressure systems, since they cannot withstand the internal pressure and compression of the soil layer.
Note! The strength of the pipe depends on SDR, as well as the brand of polyethylene. With the same dimensional coefficients, the product of durable polyethylene will be more resistant to mechanical effects, and therefore suitable for complex operating conditions.
Buy polyethylene pipes of all SDR values \u200b\u200byou can buy in our hypermarket heating - site
Also, if you already have pipes from polyethylene, but you need to buy fittings for polypropylene pipes with us you will find everything you need!
(polymer pipes - in a more general case) - Standart Dimension Ratio - standard dimensional attitude pipes that can be represented as a relationship nominal outdoor pipe diameter to nominal Pipe Wall Thickness.
SDR \u003d D N / E N
The greater the SDR value, the thinner the PE pipe wall and, on the contrary, the wall thickness grows with a decrease in SDR. In fact SDR. It is a standard value and takes values \u200b\u200bfrom a series (see table) through which the nominal thickness of the pipe wall is calculated (ratio of the nominal diameter of the pipe to the standard dimensional ratio).
| SDR 41. | SDR 33. | SDR 26. | SDR 21. | SDR 17,6 | SDR 17. | SDR 13,6 | SDR 11. | SDR 9. | SDR 7,4. | SDR 6. |
| PE100 SDR41-400X9.8 MOP \u003d 0.4 MPa | PE100 SDR6-400X66,4 MOP \u003d 2.0 MPa |
Also, the standard dimensional attitude depends on the S series series:
SDR \u003d 2S + 1
The pipe series is the normalized value for the corresponding tube size, selectable from the dimensional row R 10 according to GOST 8032 (2.5; 3.2; 4; 5; 6.3; 8; 8.3; 10; 12.5; 16 ; 20). The pipe series determines how many times the allowable voltage arising in the pipe wall from the maximum operating pressure (MOP - MAXIMUM OPERATION PRESSURE) exceeds this pressure.
In practice, the concept of "tube series" is not used because of its remoteness from the physical "design" meaning.
The maximum working pressure in the pipeline (the maximum pressure in which the estimated life of the storage and transportation conditions is 50 years) is determined by the dependence:
Mor \u003d 2 mrs /
Where MRS. - minimum long-term strength of polyethylene;
FROM - The reserves factor (pipeline gasket coefficient), depending solely on the laying conditions and the resulting values:
1,25
- for polyethylene pipes for the supply of cold water;
2 .. 3,15
- For polyethylene pipes for supplying combustible gases.
To select PE pipes in terms of "maximum working pressure", it suffices to determine the MRS - the main parameter of the raw material of the polyethylene pipe and SDR is the main structural parameter of the polyethylene pipe.