Contents
The fact that metal pipelines are being replaced with plastic ones is not news for a long time. Usually only decide which material to choose. Polypropylene is one of the best, although it is not without drawbacks. What can be the diameters of polypropylene pipes, for which systems they are intended and how to choose a diameter. Read about all this below.
Properties of polypropylene
Although polypropylene is the least dense of all plastics, it is more resistant to abrasion, tolerates heat better, begins to soften only at 140 ° C, is chemically resistant, and almost does not crack as a result of corrosion. The material is plastic. Under loads not exceeding the limit, it stretches, and then returns to its original shape without any changes in its properties and characteristics. So it’s really a good and safe option. Pipelines are made from polypropylene pipes at food enterprises.
An additional plus is that polypropylene pipes are easily connected – they are welded. In general, not only water pipes and heating are made of polypropylene. This material can be used as a frame for greenhouses, country furniture and a bunch of other useful things.
Polypropylene has two disadvantages: a large thermal expansion and a reaction to oxygen and ultraviolet. And with that, and with the other learned to fight. In order for polypropylene to tolerate UV rays and light, stabilizers are added. Reinforced pipes are made to reduce thermal expansion. But even with reinforcement, the increase remains large and compensators must be installed in the pipelines.
Another disadvantage of polypropylene pipes is that they become brittle at low temperatures. Some species begin to crumble at -5°C, others at -15°C. So outdoor pipelines made of polypropylene require UV protection and insulation. Therefore, probably, they prefer to bury them.
Types and purpose
Polypropylene pipes can be single-layer and three-layer. Single-layer will be used for water supply, sewerage, ventilation and other pipelines with a temperature of the transported medium not higher than + 45 ° C.
Three-layer PPR pipes are reinforced. Reinforcement is designed to reduce the amount of thermal expansion and nothing more. Reinforce PPR pipes with fiberglass and foil. Those with fiberglass are suitable for hot water supply, provided that the water temperature is not higher than 80°C. For heating and systems where water can be heated above 80°C, foil-reinforced polypropylene is used. Foiling may not be continuous. For such pipes, the permissible temperature of the transported medium is +95°C.
Can polypropylene pipes be used in floor heating systems? I guess, yes. The coolant temperature does not rise above +45 ° C, which is quite acceptable even for single-layer ones. But due to the large thermal expansion, PPR pipes for underfloor heating are not the best option, even reinforced with foil. There are more stable options and not more expensive.
Pressure classification
Since a certain pressure is created in the pipeline to transport the medium, polypropylene pipes also have such a classification. There are four categories:
- PN10. Operating pressure 10 bar (1 MPa), maximum temperature +45°C. For cold water and low pressure systems.
- PN16. Withstands pressure up to 15 Bar (1,5 MPa), temperatures up to +60°C. Also for cold water, but you can put it in high-rise buildings.
- PN20. Pressure 20 bar (2 MPa) and heating up to +75°C. Usually these are reinforced pipes, but with a small wall thickness. Used for hot water supply.
- PN25. The most durable pipes. Operating pressure 25 bar or 2,5 MPa, continuous heating up to +95°C. It is exclusively reinforced, and with a thick wall. They are used for hot water supply with unstable pressure (in high-rise buildings) and for heating distribution.
If we talk about which PPR pipes can withstand what pressure, then single-layer (without reinforcement) can be used up to PN20. The difference in wall thickness and this can be seen from the table. The outer diameters of polypropylene pipes do not say anything (first column). The same external dimension can be designed for different pressures. It depends on the wall thickness and the presence / absence of reinforcement. So pipe labeling is a must. The pressure class is indicated there.
| Outer diameters of polypropylene pipes, mm | PN 10 | PN 20 | PN 25 | |||
|---|---|---|---|---|---|---|
| Inner diameter, mm | Wall thickness, mm | Inner diameter, mm | Wall thickness, mm | Inner diameter, mm | Wall thickness, mm | |
| 16 | – | – | 10,6 | 2,7 | – | – |
| 20 | 16,2 | 1,9 | 13,2 | 3,4 | 13,2 | 3,4 |
| 25 | 20,4 | 2,3 | 16,6 | 4,2 | 16,6 | 4,2 |
| 32 | 26,0 | 3,0 | 21,2 | 5,4 | 21,2 | 3,0 |
| 40 | 32,6 | 3,7 | 26,6 | 6,7 | 26,6 | 3,7 |
| 50 | 40,8 | 4,6 | 33,2 | 8,4 | 33,2 | 4,6 |
| 63 | 51,4 | 5,8 | 42,0 | 10,5 | 42,0 | 5,8 |
| 75 | 61,2 | 6,9 | 50,0 | 12,5 | 50,0 | 6,9 |
| 90 | 73,6 | 8,2 | 60,0 | 15,0 | – | – |
| 110 | 90,0 | 10,0 | 73,2 | 18,4 | – | – |
Please note that the wall thickness in the third column – PN25 – is less than in the previous ones, although the pipes are designed for higher pressure. It’s not a mistake. It’s just that the pipes are only reinforced. And in the previous two categories, the wall thickness and diameters of polypropylene pipes without a reinforcing layer are indicated.
Marking of polypropylene pipes
As already mentioned, the outer diameter does not determine what pressure the pipe is designed for. Moreover, it is also difficult to determine the type of material. Therefore, all this information is indicated in the marking, which is applied to the pipe. It repeats approximately every meter, so it is simply unrealistic not to see it.
The first place is usually put the name of the company or its logo. It is better not to buy anonymous pipes. But there is also a danger of falling for a fake if the company is well-known. It is necessary to study the logo well and buy only with a complete match. The following information is provided below:
- The material from which the pipe is made. For polypropylene, it is PP. A reinforcing material may also be specified.
- If it’s aluminum it costs AL.
- Fiberglass – GF.
- Composite material with glass fiber – PPR-GF.
- Next comes the layer-by-layer enumeration of materials. For example, as in the photo PP-R100/AL/PP-R100. It also indicates the type of polypropylene. There may be such designations:
- PP-R100. These are pipes for pipelines with temperatures up to 100°C.
- PP-B80. Pipes for the sewerage with temperature of the transported environment of +70 °C.
- PP-R80. For cold and hot water supply, temperature up to 100°C.
- Dimensions of polypropylene pipes in millimeters or inches (if they are imported). The outside diameter is listed first, then the wall thickness. Read more about converting inches to millimeters here.
- Pressure class: PN10, PN20, PN25.
- Technical information in which the working pressure is coded. The SDR class is indicated here, which can be deciphered from the table below.
SDR decoding for polypropylene pipes - Operating class and working pressure. The operating classes of polypropylene pipes are encoded with a number (see the table). Indicated for domestic pipes. They reflect the scope.
- The standard according to which the product is manufactured.
So the full information is applied, which is necessary in order to decide where to use and under what conditions.
| Designation of the class of operation of PP pipes | Fluid temperature (operating/maximum) in °C | Area of use |
|---|---|---|
| XB | to 20 | For cold water supply only. |
| 1 | 60/80 | For domestic hot water with an operating temperature of 60°C. |
| 2 | 70/80 | For domestic hot water with an operating temperature of 70°C. |
| 3 | 40/60 | For underfloor heating with heating medium temperatures up to 40°C. |
| 4 | 60/70 | Heating and floor heating systems with an operating temperature not exceeding 60°C. |
| 5 | 80/90 | Heating and floor heating systems with an operating temperature not exceeding 800°C. |
Additionally, we recommend reading the article “How to choose the best pipes made of polypropylene.”
Diameters of polypropylene pipes: assortment according to GOST R 52134-2003
This GOST describes the assortment for pipes made of any type of plastic, one of which is polypropylene and its copolymers (modifications). The table shows the dimensions of polypropylene pipes (diameter and wall thickness) depending on what working pressure the pipe is designed for.
Standard diameters of polypropylene pipes and wall thickness depending on the maximum pressure in the pipeline
| Nominal outer diameter, mm | up to 25 Atm | up to 25 Atm | up to 20 Atm | up to 12 Atm | up to 7 Atm | up to 5 Atm | up to 4 Atm | up to 4 Atm |
|---|---|---|---|---|---|---|---|---|
| 10 | 2,0 | – | – | – | ||||
| 12 | 2,4 | 2,0 | 1,8 | 1,8 | ||||
| 16 | 3,3 | 2,7 | 2,2 | 1,8 | ||||
| 20 | 4,1 | 3,4 | 2,8 | 1,9 | ||||
| 25 | 5,1 | 4,2 | 3,5 | 2,3 | ||||
| 32 | 6,5 | 5,4 | 4,4 | 2,9 | 1,8 | |||
| 40 | 8,1 | 6,7 | 5,5 | 3,7 | 2,3 | 1,8 | ||
| 50 | 10,1 | 8,3 | 6,9 | 4,6 | 2,9 | 2,0 | 1,8 | |
| 63 | 12,7 | 10,5 | 8,6 | 5,8 | 3,6 | 2,5 | 2,0 | 1,8 |
| 75 | 15,1 | 12,5 | 10,3 | 6,8 | 4,3 | 2,9 | 2,3 | 1,9 |
| 90 | 18,1 | 15,0 | 12,3 | 8,2 | 5,1 | 3,5 | 2,8 | 2,2 |
| 110 | 22,1 | 18,3 | 15,1 | 10,0 | 6,3 | 4,2 | 3,4 | 2,7 |
| 125 | 25,1 | 20,8 | 17,1 | 11,4 | 7,1 | 4,8 | 3,9 | 3,1 |
| 140 | 28,1 | 23,3 | 19,2 | 12,7 | 8,0 | 5,4 | 4,3 | 3,5 |
| 160 | 32,1 | 26,6 | 21,9 | 14,6 | 9,1 | 6,2 | 4,9 | 4,0 |
| 180 | 36,1 | 29,9 | 24,6 | 16,4 | 10,2 | 6,9 | 5,5 | 4,4 |
| 200 | 33,2 | 27,4 | 18,2 | 11,4 | 7,7 | 6,2 | 4,9 | |
| 225 | 3,4 | 30,8 | 20,5 | 12,8 | 8,6 | 6,9 | 5,5 | |
| 250 | 34,2 | 22,7 | 14,2 | 9,6 | 7,7 | 6,2 | ||
| 280 | 38,3 | 25,4 | 15,9 | 10,7 | 8,6 | 6,9 | ||
| 315 | 28,6 | 17,9 | 12,1 | 9,7 | 7,7 | |||
| 355 | 32,2 | 20,1 | 13,6 | 10,9 | 8,7 | |||
| 400 | 36,3 | 22,7 | 15,3 | 12,3 | 9,8 | |||
| 450 | 40,9 | 25,5 | 17,2 | 13,8 | 11,0 | |||
| 500 | 28,4 | 19,1 | 15,3 | 12,3 | ||||
| 560 | 31,7 | 21,4 | 17,2 | 13,7 | ||||
| 630 | 35,7 | 24,1 | 19,3 | 15,4 | ||||
| 710 | 40,2 | 27,2 | 21,8 | 17,4 | ||||
| 800 | 45,3 | 30,6 | 24,5 | 19,6 | ||||
| 900 | 51,0 | 34,4 | 27,6 | 22,0 | ||||
| 1000 | 38,2 | 30,6 | 24,5 | |||||
| 1200 | 45,9 | 36,7 | 29,4 | |||||
| 1400 | 53,5 | 42,9 | 34,3 | |||||
| 1600 | 61,2 | 49,0 | 39,2 |
How long are PP pipes? If they are sold in segments, then the maximum length of the segment is 24 meters. There may be less, the multiplicity step is 25 cm. Thinner ones – up to 180 mm in diameter can be in bays. The length of the bay – as agreed. There is only a limitation on the inner diameter of the coil: it must be at least 20 times the pipe section.
As you can see, the assortment is more than extensive. What diameters of polypropylene pipes are usually used when repairing a house? This, of course, is “the average temperature in the hospital”, but in general the situation is as follows:
- For plumbing, the most common diameters are 16-25 mm. For risers, they take already thicker ones – from 30 mm to 110 mm. The stands are different.
- For heating systems, the diameter of the wiring is 32-40 mm, the taps to the radiators are one step (one size) smaller. But it depends on the type of system. Gravity flow may require both 90 and 110 mm. It definitely needs to be counted.
- Ventilation systems require large dimensions. Usually more than 110 mm.
- PPR pipes for sewerage usually differ in color, and in the presence of a socket and sealing rings. You won’t confuse them. The smallest ones are 40 mm, but they are rarely used – to connect the drain from the sinks. Layers from risers make 110 mm or more.
All given diameters of polypropylene pipes are indicative. So that you know at least in which direction to look. For each system there are methods of calculation or selection. “By eye” it is better not to choose.
Connection method
As already mentioned, polypropylene is connected by welding. But despite the high level of plasticity, the minimum bending radius does not allow making turns even with an angle of 90 °, not to mention steeper ones. All branches and turns are made using fittings. These are special elements for connecting plastic pipes. This is a whole range of different parts for each diameter.
The difference is that the marking indicates the diameter of the pipe for which these elements are intended. So you don’t need any sizing. If you use a pipe, say with a diameter of 25 mm, then just take fittings with the same marking. It’s better to buy both from the same company. Then there will be no problems. If you had to take products from different companies, to be sure, “try on” them. Take a piece of pipe to the store and check the compatibility. It should go in without any problems, but tightly, without gaps.