In the process of building your own house, you often have to face the need to lay underground utilities. This applies to plumbing, household or storm sewer, sometimes it is necessary to lay a heat main between two buildings. But it is not enough to correctly lay the pipes themselves, observing, if necessary, their required slope - it is very important to protect them from the effects of low temperatures, eliminating the possibility of freezing in the cold season.
Insulation for pipes in the ground is especially important in regions with harsh winters where the soil freezes to a considerable depth.
Surely, objections may be heard - why, they say, insulate sewer drains, which are obviously given an appropriate slope, and stagnation of water here cannot be, by definition? And, meanwhile, the thermal insulation of the sewer is a very responsible matter. There are at least two reasons that can cause water to accumulate in them - this is not a septic tank pumped out on time or a clogged pipe. In both cases, in an uninsulated pipe, freezing of the liquid will lead to the formation of an ice plug and, in the future, to rupture of the walls. But to carry out a quick repair or replacement of a damaged area in frozen ground conditions is an extremely complex and large-scale problem.
There are a lot of heat-insulating materials intended for warming underground sections of pipes. They differ in the material of manufacture, in terms of service life, in thickness, quality and, of course, in cost.
Criteria for choosing insulation for pipes
Heat insulators for pipes passing at a certain depth into the ground must meet certain requirements, which include:
- The hydrophobicity of the insulation, that is, its resistance to moisture. The material, in addition to thermal insulation, should protect the pipe from soil moisture, without letting it through, and at the same time without collapsing and without losing its thermal insulation qualities.
- Low thermal conductivity for high-quality preservation of natural heat inside the pipes.
In fact, thermal insulation under the conditions under consideration can perform two main tasks:
- If the pipe is pumping coolant (heating system) or hot water ( DHW system), then the minimization of heat losses comes to the fore.
- For pipes of cold water supply or sewerage, the main purpose of insulation is to be protected from exposure to negative temperatures, that is, from freezing.
The table shows the heat loss of pipes different diameter, depending on the thickness of the heat-insulating layer (with an average thermal conductivity of 0.04 W/m×° WITH) and the difference between the temperatures of the pumped liquid and the environment (Δt°):
| Thermal insulation thickness, mm | Δt,оС | Pipe diameter in mm | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 15 | 20 | 25 | 32 | 40 | 50 | 65 | 80 | 100 | 150 | ||
| Estimated heat loss per 1 linear pipeline, W. | |||||||||||
| 10 | 20 | 7.2 | 8.4 | 10 | 12 | 13.4 | 16.2 | 19 | 23 | 29 | 41 |
| 30 | 10.7 | 12.6 | 15 | 18 | 20.2 | 24.4 | 29 | 34 | 43 | 61 | |
| 40 | 14.3 | 16.8 | 20 | 24 | 26.8 | 32.5 | 38 | 45 | 57 | 81 | |
| 60 | 21.5 | 25.2 | 30 | 36 | 40.2 | 48.7 | 58 | 68 | 86 | 122 | |
| 20 | 20 | 4.6 | 5.3 | 6.1 | 7.2 | 7.9 | 9.4 | 11 | 13 | 16 | 22 |
| 30 | 6.8 | 7.9 | 9.1 | 10.8 | 11.9 | 14.2 | 16 | 19 | 24 | 33 | |
| 40 | 9.1 | 10.6 | 12.2 | 14.4 | 15.8 | 18.8 | 22 | 25 | 32 | 44 | |
| 60 | 13.6 | 15.7 | 18.2 | 21.6 | 23.9 | 28.2 | 33 | 38 | 48 | 67 | |
| 30 | 20 | 3.6 | 4.1 | 4.7 | 5.5 | 6 | 7 | 8 | 9 | 11 | 16 |
| 30 | 5.4 | 6.1 | 7.1 | 8.2 | 9 | 10.6 | 12 | 14 | 17 | 24 | |
| 40 | 7.3 | 8.3 | 9.5 | 10.9 | 12 | 14 | 16 | 19 | 23 | 31 | |
| 60 | 10.9 | 12.4 | 14.2 | 16.4 | 18 | 21 | 24 | 28 | 34 | 47 | |
| 40 | 20 | 3.1 | 3.5 | 4 | 4.6 | 4.9 | 5.8 | 7 | 8 | 9 | 12 |
| 30 | 4.7 | 5.3 | 6 | 6.8 | 7.4 | 8.6 | 10 | 11 | 14 | 19 | |
| 40 | 6.2 | 7.1 | 7.9 | 9.1 | 10 | 11.5 | 13 | 15 | 18 | 25 | |
| 60 | 9.4 | 10.6 | 12 | 13.7 | 14.9 | 17.3 | 20 | 22 | 27 | 37 | |
Obviously, with an increase in the thickness of the insulation, the level of heat loss decreases, but even with a thickness of 40 mm it is impossible to achieve complete insulation. In the case of cold water supply or sewerage, sometimes it is necessary to resort to additional measures - the installation of electric heating.
The required thickness of insulation for various types of pipelines will be discussed below.
- resistance to external chemical attack- the soil is a very aggressive environment in this regard.
- The heater should have a high mechanical strength, be resistant to external mechanical and atmospheric influences, withstand loads and ground pressure. Durability can also be attributed here - since it will be quite difficult to replace thermal insulation in underground areas.
- resistance to high and low temperatures environment and liquid transported through the insulated pipeline.
- The material should be easily mounted on the pipe in any position.
- An important factor is the compatibility of the materials of the insulation and the pipe, since the occurrence of a reaction between them is unacceptable - it can lead to mutual damage.
Fulfillment of all requirements for the insulation material will allow you to avoid significant heat losses, make it possible not to worry about the integrity of the pipes and the likelihood of ice plugs forming in them.
Materials used for insulation of underground pipelines
On the modern building materials market, a fairly wide range of pipe insulation is presented. Most common materials for their manufacture - foamed polyethylene, polyurethane foam, expanded polystyrene, some types of mineral wool.
For pipe insulation, material is used in the form of tapes, rolls, mats, or made with a special shape - cylinders, half-cylinders, segments, etc. Of course, profile heaters are the most convenient in installation, since they can be put on a pipe installed in any position.
Polyethylene foam insulation
Foamed polyethylene has very high technical characteristics for pipe insulation. And this — at a very affordable price.
- The thermal conductivity of the material is minimal, and is 0.035 W / m × ° C.
- This material has a structure consisting of the smallest closed cells, which contribute to the creation of effective waterproofing, which is especially important for metal pipes. This provides additional protection against corrosion, extends the life of the pipeline.
- Foamed polyethylene can have a density of 25 ÷ 40 kg/m. As a rule, the most popular are products with this indicator of 30 ÷ 35 kg / m³.
- In addition, the material has excellent elasticity, which does not change even under critical negative temperatures(up to - 55 °). This quality makes the installation of the insulation a very simple matter - the sleeve is easy to cut and put on a pipe located under any bend.
- The rupture load that polyethylene foam can withstand is 0.3 MPa, and its dynamic elasticity is 0.76 MPa.
- The compression ratio at a load of 4500 N/m² is 0.2.
- Vapor permeability - 0.001 mg / m × h × Pa, that is, polyethylene foam refers to materials that support natural vapor exchange.
- The hydrophobicity of this insulation was tested by immersing it in water for 24 hours, as a result of which the material absorbed moisture by only 1.3% of its volume. And, it should be noted that in the following hours, the absorption of moisture completely stops.
- The operating temperatures of polyethylene foam vary in the range from - 55 to + 85 degrees. More high temperatures lead to its spatial deformation, and at negative values below the specified threshold, the insulation loses its elasticity and becomes brittle.
- Fire resistance in this case is not important, since the insulated pipes will be in the ground. But this material is also used for external thermal insulation, therefore, it has an appropriate classification, and according to this parameter it is designated G2, that is, moderately combustible material. Polyethylene ignites at a temperature of 300 degrees and only with direct exposure to a flame. When burning, polyethylene decomposes into water and carbon dioxide, which is not toxic, and in small concentrations is not dangerous to human health.
The insulation from this foamed polyethylene is produced in different thicknesses, in the form of cylinders (sleeves) 2000 mm long. It is easy to cut and adheres well to the surface of pipes made of different materials.
Prices for polyethylene foam insulation
polyethylene foam insulation
Comparing the characteristics of their material with the requirements for insulation, we can conclude that this foamed polyethylene is the best suited for thermal insulation of pipelines.
You may be interested in information about the degree of insulation provided for
Another material that is actively used for pipe insulation is Penofol. This is the same polyethylene foam, but with a foil coating that has a reflective property and enhances thermal insulation qualities polyethylene.
Penofol for pipeline insulation is also produced in sleeves, but some craftsmen prefer to use material made in rolls. The first option is put on the pipe and secured with special tape. The second is cut into tapes and overlapped on the mounted pipes.
Pipe insulated with "penofol" tapes
Prices for penofol
The convenience of tape insulation lies in the fact that it is possible thermally insulate a pipeline having many bends or turns. Due to the elasticity of the material, it will accept desired shape and will provide sufficient tightness for thermal insulation.
If cylinders (sleeves) are used when insulating an already installed pipeline, then a cut is made on them along the entire length, through which they are put on the pipes. This incision is then sealed with waterproof adhesive tape. Very often, such a cut is already provided by the manufacturer.
Video: comparison of some types of pipe insulation
Expanded polystyrene pipe insulation
Pipe insulation made of expanded polystyrene is also called "shell", as it really resembles eggshell. Such a material has its advantages and disadvantages, and it is worth considering its characteristics in more detail before choosing it.
Foam insulation for pipes consists of two half-cylinders (for pipes large diameter sometimes three segments), interconnected by lateral groove-thorn locks, which allow you to completely isolate the pipeline from the influence of the environment while maintaining a positive temperature inside the "shell". Due to the form of manufacture of insulation made of expanded polystyrene, it is easy to mount it on already installed highways.
Such insulation is produced in the form of detachable pipes one or two meters long. Wall thickness and diameters, external and internal, may be different.
For the manufacture of pipe heaters of the "shell" type, PSB-S÷15, PSB-S÷25 and PSB-S÷35 foam is used. The main characteristics are given in table:
| Name of parameters | PSB-S-15U | PSB-S-15 | PSB-S-25 | PSB-S-35 | PSB-S-50 |
|---|---|---|---|---|---|
| Density kg/m³ | to 10 | up to 15 | 15.1÷25 | 25.1÷35 | 35.1÷50 |
| Compressive strength at 10% linear deformation MPa, not less than | 0.05 | 0.06 | 0.08 | 0.16 | 0.2 |
| 0.08 | 0.12 | 0.17 | 0.36 | 0.35 | |
| Dry thermal conductivity at 25°C, W /(m×°K) | 0.043 | 0.042 | 0.039 | 0.037 | 0.036 |
| Water absorption in 24 hours, % by volume, no more. | 3 | 2 | 2 | 2 | 2 |
| Humidity, % no more | 2.4 | 2.4 | 2.4 | 2.4 | 2.4 |
| Bending strength, not less than | to 10 | up to 15 | 15.1÷25 | 25.1÷35 | 35.1÷50 |
- Styrofoam or expanded polystyrene is a chemically inert, lightweight material that has a structure of closed cells that are not interconnected.
- The insulation has a low coefficient of thermal conductivity, which is 0.037 ÷ 0.042 W / m².
- moisture absorption foam per day, as tests have shown, is up to 2% of the total volume of the material, so it can be called moisture resistant.
- The operating temperature range of expanded polystyrene is from - 50 to +75 ° С. In this limit, it does not deform and does not lose its basic qualities.
- This material is resistant to the formation of foci of mold or fungus, does not rot, withstands exposure to alkali, cement and gypsum mortars, salts and other inorganic substances.
The positive qualities of polystyrene foam insulation for pipes include the following qualities:
- Low thermal conductivity.
- High moisture resistance, which allows you to maintain the thermal insulation qualities of the material for many years.
- Ease of installation.
- Resistance to environmental influences.
- It is compatible with any material from which pipes are made, as it does not react with metal and plastic.
- The heater has a very affordable price.
The disadvantages of such a heater include:
- Combustibility of the material - it is classified as G4. For underground areas, this criterion is not critical.
- Expanded polystyrene is not elastic, and it will not be possible to bend it, so only even highways can be insulated with it. And for turns, you will have to select special corner parts.
- When using this insulation for pipes laid in the ground, it is recommended to additionally create protection for it by wrapping it with dense polyethylene.
By following all the installation recommendations, carefully putting the insulating shell on the pipes and protecting it from above with a layer of waterproofing, you can create a hermetic insulation that will save the pipeline not only from freezing, but also from soil moisture.
Trubny insulation - polyurethane foam
Currently ready-made options sewer and water pipes already enclosed in a layer of thermal insulation made of polyurethane foam, which is protected from above by a metal or plastic sheath. For example, for highways passing above the ground, pipes in a galvanized metal sheath are used, and for pipelines laid underground, a polyethylene-coated option is excellent, since this material has a high degree of moisture resistance.
Such ready-made insulated pipes are rapidly replacing the previously widely used mineral wool thermal insulation. For comparison, please refer to the table below.
polyurethane foam insulation prices
polyurethane insulation
Comparative characteristics of polyurethane foam and mineral wool used for pipe insulation:
| Material parameters | unit of measurement | PPU | mineral wool |
|---|---|---|---|
| Coefficient of thermal conductivity | W/m×°C | 0.033 | 0.049 |
| Density | kg/m³ | 60÷80 | 55÷150 |
| Compressive strength | MPa | 0.3 | Not standardized, minimum load resistance |
| Water absorption, no more | % | 10 | Not standardized, moisture resistance is minimal, constant humidity included in the calculation is 4% |
| Effective service life, no more | years | 40 | 10 |
| Operating costs (specific damage) | damage per year per 100 km of pipeline | 3÷4 | 30÷40 |
Similar pipes insulated with polyurethane foam with an outer polyethylene sheath in accordance with GOST 30732÷200 are produced with a diameter of 57 mm and more. The following forms of release are provided:
| Outer diameter of steel pipes, d, mm | Type 1 | Type 2 | ||||
|---|---|---|---|---|---|---|
| PPU layer thickness, mm | Outer diameter of polyethylene sheath, D, mm | PPU layer thickness, mm | ||||
| nominal | limit deviation (+) | nominal | limit deviation (+) | |||
| 57 | 125 | 3.7 | 31.5 | 140 | 4.1 | 38.5 |
| 76 | 140 | 4.1 | 29 | 160 | 4.7 | 39 |
| 89 | 160 | 4.7 | 32.5 | 180 | 5.4 | 42.5 |
| 108 | 180 | 5.4 | 33 | 200 | 5.9 | 43 |
| 133 | 225 | 6.6 | 42.5 | 250 | 7.4 | 54.5 |
| 159 | 250 | 7.4 | 41.5 | 280 | 8.3 | 55.5 |
| 219 | 315 | 9.8 | 42 | 355 | 10.4 | 62 |
| 273 | 400 | 11.7 | 57 | 450 | 13.2 | 81.5 |
| 325 | 450 | 13.2 | 55.5 | 500 | 14.6 | 79.5 |
| 426 | 560 | 16.3 | 58.2 | 630 | 16.3 | 92.5 |
| 530 | 710 | 20.4 | 78.9 | - | - | - |
| 630 | 800 | 23.4 | 72.5 | - | - | - |
| 720 | 900 | 26.3 | 76 | - | - | - |
| 820 | 1000 | 29.2 | 72.4 | 1100 | 32.1 | 122.5 |
| 920 | 1100 | 32.1 | 74.4 | 1200 | 35.1 | 120.5 |
| 1020 | 1200 | 35.1 | 70.4 | - | - | - |
Pipe types 1 and 2 include products with conventional or reinforced insulation. The advantage of pipes immediately equipped with insulation and a protective sheath over any other options is that the heat insulator completely seals the pipe body. At the ends of the pipes, non-insulated sections are left for their connection into a solid line using welded joints with deep penetration of the seam.
The appearance and quality of the protective polyethylene sheath also have their own regulation according to the same GOST:
| Parameters | Specifications |
|---|---|
| Surface quality | Jacket pipes must have a smooth outer surface. Insignificant longitudinal stripes and waviness are allowed, which do not lead the pipe wall thickness beyond the limits of permissible deviations. Inner surface pipes must be rough. Bubbles, cracks, shells, foreign inclusions are not allowed on the outer, inner and end surfaces of the pipes. The color of the pipes is black. |
| Elongation at break, %, not less than | 350 |
| Change in the length of the shell pipes after heating at 110 °C, %, no more | 3 |
| Resistance at a temperature of 80 °C and constant internal pressure, hours, not less | 1000 (at an initial stress in the pipe wall of 3.2 MPa) |
Installation of such pipes, as mentioned above, is carried out using welding work. The seam must be checked according to a special technique. Then sections of the pipeline, without insulation at the points of their connection, after installation, the lines are closed with a heat-shrink sleeve, which is filled mounting foam. This ensures complete tightness of the insulation material and the outer shell.
The advantages of using polyurethane foam as a heater include its following qualities:
- Low thermal conductivity.
- High moisture resistance.
- Light weight - density is only 45–60 kg/m³.
- At correct installation- complete absence of cold bridges.
- The ability to give metal pipes additional anti-corrosion protection.
- The duration of the operational period, since the material is not subject to decay and decomposition, as well as resistant to atmospheric and aggressive influences and temperature extremes.
However, it should be noted that ready-made heat-insulated pipes have a rather high price, therefore, insulation is often used instead of them by spraying polyurethane foam on the installed pipeline. But in this case, the heat insulator will be deprived of external protection in the form of an outer shell.
Mineral wool
Mineral wool remains the most affordable thermal insulation material, which is divided into three types depending on the material of manufacture - these are glass wool, basalt and slag wool.
For the insulation of pipes passing in the ground, due to their characteristics, only two options are suitable - glass wool and basalt. Slag wool absorbs moisture abundantly, which means it quickly loses its thermal insulation properties. In addition, it has a high residual acidity, which contributes to the activation of corrosive processes, and for insulation metal structures absolutely unsuitable. Therefore, this option should be immediately rejected and the technical characteristics of the other two materials should be considered, especially since they have long been successfully used for insulating heating mains.
Glass and basalt wool have a number of identical positive qualities that meet almost all requirements for insulation for pipelines. This includes the following options:
- Low thermal conductivity.
- High resistance to alkaline and acid substances, as well as to other chemical compounds.
- Sufficient elasticity, which allows you to easily install not only on straight sections of the highway, but also on bends and turns.
The negative quality of mineral wool can be called its hygroscopicity - it absorbs moisture quite well ( basalt wool less susceptible to this deficiency). Therefore, if the material is used for thermal insulation of a pipeline running in the ground, it is necessary to provide reliable waterproofing for it. It can consist of roofing felt, aluminum foil or dense polyethylene, which is wound on the insulation with an overlap of 400 ÷ 500 mm and is intercepted from above by stainless steel wire or tape.
Insulation of pipes with mineral wool - mandatory external waterproofing is required
Despite the affordable price of the insulation itself, the need for additional use waterproofing material complicates installation and increases the total cost of work.
By the way, mineral wool for pipe insulation is available only in mats, sheets or slabs. On sale you can also find collapsible mineral wool cylinders, which are perfect for straight sections of the pipeline.
You might be interested in information on how to choose
What should be the thickness of the insulation layer of the underground section of the pipe?
So, the main insulation materials that are used for thermal insulation of pipelines were considered. To facilitate the perception of information and comparison when choosing, the main characteristics of heaters are summarized in a single table:
| material, product | Average density in the structure, kg/m3 | Thermal conductivity thermal insulation material(W/(m×°C)) for surfaces with temperature (°C) | Operating temperature range, °C | Flammability group | |
|---|---|---|---|---|---|
| 20 and up | 19 and below | ||||
| Mineral wool pierced plates | 120 | 0.045 | 0,044-0,035 | From - 180 to + 450 for mats, on fabric, mesh, fiberglass canvas; up to + 700 - on a metal grid | non-combustible |
| 150 | 0.049 | 0,048-0,037 | |||
| Heat-insulating slabs of mineral wool on a synthetic binder | 65 | 0.04 | 0,039-0,03 | From - 60 to + 400 | non-combustible |
| 95 | 0.043 | 0,042-0,031 | |||
| 120 | 0.044 | 0,043-0,032 | From minus - 180 to + 400 | ||
| 180 | 0,052 | 0,051-0,038 | |||
| Thermal insulation products made of foamed ethylene-polypropylene rubber Aeroflex | 60 | 0,034 | 0.033 | From - 57 to + 125 | Slightly combustible |
| Semi-cylinders and mineral wool cylinders | 50 | 0,04 | 0,039-0,029 | From - 180 to + 400 | non-combustible |
| 80 | 0,044 | 0,043-0,032 | |||
| 100 | 0,049 | 0,048-0,036 | |||
| 150 | 0,05 | 0,049-0,035 | |||
| 200 | 0,053 | 0,052-0,038 | |||
| Thermal insulation cord made of mineral wool | 200 | 0,056 | 0,055-0,04 | From - 180 to + 600 depending on the material of the mesh tube | In mesh tubes made of metal wire and glass thread - non-combustible, the rest are slightly combustible |
| Glass staple fiber mats with synthetic binder | 50 | 0,04 | 0,039-0,029 | From - 60 to + 180 | non-combustible |
| 70 | 0,042 | 0,041-0,03 | |||
| Mats and wool made of superfine glass fiber without binder | 70 | 0,033 | 0,032-0,024 | From - 180 to + 400 | non-combustible |
| Mats and wool made of super-thin basalt fiber without a binder | 80 | 0,032 | 0,031-0,24 | From - 180 to + 600 | Non-combustible |
| Perlite sand, expanded, fine | 110 | 0,052 | 0,051-0,038 | From - 180 to + 875 | non-combustible |
| 150 | 0,055 | 0,054-0,04 | |||
| 225 | 0,058 | 0,057-0,042 | |||
| Thermal insulation products made of expanded polystyrene | 30 | 0,033 | 0,032-0,024 | From - 180 to + 70 | combustible |
| 50 | 0,036 | 0,035-0,026 | |||
| 100 | 0,041 | 0,04-0,03 | |||
| Thermal insulation products made of polyurethane foam | 40 | 0,030 | 0,029-0,024 | From - 180 to + 130 | combustible |
| 50 | 0,032 | 0,031-0,025 | |||
| 70 | 0,037 | 0,036-0,027 | |||
| Thermal insulation products made of polyethylene foam | 50 | 0,035 | 0.033 | From - 70 to + 70 | combustible |
The article still does not answer the key question - what thickness should the insulation be used for? It is impossible to answer unambiguously, since this parameter depends on a large number of initial data. There are heat engineering calculation formulas established by SNiP, but they are quite cumbersome, and only specialists can understand them.
But you can also use the calculated tabular indicators. Similar tables are placed in the "Code of rules for the design and construction of thermal insulation of equipment and pipelines", approved by the State Construction Committee of the Russian Federation. Finding them is easy - any Internet search engine on request "SP 41 - 103-2000" will lead to this document.
It is simply impossible to place these tables within the framework of this publication, since there are a lot of them - they are compiled for various types of insulation, for pipelines for various purposes, type of gasket, temperatures of the pumped liquid, etc. But in this variety, there will certainly be an answer for a specific pipe laid in the ground.
It would seem that everything, however, there is one more important point. It concerns heaters, which shrink over time, become denser, which is accompanied by a decrease in the effectiveness of thermal insulation. It's about about mineral wool.
That tabular value, which is determined by SP 41 - 103-2000, may eventually not enough- the material will be compacted and the quality of thermal insulation will significantly decrease. By the way, this is very widespread a mistake that can lead to serious consequences. This means that it is necessary to provide a reserve for the thickness of the insulation, which compensates for its shrinkage.
To determine this parameter, use the following formula:
H =h× Kc× ((D+ h) / (D + 2 h) )
H- the required thickness of the insulation, taking into account future shrinkage (seal);
h- tabular value of the required thickness of the insulation;
D- outer diameter of the insulated pipe;
Ks- coefficient of compaction of thermal insulation material. This is a constant calculated for each type of insulation, which can be taken from the proposed table:
| Thermal insulation materials and products | Compaction factor Kc. |
|---|---|
| Mineral wool mats | 1.2 |
| Heat-insulating mats "TEHMAT" | 1,35-1,2 |
| Mats and canvases made of super-thin basalt fiber when laying on pipelines and equipment with nominal diameter, mm: | |
| - Doo | 3 |
| 1,5 | |
| - DN ≥ 800 at an average density of 23 kg/m³ | 2 |
| - the same, with an average density of 50-60 kg / m³ | 1,5 |
| Mats made of glass staple fiber on a synthetic binder brand: | |
| - M-45, 35, 25 | 1.6 |
| - M-15 | 2.6 |
| Mats made of glass spatula fiber "URSA" brand: | |
| - M-11: | |
| a) for pipes with DN up to 40 mm | 4,0 |
| b) for pipes with DN from 50 mm and above | 3,6 |
| - M-15, M-17 | 2.6 |
| - M-25: | |
| a) for pipes with DN up to 100 mm | 1,8 |
| b) for pipes with DN from 100 to 250 mm | 1,6 |
| c) for pipes with DN over 250 mm | 1,5 |
| Mineral wool boards on a synthetic binder brand: | |
| - 35, 50 | 1.5 |
| - 75 | 1.2 |
| - 100 | 1.1 |
| - 125 | 1.05 |
| Glass staple fiber board grades: | |
| - P-30 | 1.1 |
| - P-15, P-17 and P-20 | 1.2 |
| Expanded perlite sand fine grades 75, 100, 150 | 1.5 |
In order not to force the reader to independent calculations, we suggest using the built-in calculator.
In the practice of private construction, it is not so common, but there are still situations when heating communications need to be not only spread across the premises of the main house, but also stretched to other nearby buildings. It can be residential outbuildings, extensions, summer kitchens, economic or agricultural buildings, for example, used for keeping domestic animals or birds. The option is not excluded when, on the contrary, the autonomous boiler house itself is located in a separate building, at some distance from the main residential building. It happens that the house is connected to the central heating main, from which pipes are stretched to it.
The laying of heating pipes between buildings is possible in two ways - underground (channel or channelless) and open. The process of installing a local heating main above the ground seems to be less time-consuming, and this option, under conditions self construction come running more often. One of the main conditions for the efficiency of the system is a properly planned and well-executed thermal insulation for outdoor heating pipes. This is the question that will be considered in this publication.
Why do we need thermal insulation of pipes and the basic requirements for it
It would seem nonsense - why insulate already almost always hot pipes heating system? Perhaps someone can be misled by a kind of "play on words." In the case under consideration, of course, it would be more correct to conduct a conversation using the concept of "thermal insulation".
Thermal insulation work on any pipelines has two main goals:
- If pipes are used in heating or hot water supply systems, then the reduction of heat losses, maintaining the required temperature of the pumped liquid comes to the fore. The same principle is also valid for industrial or laboratory installations, where the technology requires maintaining a certain temperature of the substance transferred through the pipes.
- For cold water pipes or sewer communications the main factor is precisely the insulation, that is, preventing the temperature in the pipes from falling below the critical level, preventing freezing, leading to the failure of the system and deformation of the pipes.
By the way, such a precaution is required for both heating mains and hot water pipes - no one is completely immune from emergencies on boiler equipment.
Itself cylindrical shape pipes predetermines a very considerable area of constant heat exchange with environment, which means a significant heat loss. And they naturally grow as the diameter of the pipeline increases. The table below clearly shows how the value of heat loss changes depending on the temperature difference inside and outside the pipe (column Δt °), on the diameter of the pipes and on the thickness of the thermal insulation layer (data are given taking into account the use of insulation material with an average thermal conductivity coefficient λ = 0.04 W/m×°C).
| The thickness of the thermal insulation layer. mm | Δt.°С | Pipe outer diameter (mm) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 15 | 20 | 25 | 32 | 40 | 50 | 65 | 80 | 100 | 150 | ||
| The amount of heat loss (per 1 linear meter of the pipeline. W). | |||||||||||
| 10 | 20 | 7.2 | 8.4 | 10 | 12 | 13.4 | 16.2 | 19 | 23 | 29 | 41 |
| 30 | 10.7 | 12.6 | 15 | 18 | 20.2 | 24.4 | 29 | 34 | 43 | 61 | |
| 40 | 14.3 | 16.8 | 20 | 24 | 26.8 | 32.5 | 38 | 45 | 57 | 81 | |
| 60 | 21.5 | 25.2 | 30 | 36 | 40.2 | 48.7 | 58 | 68 | 86 | 122 | |
| 20 | 20 | 4.6 | 5.3 | 6.1 | 7.2 | 7.9 | 9.4 | 11 | 13 | 16 | 22 |
| 30 | 6.8 | 7.9 | 9.1 | 10.8 | 11.9 | 14.2 | 16 | 19 | 24 | 33 | |
| 40 | 9.1 | 10.6 | 12.2 | 14.4 | 15.8 | 18.8 | 22 | 25 | 32 | 44 | |
| 60 | 13.6 | 15.7 | 18.2 | 21.6 | 23.9 | 28.2 | 33 | 38 | 48 | 67 | |
| 30 | 20 | 3.6 | 4.1 | 4.7 | 5.5 | 6 | 7 | 8 | 9 | 11 | 16 |
| 30 | 5.4 | 6.1 | 7.1 | 8.2 | 9 | 10.6 | 12 | 14 | 17 | 24 | |
| 40 | 7.3 | 8.31 | 9.5 | 10.9 | 12 | 14 | 16 | 19 | 23 | 31 | |
| 60 | 10.9 | 12.4 | 14.2 | 16.4 | 18 | 21 | 24 | 28 | 34 | 47 | |
| 40 | 20 | 3.1 | 3.5 | 4 | 4.6 | 4.9 | 5.8 | 7 | 8 | 9 | 12 |
| 30 | 4.7 | 5.3 | 6 | 6.8 | 7.4 | 8.6 | 10 | 11 | 14 | 19 | |
| 40 | 6.2 | 7.1 | 7.9 | 9.1 | 10 | 11.5 | 13 | 15 | 18 | 25 | |
| 60 | 9.4 | 10.6 | 12 | 13.7 | 14.9 | 17.3 | 20 | 22 | 27 | 37 | |
As the thickness of the insulation layer increases, the total heat loss decreases. However, please note that even a fairly thick layer of 40 mm does not completely eliminate heat loss. There is only one conclusion - it is necessary to strive to use insulating materials with the lowest possible coefficient of thermal conductivity - this is one of the main requirements for thermal insulation of pipelines.
Sometimes a pipe heating system is also required!
When laying water or sewer communications, it happens that, due to the peculiarities of the local climate or specific installation conditions, thermal insulation alone is clearly not enough. We have to resort to forced installation of heating cables - this topic is discussed in more detail in a special publication of our portal.
- The material that is used for thermal insulation of pipes, if possible, should have hydrophobic qualities. There will be little current from a heater soaked with water - it will not prevent heat loss either, and it will soon collapse under the influence of negative temperatures.
- The thermal insulation structure must have reliable external protection. Firstly, it needs protection from atmospheric moisture, especially if a heater is used that can actively absorb water. Secondly, materials should be protected from exposure to the ultraviolet spectrum of sunlight, which is detrimental to them. Thirdly, one should not forget about the wind load that can violate the integrity of thermal insulation. And, fourthly, there remains the factor of external mechanical impact, unintentional, including from animals, or due to banal manifestations of vandalism.
In addition, for any owner of a private house, for sure, the moments of the aesthetic appearance of the laid heating main are also not indifferent.
- Any thermal insulation material used on heating mains must have a range of operating temperatures corresponding to the actual conditions of use.
- An important requirement for the insulation material and its outer lining is the durability of use. No one wants to return to the problems of thermal insulation of pipes even once every few years.
- From a practical point of view, one of the main requirements is the ease of installation of thermal insulation, and in any position and in any complex area. Fortunately, in this regard, manufacturers do not get tired of pleasing user-friendly developments.
- An important requirement for thermal insulation is that its materials must themselves be chemically inert and not enter into any reactions with the pipe surface. Such compatibility is the key to the duration of trouble-free operation.
The issue of cost is also very important. But in this regard, the range of prices for specialized ones is very large.
What materials are used to insulate aboveground heating mains
The choice of thermal insulation materials for heating pipes for their external laying is quite large. They are roll type or in the form of mats, they can be given a cylindrical or other figured shape convenient for installation, there are heaters that are applied in liquid form and acquire their properties only after solidification.
Insulation with polyethylene foam
Foamed polyethylene is rightly referred to as a very effective thermal insulator. And more importantly, the cost of this material is one of the lowest.
The coefficient of thermal conductivity of foamed polyethylene is usually in the region of 0.035 W / m × ° C - this is a very good indicator. The smallest gas-filled bubbles isolated from each other create an elastic structure, and with such material, if its rolled version is purchased, it is very convenient to work on pipe sections with complex configurations.
This structure becomes reliable barrier for moisture - with proper installation, neither water nor water vapor can penetrate through it to the pipe walls.
The density of polyethylene foam is low (about 30 - 35 kg / m³), and thermal insulation does not make the pipes heavier.
The material, with some assumption, can be categorized as low hazard in terms of flammability - it usually belongs to class G-2, that is, it is very difficult to ignite, and without an external flame it quickly fades. Moreover, combustion products, unlike many other thermal insulators, do not pose any serious toxic hazard to humans.
Rolled polyethylene foam for insulating external heating mains will be both inconvenient and unprofitable - you will have to wind several layers in order to achieve the required thermal insulation thickness. It is much more convenient to use material in the form of sleeves (cylinders), in which an internal channel is provided that corresponds to the diameter of the insulated pipe. For putting on pipes, usually an incision is made along the length of the cylinder on the wall, which, after installation, can be sealed with reliable adhesive tape.
Putting insulation on the pipe is not difficult A more effective type of polyethylene foam is penofol, which has one side. This shiny coating becomes a kind of thermal reflector, which significantly increases the insulating qualities of the material. In addition, it is an additional barrier against moisture penetration.
Penofol can also be of a roll type or in the form of profiled cylindrical elements - especially for thermal insulation of pipes for various purposes.
And all foamed polyethylene for thermal insulation of heating mains is used infrequently. It is more suitable for other communications. The reason for this is the rather low temperature Range operation. So. if you look at the physical characteristics, then the upper limit balances somewhere on the verge of 75 ÷ 85 degrees - higher, violations of the structure and the appearance of deformations are possible. For autonomous heating, most often, such a temperature is enough, however, on the verge, and for the central one, thermal stability is clearly not enough.
Expanded polystyrene insulation elements
The well-known expanded polystyrene (in everyday life it is often called polystyrene foam) is very widely used for the most different types thermal insulation work. Pipe insulation is no exception - for this, special parts are made of foam plastic.
Usually these are semi-cylinders (for pipes of large diameters there may be segments of a third of the circumference, 120 ° each), which are equipped with lock connection by the "thorn-groove" type. This configuration allows you to completely, over the entire surface of the pipe, provide reliable thermal insulation, without the remaining "cold bridges".
In everyday speech, such details are called "shells" - for their clear resemblance to it. Many types of it are produced, for different outer diameters of insulated pipes and different thicknesses of the thermal insulation layer. Usually the length of the parts is 1000 or 2000 mm.
For the manufacture of polystyrene foam type PSB-S is used various brands- from PSB-S-15 to PSB-S-35. The main parameters of this material are shown in the table below:
| Estimated material parameters | Styrofoam brand | ||||
|---|---|---|---|---|---|
| PSB-S-15U | PSB-S-15 | PSB-S-25 | PSB-S-35 | PSB-S-50 | |
| Density (kg/m³) | to 10 | up to 15 | 15.1 ÷ 25 | 25.1 ÷ 35 | 35.1 ÷ 50 |
| Compressive strength at 10% linear deformation (MPa, not less) | 0.05 | 0.06 | 0.08 | 0.16 | 0.2 |
| Bending strength (MPa, not less than) | 0.08 | 0.12 | 0.17 | 0.36 | 0.35 |
| Dry thermal conductivity at 25°C (W/(m×°K)) | 0,043 | 0,042 | 0,039 | 0,037 | 0,036 |
| Water absorption in 24 hours (% by volume, no more) | 3 | 2 | 2 | 2 | 2 |
| Humidity (%, no more) | 2.4 | 2.4 | 2.4 | 2.4 | 2.4 |
The advantages of polystyrene foam as an insulating material have long been known:
- It has a low thermal conductivity.
- The low weight of the material greatly simplifies the insulation work, which does not require any special mechanisms or devices.
- The material is biologically inert - it will not be a breeding ground for the formation of mold or fungus.
- Moisture absorption is negligible.
- The material is easy to cut, fit to right size.
- Polyfoam is chemically inert, absolutely safe for pipe walls, no matter what material they are made of.
- One of the key advantages - polystyrene is one of the most inexpensive heaters.
However, it also has many disadvantages:
- First of all, it is a low level of fire safety. The material cannot be called non-combustible and does not spread flame. That is why when using it for warming ground pipelines, fire breaks must be left.
- The material does not have elasticity, and it is convenient to use it only on straight sections of the pipe. True, you can find special curly details.
- Polyfoam does not belong to durable materials - it is easily destroyed under external influence. It has a negative effect on him ultraviolet radiation. In a word, the above-ground sections of the pipe, insulated with polystyrene foam shells, will definitely require additional protection in the form of a metal casing.
Usually, in stores that sell foam shells, they also offer galvanized sheets, cut into the desired size, corresponding to the diameter of the insulation. An aluminum shell can also be used, although it is certainly much more expensive. Sheets can be fixed with self-tapping screws or clamps - the resulting casing will simultaneously create anti-vandal, anti-wind, waterproofing protection and a barrier from sunlight.
- And yet even this is not the main thing. The upper limit of normal temperatures for operation is only around 75 ° C, after which linear and spatial deformation of parts can begin. Like it or not, this value may not be enough for heating. Perhaps it makes sense to look for a more reliable option.
Insulation of pipes with mineral wool or products based on it
The most "ancient" method of thermal insulation of external pipelines is with the use of mineral wool. By the way, it is also the most budgetary, if it is not possible to purchase a foam shell.
Used for thermal insulation of pipelines different kinds mineral wool - glass wool, stone (basalt) and slag. Slag wool is the least preferred: firstly, it most actively absorbs moisture, and secondly, its residual acidity can be very destructive to steel pipes. Even the cheapness of this cotton wool does not at all justify the risks of its use.
But mineral wool based on basalt or glass fibers is fully suitable. She has good performance thermal resistance to heat transfer, high chemical resistance, the material is elastic, and it is easy to lay even on complex sections of pipelines. Another advantage - you can be, in principle, completely calm in terms of fire safety. It is almost impossible to heat up mineral wool to the degree of ignition in the conditions of an external heating main. Even exposure to an open flame will not cause the spread of fire. That is why mineral wool is used to fill fire gaps when using other pipe insulation.
The main disadvantage of mineral wool is its high water absorption (basalt is less susceptible to this “ailment”). This means that any pipeline will require mandatory protection from moisture. In addition, the structure of wool is not resistant to mechanical stress, it is easily destroyed, and it should be protected with a strong casing.
Usually, a strong polyethylene film is used, which is securely wrapped with a layer of insulation, with a mandatory overlap of strips by 400 ÷ 500 mm, and then all this is covered with metal sheets from above - exactly by analogy with a polystyrene shell. Roofing material can also be used as a waterproofing - in this case, 100 ÷ 150 mm of overlap of one strip on another will be enough.
The existing GOSTs determine the thickness of protective metal coatings for open sections of pipelines for any type of thermal insulation materials used:
| Cover material | The minimum thickness of the metal, with the outer diameter of the insulation | ||
|---|---|---|---|
| 350 or less | Over 350 and up to 600 | Over 600 and up to 1600 | |
| Stainless steel strips and sheets | 0.5 | 0.5 | 0.8 |
| Sheet steel, galvanized or color coated | 0.5 | 0.8 | 0.8 |
| Sheets of aluminum or aluminum alloys | 0.3 | 0.5 | 0.8 |
| Tapes made of aluminum or aluminum alloys | 0.25 | - | - |
Thus, despite the seemingly inexpensive price of the insulation itself, its full installation will require considerable additional costs.
Mineral wool for pipeline insulation can also act in a different capacity - it serves as a material for the manufacture of finished thermal insulation parts, by analogy with polyethylene foam cylinders. Moreover, such products are produced both for straight sections of pipelines, and for turns, tees, etc.
Typically, such insulating parts are made of the most dense - basalt mineral wool, have an external foil coating, which immediately removes the problem of waterproofing and increases the efficiency of insulation. But you still can’t get away from the outer casing - thin layer foil will not protect against accidental or intentional mechanical impact.
Warming of the heating main with polyurethane foam
One of the most efficient and safest modern insulation materials It's polyurethane foam. He has a lot of various advantages, so the material is used on almost any structure that requires reliable insulation.
What are the features of polyurethane foam insulation?
Polyurethane foam for insulation of pipelines can be used in various forms.
- PPU-shell is widely used, usually having an external foil coating. It can be collapsible, consisting of half-cylinders with tongue-and-groove locks, or, for pipes of small diameter, with a cut along the length and a special valve with a self-adhesive back surface, which greatly simplifies the installation of insulation.
- Another way to insulate a heating main with polyurethane foam is to spray it in liquid form using special equipment. The resulting foam layer after complete hardening becomes an excellent insulation. This technology is especially convenient at complex interchanges, pipe bends, in nodes with shut-off and control valves, etc.
The advantage of this technology is also that due to the excellent adhesion of polyurethane foam spraying to the pipe surface, excellent waterproofing and corrosion protection are created. True, polyurethane foam itself also requires mandatory protection - from ultraviolet rays, so again it will not be possible to do without a casing.
- Well, if you need to lay a sufficiently long heating main, then, probably, the most the best choice will be the use of pre-insulated (pre-insulated) pipes.
In fact, such pipes are a multilayer structure assembled at the factory:
- The inner layer is, in fact, the steel pipe itself of the required diameter, through which the coolant is pumped.
- External coating - protective. It can be polymeric (for laying a heating main in the thickness of the soil) or galvanized metal - what is required for open sections of the pipeline.
- Between the pipe and the casing, a monolithic, seamless layer of polyurethane foam is poured, which performs the function of effective thermal insulation.
An assembly section was left at both ends of the pipe for welding during the assembly of the heating main. Its length is calculated in such a way that the heat flux from the welding arc will not damage the polyurethane foam layer.
After the installation, the remaining non-insulated areas are primed, covered with a polyurethane foam shell, and then with metal belts, comparing the coating with the common outer casing of the pipe. Often, it is in such areas that fire breaks are organized - they are densely filled with mineral wool, then they are waterproofed with roofing material and still covered with a steel or aluminum casing from above.
The standards establish a certain assortment of such sandwich pipes, that is, it is possible to purchase products of the desired conditional diameter with optimal (normal or reinforced) thermal insulation.
| Outside diameter steel pipe and minimum thickness of its wall (mm) | Dimensions of galvanized sheet steel sheath | Estimated thickness of the thermal insulation layer of polyurethane foam (mm) | |
|---|---|---|---|
| nominal outside diameter (mm) | minimum thickness steel sheet(mm) | ||
| 32×3.0 | 100; 125; 140 | 0.55 | 46,0; 53,5 |
| 38×3.0 | 125; 140 | 0.55 | 43,0; 50,5 |
| 45×3.0 | 125; 140 | 0.55 | 39,5; 47,0 |
| 57×3.0 | 140 | 0.55 | 40.9 |
| 76×3.0 | 160 | 0.55 | 41.4 |
| 89×4.0 | 180 | 0.6 | 44.9 |
| 108×4.0 | 200 | 0.6 | 45.4 |
| 133×4.0 | 225 | 0.6 | 45.4 |
| 159×4.5 | 250 | 0.7 | 44.8 |
| 219×6.0 | 315 | 0.7 | 47.3 |
| 273×7.0 | 400 | 0.8 | 62.7 |
| 325×7.0 | 450 | 0.8 | 61.7 |
Manufacturers offer such sandwich pipes not only for straight sections, but also for tees, bends, expansion joints, etc.
The cost of such pre-insulated pipes is quite high, but with their purchase and installation, a whole range of problems is solved at once. So these costs seem to be quite justified.
Video: production process of pre-insulated pipes
Insulation - foamed rubber
Recently, thermal insulation materials and products made of synthetic foam rubber have become very popular. This material has a number of advantages that bring it to a leading position in the issues of insulation of pipelines, including not only heating mains, but also more responsible ones - on complex technological lines, in machine, aircraft and shipbuilding:
- Foamed rubber is very elastic, but at the same time it has a large margin of tensile strength.
- The density of the material is only from 40 to 80 kg / m³.
- The low thermal conductivity provides very effective thermal insulation.
- The material does not shrink over time, completely retaining its original shape and volume.
- Foamed rubber is difficult to ignite and has the property of rapid self-extinguishing.
- The material is chemically and biologically inert, it never contains any foci of mold or fungus, or nests of insects or
- The most important quality is almost absolute water and vapor impermeability. Thus, the insulation layer immediately becomes an excellent waterproofing for the pipe surface.
Such thermal insulation can be produced in the form of hollow tubes with an internal diameter of 6 to 160 mm and a layer thickness of insulation from 6 to 32 mm, or in the form of sheets, which are often given the function of “self-adhesive” on one side.
| The name of indicators | Values |
|---|---|
| Length of finished tubes, mm: | 1000 or 2000 |
| Color | black or silver, depending on the type of protective coating |
| Temperature range of application: | from - 50 to + 110 °С |
| Thermal conductivity, W / (m × ° С): | λ≤0.036 at 0°C |
| λ≤0.039 at +40°C | |
| Vapor permeability coefficient: | μ≥7000 |
| Degree of fire hazard | Group G1 |
| Permissible length change: | ±1.5% |
But for outdoor heating mains, ready-made insulation elements made using Armaflex ACE technology, which have a special protective covering"ArmaChek".
Coating "ArmaChek" can be of several types, for example:
- Arma-Chek Silver is a multi-layered PVC-based shell with a silver reflective coating. This coating provides excellent insulation protection against both mechanical stress and ultraviolet rays.
- The black "Arma-Chek D" finish has a high strength fiberglass backing that retains excellent flexibility. This is an excellent protection against all possible chemical, weather, mechanical influences, which will keep the heating pipe intact.
Typically, such products using ArmaChek technology have self-adhesive valves that hermetically “seal” the insulating cylinder on the pipe body. Figured elements are also produced, allowing installation on difficult sections of the heating main. Skillful use of such thermal insulation allows you to quickly and reliably mount it without resorting to the creation of an additional external protective casing - there is simply no need for it.
Probably the only thing that slows down wide application such thermal insulation products for pipelines are still prohibitively high prices for real, “brand” products.
Prices for thermal insulation for pipes
Thermal insulation for pipes
A new direction in insulation - heat-insulating paint
Can't miss another one modern technology insulation. And it is all the more pleasant to talk about it, since it is the development of Russian scientists. We are talking about ceramic liquid insulation, which is also known as heat-insulating paint.
This, without any doubt, is an "alien" from the field of space technology. It is in this scientific and technical branch that the issues of thermal insulation from critically low (in open space) or high (during the launch of ships and landing of descent vehicles) are especially acute.
The thermal insulation qualities of ultra-thin coatings seem simply fantastic. At the same time, such a coating becomes an excellent hydro and vapor barrier, protecting the pipe from all possible external influences. Well, the heating main itself takes on a well-groomed, pleasing look.
The paint itself is a suspension of microscopic, vacuum-filled silicone and ceramic capsules, suspended in a liquid state in a special composition, including acrylic, rubber and other components. After applying and drying the composition, a thin elastic film is formed on the surface of the pipe, which has outstanding thermal insulation qualities.
| Names of indicators | unit of measurement | Value |
|---|---|---|
| paint color | white (can be customized) | |
| Appearance after application and complete curing | matte, even, uniform surface | |
| Flexural elasticity of the film | mm | 1 |
| Adhesion of the coating according to the force of separation from the painted surface | ||
| - to the concrete surface | MPa | 1.28 |
| - to the brick surface | MPa | 2 |
| - to steel | MPa | 1.2 |
| Coating resistance to temperature difference from -40 °С to + 80 °С | without changes | |
| Resistance of the coating to the effects of temperature +200 °C for 1.5 hours | no yellowing, cracks, peeling or blisters | |
| Durability for concrete and metal surfaces in a moderately cold climatic region (Moscow) | years | at least 10 |
| Thermal conductivity | W/m °C | 0,0012 |
| Vapor permeability | mg/m × h × Pa | 0.03 |
| Water absorption in 24 hours | % by volume | 2 |
| Operating temperature range | °C | from - 60 to + 260 |
Such coverage does not require additional protective layers- it is strong enough to cope with all the influences on its own.
Such a liquid insulation is sold in plastic cans (buckets), like ordinary paint. There are several manufacturers, and among the domestic brands, the brands "Bronya" and "Korund" can be especially noted.
Such thermal paint can be applied by aerosol spraying or in the usual way - with a roller and brush. The number of layers depends on the operating conditions of the heating main, the climatic region, the diameter of the pipes, the average temperature of the pumped coolant.
Many experts believe that such heaters will eventually replace the usual thermal insulation materials on a mineral or organic basis.
Video: presentation of ultra-thin thermal insulation brand "Korund"
Thermal insulation paint prices
Thermal insulation paint
What thickness of heating mains insulation is required
Summing up the review of the materials used for thermal insulation of heating pipes, you can see the performance indicators of the most popular of them in the table - for clarity of comparison:
| Thermal insulation material or product | Average density in finished structure, kg/m3 | Thermal conductivity of thermal insulation material (W/(m×°C)) for surfaces with temperature (°C) | Operating temperature range, °C | Flammability group | |
|---|---|---|---|---|---|
| 20 and up | 19 and below | ||||
| Mineral wool pierced plates | 120 | 0,045 | 0.044 ÷ 0.035 | From - 180 to + 450 for mats, on fabric, mesh, fiberglass canvas; up to + 700 - on a metal grid | non-combustible |
| 150 | 0,05 | 0.048 ÷ 0.037 | |||
| Heat-insulating slabs of mineral wool on a synthetic binder | 65 | 0.04 | 0.039 ÷ 0.03 | From - 60 to + 400 | non-combustible |
| 95 | 0,043 | 0.042 ÷ 0.031 | |||
| 120 | 0,044 | 0.043 ÷ 0.032 | From - 180 + 400 | ||
| 180 | 0,052 | 0.051 ÷ 0.038 | |||
| Thermal insulation products made of foamed ethylene-polypropylene rubber Aeroflex | 60 | 0,034 | 0,033 | From - 55 to + 125 | Slightly combustible |
| Semi-cylinders and mineral wool cylinders | 50 | 0,04 | 0.039 ÷ 0.029 | From - 180 to + 400 | non-combustible |
| 80 | 0,044 | 0.043 ÷ 0.032 | |||
| 100 | 0,049 | 0.048 ÷ 0.036 | |||
| 150 | 0,05 | 0.049 ÷ 0.035 | |||
| 200 | 0,053 | 0.052 ÷ 0.038 | |||
| Thermal insulation cord made of mineral wool | 200 | 0,056 | 0.055 ÷ 0.04 | From - 180 to + 600 depending on the material of the mesh tube | In mesh tubes made of metal wire and glass thread - non-combustible, the rest are slightly combustible |
| Glass staple fiber mats with synthetic binder | 50 | 0,04 | 0.039 ÷ 0.029 | From - 60 to + 180 | non-combustible |
| 70 | 0,042 | 0.041 ÷ 0.03 | |||
| Mats and wool made of superfine glass fiber without binder | 70 | 0,033 | 0.032 ÷ 0.024 | From - 180 to + 400 | non-combustible |
| Mats and wool made of super-thin basalt fiber without a binder | 80 | 0,032 | 0.031 ÷ 0.024 | From - 180 to + 600 | Non-combustible |
| Perlite sand, expanded, fine | 110 | 0,052 | 0.051 ÷ 0.038 | From - 180 to + 875 | non-combustible |
| 150 | 0,055 | 0.054 ÷ 0.04 | |||
| 225 | 0,058 | 0.057 ÷ 0.042 | |||
| Thermal insulation products made of expanded polystyrene | 30 | 0,033 | 0.032 ÷ 0.024 | From - 180 to + 70 | combustible |
| 50 | 0,036 | 0.035 ÷ 0.026 | |||
| 100 | 0,041 | 0.04 ÷ 0.03 | |||
| Thermal insulation products made of polyurethane foam | 40 | 0,030 | 0.029 ÷ 0.024 | From - 180 to + 130 | combustible |
| 50 | 0,032 | 0.031 ÷ 0.025 | |||
| 70 | 0,037 | 0.036 ÷ 0.027 | |||
| Thermal insulation products made of polyethylene foam | 50 | 0,035 | 0,033 | From - 70 to + 70 | combustible |
But for sure, an inquisitive reader will ask: where is the answer to one of the main questions that arise - what should be the thickness of the insulation?
This question is quite complex, and there is no single answer to it. If you wish, you can use cumbersome calculation formulas, but they are probably understandable only to qualified heating engineers. However, not everything is so scary.
Manufacturers of finished thermal insulation products (shells, cylinders, etc.) usually lay required thickness calculated for a particular region. And if mineral wool insulation is used, then you can use the data of the tables that are given in a special Code of Rules, which is designed specifically for thermal insulation of pipelines and technological equipment. This document is easy to find on the web by entering a search query "SP 41-103-2000".
Here, for example, is a table from this handbook regarding the above-ground placement of the pipeline in Central region Russia, when using glass staple fiber mats M-35, 50:
| Outer diameter pipeline, mm | Type of heating pipe | |||||
|---|---|---|---|---|---|---|
| innings | return line | innings | return line | innings | return line | |
| Average temperature regime coolant, °С | ||||||
| 65 | 50 | 90 | 50 | 110 | 50 | |
| Required insulation thickness, mm | ||||||
| 45 | 50 | 50 | 45 | 45 | 40 | 40 |
| 57 | 58 | 58 | 48 | 48 | 45 | 45 |
| 76 | 67 | 67 | 51 | 51 | 50 | 50 |
| 89 | 66 | 66 | 53 | 53 | 50 | 50 |
| 108 | 62 | 62 | 58 | 58 | 55 | 55 |
| 133 | 68 | 68 | 65 | 65 | 61 | 61 |
| 159 | 74 | 74 | 64 | 64 | 68 | 68 |
| 219 | 78 | 78 | 76 | 76 | 82 | 82 |
| 273 | 82 | 82 | 84 | 84 | 92 | 92 |
| 325 | 80 | 80 | 87 | 87 | 93 | 93 |
Similarly, you can find the desired parameters for other materials. By the way, the same Code of Rules does not recommend significantly exceeding the specified thickness. Moreover, the maximum values of the insulation layer for pipelines are also determined:
| Outer diameter of the pipeline, mm | Maximum thickness of the thermal insulation layer, mm | |
|---|---|---|
| temperature 19 ° C and below | temperature 20 ° C or more | |
| 18 | 80 | 80 |
| 25 | 120 | 120 |
| 32 | 140 | 140 |
| 45 | 140 | 140 |
| 57 | 150 | 150 |
| 76 | 160 | 160 |
| 89 | 180 | 170 |
| 108 | 180 | 180 |
| 133 | 200 | 200 |
| 159 | 220 | 220 |
| 219 | 230 | 230 |
| 273 | 240 | 230 |
| 325 | 240 | 240 |
However, one should not forget important nuance. The fact is that any insulation with a fibrous structure inevitably shrinks over time. And this means that after a certain period of time, its thickness may become insufficient for reliable thermal insulation of the heating main. There is only one way out - even when installing insulation, immediately take into account this amendment for shrinkage.
To calculate, you can apply the following formula:
H = ((D + h) : (D + 2 h)) × h× Kc
H- the thickness of the mineral wool layer, taking into account the correction for compaction.
D- outer diameter of the pipe to be insulated;
h- the required thickness of insulation according to the table of the Code of Practice.
Ks- coefficient of shrinkage (compaction) of fibrous insulation. It is a calculated constant whose value can be taken from the table below:
| Thermal insulation materials and products | Compaction factor Kc. |
|---|---|
| Mineral wool mats | 1.2 |
| Heat-insulating mats "TEHMAT" | 1.35 ÷ 1.2 |
| Mats and canvases made of super-thin basalt fiber when laying on pipelines and equipment with nominal diameter, mm: | |
| Doo | 3 |
| 1,5 | |
| DN ≥ 800 at an average density of 23 kg/m3 | 2 |
| ̶ the same, with an average density of 50-60 kg/m3 | 1,5 |
| Mats made of glass staple fiber on a synthetic binder brand: | |
| M-45, 35, 25 | 1.6 |
| M-15 | 2.6 |
| Glass staple fiber mats "URSA" brand: | |
| M-11: | |
| ̶ for pipes with DN up to 40 mm | 4,0 |
| ̶ for pipes with DN from 50 mm and above | 3,6 |
| M-15, M-17 | 2.6 |
| M-25: | |
| ̶ for pipes with DN up to 100 mm | 1,8 |
| ̶ for pipes with DN from 100 to 250 mm | 1,6 |
| ̶ for pipes with DN over 250 mm | 1,5 |
| Mineral wool boards on a synthetic binder brand: | |
| 35, 50 | 1.5 |
| 75 | 1.2 |
| 100 | 1.10 |
| 125 | 1.05 |
| Glass staple fiber board grades: | |
| P-30 | 1.1 |
| P-15, P-17 and P-20 | 1.2 |
To help the interested reader, a special calculator is placed below, in which the indicated ratio is already included. It is worth entering the requested parameters - and immediately get the required thickness of mineral wool insulation, taking into account the amendment.
By nature, people are thermophilic, so each owner tries to warm his home as much as possible.. Someone uses a heater, someone insulates the facade, and someone arranges a warm floor. If all these methods of accumulating heat indoors are used together, then you definitely won’t have to worry about the fact that it will be cold in the house in winter. The harm from an electric heater is obvious - it dries out the air in the room, but is a warm floor harmful to health? This should be sorted out.
Benefits of underfloor heating
- environmental friendliness. This type of heating proved to be an order of magnitude better than electric heater. The carrier temperature is at such a level that the operation of the system does not affect the environment in any way;
- economy. This is hardly the most economical system heating today;
- rapid heating of the room. The convector will first heat up and then dry the air in the room, while the warm floor from the first minutes will begin to maintain a comfortable temperature in the room;
- heating elements are hidden from view. This allows you to implement any design idea, because you do not need to install any bulky boilers and pipes;
- durability and structural strength. Using quality materials and compliance with the installation technology, the need for preventive maintenance will not arise for many years;
- versatility. Such a heating system can be used both in residential and office premises..
Reading the above information, it is easy to understand why the warm floor is in such demand among the consumer. And yet, what is it Negative influence on human health?
Fiction or real harm
The harm and benefits of underfloor heating - this is what you should understand before installing it in your home. Which accusations against this heating system are fiction, and which ones are really true?
The following negative characteristics are attributed to this heating system:
- Release of toxic substances when heated floor covering. This assumption can be immediately refuted. Even if you lay linoleum or PVC tiles on the floor, no toxic substances will be released into the air. To harm a person from fumes from the surface of low-quality materials, you need to decently heat the floor. Does anyone walk around their home like hot coals? The temperature of the coolant is 45C, and the floor is usually heated to 28C, which is quite safe.
- Harmfulness of electromagnetic radiation. Warm floors are made not only from pipes that cut into the heating system. The design of this heating system can be of several more types: heating mats, infrared thermal film, electrical cables. All of these options involve connecting to the mains, and like any household appliances that run on electricity, such warm floors emit electromagnetic waves. However, no matter what cable is used for the floor construction, single-core or twin-core, the radiation intensity will be negligible. Nevertheless, doctors do not recommend increasing the level of electromagnetic radiation in your home. Many consumers think about the dangers of infrared underfloor heating. In fact, this radiation is safe for humans.
- Furniture can not be placed on a warm floor. But this is just the opposite. If you do not provide for the installation of heating elements in areas with furniture, then what to do when you want to update the room and make a rearrangement? It turns out that sofas and cabinets will move to the heated areas of the room, and you will have to walk on the cold floor. This is not rational. If you look at this issue from the point of view that the temperature of the coating can affect the durability of furniture, then you definitely should not be afraid of this. After all, the floor is not hot, and under the influence of 28C nothing will happen to the furniture.
- Walking on a warm floor is harmful. Why should this fear be true, if on the hottest days of summer everyone is happy to walk barefoot on hot sand? Yes, and children love to take off their shoes and run barefoot on warm ground, because adults themselves say that this is useful.
- Underfloor heating dries out the air in the room. Of course, if you place the heating elements too close to each other, then the room will be too hot, and this threatens that the mucous membranes of the eyes and nose will dry out. There is nothing left but to ensure the humidification of the room by regularly using a humidifier. But, if the floor design is thought out correctly, then this will not reduce the level of humidity in the apartment.
- Because of the warm floor, the room is very dusty. The idea of this heating system is not to dilute cold air with warm air, but to radiate heat, i.e. it does not lift air masses from the floor covering. If a person is allergic to house dust, then there is nothing left but to clean more often, and it doesn’t matter if the house has a warm floor. Breathing dust is harmful, however, the wind raises whole clouds of dust on the street and few people think about its harm.
The above accusations against underfloor heating are mostly untrue. Of course, some of these problems come up, but they are always the result of improperly laid heating elements.
What is the negative impact of underfloor heating on human health
Now we should talk about more significant problems that may arise during the operation of a warm floor:
- Uncomfortable temperature conditions for sleep. There really is such a problem, since at the height at which the sleeping place is located, the air temperature reaches 23C. It is too hot and not everyone can sleep peacefully under such conditions. Somnologists say that the most comfortable temperature for sleeping is 18-20C, so heating at night will have to be turned off, and this is not economically viable. However, there is a way out: you need to install a thermostat and connect it to the heating system. With it, you can easily adjust the temperature and set the most comfortable sleep mode.. In addition, in the bedrooms it is better to have heating elements with big step.
- Warm floors are harmful to the health of people with vascular diseases. This is true, because it is harmful for a person who suffers from varicose veins or swelling of the lower extremities to keep their feet warm. In this case, again, you will need a thermostat that will allow you to choose the most appropriate mode.
- Most of all, housewives suffer from such a heating system. This opinion came because women, standing at a hot stove on warm coating, risk earning a gynecological disease and varicose veins. To avoid this outcome, it is recommended to cover the floor with a parquet board, and not artificial material and, if possible, install an adjustable system.
What you should pay attention to when installing a warm floor:
- compliance technological process when installing a heating system;
- arrangement of heating elements with a large step in the bedrooms;
- provide the ability to set different temperature conditions;
- choose a high-quality natural coating, for example, a special parquet board, which will not dry out and will be safe for health.
There is no need to talk about some incredible harm of a warm floor for human health. This modern system heating, which allows you to heat the room well and at the same time save.
