Thermal insulation of pipelines is a set of measures aimed at preventing the heat exchange of the medium transported through them with the environment. Thermal insulation of pipelines is used not only in heating systems and hot water supply, but also where technology requires transportation of substances with a certain temperature, for example, refrigerants.
The meaning of thermal insulation is the use of means that provide thermal resistance to heat transfer of any kind: contact and carried out through infrared radiation.
The greatest application, expressed in numbers, is thermal insulation pipelines of heating networks. Unlike Europe, a centralized heating system dominates throughout the post-Soviet space. In Russia alone, the total length of heating networks is more than 260 thousand kilometers.
Much less often, insulation for heating pipes is used in private households with an autonomous heating system. Only in a few northern regions are private houses connected to the central heating main with heating pipes placed on the street.
For some types of boilers, for example, powerful gas or diesel boilers, the requirements of the set of rules SP 61.13330.2012 “Thermal insulation of equipment and pipelines” are required to be placed separately from the building - in a boiler room several meters away from the heated object. In their case, a fragment of the piping passing through the street necessarily needs insulation.
On the street, insulation of heating pipelines is required both when installed above ground and when laid hidden - underground. The latter method is a channel method - a reinforced concrete trench is first laid in the trench, and pipes are already placed in it. Channelless placement method - directly in the ground. The insulating materials used differ not only in thermal conductivity, but also in steam and water resistance, durability and installation methods.
The need to insulate cold water supply pipes is not so obvious. However, you cannot do without it when the water supply is laid open above ground - the pipes must be protected from freezing and subsequent damage. But inside buildings, water supply pipes also have to be insulated - to prevent moisture condensation on them.
Glass wool, mineral wool
Insulating materials proven by practice. Meet the requirements of SP 61.13330.2012, SNiP 41-03-2003 and fire safety standards for any installation method. They are fibers with a diameter of 3-15 microns, close to crystals in structure.
Glass wool is made from waste from glass production, mineral wool from silicon-containing slag and silicate waste from metallurgy. The differences in their properties are insignificant. Available in the form of rolls, stitched mats, plates and pressed cylinders.
It is important to be careful with materials and know how to handle them correctly. Any manipulations must be performed in protective overalls, gloves and a respirator.
Installation
The pipe is wrapped or lined with cotton wool, ensuring uniform filling density over the entire surface. Then the insulation, without too much pressure, is fixed using a knitting wire. The material is hygroscopic and easily gets wet, so insulation of external pipelines made of mineral or glass wool requires the installation of a vapor barrier layer made of a material with low vapor permeability: roofing felt or polyethylene film.
A covering layer is placed on top of it to prevent the penetration of precipitation - a casing made of roofing tin, galvanized iron or sheet aluminum.
Basalt (stone) wool
More dense than glass wool. The fibers are made from the melt of gabbro-basalt rocks. Absolutely non-flammable, can withstand temperatures up to 900° C for a short time. Not all insulating materials, like basalt wool, can be in long-term contact with surfaces heated to 700° C.
Thermal conductivity is comparable to polymers, ranging from 0.032 to 0.048 W/(m K). High performance indicators allow it to be used thermal insulation properties not only for pipelines, but also when installing hot chimneys.
Available in several versions:
- like glass wool, in rolls;
- in the form of mats (stitched rolls);
- in the form of cylindrical elements with one longitudinal slot;
- in the form of pressed fragments of a cylinder, the so-called shells.
The last two versions have different modifications, differing in density and the presence of heat-reflecting film. The cylinder slot and the edges of the shells can be made in the form of a tenon joint. 
SP 61.13330.2012 contains instructions that thermal insulation of pipelines must meet safety and protection requirements environment. Basalt wool itself fully complies with this instruction.
Manufacturers often resort to tricks: to improve consumer performance - to give it hydrophobicity, greater density, and vapor permeability, they use impregnations based on phenol-formaldehyde resins. Therefore, it cannot be called 100% safe for humans. Before using basalt wool in a residential area, it is advisable to study its hygienic certificate.
Installation
The insulation fibers are stronger than glass wool, so it is almost impossible for its particles to enter the body through the lungs or skin. However, it is still recommended to use gloves and a respirator when working.
Installation of rolled sheets is no different from the method of insulating heating pipes with glass wool. Thermal protection in the form of shells and cylinders is attached to the pipes using mounting tape or a wide bandage. Despite some hydrophobicity of basalt wool, pipes insulated with it also require a waterproof, vapor-permeable shell made of polyethylene or roofing felt, and an additional one made of tin or dense aluminum foil.
Foamed polyurethane (polyurethane foam, PPU)
Reduces by more than half heat losses compared to glass wool and mineral wool. Its advantages include: low thermal conductivity, excellent waterproofing properties. The service life declared by the manufacturers is 30 years; Range operating temperature from -40 to +140 °C, the maximum withstandable for a short time is 150 °C.
The main brands of polyurethane foam belong to the flammability group G4 (highly flammable). When the composition is changed by adding fire retardants, they are assigned G3 (normally flammable).
Although polyurethane foam is excellent as an insulating material for heating pipes, keep in mind that SP 61.13330.2012 allows the use of such thermal insulation only in single-family residential buildings, and SP 2.13130.2012 limits their height to two floors.
Thermal insulation coating is produced in the form of shells - semicircular segments with tongue and groove locks at the ends. Ready-made steel pipes insulated from polyurethane foam with a protective sheath made of polyethylene.
Installation
The shells are secured to the heating pipe using ties, clamps, plastic or metal bandage. Like many polymers, the material does not tolerate prolonged exposure to sunlight, so an open ground pipeline when using PPU shells requires a covering layer, for example, galvanized steel.
For underground ductless placement, thermal insulation products are laid on waterproof and temperature-resistant mastics or adhesives, and the outside is insulated with a waterproof coating. It is also necessary to take care of the anti-corrosion treatment of the surface of metal pipes - even the glued joint of the shells is not tight enough to prevent the condensation of water vapor from the air.
Expanded polystyrene (foam plastic, EPS)
It is produced in the form of shells, practically no different in appearance from polyurethane foam - the same dimensions, the same tongue-and-groove locking connection. But the application temperature range, from -100 to +80 °C, with all this external similarity, makes its use for thermal insulation of heating pipelines impossible or limited.
SNiP 41-01-2003 “Heating, ventilation and air conditioning” states that in the case of two-pipe system heating supply, the maximum supply temperature can reach 95°C. As for the return heating risers, not everything is so simple: it is believed that the temperature in them does not exceed 50 °C.
Foam insulation is more often used for cold water and sewer pipes. However, it can be used on top of other insulation materials with a higher permissible temperature of use.
The material has a number of disadvantages: it is highly flammable (even with the addition of fire retardants), does not tolerate chemical influences (dissolves in acetone), and crumbles into balls during prolonged exposure to solar radiation.
There are other non-polystyrene foams - formaldehyde, or phenolic for short. In fact, it is a completely different material. He is deprived the mentioned shortcomings, is successfully used as thermal insulation for pipelines, but is not so widely used.
Installation
The shells are secured to the pipe using a bandage or foil tape; they can be glued to the pipe and to each other.
Foamed polyethylene
Temperature range at which the use of foamed polyethylene is allowed high pressure, from -70 to +70 °C. The upper limit is not compatible with the maximum temperature of the heating pipe, usually accepted in calculations. This means that the material is of little use as thermal insulation for pipelines, but can be used as an insulating layer over a heat-resistant one.
Polyethylene foam insulation has found virtually no alternative use as protection against freezing of water pipes. Very often it is used as a vapor barrier and waterproofing.
The material is produced in the form of sheets or in the form of a flexible thick-walled pipe. The latter form is more often used, as it is more convenient for insulating water pipes. Standard length is 2 meters. Color varies from white to dark gray. There may be a coating of aluminum foil that reflects IR radiation. The differences relate to internal diameters (from 15 to 114 mm), wall thickness (from 6 to 30 mm).
The application ensures the temperature on the pipe is above the dew point, which means it prevents the formation of condensation.
Installation
A simple way with worse vapor barrier results is to cut the foam material along a small depression along the side surface, open the edges and put it on the pipe. Then wrap it along the entire length with mounting tape.
A more complex solution (and not always feasible) is to turn off the water, completely disassemble the insulated sections of the water supply system and put on solid sections. Then put everything back together. Secure the polyethylene with ties. In this case, only the junction of the segments will become a vulnerable point. It can be glued or also wrapped with tape.
Foam rubber
Foamed synthetic rubber with a closed-cell structure is the most versatile material for preserving heat and cold. Designed for a temperature range from -200 to +150 °C. Meets all environmental safety requirements.
Used as pipeline insulation cold water, heating pipe insulation, often found in refrigeration and ventilation systems. Heating pipes laid inside buildings and insulated with rubber do not require the installation of a vapor barrier layer.
Externally similar to foamed polyethylene, it is also available in the form of sheets and flexible thick-walled pipes. Installation is also practically no different, except that such thermal insulation of pipes can be attached with glue.
Liquid insulation
A technology has been successfully used that allows you to independently spray foam from a polyurethane composition onto ready-made structures. Excellent adhesive properties allow it to be used not only for insulating pipelines, but also applied to other elements that require insulation: foundations, walls, roofs. The coating, in addition to thermal protection, provides hydro, vapor barrier, and provides anti-corrosion resistance.
Conclusion
Proper installation of thermal insulation is a guarantee that the pipe will not lose heat and the consumer will not freeze. Freezing of a cold water supply pipeline invariably leads to its rupture. Until recently, glass wool was the usual insulating material for hidden and open heating mains. Its shortcomings stem from one another. This coating requires constant monitoring.
Even with slight damage to the protective surface layer, vapor permeability and hygroscopicity reduce all savings to nothing. Moisture causes low thermal resistance and premature failure. Modern insulating materials with a cellular structure, inert to the effects of steam and water: polyurethane foam, foam rubber, polyethylene foam will help to significantly improve the situation.
In the practice of private construction, it is not so common, but there are still situations when heating communications need to be not only distributed throughout the premises of the main house, but also extended to other nearby buildings. These could be residential outbuildings, outbuildings, summer kitchens, utility or agricultural buildings, for example, used for keeping pets or birds. The option cannot be ruled out when, on the contrary, the autonomous boiler room itself is located in a separate building, at some distance from the main residential building. It happens that a house is connected to a central heating main, from which pipes are extended to it.
There are two options for laying heating pipes between buildings - underground (ducted or ductless) and open. The process of installing a local heating main above the ground seems less labor-intensive, and this option in conditions self-construction come running more often. One of the main conditions for the efficiency of the system is properly planned and well-executed thermal insulation for outdoor heating pipes. It is this issue that will be addressed in this publication.
Why do you 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 may be misled by a peculiar “play on words”. In the case under consideration, of course, it would be more correct to conduct the 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 reducing heat losses and maintaining the required temperature of the pumped liquid comes to the fore. The same principle is also true for industrial or laboratory installations, where technology requires maintaining a certain temperature of the substance transmitted through pipes.
- For cold water supply pipelines or sewer communications, the main factor is insulation, that is, preventing the temperature in the pipes from falling below a critical level, preventing freezing, leading to 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 emergency situations with boiler equipment.
The cylindrical shape of the pipes itself predetermines a very large area of constant heat exchange with the environment, which means significant heat loss. And they naturally increase as pipeline diameters increase. The table below clearly shows how the amount of heat loss changes depending on the temperature difference inside and outside the pipe (Δt° column), on the diameter of the pipes and on the thickness of the thermal insulation layer (data 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 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 overall heat loss rate 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 insulation materials with the lowest possible thermal conductivity coefficient - this is one of the main requirements for thermal insulation of pipelines.
Sometimes a pipeline heating system is also required!
When laying water supply or sewer lines, it happens that due to 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 on our portal.
- The material used for thermal insulation of pipes, if possible, should have hydrophobic properties. There will be little current from insulation soaked in water - it will not prevent heat loss, and itself will soon collapse under the influence of negative temperatures.
- The thermal insulation structure must have a reliable external protection. Firstly, it needs protection from atmospheric moisture, especially if insulation is used that can actively absorb water. Secondly, materials should be protected from exposure to the ultraviolet spectrum of sunlight, which has a detrimental effect on them. Thirdly, we should not forget about the wind load, which can damage the integrity of the 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, any owner of a private home is probably not indifferent to aspects of aesthetic appearance laid heating main.
- Any thermal insulation material used on heating mains must have an operating temperature range that corresponds to the actual conditions of use.
- An important requirement for insulating material and its external cladding is 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, in any position and in any difficult area. Fortunately, in this regard, manufacturers never tire of delighting with easy-to-use developments.
- An important requirement for thermal insulation is that its materials themselves must be chemically inert and not enter into any reaction with the surface of the pipes. Such compatibility is the key to long-term trouble-free operation.
The issue of cost is also very important. But in this regard, the range of prices among specialized ones is very large.
What materials are used for insulation of above-ground heating mains
The choice of thermal insulation materials for heating pipes when they are laid externally is quite large. They come in roll type or in the form of mats; they can be given a cylindrical or other shaped shape that is convenient for installation; there are insulation materials that are applied in liquid form and acquire their properties only after hardening.
Insulation using foamed polyethylene
Foamed polyethylene is rightly classified as a very effective thermal insulator. And what is also very important, the cost of this material is one of the lowest.
The thermal conductivity coefficient of foamed polyethylene is usually around 0.035 W/m×°C - this is a very good indicator. The smallest bubbles, isolated from each other, filled with gas, create an elastic structure, and with such material, if you purchase a roll version, it is very convenient to work on sections of pipes with complex configurations.
Such a structure becomes a reliable barrier to moisture - if installed correctly, neither water nor water vapor will be able to penetrate through it to the pipe walls.
The density of polyethylene foam is low (about 30 - 35 kg/m³), and thermal insulation will not make the pipes heavier.
The material, with some assumption, can be classified 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 extinguishes. Moreover, combustion products, unlike many other thermal insulators, do not pose any serious toxic danger to humans.
Rolled foam polyethylene for insulation of external heating mains will be both inconvenient and unprofitable - you will have to wind it in several layers to achieve the required thickness of thermal insulation. Much more convenient to use is material in the form of sleeves (cylinders), which have an internal channel corresponding to the diameter of the insulated pipe. To put it on pipes, an incision is usually made along the length of the cylinder on the wall, which after installation can be sealed with reliable tape.
Putting insulation on a pipe is not difficult A more effective type of polyethylene foam is penofol, which has on 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 profile cylindrical elements - especially for thermal insulation of pipes for various purposes.
And foamed polyethylene is rarely used for thermal insulation of heating mains. It is more likely to be suitable for other communications. The reason for this is the rather low operating temperature range. So. if you look at the physical characteristics, the upper limit balances somewhere on the verge of 75 ÷ 85 degrees - above that, structural disturbances and the appearance of deformations are possible. For autonomous heating, more often than not, this temperature is sufficient, although on the edge, and for the central temperature, thermal stability is clearly not enough.
Insulation elements made of polystyrene foam
The well-known expanded polystyrene (in everyday life it is more often called polystyrene foam) is very widely used for the most different types thermal insulation works. The insulation of pipes is no exception - special parts are made from foam plastic for this purpose.
Usually these are half-cylinders (for pipes of large diameters there may be segments of a third of the circumference, 120° each), which are equipped with a tongue-and-groove locking connection for assembly into a single structure. This configuration makes it possible to provide reliable thermal insulation completely over the entire surface of the pipe, without remaining “cold bridges.”
In everyday speech, such details are called “shells” for their obvious resemblance to it. Many types are produced, for different outer diameters of insulated pipes and different thicknesses of the thermal insulation layer. Typically the length of the parts is 1000 or 2000 mm.
For production, polystyrene foam of the PSB-S type of various grades is used - from PSB-S-15 to PSB-S-35. The main parameters of this material are shown in the table below:
| Estimated material parameters | Brand of expanded polystyrene | ||||
|---|---|---|---|---|---|
| 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) | 0.08 | 0.12 | 0.17 | 0.36 | 0.35 |
| Thermal conductivity in dry condition at a temperature of 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 coefficient.
- The light weight of the material greatly simplifies 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 mildew.
- Moisture absorption is negligible.
- The material can be easily cut and adjusted to fit right size.
- Polystyrene foam is chemically inert and absolutely safe for pipe walls, no matter what material they are made of.
- One of the key advantages is that polystyrene foam is one of the most inexpensive insulation materials.
However, it also has many disadvantages:
- First of all, this is a low level of fire safety. The material cannot be called non-flammable and does not spread flame. That is why, when using it to insulate above-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 pipe. True, you can also find special figured parts.
- Polystyrene foam is not a durable material - it is easily destroyed under external influence. Ultraviolet radiation also has a negative effect on it. In a word, above-ground sections of the pipe, insulated with polystyrene foam shells, will definitely require additional protection in the form of a metal casing.
Usually, stores that sell foam shells also offer galvanized sheets, cut to the required size, corresponding to the diameter of the insulation. An aluminum shell can also be used, although it is of course much more expensive. The sheets can be secured 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 this is not even the main thing. The upper limit of normal operating temperatures is only around 75°C, after which linear and spatial deformation of parts may begin. Whatever one may say, this value may not be enough for heating. It probably 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 using mineral wool. By the way, it is also the most budget-friendly, if it is not possible to purchase a foam shell.
For thermal insulation of pipelines, various types of mineral wool are used - glass wool, stone (basalt) and slag. Slag is the least preferable: firstly, it absorbs moisture most actively, and secondly, its residual acidity can have a very destructive effect on steel pipes. Even the cheapness of this cotton wool does not in any way justify the risks of its use.
But mineral wool based on basalt or glass fibers is fully suitable. It has good thermal resistance to heat transfer, high chemical resistance, the material is elastic, and it is easy to install even on complex pipeline sections. Another advantage is that you can, in principle, be completely calm in terms of fire safety. It is almost impossible to heat mineral wool to the point of ignition in the conditions of an external heating main. Even exposure to an open flame will not cause a fire to spread. That is why mineral wool is used to fill fire gaps when using other pipe insulation materials.
Main disadvantage mineral wool – high water absorption (basalt wool is less susceptible to this “disease”). This means that any pipeline will require mandatory protection from moisture. In addition, the structure of the wool is unstable to mechanical stress, is easily destroyed, and should be protected with a durable casing.
Usually use durable plastic film, which is securely wrapped in a layer of insulation, with the obligatory overlap of the strips by 400 ÷ 500 mm, and then the whole thing is covered with metal sheets on top - exactly by analogy with a polystyrene foam shell. Roofing felt can also be used as waterproofing - in this case, 100 ÷ 150 mm of overlap of one strip over another will be sufficient.
Existing GOST standards determine the thickness of protective metal coatings for open sections of pipelines for any type of thermal insulation materials used:
| Protective cover layer material | Minimum metal thickness, with outer diameter of 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 |
| Sheets made of thin sheet steel, galvanized or polymer coated | 0.5 | 0.8 | 0.8 |
| Aluminum or aluminum alloy sheets | 0.3 | 0.5 | 0.8 |
| Aluminum or aluminum alloy tapes | 0.25 | - | - |
Thus, despite the seemingly inexpensive price of the insulation itself, its full installation will require considerable additional costs.
Mineral wool for insulation of pipelines can also act in another 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 bends, tees, etc.
Typically, such insulating parts are made from the densest material - basalt mineral wool, and have an external foil coating, which immediately eliminates the problem of waterproofing and increases the efficiency of insulation. But you still won’t be able to get away from the outer casing - a thin layer of foil will not protect you from accidental or intentional mechanical impact.
Insulation of heating mains with polyurethane foam
One of the most effective and safest modern insulation materials is polyurethane foam. It 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 pipeline insulation can be used in various forms.
- PPU shells are widely used, usually having an outer foil coating. It can be collapsible, consisting of half-cylinders with tongue-and-groove locks, or, for pipes, not large diameter– with a cut along the length and special valve with a self-adhesive back surface, which greatly simplifies the installation of insulation.
- Another way to thermally insulate a heating main with polyurethane foam is to spray it in liquid form using special equipment. The resulting layer of foam, after complete hardening, becomes an excellent insulation material. This technology is especially convenient at complex junctions, pipe turns, in units with shut-off and control valves, etc.
The advantage of this technology is that, thanks to excellent adhesion polyurethane foam spraying with the surface of the pipes, excellent waterproofing and anti-corrosion protection is created. True, the 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 optimal choice will be the use of pre-insulated (pre-insulated) pipes.
In fact, such pipes are a multilayer structure assembled in a factory:
— The inner layer is, in fact, the steel pipe itself of the required diameter, through which the coolant is pumped.
— The outer coating is protective. It can be polymer (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.
Left at both ends of the pipe installation area for welding work when assembling the heating main. Its length is designed in such a way that the heat flow from the welding arc will not damage the polyurethane foam layer.
After installation, the remaining uninsulated areas are primed, covered with a polyurethane foam shell, and then with metal belts, comparing the coating with the overall outer casing of the pipe. It is often in such areas that fire breaks are organized - they are tightly filled with mineral wool, then waterproofed with roofing felt and still covered on top with a steel or aluminum casing.
The standards establish a certain range of such sandwich pipes, that is, it is possible to purchase products of the required nominal diameter with optimal (regular or reinforced) thermal insulation.
| Outer diameter of steel pipe and minimum wall thickness (mm) | Dimensions of galvanized sheet steel shell | Estimated thickness of the thermal insulation layer of polyurethane foam (mm) | |
|---|---|---|---|
| nominal outer diameter (mm) | minimum thickness of 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, compensators, etc.
The cost of such pre-insulated pipes is quite high, but their acquisition and installation solves a whole range of problems at once. So such costs seem quite justified.
Video: the production process of pre-insulated pipes
Insulation – foam rubber
Thermal insulation materials and products made from synthetic foam rubber have recently become very popular. This material has whole line advantages that bring it to a leadership position in matters of insulation of pipelines, including not only heating mains, but also more responsible ones - on complex technological lines, in mechanical engineering, aircraft and shipbuilding:
- Foam rubber is very elastic, but at the same time has a large margin of tensile strength.
- The density of the material is only from 40 to 80 kg/m³.
- The low thermal conductivity coefficient 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; there are no pockets of mold or mildew, no nests of insects or
- The most important quality is almost absolute water and vapor tightness. Thus, the insulating layer immediately becomes an excellent waterproofing for the surface of the pipe.
Such thermal insulation can be produced in the form of hollow tubes with internal diameter from 6 to 160 mm and an insulation layer thickness from 6 to 32 mm, or in the form of sheets, which are often given a “self-adhesive” function 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 °C |
| Thermal conductivity, W/(m ×°C): | λ≤0.036 at 0°C |
| λ≤0.039 at a temperature of +40°C | |
| Vapor permeation resistance coefficient: | μ≥7000 |
| Fire hazard level | Group G1 |
| Allowable length change: | ±1.5% |
But for heating mains located in the open air, ready-made insulation elements made using the Armaflex ACE technology, which have a special protective covering"ArmaChek".
ArmaChek coating can be of several types, for example:
- "Arma-Chek Silver" is a multi-layer PVC-based shell with a silver reflective coating. This coating provides excellent protection of the insulation from both mechanical stress and ultraviolet rays.
- The black Arma-Chek D coating has a fiberglass base that is highly durable but retains excellent flexibility. This is excellent protection against all possible chemical, weather, and mechanical influences, which will keep the heating pipe intact.
Typically, such products using the ArmaChek technology have self-adhesive valves that hermetically “seal” the insulating cylinder on the pipe body. Curved elements are also produced that allow installation on difficult sections of the heating main. Skillful use of such thermal insulation allows you to quickly and reliably install it, without resorting to creating an additional external protective casing - there is simply no need for it.
The only thing, probably, that is hindering the widespread use of such thermal insulation products for pipelines is the still prohibitively high price for real, “branded” products.
Prices for thermal insulation for pipes
Thermal insulation for pipes
A new direction in insulation - thermal insulation paint
You can't miss another one modern technology insulation. And it’s 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 is, without any doubt, an “alien” from the sphere of space technology. It is in this scientific and technical field that the issues of thermal insulation from critically low (in outer 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 appearance.
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 properties.
| Names of indicators | Unit | Magnitude |
|---|---|---|
| Paint color | white (can be customized) | |
| Appearance after application and complete hardening | matte, smooth, homogeneous surface | |
| Film elasticity when bending | mm | 1 |
| Coating adhesion based on pull-off force from the painted surface | ||
| - to the concrete surface | MPa | 1.28 |
| - to a brick surface | MPa | 2 |
| - to steel | MPa | 1.2 |
| Resistance of the coating to temperature changes from -40 °C to + 80 °C | without changes | |
| Resistance of the coating to temperatures of +200 °C for 1.5 hours | no yellowing, cracks, peeling or bubbles | |
| Durability for concrete and metal surfaces in 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 a coating will not require additional protective layers - it is strong enough to independently cope with all impacts.
This is being implemented liquid insulation in plastic cans (buckets), like regular paint. There are several manufacturers, and among the domestic ones we can particularly note the brands “Bronya” and “Korund”.
This 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, climatic region, pipe diameter, and average temperature of the pumped coolant.
Many experts believe that such insulation materials will eventually replace conventional thermal insulation materials on a mineral or organic basis.
Video: presentation of ultra-thin thermal insulation of the Korund brand
Prices for thermal insulation paint
Thermal insulation paint
What thickness of heating main insulation is required?
To summarize the review of materials used for thermal insulation of heating pipes, we can put the performance indicators of the most popular ones in the table - for clarity of comparison:
| Thermal insulation material or product | Average density in the 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 above | 19 and below | ||||
| Mineral wool slabs pierced | 120 | 0,045 | 0.044 ÷ 0.035 | From - 180 to + 450 for mats, on fabric, mesh, fiberglass canvas; up to + 700 - on a metal mesh | Non-flammable |
| 150 | 0,05 | 0.048 ÷ 0.037 | |||
| Thermal insulation slabs made of mineral wool with a synthetic binder | 65 | 0.04 | 0.039 ÷ 0.03 | From - 60 to + 400 | Non-flammable |
| 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 | Low flammable |
| Half-cylinders and mineral wool cylinders | 50 | 0,04 | 0.039 ÷ 0.029 | From - 180 to + 400 | Non-flammable |
| 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-flammable, the rest are low-flammable |
| Glass staple fiber mats with synthetic binder | 50 | 0,04 | 0.039 ÷ 0.029 | From - 60 to + 180 | Non-flammable |
| 70 | 0,042 | 0.041 ÷ 0.03 | |||
| Mats and wadding made of superfine glass fiber without binder | 70 | 0,033 | 0.032 ÷ 0.024 | From - 180 to + 400 | Non-flammable |
| Mats and wool made of superfine basalt fiber without binder | 80 | 0,032 | 0.031 ÷ 0.024 | From - 180 to + 600 | Non-flammable |
| Perlite sand, expanded, fine | 110 | 0,052 | 0.051 ÷ 0.038 | From - 180 to + 875 | Non-flammable |
| 150 | 0,055 | 0.054 ÷ 0.04 | |||
| 225 | 0,058 | 0.057 ÷ 0.042 | |||
| Thermal insulation products made of polystyrene foam | 30 | 0,033 | 0.032 ÷ 0.024 | From - 180 to + 70 | Flammable |
| 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 | Flammable |
| 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 | Flammable |
But surely an inquisitive reader will ask: where is the answer to one of the main questions that arises - what should be the thickness of the insulation?
This question is quite complex, and there is no clear answer to it. If desired, 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 provide the required thickness calculated for a specific region. And if mineral wool insulation is used, then you can use the data from 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 Internet by entering a search query "SP 41-103-2000".
Here, for example, is a table from this reference book regarding the above-ground placement of a pipeline in the Central region of Russia, when using mats made of glass staple fiber grade M-35, 50:
| Outer diameter pipeline, mm | Heating pipe type | |||||
|---|---|---|---|---|---|---|
| innings | return | innings | return | innings | return | |
| Average temperature regime of the coolant, °C | ||||||
| 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 |
In a similar way, you can find the necessary 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 insulating layer for pipelines have been determined:
| Pipeline outer diameter, mm | Maximum thickness of 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, do not forget one thing important nuance. The fact is that any insulation with a fibrous structure inevitably shrinks over time. 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 adjustment for shrinkage.
To calculate, you can use the following formula:
N = ((D + h) : (D + 2 h)) × h× Kc
N– thickness of the mineral wool layer, taking into account the correction for compaction.
D– outer diameter of the pipe to be insulated;
h– required insulation thickness according to the table of the Code of Rules.
KS– shrinkage (compaction) coefficient of fiber insulation. It is a calculated constant, the value of which can be taken from the table below:
| Thermal insulation materials and products | Compaction coefficient Kc. |
|---|---|
| Stitched mineral wool mats | 1.2 |
| Heat-insulating mats "TEKHMAT" | 1.35 ÷ 1.2 |
| Mats and canvases made of super-thin basalt fiber when laid on pipelines and equipment with a nominal diameter, mm: | |
| Du | 3 |
| 1,5 | |
| DN ≥ 800 with 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 from glass staple fiber "URSA" brand: | |
| M-11: | |
| ̶ for pipes with DN up to 40 mm | 4,0 |
| ̶ for pipes with DN 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 slabs with synthetic binder brand: | |
| 35, 50 | 1.5 |
| 75 | 1.2 |
| 100 | 1.10 |
| 125 | 1.05 |
| Glass staple fiber slabs brand: | |
| P-30 | 1.1 |
| P-15, P-17 and P-20 | 1.2 |
To help the interested reader, below is a special calculator, which already contains the indicated ratio. You just need to enter the requested parameters and immediately get the required thickness of mineral wool insulation, taking into account the correction.
Modern people want to live in complete comfort both in the city and in the countryside. And this requires heat, cold, hot water and a sewage system. In most regions of our country, such communications require mandatory insulation. Today the building materials market offers a wide range various insulation materials, among which there are special products, mounted on pipes.
Materials suitable for pipe insulation
Is thermal insulation always required for pipes?
When is pipe insulation needed? In regions where winter time the ground freezes, pipe insulation must be used without fail. Otherwise, pipeline rupture is guaranteed. And correcting such a mistake when the temperature outside is sub-zero is neither easy nor quick. In addition, effective thermal insulation of heating or hot water supply pipes reduces heat loss. The heat will not be spent on heating the ground, and the temperature of the water will not decrease when entering the house.
It happens that hot water supply or heating systems in country houses pass through unheated rooms, attics, basements, if the autonomous boiler room is located outside the house. In this case, effective insulation of pipelines will reduce heat loss, you will not have to turn on additional heaters and pay for extra kilowatts, and the heating unit will last longer without being used to the maximum.
Sewage systems also require insulation, even though in such structures, as a rule, liquid does not stagnate if the correct slope is made when installing the pipes. But it happens that various deposits accumulate inside the pipes, which can cause blockages, and then the sewage drains at low temperatures can freeze, which will lead to pipe rupture. Also, untimely pumping of a septic tank in an autonomous sewer system can lead to a similar nuisance.
Insulation is carried out not only to maintain the temperature of the coolant and as protection against freezing during the cold season. Sometimes it is necessary to protect pipes from exposure to high ambient temperatures. For example, in refrigeration devices, various industrial systems through which chemical liquids, gases.
What properties should an insulating material have?
Insulation for pipes, depending on the scope of application (laying underground or external communications), must meet the following requirements:
- Low level of thermal conductivity, which will help maintain the temperature of the coolant in heating and hot water supply pipelines, as well as prevent warm ambient air from heating the pipeline in cooling devices and appliances.
- Materials used for insulation must meet sanitary and fire safety standards and have self-extinguishing properties.
- Insulation cannot be overly hygroscopic, since the amount of air in the structure of a wet material decreases, the amount of which determines its thermal insulation properties.
- Thermal insulation should be easily installed on pipes of any diameter and configuration, with the formation of a minimum number of joints, which eliminates the presence of cold bridges.
- The material must be durable and maintainable, as well as the possibility of its repeated use.
- Possess high resistance to aggressive environments, mechanical strength, and withstand sudden temperature changes.
- Material available at an affordable price.
But you shouldn’t buy cheap insulation, as this can lead to even greater costs if the pipe freezes in winter.
Types of thermal insulation for pipelines
The above requirements may have the following types of insulation:
- types of mineral wool - glass wool, basalt and others;
- Styrofoam;
- expanded polystyrene;
- foamed polyethylene, plain and foil-coated;
- polyurethane foam;
- expanded clay
Mineral wool
Mineral wool cylinders All types of insulation material based on fiberglass or natural stone rocks are characterized by a high degree of thermal insulation and optimal cost. True, glass wool in its properties to retain heat is an order of magnitude lower than such a material as. The advantages of this type of insulation include:
- resistance to high temperatures, when the material can withstand up to 700 degrees;
- sufficient mechanical strength, when after deformation it almost completely restores its shape;
- resistance to aggressive chemicals - alkaline, acidic solutions, oils, etc.;
- environmental safety, as a derivative from natural raw materials.
- affordable price.
The disadvantages of mineral wool include their sensitivity to moisture. Therefore, an additional waterproofing layer is required. In addition, waterproofing will not only help protect the insulation from exposure to water, but will also prevent the smallest fibers of stone or glass from clogging the air in the room. Such work increases the cost of construction and extends its duration.
Mineral wool is produced in rolls, mats, slabs and shells with foil glued on top. It is these products that are most convenient for performing thermal insulation work on pipelines, when protecting wooden roof structures from fire in the area where the chimneys of stoves and fireplaces pass.
Polystyrene foam and polystyrene foam
Foam shells for pipe insulation This material, which contains more than half air, is one of the most effective heat insulators. Non-pressed foam is bad only because it has low mechanical strength. To insulate pipes, the industry produces foam half-cylinders called shells. These products have many advantages:
- simple and quick installation;
- long-term operation;
- absence of cold bridges, since the connection of individual segments is carried out according to the tongue-and-groove principle;
- products can be operated in temperatures from +80 to -110 degrees Celsius. At a higher temperature of the pipeline, an additional layer of natural cork or basalt fiber is laid;
- the ability to lay the heating cable in specially designed grooves along the entire length of the products;
- fireproof, do not support open fire;
- foam shells can be used repeatedly.
The shells can be covered with a layer of foil, which acts as a deflector for the ceilings of air - hot or cold.
Extruded polystyrene insulation Exactly the same half-cylinders are made from pressed (extruded) foam, which is already called. It has similar technical characteristics, but with the same degree of thermal conductivity as foam, it has a smaller thickness, which is convenient when insulating pipes running next to walls or other structures. Penoplex has a more rigid structure and greater ductility than polystyrene foam, so it can be bent to a certain limit.
Polyethylene foam insulation materials
Insulation with foamed polyethylene with a protective foil coating Compared to other types of insulation, foamed polyethylene has the best properties:
- The material is more durable, withstands a tensile load of 0.3 MPa, after exposure to pressure, it is somewhat deformed, but quickly returns to its original shape.
- Practically does not absorb water. Can be used in humid environments without causing corrosion on pipes.
- Resistant to exposure to materials such as cement and lime, concrete and other contacts.
- Withstands temperature changes from +90 to -60 degrees. At higher temperatures, products lose their shape.
- The material is quite fireproof. Foamed polyethylene can only ignite at an open fire temperature of 300 degrees. Moreover, during combustion the material does not release harmful toxic substances into the environment.
- Easy to install, it can serve as thermal insulation for pipes of any configuration, with a diameter of up to 150-200 mm.
- Low cost compared to polystyrene foam or polyurethane products.
It is produced in hollow cylinders up to two meters long with a wall thickness of 6 to 20 mm or in rolls.
This is how foamed polyethylene is mounted on pipes A product made of foamed polyethylene is cut to length and placed on the pipe; the cut site is secured with a special bandage or regular tape. Some brands of polyethylene foam insulation have a protective coating of aluminum foil that acts as a reflector. If rolled material is used, it is cut into strips that are used to wrap the pipes. This method is best suited if the pipeline has many bends and different diameters in individual sections.
Polyurethane foam
Spraying polyurethane foam on pipes This material is gaining increasing popularity in construction due to its high technical characteristics. He:
- does not rot or rust;
- can be mounted on pipes lying in the ground without any trays or channels;
- creates an absolutely hermetic shell on insulated structures;
- has low specific gravity and low thermal conductivity; service life is estimated at fifty or more years;
- resistant to weak solutions of acids and alkalis;
- has excellent adhesion to almost all materials.
Thermal insulation with polyurethane foam can be applied to pipes using various methods - spraying liquid material and hard shell-type products. Spraying is carried out using special equipment and requires certain skills and knowledge. The shell, which has the form of two hollow half-cylinders, is mounted on pipes simply, due to the existing tongue-and-groove connecting structure, and those products that have a smooth end are secured to the pipeline with special clamps, bandages, or ordinary binding wire.
Factory applied polyurethane coating But in addition, today ready-made pipes, on which a thermal insulating coating of polyurethane foam and a protective layer are applied at the factory, are becoming widely popular. When using such products outdoors, the protective shell is made of galvanized steel; when laying underground communications, the protection is made of polyethylene. The advantages of such pre-insulated pipes are obvious: reduction in construction time for communications, since the installation utility networks no longer requires insulation work, and the quality of insulation is checked by the factory quality control department.
Expanded clay
Another traditional representative of insulation for pipelines is expanded clay gravel. It is used primarily for insulating external water supply and sewerage networks. Since the material is loose, it requires the construction of trays from wooden planks or use special concrete structures.
In addition to all of the above types of insulation, not long ago a new material for pipe insulation appeared - thermal paint, which is applied in the usual way– brush, roller or spray. With a minimum thickness of the insulating layer, the quality of thermal insulation is quite high. But the cost of this material is also not small.
Installation of thermal insulation
The most popular material for pipe insulation is products in the form of hollow cylinders. They are installed quite easily and do not require special knowledge or high qualifications of the worker.
First of all, the condition of the pipe is checked. It should not have leaks, be cleaned of rust and dirt and treated with an anti-corrosion agent.
If insulation products are not equipped with tongues and grooves, they should be secured using double sided tape.
Displacement of individual shell elements along the length In this case, the individual elements of the hollow cylinder are shifted along the length by 10-20 cm, so that the connecting seams do not converge in one place. The foam shell, after it is fixed to the pipeline, must be protected from exposure to ultraviolet radiation. The material for such protection can be roofing felt, glassine, roofing felt, foil insulation and other opaque panels. To insulate complex sections of the pipeline, you can use ready-made shaped products or use rolled thermal insulation materials.
Cylinders made of polyethylene foam and having a foil layer do not need such protection.
The main point of the article
When insulating pipes, any available material is used that meets the thermal insulation requirements regulated by building codes. A correct installation the selected insulation will extend the service life of utility networks and reduce, and perhaps completely eliminate, the number of repairs associated with pipe ruptures due to freezing temperatures.
Pipe insulation is a material that guarantees effective work systems, maintaining a comfortable temperature in the house and uninterrupted circulation of the contents of the main. In our latitudes, all communications have to be insulated. Choosing thermal insulation is a responsible task that is not easy to cope with, given the wide range. A short excursion into the possible options is in this review from the HouseChief editors.
Good thermal insulation of the pipeline is a prerequisite for its successful operation
PHOTO: kimberia.ru
Read in the article
Thermal insulation: an urgent need or reinsurance
The soil freezes in almost all our latitudes. If a pipeline with liquid contents ends up in frozen ground, it will most likely rupture. In addition, direct contact with cold soil or air leads to significant heat loss. Part of the thermal energy will be wasted on heating the environment and will not reach its destination.
In houses, the boiler room is often located outside the main room, and the coolant has to travel some distance before getting into the radiators. The route of the main line can run through an attic, basement or unheated corridor.
The loss of part of the energy leads to unreasonable costs and excessive wear and tear of equipment PHOTO: torufix.ee
The sewage system is also very temperature dependent. Even if the pipeline is laid according to all the rules, with the required slope, a coating forms inside the pipes, which, when frozen, can clog the system and lead to pipe rupture. Such problems affect not only centralized systems, but also autonomous structures with a septic tank.
There is always water in the water pipes. It begins to circulate when the tap is opened, and the rest of the time it can turn into ice in the freezing soil.
So there is no question of reinsurance. Thermal insulation is real necessary procedure, which should not be neglected if you do not want to constantly repair utility networks
PHOTO: vodakanazer.ru
Requirements for heat insulators for pipelines
In order for the insulation to effectively perform its task, it must meet several important requirements:
- the level of thermal conductivity should be as low as possible to effectively maintain the temperature of the contents of the line in the cold and warm seasons;
- thermal insulation must be safe for humans;
- the material must not be flammable and must not support combustion;
- the insulation should not accumulate moisture, as this process reduces its ability to retain heat;
- installation of the material should be simple, with minimum quantity joints and the ability to isolate nodes of complex configuration;
- the maintainability of the insulation and the possibility of its repeated use are important;
- the material must be resistant to external influences, mechanical, atmospheric and chemical, as well as to sudden changes in temperature.
Does the cost of the material matter? As a rule, good insulation cannot be too cheap, although these materials usually do not require large expenses PHOTO: aiss33.ru
Which insulation materials meet these requirements? There are several options that are excellent for insulating pipes: these are mineral wool materials, thermal insulators made of foam materials and some bulk and liquid substances that can perform similar tasks.
Types of pipe insulation and their features
Let's consider the main options for heat insulators, which are most effective for insulating sewerage, heating and water supply systems.
Mineral wool materials
Fiberglass or stone wool retain heat perfectly. If we compare these two types of insulation, stone wool wins in terms of insulating properties. It can withstand temperatures up to 700ºC and holds its shape perfectly even under mechanical stress. This insulation is resistant to aggressive chemicals and is relatively inexpensive.
But it also has its own unpleasant features. The main one is the ability to absorb moisture. With this process, stone wool gradually loses its insulating properties. Therefore, if you choose this material, you should consider another outer layer of waterproofing to protect against water.
This insulation is sold in slabs, cylinders and rolls. The material can already be protected on one side with foil PHOTO: ecotherm.bg
Polystyrene foam insulation
Foam insulation contains more than 50% air in its mass, which makes it one of the best. Its only drawback is its fragility, which does not allow it to be bent to the shape of a pipe. But manufacturers solved this problem by releasing a foam shell, which has the shape of a half-cylinder and can be worn on the pipe like a shirt.
The semi-cylinders are connected using a tongue-and-groove method, which eliminates the formation of cold bridges PHOTO: build-experts.ru
This shell can withstand temperature changes from -110ºС to +80ºС degrees. If your heating pipes heat up to a higher temperature, then a cork membrane should be laid between them and the foam.
This insulation does not support combustion and can be used more than once.
A more advanced version of the shell is penoplex, which, with a smaller thickness, has better heat-insulating properties. Penoplex is more elastic, so it can bend a little if necessary.
Liquid penoizol
This material is applied by spraying and is most often used for pipe insulation in industrial premises. After this treatment, the pipe is completely hidden under a layer of insulator, without the formation of cold bridges. This method is convenient for insulating pipes with complex configurations. Spraying services are not cheap. In private households, an analogue to such insulation can be ordinary polyurethane foam.
This way you can insulate a small section of pipe
PHOTO: prorab.help
Foamed polyethylene
Polyethylene is a fairly durable material that can withstand mechanical loads well. This type of insulation is not afraid of moisture and protects metal pipes from corrosion damage. Operating temperature range – from -60ºС to +90ºС. Foamed polyethylene resists fire for a long time, but even if it burns, it does not release toxins.
This insulation is easy to install, it is elastic and suitable for pipes of any diameter. PHOTO: polifasplus.ru
The price of foamed polyethylene is an order of magnitude lower than, for example, polyurethane. Thermal insulation for pipes made from this material is produced in the form of hollow cylinders up to 200 cm long and with a wall thickness of up to 20 mm.
To put such a cylinder on a pipe, it is cut lengthwise, and then the cut site is secured with tape. Roll material They just wrap the pipes.
Foil penofol
Foil insulation is a modern and popular type of thermal insulation, easy to install and effective in operation. Foil penofol can also be used to insulate pipes. It is produced in rolls and hollow cylinders.
Installation of penofol is similar to foamed polyethylene PHOTO: vystroim.com
Energoflex
This type of insulation is flexible. In fact, energyflex is a type of high-density polyethylene foam. This material can be used outdoors. It is not afraid of water and can withstand temperatures from -60ºС to +90ºС.
LDPE is resistant to aggressive chemicals and can be used for at least 25 years PHOTO: 7.allegroimg.com
Available in rolls and hollow cylinders.
The disadvantage of Energoflex is its sensitivity to direct ultraviolet radiation.
Thermal insulating dyes
It's comparative the new kind thermal insulation, which is applied with a regular brush or roller. The thickness of the resulting layer is minimal, and the thermal insulation effect is quite high. The price of such paints is steep, and the secret of their production is vigilantly kept by the manufacturers. What is known is that the heat-insulating effect is present due to the presence of microspheres with air in the paint. This coating can replace a five-centimeter layer of mineral wool.
At the same time, the dye protects pipes from corrosion and prevents condensation from forming on their surface PHOTO: gidpokraske.ru
Bulk insulation materials
In addition to the listed materials, pipes in the ground are traditionally insulated with expanded clay. A layer of this material is capable of retaining heat efficiently and for a long time. To prevent the insulation from mixing with the soil, it is placed together with the pipes in a box made of boards or in concrete shells.
Thermal insulation for pipes: how to choose
The choice of insulation depends on three main factors: the location of the pipeline, installation features and cost. In principle, any of the insulation listed above is easy to install with your own hands.
To protect pipes from overheating outside, foil insulation is used. In terms of material cost, the most expensive will be mineral wool, and the cheapest will be foamed polyethylene.
In cases where it is not possible to wrap pipes with a heat insulator due to their complex structure or location, it is logical to use thermal paint.
For heating system
For the heating system, thermal insulation materials should be used that can be used in contact with high-temperature objects. These include mineral wool, penoplex and polyurethane foam.
To insulate a water supply system, two conditions are important: maximum heat retention and protection against corrosion. Polyurethane foam, which is applied in a liquid state, and heat-insulating paint are most suitable for this. Both of these options eliminate the formation of condensation and protect pipes from rust.
For sewerage
Sewer pipes with insufficient slope or running less than half a meter from the ground surface must be insulated. This will require materials that do not absorb moisture and are resistant to mechanical stress.
Foamed polyethylene and penoizol are perfect for such purposes. PHOTO: tehnopena.ru
How to install insulation on pipes yourself
Installing thermal insulation on pipes is a fairly simple task that even a beginner can solve. Here is a short video on this topic that will help you quickly understand the process:
Some nuances of installation in special conditions
To obtain effective insulation of pipe lines, you should follow a few simple recommendations:
- when insulating in unheated rooms it is important to exclude cold bridges;
- in damp rooms, a vapor barrier should be used over the thermal insulation;
- Insulation with a self-adhesive layer will greatly facilitate installation work;
- to eliminate minor flaws in installation, use additional winding and reinforcing tape;
- carefully select rigid insulation materials - they must exactly match the diameter of the pipes.
If everything is done correctly, you will forget about problems with communications. PHOTO: bt-wpstatic.freetls.fastly.net
How did you insulate the pipes in your house? Write about it in the comments!
Functional diversity of pipelines, as well as climatic conditions our country has determined the variety of ways in which thermal insulation for pipes is carried out.
Pipelines are classified according to several criteria. Depending on the type of product that is transported through them, they are divided into the following types:
- For steam;
- For water;
- For gas;
- For oil;
- For air;
- For oil, etc.
Depending on the distance over which transportation is carried out, pipelines are:
- Trunk, which includes pipelines that transport over long distances. Thermal insulation of main-line pipelines is the responsibility of specialized enterprises;
- Local, which includes pipelines, for example, city utility networks, including water supply, sewerage and heating systems. Thermal insulation of heating mains of water supply networks, sewerage and heating lines is a task that city dwellers most often face.
A separate group includes technological pipelines that serve industrial needs, being located directly at the production site.
In addition, there is a division of pipelines into types according to the characteristics of the transported medium and operating pressure.
Purpose of thermal insulation
Depending on the purpose of the pipeline, thermal insulation for pipes can solve different problems. Let's list them:
- Providing specified temperature characteristics on the surface of the insulating layer. This task is posed when the temperature of the medium inside the pipe does not matter, but it is necessary, for example, to avoid burns when contacting the surface of the pipes.
- Providing protection against freezing of liquids passing through thermally insulated pipes. In our climate, this is one of the most pressing tasks, especially for utility networks, that is, water supply, sewer systems and heating routes.
- Preventing the formation and accumulation of condensate on the surface of pipes. This problem arises when the temperature of the liquid in the pipeline is lower than the temperature of the outside air, as happens, for example, in water and sewer pipes with cold water indoors.
- Preventing heat loss in the pipes of heating networks and insulating the heating main. Heating and hot water supply lines for urban and industrial networks laid in the ground or on the surface of the earth inevitably lose some heat due to the lower ambient temperature. The task of insulating water pipes and heating lines in urban networks is to minimize these losses.
Types of thermal insulation materials
The choice of material and method of thermal insulation is made based on its purpose.
There are two main methods of insulation:
- The insulating material is applied or sprayed in the form of mastic or paint.
- The finished insulating material is attached around the pipe.
Today, insulating materials are produced in the following forms:
- Cylinders;
- Half cylinders;
- Segments;
- Rolls;
- Mats.
Important! When choosing insulation, it is necessary to take into account what types of pipeline it is intended for. Failure to comply with this rule can lead not only to a violation of the thermal protection, but also to damage to the pipeline itself.
Let's consider the most common types of insulation, as well as methods of their installation.
Mineral wool
Of all types of insulation, mineral wool has the lowest cost. Installation of insulation from this material is simple, but labor-intensive.
To do this, a roll of cotton wool is cut crosswise into pieces 200 mm thick and then wrapped around the pipes. Moreover, first a layer of mineral wool is wound, and on top of it a layer of fiberglass.
The fiberglass fabric must be laid tightly, but so that it does not compress the insulation. The thickness of the layer of wool covering thermally insulated pipes should be about 100 mm. This indicator depends on the ambient temperature.
When winding mineral wool, you should ensure that it lays evenly and does not wrinkle.
Mineral wool is used as thermal insulation for large-diameter pipelines, most often for heating routes in urban networks and for sewer systems.
For water supply, heating, and sewer pipes of small diameter, this type of insulation is usually not practiced.
Shell
This type of insulation is used for sewer, water and heating pipes with a diameter of more than 50 mm. The shell consists of insulation and a protective shell.
The insulation is made of mineral wool or polyurethane foam, and the protective shell is a thin sheet of metal bent in the shape of half a nut shell.
During installation, the shell halves are placed on the pipe, forming a protective cocoon around it, and fastened together with clamps or mounting wire.
To insulate corner elements, the shell can be made bent at an angle of 45 or 90 degrees.
By average cost shell is superior to other types of thermal insulation.
Polyurethane sealant
This type of insulation or, in other words, liquid insulation, is a composite material. It consists of a two-component polyurethane sealant and a protective shell, which is made of thin stainless steel sheet or galvanized steel.
It is also used to insulate large diameter pipelines.
The installation process consists of the following steps:
- A protective shell is fixed to the pipe, which is centered relative to the axis of the main line using wooden wedges.
- The main component of the sealant is poured into the protective shell. In order for thermally insulated pipes to serve well and for a long time, it is necessary to strictly follow the proportions specified in the instructions.
- An auxiliary component is poured into the protective shell.
During the reaction between the components, polyurethane foam is formed, filling the space between the shell and the surface of the pipe.
Important! When working with polyurethane sealant, safety precautions must be strictly observed. Do not allow it to come into contact with the skin.
Tubular insulation
Tubular insulation - Merylon, is made of polyethylene foam. It is used for insulation of water supply lines with a diameter of no more than 100 mm.
To install the Merilon, remove the tape attached along the tube. After this, the tube opens up and can be easily inserted onto the water pipe. Then the merilon is secured with electrical tape or tape.
It insulates pipes in home networks, water supply, sewer or heating, located in a building or buried to a depth of no more than a meter.
Important! Merilon is not intended for outdoor use.
