The vast majority of regions of our country are characterized by very harsh winters. Frosts of minus 20 degrees and below will not surprise anyone. And even in the southern regions, with a mild climate, the weather sometimes brings “surprises” when the thermometer drops below zero for quite a long time. That is, at almost any point during private construction you have to think about how to protect against freezing.
Frozen water in pipes is not only and not even so much a temporary loss of one of the communal “conveniences”. Most often, such troubles lead to literally catastrophic consequences - they end in rupture of pipe walls, complete failure of the entire home system, the need for large-scale repair and restoration work. And hoping for some illusory luck, like this won’t happen to me, is extremely short-sighted. In any case, it is impossible to do without high-quality insulation of the system.
Let's see what kind of thermal insulation can be used for water supply pipes, let's look at the types of materials, their advantages and disadvantages. And with the main question - what should be the thickness of this insulating layer.
What methods are used to protect water pipes from freezing?
It doesn't matter if he gets a private house distribution of water from the central collector (and this also often happens), or will be used standalone source(well or borehole), it is still assumed that the pipe will be laid where negative external temperatures are likely. The only exceptions can be considered those rare cases when the well is drilled directly in the basement of the house. And even then, on the way to the points of consumption there may also be sections of water supply passing through an unheated basement or basement. But in order to disable the water supply system, a very short uninsulated section is enough.
What approaches are used to protect water pipes from freezing?
- First of all, if possible, the water main should be laid below the freezing level of the soil in a given region. At this depth of the route (and it is taken with a reserve - the freezing level plus another 300÷500 mm), the temperature should never reach negative values. That is, the probability of getting an “ice jam” tends to zero.
However, this approach is not always fully feasible. In some regions, the soil freezes to a very significant depth, and digging such deep trenches significantly complicates the implementation of the project. It is not uncommon to find areas where the soil characteristics completely exclude such an arrangement of pipes.
In many regions, the level of soil freezing reaches very significant depths. It is not always possible to dig such deep trenches for laying water pipes. In addition, the pipe, one way or another, must be lifted up in order for it to enter the house. And in any case, it will pass through “dangerous” areas - the upper sections of the route, passage through the foundation, through the basement, basement, or even just an unheated room, where negative temperatures can be observed in winter.
How to build an autonomous water supply system in a private house
Much depends on the source of water, its location on the site, distance from the residential building, the climatic conditions of the region and the design features of the building itself. Read more about this in a special publication on our portal.
- Those very “problem areas” of the water supply route can be artificially heated using electrical energy. For these purposes, special heating cables are used, which are laid on the pipe walls under a layer of thermal insulation, or even placed directly in the pipe cavity.
There are many varieties of such cables, as well as blocks, on sale these days. automatic control heating, which turn on the power when required.
How to organize heating of water supply?
The advent of heating cable systems has eliminated many problems when organizing autonomous water intakes in private homes. By the way, if you strictly follow the instructions of the manufacturers of such products, then it is quite possible to install and launch it yourself. More details can be found in a special publication on our portal.
- In the basement, basement or other areas of the house, where negative temperatures are not excluded, laying a “thermal satellite” is sometimes practiced. This is a pipe running parallel to the water supply and enclosed in a common thermal insulation shell, which is nothing more than one of the branches of the general heating circuit of the house.
Such a hike, of course, complicates both the plumbing and heating systems. But you no longer have to worry about the integrity of areas with such heating. True, only when the heating is on.
- One of radical ways Preventing water from freezing in pipes is to maintain a constant high pressure in them. To do this, the autonomous water supply system is supplemented with special equipment, and the pipes themselves must be able to withstand these increased loads.
The approach, although effective, is quite complex in organization and in everyday use. In addition, it turns out to be more expensive in terms of energy consumption. Such systems have not gained much popularity.
- The most common method is thermal insulation of pipes, that is, what this publication is essentially devoted to. The use of various insulation materials helps to avoid freezing of the water supply system, if, of course, the material and thickness of the insulation are selected correctly.
All this will be discussed in more detail below.
A special type of insulation sometimes includes the creation of a stationary air gap between the water pipe and the casing, which prevents direct contact of the pipe with the ground. In a nutshell, this can be described as a “pipe within a pipe.”
But, to be honest, this method is not used in its “pure form”. The hollow space, at least in order to accurately position the water pipe inside the outer shell, is still filled with insulating material. Which, in principle, is insulation only because of its ability to create a layer of immobilized air. So the result is classic thermal insulation of the pipe with the creation of an external casing. And by the way, it is always welcome to protect both the insulation and the pipe itself from mechanical influences, from ground moisture, and from damage that can be caused by rodents living underground, attracted by the winter heat.
In practice, a combination of most of the listed methods for protecting water pipes from freezing is usually used. That is, they try to deepen the route from the well or well as much as possible, insure the most vulnerable areas with additional heating and, of course, provide reliable thermal insulation, usually along the entire length of the water pipe.
Such an integrated approach is also necessary for the reasons that even high-quality insulation often does not guarantee complete protection of the water supply system. The table below shows the volumes of heat loss calculated for pipes of different external diameters, enclosed in a layer of thermal insulation of different thicknesses. The thermal conductivity coefficient of the insulation is taken as average, characteristic of most thermal insulating materials, used in the role under consideration – 0.04 W/(m×K).
Naturally, the amount of heat loss depends directly on the difference in ambient temperatures and the liquid pumped through the pipe. The table shows several options - from Δt = 20 ℃ to Δt = 60 ℃. For example, if the temperature of water from a well (well) in winter is +2 ÷ 4 ℃, and in the winter the pipe passes through the base of the house, frozen to - 15 ℃, then the temperature difference can be considered 20 degrees.
| Insulation layer thickness | Temperature difference (Δt, °С) | Pipe outer diameter (mm) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 15 | 20 | 25 | 32 | 40 | 50 | 65 | 80 | 100 | 150 | ||
| Average heat loss (W per each linear meter pipeline) | |||||||||||
| 10 mm | 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 mm | 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 mm | 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 mm | 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 you can see, even with a fairly thick insulation layer of 40 mm, a pipe with a diameter of 32 mm under the example conditions taken above will lose almost 5 W of thermal energy per linear meter. It doesn’t seem like much, but if there is no water movement in the pipe for several hours, an ice plug may appear in such an area. This means that these heat losses will have to be replenished in one way or another.
That is, when designing your water supply system, you need to carefully analyze theoretically vulnerable areas, and strengthen thermal insulation on them (if possible) or take steps to heat these “dangerous” areas. Which, by the way, are usually located in close proximity to the house or even directly in it. Although, it also happens that you have to heat the entire route from the source to the house, since, for example, rocky soil or a high location groundwater make it impossible to dig trenches below the freezing level.
But even in this case, the importance of pipe insulation only increases. The heat generated by the heating system should not be wasted, but should fulfill its intended purpose. And without high-quality thermal insulation it is impossible to achieve this.
Thermal insulation requirements for water pipes
So, let's move directly to thermal insulation for water pipes. And first of all, let’s figure out what requirements it should ideally meet.
From the above it should already be clear that pipe thermal insulation is designed to perform two key interrelated tasks:
Protecting the water supply system from dropping its temperature below zero - in order to avoid freezing of water, leading to loss of system functionality and rupture of pipes.
In areas with forced heating - minimizing heat losses for efficient and economical operation of the heating cable.
High-quality insulation must meet the following criteria:
- Of course, its thermal insulation qualities should be put in first place. The lower the thermal conductivity coefficient, the more efficiently heat is retained, the thinner the thermal insulation layer can be provided.
- The water supply system in an autonomous system is predominantly located in the ground, that is, in a moist soil environment. This means that thermal insulation must be resistant to moisture, preferably hydrophobic. Wet insulation always sharply loses its thermal insulation qualities. Those sections of pipelines that run outdoors also need protection from moisture.
Not all materials meet this criterion equally. But this can be partly solved by enclosing the insulated pipes in a waterproof shell or casing.
- The soil is often saturated with very aggressive chemical compounds. This means that both the insulation itself and the layer protecting it must be inert to such effects.
- An important criterion is the mechanical strength of the material. The insulation layer in the ground will experience serious soil pressure. On open areas External mechanical influences cannot be excluded.
- The laying of water pipelines, especially in buried areas, is done with the expectation of many years of operation. This indicates the need for pronounced durability of the insulating material.
- Good modern thermal insulation should not cause installation difficulties. Very often when creating a water supply system they use ready-made solutions- already insulated pipes, which all that remains is to install them into a common pipeline, and then insulate the joints.
- Of course, the availability of material always remains an important criterion - both in terms of supply in stores and in terms of cost. But here it should be immediately noted that high-quality modern pre-insulated pipes a priori cannot be cheap.
Now let's see what materials are used to insulate water pipes.
Insulation materials for thermal insulation of water pipes.
Mineral wool is widely used to insulate water pipes. various types, polystyrene foam, polyurethane foam, polyethylene foam. IN Lately A relatively new insulation material, foam rubber, has begun to be used more and more often.
Mineral wool
This is perhaps the most affordable thermal insulation material for such purposes. But it’s also far from the most convenient.
Of the three existing types mineral wool For insulation of pipelines, only two are actually used - glass wool and stone (basalt). The so-called slag wool, made from metallurgical waste, is poorly suited for such purposes. It loses in thermal insulation qualities, quickly becomes saturated with water, and not everything is in order with its chemical composition, which under certain conditions can become a catalyst for active corrosion of metal pipes.
What are dignity mineral wool insulation:
- Low thermal conductivity coefficient.
- One of important advantages before many other insulation materials - plasticity. Mineral wool can be used to insulate curved or flat surfaces, tees, bends, valves and other fittings.
- Chemical inertness to most acidic or alkaline compounds that may occur in soil moisture.
- A variety of release forms, any of which, in principle, can be used for pipe insulation. Thus, mineral wool is also produced in mats, including pierced ones, in separate slabs (blocks) of various thicknesses. This allows, by the way, to independently vary the thickness of the created insulation layer, depending on the initial conditions.
Special products for thermal insulation of pipes are also made from mineral wool - semi-cylinders (“shells” in common parlance) of various internal and external diameters, with or without an external coating. Very convenient for quick installation on straight sections of water pipeline.
- Mineral wool - practically not flammable material. For underground sections of the water supply system, this quality may not be so important, but for open sections it will be useful.
Now let's go through shortcomings of this material:
- First of all, it should be noted that many types of mineral wool are hygroscopic. This applies to a greater extent to fiberglass materials. They can quite actively absorb moisture, losing their insulating characteristics. And when wet mineral wool freezes, it undergoes destructuring and severe shrinkage.
Basalt types of mineral wool usually undergo special hydrophobic treatment, and are more resistant to contact with water.
But in any case, such insulation must be protected from direct contact with wet soil. This is achieved by creating a surface protective layer of aluminum foil, roofing felt or even just dense polyethylene film. The task is not particularly difficult: such an outer covering is simply wound on top with a certain overlap (overlapping) of turns, and then fixed with wire or other clamps. But at the same time, such additional operations complicate the installation of thermal insulation.
As we saw above, some types of mineral wool pipe insulation are already equipped with an applied external coating. This greatly simplifies thermal insulation work, but such materials are also more expensive.
- Working with mineral wool requires certain precautions and the use of skin, eye, and respiratory protection. The fibers are brittle (again, glass wool suffers more from this; basalt fibers have much better elasticity), and sharp microscopic fragments often cause serious irritation skin and mucous membranes.
- Another disadvantage is the tendency of mineral wool to gradually cake and lose volume (the thickness of the insulation layer). The reason for this is the same fragility of the fibers, which can increase under unfavorable conditions (overmoistening + negative temperatures) or under vibration.
The shrinkage of mineral wool insulation should be taken into account when planning the thermal insulation of pipes. How this is taken into account will be discussed below.
Insulation made from expanded polystyrene (PPR)
Expanded polystyrene (or, as it is often called, polystyrene foam) is very widely used specifically for the purpose of thermal insulation of various areas of the building. Plumbing is no exception.
By the way, this material is rightly criticized for whole line very negative qualities that limit its use in residential premises. First of all, these include problems from an environmental point of view, flammability and extremely toxic combustion products. But in terms of use for thermal insulation of underground sections of water supply, these qualities are completely unimportant. So the use of PPR should not cause any special concern.
The advantages of expanded polystyrene include:
- Excellent thermal insulation properties.
- Low density - the material is lightweight, very easy to process and install.
- High-quality PPR is not afraid of moisture - it practically does not penetrate its structure.
- The cost of products made from PPR is low - the cost of insulation will be small.
- The material is durable if it is protected from external mechanical damage and from contact with organic solvents.
The most convenient way, of course, to insulate pipes is to use a “shell” - half-cylinders with the required internal and external diameters. High-quality products of this type are also equipped with a tongue-and-groove lock, which prevents the appearance of cold bridges at the border of the two halves.
Such half-cylinders are put on both sides of the pipe, connected in locks, and then tied with tape or even just wire clamps. On straight sections of the water supply route, thermal insulation will not take much time.
Disadvantages In addition to those already listed above, the following can be considered:
- The material is quite fragile, and the “shell” is easy to break if handled carelessly.
- Complete absence of any plasticity. That is, even at a slight bend in the route, this section will have to be isolated separately, and then again switched to half-cylinders.
True, many companies engaged in the production of such “shells” also offer in their assortment special shaped parts for turns, tees and some other components. But, traditionally, the cost of such fittings is significantly higher than the price of “linear” elements. Therefore, many experienced craftsmen try to independently cut out the required parts for bends, tees, etc. from half-cylinders. Or these areas are insulated with mineral wool and then covered with a waterproof casing.
Used to insulate water pipes and polystyrene foam boards. For example, they are laid on top of the pipe before backfilling the trench - this creates a kind of screen that prevents vertical penetration of cold into the depths.
Another option is to build a box from expanded polystyrene slabs at the bottom of the trench into which the pipes are laid. After installing the water supply, the box is closed with a lid made of the same slab, and then the soil is backfilled.
Given the affordable cost of white foam boards, this insulation option will probably be the least expensive.
- Expanded polystyrene cannot be classified as a chemically resistant polymer. Even ordinary fuels and lubricants can cause its destructuring.
Therefore, such insulation should be used with caution if the soil is saturated with petroleum products (which often happens, for example, near a car park). Or, what would be more correct, provide external protection for the “shell”, for example, from thick polyethylene film.
Polyurethane foam insulation for pipes
With a certain external similarity to polystyrene foam (more precisely, with its extruded variety), polyurethane foam is significantly superior to it in almost all respects.
As a rule, polyurethane foam insulation for pipes is not produced in its “pure form”. But manufacturers offer a wide range of pre-insulated pipes. On such products, ready for installation, the pipe is already protected by a layer of high-quality PPU insulation and an external coating that is resistant to mechanical stress, moisture, and chemical attack. By the way, polyurethane foam itself is already much more resistant to various aggressive compounds. Moreover, sprayed onto the outer walls of the pipe, it also becomes an excellent anti-corrosion protection.
Consumers are offered a wide range of metal pipes in finished polyurethane foam thermal insulation. But their diameter usually starts from 57 mm and above. As a rule, during installation autonomous system plumbing has to use smaller pipes.
Therefore some well-known companies launched the production of plastic or metal plastic pipes small diameter, also having PPU thermal insulation and an external polymer coating. Such ready-made solutions extremely simplify the entire process of installing water pipes, laid both in the ground and in open areas - in basements, ground floors, unheated rooms.
On both sides of these pipes, a small “bare” section protrudes from the thermal insulation, which is sufficient for connection by welding or fitting. After this, a heat-shrinkable sleeve, previously placed on the pipe, is placed over this connecting node. It remains to fill the coupling cavity polyurethane foam(which itself is also polyurethane foam), so that after the foam hardens, a perfectly insulated, airtight connection is obtained.
As can be seen in the figure above, customers are also offered ready-made parts for installing individual sections of the water supply system - bends with different angles of rotation, tees, transitions, etc. That is, the installation of the system turns into a kind of “constructor assembly”.
By the way, despite the fact that polyurethane foam cannot be called a very plastic material, some polymer pipes in such thermal insulation with an external coating still have a certain flexibility, which allows laying curved sections without the use of additional bends.
An example of this is products Russian company Polimerteplo Group, Isoproflex pipes. The pipe itself is made of cross-linked polyethylene PEX-A, reinforced with high-strength fiber, has a protective anti-diffusion layer, insulation base made of semi-rigid polyurethane foam, and externally protective covering made of durable polyethylene.
Such pipes are sold in coils, which in itself indicates their flexibility. The installation task becomes even simpler - if there are no sharp turns, then one hose, already insulated and protected from the outside in advance, can be laid from the water intake to the entrance to the house, without making a single extra joint.
Polyethylene foam insulation
Another material widely used for insulation of pipelines. In its closed cellular structure filled with air, it is very similar to polyurethane foam. Quite a glare and their thermal conductivity indicators - both are excellent thermal insulators. But unlike polyurethane foam, foamed polyethylene also has high flexibility and ductility. Not at the expense of strength qualities.
The material is very light - usually its density does not exceed 30÷35 kg/m³, that is, no special physical effort will be required when installing thermal insulation. The closed cellular structure becomes an insurmountable barrier to water; the material itself practically does not absorb moisture - no more than 1.5% of the volume even when completely immersed.
Chemical inertness is also a clear advantage - it is difficult to imagine which of the compounds that got into the soil could cause destructuring of polyethylene foam. The operating temperature range is also impressive - from minus 55 to plus 85 ℃, which is more than enough for plumbing.
Produced various shapes such insulation. These can be simply rolls, usually with one foil side - many craftsmen prefer this kind of material. But nowadays, ready-made sleeves for pipes of different diameters and with different thicknesses of the insulating layer, usually 2 meters long, are more popular.
Installation of such sleeves is not difficult - along the entire length on the side they have a seam along which they can be opened. The insulation is put on the pipe, and then this seam is glued together almost without a trace due to the applied self-adhesive layer.
But, again, the most convenient solution is to use ready-made plastic pipes, already “clad” in insulation and an outer protective sheath. Several leading manufacturers offer a wide range of such products.
For example, the FLEXALEN company offers products with a pressure pipe made of polybutene, with multilayer polyethylene foam insulation and an external protective casing made of low-density polyethylene (HDPE).
Traditionally, the products of the companies “Uponor” (the old name “Ecoflex” may appear) and “Watts” are in high demand. Microflex". The pressure part of the pipes is made of cross-linked polyethylene, the insulation is several layers of foamed polyethylene, and the outer shell is HDPE.
Please note - in model range All of these companies present samples with two or more pressure pipes in a common layer of thermal insulation and a protective casing. This can also be very convenient if, for example, water is sent to two different places, or in heating systems - for supply and return pipes, or for the thermal satellite already mentioned above.
Find out how to insulate a water supply using a heating cable from our new article -
Concluding the review of insulation materials, we should also mention thermal insulation made of foam rubber. In terms of thermal conductivity, this material outperforms polyethylene foam and competes almost equally with polyurethane foam. And at the same time, it is distinguished by excellent ductility and all other properties necessary for a high-quality insulating material.
The traditional form of release of such insulation is similar - in the form of insulating sleeves (cylinders). How insulation is carried out, including complex sections of the water supply system, is clearly shown in the video below:
Video: Thermal insulation of water pipes with Kaiflex foam rubber sleeves
It would be logical to finish the review of materials with a comparative table with the main parameters of the insulation materials mentioned above.
Comparative table of key parameters of popular pipe insulation materials
| Material, product | Average density as part of the insulating structure, kg/m3 | Thermal conductivity of insulation (W/(m×K)) 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 | 0.049 | 0,048-0,037 | |||
| Thermal insulation slabs made of mineral wool with a synthetic binder | 65 | 0.04 | 0,039-0,03 | -60 to +400 | Non-flammable |
| 95 | 0.043 | 0,042-0,031 | |||
| Half-cylinders and mineral wool cylinders | 50 | 0,04 | 0,039-0,029 | -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 | |||
| Glass staple fiber mats with synthetic binder | 50 | 0,04 | 0,039-0,029 | -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 | -180 to +400 | Non-flammable |
| Mats and wool made of superfine basalt fiber without binder | 80 | 0,032 | 0,031-0,24 | -180 to +600 | Non-flammable |
| Thermal insulation products made of polystyrene foam | 30 | 0,033 | 0,032-0,024 | -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 | -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 | -70 to +70 | Flammable |
| Thermal insulation products made of foamed ethylene-polypropylene rubber "Aeroflex" | 60 | 0,034 | 0.033 | -57 to +125 | Low flammable |
What thickness of insulation is required?
Surely, an interested reader will have a question - what should be the thickness of the insulating layer in order to be guaranteed to protect the water pipe from freezing.
The answer to this is not so simple. There is a calculation algorithm that takes into account the mass of initial quantities and includes several formulas that are difficult even for visual perception. This technique is set out in the Code of Rules SP 41-103-2000. If anyone wants to find this document and try to make an independent calculation, you are welcome.
But there is an easier way. The fact is that experts have already taken on the brunt of the calculations - in the same document (SP 41-103-2000), which is easy to find with any search engine, the appendix contains many tables with ready-made insulation thickness values. The only problem is that it is physically impossible to present these tables here in our publication. They are compiled for each type of insulation separately, and - with gradation also by location - soil, open air or room. In addition, the type of pipeline and the temperature of the pumped liquid are taken into account.
But if you spend 10–15 minutes studying the tables, then you will probably find an option in them that is as close as possible to the conditions that interest the reader.
It would seem that that’s all, but we need to dwell on one more thing important nuance. It only applies to cases of water pipe insulation with mineral wool.
When it came to this thermal insulation material, a series of mineral wool disadvantages included its tendency to gradual caking and shrinkage. This means that if you initially set only the calculated thickness of the insulation, then after some time the thickness of the insulation layer may become insufficient for complete thermal insulation of the pipe.
Therefore, when performing insulation, it is advisable to lay out a certain reserve of thickness in advance. The question is - which one?
This is easy to calculate. There is a formula that, I think, makes no sense to demonstrate here, since the online calculator we offer is based on it.
The two initial values for the calculation are the outer diameter of the insulated pipe and the recommended value of the thermal insulation thickness found from the tables.
One more parameter remains unclear - the so-called “compaction coefficient”. We take it from the table below, focusing on the selected thermal insulation material and the diameter of the pipe to be insulated.
| Mineral wool insulation, diameter of insulated pipe | Compaction coefficient Kc. |
|---|---|
| Stitched mineral wool mats | 1.2 |
| Thermal insulating mats "TEKHMAT" | 1.35 ÷ 1.2 |
| Mats and sheets made of super-thin basalt fiber (depending on the nominal pipe 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 with a synthetic binder, brand: | |
| → M-45, 35, 25 | 1.6 |
| → M-15 | 2.6 |
| Glass spatula fiber mats “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 a diameter of more than 250 mm | 1,5 |
| Mineral wool slabs with synthetic binder brand: | |
| → 35, 50 | 1.5 |
| → 75 | 1.2 |
| → 100 | 1.1 |
| → 125 | 1.05 |
| Glass staple fiber slabs brand: | |
| → P-30 | 1.1 |
| → P-15, P-17 and P-20 | 1.2 |
Now, armed with all the initial values, you can use the calculator.
Grigory Borisov
How to insulate outdoor water pipes in a private house or country house?
Nowadays, running water in a country house is no longer something inaccessible; rather, it is an obligatory attribute of country life. It usually takes place on the street underground. Many people are interested in how to insulate or insulate a dacha with their own hands? It's quite simple. You need special material and a little patience. If you do not insulate the pipes before the onset of frost, then not only may they freeze, but also rupture. And this is fraught with emergency work and a complete replacement of the plumbing system.
What is needed to insulate a water supply?
The following insulating materials are most often used to insulate water pipes:
When choosing insulation, you should pay attention to some of its characteristics: low thermal conductivity, resistance to external factors.
Attention! Ease of installation, the possibility of reuse after dismantling the structures, a suitable price, tightness and durability - these are the qualities that are paramount when choosing insulation for water supply in a country house or in a private house.
How to insulate pipes?
The process of insulating pipes will not take much time and will not require specific skills. Installation of insulation is carried out in several steps.
Work on insulation of water pipes
So, water pipes are wrapped in glass wool and secured with a plastic band or tape. And waterproofing is provided through the use of roofing felt.
With basalt wool and polystyrene the situation is different. These building materials have the shape of a shell, but they are also easy and simple to install.
Advice. The size of the material is selected so that the insulation and water supply fit snugly against each other.
Maintaining pressure as a remedy for frozen pipes
Few people know the fact that under some pressure, water never freezes. This is an effective and proven method for years. To bring it to life, you need to install a receiver in the pipe. And in order for the pressure to be present throughout the entire section of the pipe, after the pump it is necessary to install check valve. Start the pump by first closing the tap in front of the receiver. This is a guaranteed way to ensure that the water supply does not freeze in winter.
Heating cable protection
Installing a heating electric cable to insulate the water supply is a reliable option for protecting pipes from freezing in winter. This is how water supply and sewerage systems are insulated both at a summer cottage and in a private house. The cable is placed both inside and outside the water supply.
Advice. When using the heating cable method, there is no need for deep pipe laying. The usual burial 2 m underground can be replaced by laying pipes in a half-meter hole.
Unfortunately, the main disadvantage of using an electric cable is its complete dependence on electricity. If it is turned off or absent, heating will stop completely.
Attention! In order to heat the pipes from the inside, it is necessary to include a tee in the water supply circuit. It will provide input for the heating cable.
Heating cable installation instructions
- Carrying out cable installation. There are two installation options: longitudinal and spiral.
- You need to wrap insulating material around the water pipe.
- Apply a protective coating on top.
- Electrical connection.
Insulation of water pipes in a private house with a heating cable
You should not neglect the insulation of the water supply, even if you do not plan to live in the country in winter. Water remains in the pipes, which can freeze and cause them to burst. There are several options for insulating a water supply: installing a heating cable, maintaining the required pressure and using insulating materials. In general, any man can do this job.
Heating water pipes: video
A completely new method of insulation is the use of special coloring compounds. Even a thin layer of such paint can replace yourself isolation 10-20 mm thick. And if you apply the composition in several layers, you can achieve much more best results. Heat loss can be reduced by up to 40%, while the coating does not allow water and moisture to pass through, but remains “breathable”. Liquid insulation is classified as energy-saving thermal paint K shortcomings include:
- High cost of the composition;
- If you choose a foam composition as insulation, you will need to seek help from specialists to apply it. Which, as you know, provide their services only for large volumes of work. If you want to spray just a few meters of pipeline, you may simply not find a contractor.
10. Thermal insulation using high pressure method
As a method of insulating a pipeline in a private house or country house, one can consider creating and maintaining high pressure in it. How it's done:
11. Air insulation
Understanding the characteristics of soil freezing in winter, you can apply the thermal insulation method when you use it to heat the pipe. warm air
and subsoil land. As you know, the soil freezes from top to bottom, while heat continues to flow from below. When to use thermal insulation shells, this heat is simply cut off and not used. 
To get a little save money Based on the amount of insulation materials, you can create a structure that will resemble an umbrella. And work on the same principle. The cold from above will be insulated, and the heat coming from below will be concentrated at the depth of the pipeline. This can be done using a flexible material with low thermal conductivity, which is laid in an arc over the pipe in a trench and then simply covered with soil. Additionally, you can fill up the free space around the pipe.
One of the main problems faced by owners of private houses or summer cottages in winter time, is freezing of the water supply and, as a result, the inability to use water. In addition, there is a danger of pipes bursting when the ice in them begins to thaw.
The best way to solve this problem is by laying the pipes supplying water to the house at a depth below the soil freezing zone. But how to insulate with your own hands? sewer system when it is not possible to bury pipes deep into the ground? Let's talk about this in more detail.
Insulation of the water supply system to the house: alternative approaches
Create in the pipes that supply water to the room, high pressure. As you know, water, being under pressure, does not freeze when the temperature drops. In this regard, it is recommended to supplement the system with a receiver - a device that maintains constant pressure in the water pipes.
Before leaving with summer cottage you should turn on the receiver and set the pressure to 3 atmospheres. This will be enough to prevent the contents of the pipes from freezing. In the new season, it will be necessary to relieve some of the pressure, and the water supply system will return to normal.
Using this method, pay Special attention to ensure uniform pressure throughout the system, and also make sure that the pipes have the necessary strength to withstand the increase in pressure without ruptures or other damage.
Pipe heating
Equip the heating of the pipes supplying the house with water using an electric wire. To insulate a water supply system in this way, you need to wrap an electric cable around the problem areas of the pipes and connect it to the electrical network. Under voltage, the cable will heat up, warm the pipe, and therefore the water inside it will not freeze.
The main nuances of this method of water inlet insulation are an increase in electricity costs and the impossibility of heating pipes in the absence of voltage in the network. Speaking about the first “but”, it should be noted that the overpayment for electricity will be much less significant than the labor intensity of the process of defrosting an icy water supply. The solution to the second problem can be the purchase of an autonomous generator.
Insulation
Supplying water to the house with air. When water pipes are buried in the ground, they are subject to different temperatures: above - cold air, penetrating into the soil thickness from its surface, from below - heat from the depths of the soil.
If you insulate the pipeline from all sides, it will be insulated not only from cold, but also from heat, so a more suitable option in this case would be to insulate it with an umbrella-shaped casing so that the heat coming from below naturally warms the pipe.
Pipe in pipe
Use the pipe-in-pipe method. To insulate in this way, water pipes should be placed inside other, larger-diameter pipes, and the voids should be filled with expanded clay, polystyrene foam, mineral wool, polyurethane foam or other heat insulator.
Hot air can also be pumped into the space between the pipes. With this method of installing water supply, your financial costs will not increase too much, since polypropylene pipes are inexpensive. The pipe in a pipe is laid directly into the ground or into a specially prepared brick tray (if the soil is loose or excessively wet).
What materials are best used to insulate the water supply system?
Water pipes can be insulated using various means, but the first must meet the following requirements:
- be durable in operation, that is, provide reliable protection systems for introducing water into the room without the need for frequent repairs;
- be easy to use, which is especially important for those who carry out insulation with their own hands and want to know for sure that the water supply system into the house will function stably and uninterruptedly;
- be waterproof, since wet insulation is unable to fully perform its functions;
- have low thermal conductivity;
- be wear-resistant, especially in relation to aggressive environmental factors.
Glass wool
Glass wool is a type of fiberglass-based insulation. The most famous brands– these are “Knauf”, “Isover”, “Ursa”.
Glass wool is used for insulation mainly metal-plastic pipes, intended for introducing water into the house. Thermal insulation with glass wool requires equipping the water supply with additional external protection in the form of a layer of fiberglass or roofing felt.
Basalt fiber is supplied in the form of cylinders. Such thermal insulation is easy to install and can be laid directly into the ground. The protective cover of basalt fiber is folgoizol, roofing felt or glassine. The only disadvantage of this material is its high cost.
Expanded polystyrene
Expanded polystyrene is the most acceptable option in terms of ease of use, characteristics, and cost. The expanded polystyrene “shell” can be installed with or without a protective casing, and there is no need to lay trays in trenches.
Expanded polystyrene thermal insulation can be used repeatedly, since it is not only easily attached to pipes, but can also be dismantled without unnecessary problems. Expanded polystyrene provides effective insulation elements of the water supply system located in the ground, above the ground surface and in rooms without heating.
In order to lay polystyrene foam “shell” on water pipes, it is not necessary to have special skills and equipment. The “shell” halves, selected according to the diameter of the pipe, are mounted on the pipe with an offset of 100-200 mm relative to each other and secured with ordinary tape. This “overlapping” reduces the likelihood of cracks forming in the thermal insulation.
If it is necessary to repair or replace pipes, dismantling the polystyrene foam is carried out in the reverse order.
Thermal insulation paint
Thermal insulation paint is a new product on the market of thermal insulation products. This paint is based on water or varnish with the addition of fillers and acrylic dispersion. Available in the form of a thick pasty mass of white or gray color.
According to its thermal insulation characteristics, 1 mm of such paint corresponds to a 50 mm layer of mineral wool insulation.
This coating not only prevents the release of heat from the pipes into the ground, but also returns up to 70% of infrared radiation back. Accordingly, the thicker the paint layer, the more reliable insulation pipes
Thermal insulation paint is not only an excellent insulation material, but also a means of preventing corrosive changes in metal, and therefore is recommended for insulating metal pipes supplying water to the house. The service life of this material is from 15 to 40 years.
Thermal insulating paint is applied with a spray, and small areas of water supply with a complex configuration are processed manually using a brush or roller.
Under construction own home we have to face more than once the need to lay underground engineering communications. This applies to plumbing, domestic or storm sewer, sometimes it is necessary to lay a heating main between two buildings. But it is not enough to lay the pipes themselves correctly, 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 sewage, which are obviously given an appropriate slope, and by definition there cannot be stagnation of water here? Meanwhile, thermal insulation of sewerage is a very responsible matter. There are at least two reasons that can cause water to accumulate in them - a septic tank that was not pumped out on time or clogged pipes. In both cases, freezing of the liquid in an uninsulated pipe will lead to the formation of an ice plug and subsequently to rupture of the walls. But to carry out quick repair or replacing a damaged area in frozen ground conditions is an extremely complex and large-scale problem.
There are quite a lot of thermal insulation materials intended for insulating underground sections of pipes. They differ in the material of manufacture, service life, thickness, quality and, of course, cost.
Criteria for choosing insulation for pipes
Thermal insulators for pipes running at a certain depth into the ground must meet certain requirements, which include:
- The hydrophobicity of the insulation, that is, its resistance to moisture. In addition to thermal insulation, the material must protect the pipe from soil moisture, preventing it from passing through, and without collapsing or 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 coolant is pumped through the pipe (heating system) or hot water(DHW system), then minimizing heat loss comes to the fore.
— For cold water supply or sewerage pipes, the main purpose of insulation is to protect against the effects of negative temperatures, that is, from freezing.
The table shows the heat loss of pipes of different diameters, depending on the thickness of the insulating layer (with an average thermal conductivity coefficient of 0.04 W/m×° WITH) and the difference between the temperatures of the pumped liquid and the environment (Δt°):
| Thermal insulation thickness, mm | Δт,оС | Pipe diameter in mm | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 15 | 20 | 25 | 32 | 40 | 50 | 65 | 80 | 100 | 150 | ||
| Calculated heat losses for 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, as the thickness of the insulation increases, 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 you have to resort to additional measures– installation of electric heating.
The required thickness of insulation for various types of pipelines will be discussed below.
- Resistance to external chemical influences - soil is a very aggressive environment in this regard.
- The insulation must have high mechanical strength, be resistant to external mechanical and atmospheric influences, and withstand loads and soil pressure. This also includes durability - since replacing thermal insulation in underground areas will be quite difficult.
- Resistance to high and low ambient temperatures and liquids transported through insulated pipelines.
- The material should be easily mounted on a pipe in any position.
- An important factor is the compatibility of the insulation materials and the pipe, since a reaction between them is unacceptable - it can lead to mutual damage.
Fulfilling all the requirements for insulating material will allow you to avoid significant heat loss and 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
The modern building materials market offers a fairly wide range of pipe insulation materials. Most common materials for their manufacture are polyethylene foam, polyurethane foam, polystyrene foam, and some types of mineral wool.
To insulate pipes, material is used in the form of tapes, rolls, mats, or made into a special shape - cylinders, half-cylinders, segments, etc. Of course, profile insulation is the most convenient to install, since they can be put on a pipe installed in any position.
Polyethylene foam insulation
Foamed polyethylene has very high specifications for pipe insulation. And this — at a very affordable price.
- The thermal conductivity of the material is minimal and amounts to 0.035 W/m×°C.
- This material has a structure consisting of tiny closed cells that help create effective waterproofing, which is especially important for metal pipes. This gives additional protection from corrosion, prolongs the life of the pipeline.
- Foamed polyethylene can have a density of 25 ÷ 40 kg/m. As a rule, the most popular products are those with this indicator of 30 ÷ 35 kg/m³.
- In addition, the material has excellent elasticity, which does not change even under critical conditions. negative temperatures(up to - 55°). This quality makes installation of insulation very a simple matter— the sleeve is easy to cut and put on a pipe located under any bend.
- The tensile load that foamed polyethylene can withstand is 0.3 MPa, and its dynamic elasticity is 0.76 MPa.
- The compression coefficient at a load of 4500 N/m² is 0.2.
- Vapor permeability is 0.001 mg/m×h×Pa, that is, foamed polyethylene is a material that supports 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. Moreover, it should be noted that in the following hours the absorption of moisture completely stops.
- Operating temperatures of foamed polyethylene vary 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 located 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, a moderately flammable material. Polyethylene ignites at a temperature of 300 degrees and only when exposed to direct flame. When burned, polyethylene breaks down into water and carbon dioxide, which is non-toxic and in small concentrations is not dangerous to human health.
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
Having compared the characteristics of their material with the requirements for insulation, we can conclude that this foamed polyethylene is ideally suited for thermal insulation of pipelines.
You may be interested in information about what degree of insulation is provided for
Another material that is actively used for pipe insulation is Penofol. This is the same foamed polyethylene, but has a foil coating, which has a reflective property and enhances the thermal insulation properties of polyethylene.
“Penofol” for insulation of pipelines 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 strips and overlapped onto the mounted pipes.
Pipe insulated with penofol tapes
Penofol prices
The convenience of tape insulation is that it can thermally insulate a pipeline that has many bends or turns. Due to the elasticity of the material, it will accept the required form and will provide sufficient tightness for thermal insulation.
If cylinders (sleeves) are used to insulate an already installed pipeline, then a cut is made along their entire length, through which they are put on the pipes. This cut is then secured with waterproof adhesive tape. Very often such a cut is already provided by the manufacturer.
Video: comparison of some types of pipe insulation
Insulation for polystyrene foam pipes
Pipe insulation made from polystyrene foam is also called “shell”, as it really resembles an eggshell. This 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 side tongue-and-groove locks, which allow the pipeline to be completely isolated from environmental influences while maintaining a positive temperature inside the “shell.” Due to the form of the insulation made from polystyrene foam, it is easy to install on existing lines.
This insulation is produced in the form of detachable pipes one or two meters long. The wall thickness and diameters, external and internal, may be different.
For the manufacture of shell-type pipe insulation, PSB-S÷15, PSB-S÷25 and PSB-S÷35 foam plastics are used. Main characteristics - 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 | 0.05 | 0.06 | 0.08 | 0.16 | 0.2 |
| 0.08 | 0.12 | 0.17 | 0.36 | 0.35 | |
| Thermal conductivity in a dry state 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 | to 10 | up to 15 | 15.1÷25 | 25.1÷35 | 35.1÷50 |
- Polystyrene foam 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 thermal conductivity coefficient of 0.037÷0.042 W/m².
- Moisture absorption polystyrene foam per day, as tests have shown, amounts to 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 °C. In this limit, it does not deform and does not lose its basic qualities.
- This material is resistant to the formation of mold or mildew, does not rot, and can withstand exposure to alkali, cement and gypsum solutions, salts and other inorganic substances.
The positive qualities of polystyrene foam insulation for pipes include the following:
- Low thermal conductivity.
- High moisture resistance, which allows you to preserve the thermal insulation qualities of the material for many years.
- Easy to install.
- 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 insulation has completely affordable price.
The disadvantages of such insulation include:
- Combustibility of the material - it is classified as G4. For underground areas this criterion is not decisive.
- Expanded polystyrene is not elastic, and it will not be possible to bend it, so only smooth pipelines 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 provide additional protection for it by wrapping it in thick polyethylene.
By following all the installation recommendations, carefully placing the insulating shell on the pipes and protecting it on top with a layer of waterproofing, you can create a hermetic insulation that will protect the pipeline not only from freezing, but also from soil moisture.
Pipe insulation - polyurethane foam
Currently ready-made options sewer and water pipes are already enclosed in a layer of thermal insulation made of polyurethane foam, which is protected on top by a metal or plastic shell. For example, for pipelines passing above the ground, pipes in a galvanized metal sheath are used, and for pipelines laid underground, the option coated with polyethylene is excellent, since this material has a high degree of moisture resistance.
Such ready-made insulated pipes are rapidly replacing the previously widely used thermal insulation made of mineral wool. For comparison, please refer to the table below.
Prices for polyurethane foam insulation
polyurethane insulation
Comparative characteristics of polyurethane foam and mineral wool used for pipe insulation:
| Material parameters | Unit | PPU | Minvata |
|---|---|---|---|
| Coefficient of thermal conductivity | W/m×°С | 0.033 | 0.049 |
| Density | kg/m³ | 60÷80 | 55÷150 |
| Compressive Strength | MPa | 0.3 | Not standardized, load resistance is minimal |
| 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 rate) | 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 above. The following release forms are provided:
| Outside diameter steel pipes, d, mm | Type 1 | Type 2 | ||||
|---|---|---|---|---|---|---|
| PPU layer thickness, mm | Outer diameter of polyethylene shell, D, mm | PPU layer thickness, mm | ||||
| nominal | maximum deviation (+) | nominal | maximum 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 | - | - | - |
Types 1 and 2 of pipes mean products with regular or reinforced insulation. The advantage of pipes immediately equipped with insulation and a protective shell over any other options is that the heat insulator completely seals the body of the pipe. Non-insulated areas are left at the ends of the pipes for connecting them into a solid pipeline using welded joints with deep seam penetration.
The appearance and quality of the protective polyethylene shell also have its own regulations according to the same GOST:
| Options | Characteristics |
|---|---|
| Surface quality | Shell pipes must have a smooth surface outer surface. Minor longitudinal stripes and waviness are allowed, which do not take the pipe wall thickness beyond the limits of permissible deviations. Inner surface pipes must have roughness. Bubbles, cracks, cavities, and foreign inclusions are not allowed on the outer, inner and end surfaces of pipes. The color of the pipes is black. |
| Elongation at break, %, not less | 350 |
| Change in the length of shell pipes after heating at 110 °C, %, no more | 3 |
| Resistance at temperature 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 using a special method. Then the pipeline sections without insulation at the points of their connection, after installation, the lines are closed with a heat-shrink sleeve, which is filled with polyurethane foam. This ensures complete tightness of the insulating material and the outer shell.
The advantages of using polyurethane foam as insulation include its following qualities:
- Low thermal conductivity.
- High moisture resistance.
- Light weight - density only 45–60 kg/m³.
- When installed correctly, there is a complete absence of cold bridges.
- Ability to give metal pipes additional anti-corrosion protection.
- Duration of the operational period, since the material is not subject to rotting and decomposition, and is also resistant to atmospheric and aggressive influences and temperature changes.
However, it should be noted that ready-made thermally insulated pipes have a fairly high price, so insulation is often used instead by spraying polyurethane foam onto the installed pipeline. But in this case the heat insulator will be deprived external protection in the form of an outer shell.
Mineral wool
The most affordable thermal insulation material remains mineral wool, which is divided into three types depending on the material of manufacture - glass wool, basalt and slag wool.
Due to their characteristics, only two options are suitable for insulating pipes running in the ground - glass wool and basalt. Slag wool absorbs moisture abundantly, which means it quickly loses its thermal insulation properties. In addition, it has high residual acidity, which contributes to the activation of corrosion processes, and for the insulation of 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, which meet almost all the requirements of insulation for pipelines. These include the following parameters:
- Low thermal conductivity.
- High resistance to alkaline and acidic substances, as well as other chemical compounds.
- Sufficient elasticity, which allows easy installation not only on straight sections of the highway, but also on bends and turns.
A negative quality of mineral wool can be called its hygroscopicity - it absorbs moisture quite well (basalt wool is less susceptible to this drawback). 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 onto the insulation with an overlap of 400 ÷ 500 mm and intercepted on top with 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 overall cost of work.
By the way, mineral wool for pipe insulation is produced only in mats, sheets or slabs. You can also find collapsible mineral wool cylinders on sale, which are perfect for straight sections of pipeline.
You might be interested in information on how to choose
What should be the thickness of the insulation layer for the underground section of the pipe?
So, the main insulation materials, which are used for thermal insulation of pipelines. To facilitate the perception of information and make comparisons when choosing, the main characteristics of insulation materials are summarized in a single table:
| Material, product | Average density in the structure, kg/m3 | Thermal conductivity thermal insulation material(W/(m×°С)) for surfaces with temperature (°С) | 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 | 0.049 | 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 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 | 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 | 0,031-0,24 | 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 |
The article still does not answer the key question - what thickness of insulation should be used? It is impossible to answer unequivocally, since this parameter depends on a large number of initial data. There are thermotechnical 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 not difficult - any Internet search engine upon 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 laying, temperatures of the pumped liquid, etc. But in this diversity there will certainly be an answer for a specific pipe laid in the ground.
It would seem that everything is, however, there is one more important point. It concerns insulation materials that shrink and become denser over time, which is accompanied by a decrease in the effectiveness of thermal insulation. We are talking about mineral wool.
The table value determined according to SP 41-103-2000 may, over time, become not enough– the material will become compacted and the quality of thermal insulation will significantly decrease. By the way, this is very common a mistake that can lead to serious consequences. This means that it is necessary to provide a reserve of insulation thickness that compensates for its shrinkage.
To determine this parameter, use the following formula:
N =h× Kc× ((D+ h) / (D + 2 h) )
N– the required thickness of the insulation, taking into account future shrinkage (compaction);
h– table value of the required insulation thickness;
D– outer diameter of the insulated pipe;
KS– compaction coefficient 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 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 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 slabs with synthetic binder brand: | |
| - 35, 50 | 1.5 |
| - 75 | 1.2 |
| - 100 | 1.1 |
| - 125 | 1.05 |
| Glass staple fiber slabs brand: | |
| - P-30 | 1.1 |
| - P-15, P-17 and P-20 | 1.2 |
| Fine expanded perlite sand, grades 75, 100, 150 | 1.5 |
In order not to force the reader to carry out independent calculations, we suggest using the capabilities of the built-in calculator.
