Modern insulating materials for pipelines of thermal routes. Device for thermal insulation of pipelines for heating networks. The nuances of mounting the shell

When laying pipelines, a prerequisite is the performance of work on the thermal insulation of networks. This applies to all pipelines - not only water supply, but also sewage systems. The need for this is due to the fact that winter time water passing through pipes can freeze. And if a coolant circulates through the communications, then this leads to a decrease in its temperature. To minimize heat loss, when laying pipelines, they resort to the device of a heat-insulating layer. What materials and methods can be used for thermal insulation of networks - this will be discussed in this article.

Thermal insulation of pipelines: ways to solve the problem

Provide effective protection for piping systems, from environmental factors, mainly from the outdoor temperature, it is possible if the following measures are taken:

Since the latter method is most often used, it makes sense to talk about it in more detail.

Norms for thermal insulation of pipelines

Requirements for thermal insulation of equipment pipelines are formulated in SNiP. The regulations contain detailed information about the materials, which can be used for thermal insulation of pipelines, and besides this, methods of work. In addition, in the regulations standards for thermal insulation contours are indicated, which are often used to insulate pipelines.

regardless of what temperature the coolant has, any piping system must be insulated;
both ready-made and prefabricated structures can be used to create a heat-insulating layer;
corrosion protection shall be provided for metal parts of pipelines.

It is desirable to use a multilayer circuit design for pipeline insulation. It must include the following layers:

insulation;
vapor barrier;
protection made of dense polymer, non-woven fabric or metal.

In some cases reinforcement can be built, which eliminates the collapse of materials, and in addition prevents the deformation of pipes.

It should be noted that most of the requirements contained in regulatory documents relate to the insulation of high-capacity main pipelines. But even in the case of installation of household systems, it would be useful to familiarize yourself with them and take them into account when installing sewage water supply systems on your own.

Materials for thermal insulation of pipelines

At the moment, the market offers a large selection of materials that can be used to insulate pipelines. Each of them has its own advantages and disadvantages, and besides this, and application features. For right choice a heat insulator needs to know all this.

Polymer heaters

When the task is to create an effective system of thermal insulation of pipelines, most often attention is paid to foam-based polymers. A large assortment allows you to choose the right material, thanks to which can provide effective protection from the external environment and avoid heat loss.

If we talk in more detail about polymeric materials, then the following can be distinguished from those available on the market.

Polyethylene foam.

The main characteristic of the material is its low density. In addition, it is porous and has high mechanical strength. This insulation is used for the manufacture of cylinders with a cut. Their installation can be performed even by people who are far from the sphere of thermal insulation of pipelines. However, this material is characterized by one drawback: structures made of polyethylene foam, have rapid wear and in addition to this, they have poor heat resistance.

If polyethylene foam cylinders are chosen for the thermal insulation of pipelines, then special attention must be paid to their diameter. It must match the diameter of the collector. Taking this rule into account when choosing the design of insulation, it is possible to exclude spontaneous removal of casings from polyethylene foam.

Styrofoam.

The main feature of this material is elasticity. It is also characterized by high strength indicators. Protective products for thermal insulation of pipelines from this material are produced in the form of segments that resemble shells in their appearance. Special locks are used to connect parts. They have spikes and grooves, which ensure the speed of installation of these products. The use of a shell made of expanded polystyrene with technical locks eliminates the occurrence of "cold bridges" after installation. In addition, during installation there is no need to use additional fasteners.

Polyurethane foam.

This material is mainly used for pre-installed thermal insulation of pipelines of heating networks. However, it can also be used for warming domestic piping systems. This the material is produced in the form of foam or shell, which consists of two or four segments. Insulation by spraying provides reliable thermal insulation with a high degree of tightness. The use of such insulation is most suitable for communication systems that have a complex configuration.

Using polyurethane foam in the form of foam for thermal insulation of pipelines of heating networks, it is necessary to know that it is destroyed under the influence of ultraviolet rays. Therefore, in order for the insulating layer to serve for a long time, it is necessary to ensure its protection. To do this, a layer of paint is applied over the foam or a non-woven fabric with good permeability is laid.

Fiber materials

Heaters of this type are mainly represented by mineral wool and its varieties. At present they are the most popular among consumers as a heater. Materials of this type are also in high demand, as well as polymeric materials.

For thermal insulation, performed using fibrous insulation, certain advantages are characteristic. These include the following:

low coefficient of thermal conductivity;
resistance of the heat-insulating material to the effects of such aggressive substances as acids, alkalis, oil;
the material is able to maintain a given shape without an additional frame;
the cost of insulation is quite acceptable and affordable for most consumers.

Please note that during the work on the thermal insulation of pipelines with such materials fiber compression must be avoided when installing insulation. It is also important to ensure that the material is protected from moisture.

Products for thermal insulation made from polymer and mineral wool insulation can in some cases be covered with aluminum or steel foil. The use of such screens reduces heat dissipation.

Laminated structures for protecting pipelines

Often, for the insulation of pipelines, thermal insulation is arranged according to the "pipe in pipe" method. When using this scheme, a heat shield is installed. The main task of the specialists who install such a circuit is to correctly connect all the parts into a single structure.

At the end of the work, a structure is obtained that looks like this:

a pipe made of metal or polymer material acts as the basis of the heat-protective circuit. It is the supporting element of the entire device;
the heat-insulating layers of the structure are made of foamed polyurethane foam. The application of the material is carried out according to the pouring technology, a specially created formwork is filled with the molten mass;
protective cover. Pipes made of galvanized steel or polyethylene are used for its manufacture. The first are used for laying networks in open space. The latter are used in cases where pipeline systems are laid in the ground using channelless technology. In addition, often when creating this type of protective casing in a heater based on polyurethane foam copper conductors are laid, the main purpose of which is remote monitoring of the state of the pipeline, including the integrity of the thermal insulation layer;
if the pipes are delivered to the installation site assembled, then the welding method is used to connect them. Experts use special heat-shrink cuffs to assemble a heat-protective circuit. Or slip-on couplings can be used made on the basis mineral wool which are covered with a layer of foil.

Do-it-yourself thermal insulation device for pipelines

There are a number of factors on which the technology of creating a heat-insulating layer on pipelines may depend. One of the most important is how the collector is laid - outside or its installation is carried out in the ground.

Insulation of underground networks

To solve the problem of ensuring thermal protection of buried communications, insulation work is carried out in the following order:

Thermal insulation of the outer pipeline

In accordance with existing regulations, pipelines located on the surface of the earth are thermally insulated as follows:

insulation work begins with the fact that all parts are cleaned of rust;
then the pipes are treated with an anti-corrosion compound. After that proceed to the installation of the polymer shell followed by wrapping the pipes with mineral wool roll insulation;
please note that to cover the structure, you can use a layer of polyurethane foam or you can cover the structure with several layers of heat-insulating paint;
the next step is to wrap the pipe as in the previous version.

Along with fiberglass, other materials can be used, for example, foil film with polymer reinforcement. When this work is done, the structures are fixed using steel or plastic clamps.

Thermal insulation of pipelines is an important task that must be carried out when laying communications. There are many materials and technologies for its implementation. Having chosen the appropriate method of thermal insulation, it is necessary to adhere to the technology of work. In this case heat loss will be minimal., and besides this, the pipeline structure will be protected from various factors, which will positively affect their service life.

In the practice of private construction, it is not so common, but there are still situations when heating communications need to be not only spread across the premises of the main house, but also stretched to other nearby buildings. It can be residential outbuildings, extensions, summer kitchens, economic or agricultural buildings, for example, used for keeping domestic animals or birds. The option is not excluded when, on the contrary, the autonomous boiler house itself is located in a separate building, at some distance from the main residential building. It happens that the house is connected to the central heating main, from which pipes are stretched to it.

The laying of heating pipes between buildings is possible in two ways - underground (channel or channelless) and open. The process of installing a local heating main above the ground seems less time-consuming, and this option is used more often in conditions of independent construction. One of the main conditions for the efficiency of the system is a properly planned and well-executed thermal insulation for heating pipes on outdoors. This is the question that will be considered in this publication.

Why do we need thermal insulation of pipes and the basic requirements for it

It would seem nonsense - why insulate the already almost always hot pipes of the heating system? Perhaps someone can be misled by a kind of "play on words." In the case under consideration, of course, it would be more correct to conduct a conversation using the concept of "thermal insulation".

Thermal insulation work on any pipelines has two main goals:

If pipes are used in heating or hot water supply systems, then the reduction of heat losses, maintaining the required temperature of the pumped liquid comes to the fore. The same principle is also valid for industrial or laboratory installations, where the technology requires maintaining a certain temperature of the substance transferred through the pipes.
For pipelines of cold water supply or sewer communications, it is insulation that becomes the main factor, 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 emergencies on boiler equipment.

The very cylindrical shape of the pipes predetermines a very large area of constant heat exchange with the environment, which means significant heat losses. And they naturally grow as the diameter of the pipeline increases. The table below clearly shows how the value of heat loss changes depending on the temperature difference inside and outside the pipe (column Δt °), on the diameter of the pipes and on the thickness of the thermal insulation layer (data are given taking into account the use of insulation material with an average coefficient of thermal conductivity 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 running 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 total heat loss decreases. However, please note that even a fairly thick layer of 40 mm does not completely eliminate heat loss. There is only one conclusion - it is necessary to strive to use insulating materials with the lowest possible coefficient of thermal conductivity - this is one of the main requirements for thermal insulation of pipelines.

Sometimes a pipe heating system is also required!

When laying water or sewer communications, it happens that, due to the peculiarities of the local climate or specific installation conditions, thermal insulation alone is clearly not enough. We have to resort to forced installation of heating cables - this topic is discussed in more detail in a special publication of our portal.

The material that is used for thermal insulation of pipes, if possible, should have hydrophobic qualities. There will be little current from a heater soaked with water - it will not prevent heat loss either, and it will soon collapse under the influence of negative temperatures.
The thermal insulation structure must have reliable external protection. Firstly, it needs protection from atmospheric moisture, especially if a heater is used that can actively absorb water. Secondly, the materials should be protected from exposure to the ultraviolet spectrum. sunlight which is detrimental to them. Thirdly, we should not forget about wind load capable of compromising 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, for any owner of a private house, moments of aesthetic appearance laid heating pipeline.

Any thermal insulation material used on heating mains must have a range of operating temperatures corresponding to the actual conditions of use.
An important requirement for the insulation material and its outer lining is the durability of use. No one wants to return to the problems of thermal insulation of pipes even once every few years.
From a practical point of view, one of the main requirements is the ease of installation of thermal insulation, and in any position and in any complex area. Fortunately, in this regard, manufacturers do not get tired of pleasing user-friendly developments.
An important requirement for thermal insulation is that its materials must themselves be chemically inert and not enter into any reactions with the pipe surface. Such compatibility is the key to the duration of trouble-free operation.

The issue of cost is also very important. But in this regard, the range of prices for specialized ones is very large.

What materials are used to insulate aboveground heating mains

The choice of thermal insulation materials for heating pipes for their external laying is quite large. They are of a roll type or in the form of mats, they can be given a cylindrical or other figured shape convenient for installation, there are heaters that are applied in liquid form and acquire their properties only after solidification.

Insulation with polyethylene foam

Foamed polyethylene is rightly referred to as a very effective thermal insulator. And more importantly, the cost of this material is one of the lowest.

The coefficient of thermal conductivity of foamed polyethylene is usually in the region of 0.035 W / m × ° C - this is a very good indicator. The smallest gas-filled bubbles isolated from each other create an elastic structure, and with such material, if its rolled version is purchased, it is very convenient to work on pipe sections with complex configurations.

Such a structure becomes a reliable barrier to moisture - with proper installation, neither water nor water vapor can penetrate through it to the pipe walls.

The density of polyethylene foam is low (about 30 - 35 kg / m³), and thermal insulation does not make the pipes heavier.

The material, with some assumption, can be categorized as low hazard in terms of flammability - it usually belongs to class G-2, that is, it is very difficult to ignite, and without an external flame it quickly fades. Moreover, combustion products, unlike many other thermal insulators, do not pose any serious toxic hazard to humans.

Rolled polyethylene foam for insulating external heating mains will be both inconvenient and unprofitable - you will have to wind several layers in order to achieve the required thermal insulation thickness. It is much more convenient to use material in the form of sleeves (cylinders), in which an internal channel is provided that corresponds to the diameter of the insulated pipe. For putting on pipes, usually an incision is made along the length of the cylinder on the wall, which, after installation, can be sealed with reliable adhesive tape.

Putting insulation on the pipe is not difficult

A more effective type of polyethylene foam is penofol, which has one side. This shiny coating becomes a kind of thermal reflector, which significantly increases the insulating qualities of the material. In addition, it is an additional barrier against moisture penetration.

Penofol can also be of a roll type or in the form of profiled cylindrical elements - especially for thermal insulation of pipes for various purposes.

And all foamed polyethylene for thermal insulation of heating mains is used infrequently. It is more suitable for other communications. The reason for this is the rather low temperature range of operation. So. if you look at the physical characteristics, then the upper limit balances somewhere on the verge of 75 ÷ 85 degrees - higher, violations of the structure and the appearance of deformations are possible. For autonomous heating, most often, such a temperature is enough, however, on the verge, and for the central one, thermal stability is clearly not enough.

Expanded polystyrene insulation elements

The well-known expanded polystyrene (in everyday life it is often called polystyrene foam) is very widely used for the most different types thermal insulation work. Pipe insulation is no exception - for this, special parts are made of foam plastic.

Usually these are semi-cylinders (for pipes of large diameters there may be segments of a third of the circumference, 120 ° each), which are equipped with a tongue-and-groove lock for assembly into a single structure. This configuration allows you to completely, over the entire surface of the pipe, provide reliable thermal insulation, without the remaining "cold bridges".

In everyday speech, such details are called "shells" - for their clear resemblance to it. Many types of it are produced, for different outer diameters of insulated pipes and different thicknesses of the thermal insulation layer. Usually the length of the parts is 1000 or 2000 mm.

For the manufacture of polystyrene foam type PSB-S 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	Styrofoam brand
	PSB-S-15U	PSB-S-15	PSB-S-25	PSB-S-35	PSB-S-50
Density (kg/m³)	to 10	up to 15	15.1 ÷ 25	25.1 ÷ 35	35.1 ÷ 50
Compressive strength at 10% linear deformation (MPa, not less)	0.05	0.06	0.08	0.16	0.2
Bending strength (MPa, not less than)	0.08	0.12	0.17	0.36	0.35
Dry thermal conductivity at 25°C (W/(m×°K))	0,043	0,042	0,039	0,037	0,036
Water absorption in 24 hours (% by volume, no more)	3	2	2	2	2
Humidity (%, no more)	2.4	2.4	2.4	2.4	2.4

The advantages of polystyrene foam as an insulating material have long been known:

It has a low thermal conductivity.
The low weight of the material greatly simplifies the insulation work, which does not require any special mechanisms or devices.
The material is biologically inert - it will not be a breeding ground for the formation of mold or fungus.
Moisture absorption is negligible.
The material is easy to cut, fit to right size.
Polyfoam is chemically inert, absolutely safe for pipe walls, no matter what material they are made of.
One of the key advantages - polystyrene is one of the most inexpensive heaters.

However, it also has many disadvantages:

First of all, it is a low level fire safety. The material cannot be called non-combustible and does not spread flame. That is why when using it for warming ground pipelines, fire breaks must be left.
The material does not have elasticity, and it is convenient to use it only on straight sections of the pipe. True, you can find special curly details.

Polyfoam does not belong to durable materials - it is easily destroyed under external influence. Ultraviolet radiation also has a negative effect on it. In a word, the above-ground sections of the pipe, insulated with polystyrene shells, will definitely require additional protection in the form of a metal casing.

Usually, in stores that sell foam shells, they also offer galvanized sheets, cut into the desired size, corresponding to the diameter of the insulation. An aluminum shell can also be used, although it is certainly much more expensive. Sheets can be fixed with self-tapping screws or clamps - the resulting casing will simultaneously create anti-vandal, anti-wind, waterproofing protection and a barrier from sunlight.

And yet even this is not the main thing. The upper limit of normal temperatures for operation is only around 75 ° C, after which linear and spatial deformation of parts can begin. Like it or not, this value may not be enough for heating. Perhaps it makes sense to look for a more reliable option.

Insulation of pipes with mineral wool or products based on it

The most "ancient" method of thermal insulation of external pipelines is with the use of mineral wool. By the way, it is also the most budgetary, if it is not possible to purchase a foam shell.

Used for thermal insulation of pipelines different kinds mineral wool - glass wool, stone (basalt) and slag. Slag wool is the least preferred: firstly, it most actively absorbs moisture, and secondly, its residual acidity can be very destructive to steel pipes. Even the cheapness of this cotton wool does not at all justify the risks of its use.

But mineral wool based on basalt or glass fibers is fully suitable. It has good indicators of thermal resistance to heat transfer, high chemical resistance, the material is elastic, and it is easy to lay it even on complex sections of pipelines. Another advantage - you can be, in principle, completely calm in terms of fire safety. It is almost impossible to heat up mineral wool to the degree of ignition in the conditions of an external heating main. Even exposure to an open flame will not cause the spread of fire. That is why mineral wool is used to fill fire gaps when using other pipe insulation.

The main disadvantage of mineral wool is its high water absorption (basalt is less susceptible to this “ailment”). This means that any pipeline will require mandatory protection from moisture. In addition, the structure of wool is not resistant to mechanical stress, it is easily destroyed, and it should be protected with a strong casing.

Usually, a strong polyethylene film is used, which is securely wrapped with a layer of insulation, with the obligatory overlap of the strips by 400 ÷ 500 mm, and then all this is covered with metal sheets from above - exactly by analogy with a polystyrene shell. Roofing material can also be used as a waterproofing - in this case, 100 ÷ 150 mm of overlap of one strip on another will be enough.

The existing GOSTs determine the thickness of protective metal coatings for open sections of pipelines for any type of thermal insulation materials used:

Cover material	The minimum thickness of the metal, with the outer diameter of the insulation
	350 or less	Over 350 and up to 600	Over 600 and up to 1600
Stainless steel strips and sheets	0.5	0.5	0.8
Sheet steel, galvanized or color coated	0.5	0.8	0.8
Sheets of aluminum or aluminum alloys	0.3	0.5	0.8
Tapes made of aluminum or aluminum alloys	0.25	-	-

Thus, despite the seemingly inexpensive price of the insulation itself, its full installation will require considerable additional costs.

Mineral wool for pipeline insulation can also act in a different capacity - it serves as a material for the manufacture of finished thermal insulation parts, by analogy with polyethylene foam cylinders. Moreover, such products are produced both for straight sections of pipelines, and for turns, tees, etc.

Typically, such insulating parts are made of the most dense - basalt mineral wool, have an external foil coating, which immediately removes the problem of waterproofing and increases the efficiency of insulation. But you still won’t be able to get away from the outer casing - a thin layer of foil will not protect against accidental or intentional mechanical impact.

Warming of the heating main with polyurethane foam

One of the most effective and safest modern insulation materials in operation is polyurethane foam. He has a lot of various advantages, so the material is used on almost any structure that requires reliable insulation.

What are the features of polyurethane foam insulation?

Polyurethane foam for insulation of pipelines can be used in various forms.

PPU-shell is widely used, usually having an external foil coating. It can be collapsible, consisting of half-cylinders with tongue-and-groove locks, or, for pipes of small diameter, with a cut along the length and a special valve with a self-adhesive back surface, which greatly simplifies the installation of insulation.

Another way to insulate a heating main with polyurethane foam is to spray it in liquid form using special equipment. The resulting foam layer after complete hardening becomes an excellent insulation. This technology is especially convenient at complex interchanges, pipe bends, in nodes with shut-off and control valves, etc.

The advantage of this technology is also that due to the excellent adhesion of polyurethane foam spraying to the pipe surface, excellent waterproofing and corrosion protection are created. True, polyurethane foam itself also requires mandatory protection - from ultraviolet rays, so again it will not be possible to do without a casing.

Well, if you need to lay a sufficiently long heating main, then probably the best choice would be to use pre-insulated (pre-insulated) pipes.

In fact, such pipes are a multilayer structure assembled at the factory:

- The inner layer is, in fact, the steel pipe itself of the required diameter, through which the coolant is pumped.

- External coating - protective. It can be polymeric (for laying a heating main in the thickness of the soil) or galvanized metal - what is required for open sections of the pipeline.

- Between the pipe and the casing, a monolithic, seamless layer of polyurethane foam is poured, which performs the function of effective thermal insulation.

An assembly section was left at both ends of the pipe for welding during the assembly of the heating main. Its length is calculated in such a way that the heat flux from the welding arc will not damage the polyurethane foam layer.

After the installation, the remaining non-insulated areas are primed, covered with a polyurethane foam shell, and then with metal belts, comparing the coating with the common outer casing of the pipe. Often, it is in such areas that fire breaks are organized - they are densely filled with mineral wool, then they are waterproofed with roofing material and still covered with a steel or aluminum casing from above.

The standards establish a certain assortment of such sandwich pipes, that is, it is possible to purchase products of the desired nominal diameter with optimal (normal or reinforced) thermal insulation.

Steel pipe outer diameter and minimum wall thickness (mm)	Dimensions of galvanized sheet steel sheath		Estimated thickness of the thermal insulation layer of polyurethane foam (mm)
	nominal outside 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, expansion joints, etc.

The cost of such pre-insulated pipes is quite high, but with their purchase and installation, a whole range of problems is solved at once. So these costs seem to be quite justified.

Video: production process of pre-insulated pipes

Insulation - foamed rubber

Recently, thermal insulation materials and products made of synthetic foam rubber have become very popular. This material has a number of advantages that bring it to a leading position in the issues of insulation of pipelines, including not only heating mains, but also more responsible ones - on complex technological lines, in machine, aircraft and shipbuilding:

Foamed rubber is very elastic, but at the same time it has a large margin of tensile strength.
The density of the material is only from 40 to 80 kg / m³.
The low thermal conductivity provides very effective thermal insulation.
The material does not shrink over time, completely retaining its original shape and volume.
Foamed rubber is difficult to ignite and has the property of rapid self-extinguishing.
The material is chemically and biologically inert, it never contains any foci of mold or fungus, or nests of insects or
The most important quality is almost absolute water and vapor impermeability. Thus, the insulation layer immediately becomes an excellent waterproofing for the pipe surface.

Such thermal insulation can be produced in the form of hollow tubes with an internal diameter of 6 to 160 mm and a layer thickness of insulation from 6 to 32 mm, or in the form of sheets, which are often given the function of "self-adhesive" on one side.

The name of indicators	Values
Length of finished tubes, mm:	1000 or 2000
Color	black or silver, depending on the type of protective coating
Temperature range of application:	from - 50 to + 110 °С
Thermal conductivity, W / (m × ° С):	λ≤0.036 at 0°C
Thermal conductivity, W / (m × ° С):	λ≤0.039 at +40°C
Vapor permeability coefficient:	μ≥7000
Degree of fire hazard	Group G1
Permissible length change:	±1.5%

But for outdoor heating mains, ready-made insulation elements made using the Armaflex ACE technology, with a special protective coating ArmaChek, are especially convenient.

Coating "ArmaChek" can be of several types, for example:

Arma-Chek Silver is a multi-layered PVC-based shell with a silver reflective coating. This coating provides excellent insulation protection against both mechanical stress and ultraviolet rays.
The black "Arma-Chek D" finish has a high strength fiberglass backing that retains excellent flexibility. This is an excellent protection against all possible chemical, weather, mechanical influences, which will keep the heating pipe intact.

Typically, such products using ArmaChek technology have self-adhesive valves that hermetically “seal” the insulating cylinder on the pipe body. Figured elements are also produced, allowing installation on difficult sections of the heating main. Skillful use of such thermal insulation allows you to quickly and reliably mount it without resorting to the creation of an additional external protective casing - there is simply no need for it.

Probably the only thing that hinders the widespread use of such thermal insulation products for pipelines is the still prohibitively high price for real, "brand" products.

Prices for thermal insulation for pipes

Thermal insulation for pipes

A new direction in insulation - heat-insulating paint

Can't miss another one modern technology insulation. And it is all the more pleasant to talk about it, since it is the development of Russian scientists. We are talking about ceramic liquid insulation, which is also known as heat-insulating paint.

This, without any doubt, is an "alien" from the field of space technology. It is in this scientific and technical branch that the issues of thermal insulation from critically low (in open space) or high (during the launch of ships and landing of descent vehicles) are especially acute.

The thermal insulation qualities of ultra-thin coatings seem simply fantastic. At the same time, such a coating becomes an excellent hydro and vapor barrier, protecting the pipe from all possible external influences. Well, the heating main itself takes on a well-groomed, pleasing look.

The paint itself is a suspension of microscopic, vacuum-filled silicone and ceramic capsules, suspended in a liquid state in a special composition, including acrylic, rubber and other components. After applying and drying the composition, a thin elastic film is formed on the surface of the pipe, which has outstanding thermal insulation qualities.

Names of indicators	Unit	Value
paint color	white (can be customized)
Appearance after application and complete curing	matt, even, uniform surface
Flexural elasticity of the film	mm	1
Adhesion of the coating according to the force of separation from the painted surface
- to the concrete surface	MPa	1.28
- to the brick surface	MPa	2
- to steel	MPa	1.2
Coating resistance to temperature difference from -40 °С to + 80 °С	without changes
Resistance of the coating to the effects of temperature +200 °C for 1.5 hours	no yellowing, cracks, peeling or blisters
Durability for concrete and metal surfaces in a moderately cold climatic region (Moscow)	years	at least 10
Thermal conductivity	W/m °C	0,0012
Vapor permeability	mg/m × h × Pa	0.03
Water absorption in 24 hours	% by volume	2
Operating temperature range	°C	from - 60 to + 260

Such a coating does not require additional protective layers - it is strong enough to cope with all the impacts on its own.

Such a liquid insulation is implemented in plastic jars(buckets), as well as regular paint. There are several manufacturers, and among the domestic brands, the brands "Bronya" and "Korund" can be especially noted.

Such thermal paint can be applied by aerosol spraying or in the usual way - with a roller and brush. The number of layers depends on the operating conditions of the heating main, the climatic region, the diameter of the pipes, average temperature pumped coolant.

Many experts believe that such heaters will eventually replace the usual thermal insulation materials on a mineral or organic basis.

Video: presentation of ultra-thin thermal insulation brand "Korund"

Thermal insulation paint prices

Thermal insulation paint

What thickness of heating mains insulation is required

Summing up the review of the materials used for thermal insulation of heating pipes, you can see the performance indicators of the most popular of them in the table - for clarity of comparison:

Thermal insulation material or product	Average density in finished structure, kg/m3	Thermal conductivity of thermal insulation material (W/(m×°C)) for surfaces with temperature (°C)		Operating temperature range, °C	Flammability group
		20 and above	19 and below
Mineral wool pierced plates	120	0,045	0.044 ÷ 0.035	From - 180 to + 450 for mats, on fabric, mesh, fiberglass canvas; up to + 700 - on a metal grid	non-combustible
Mineral wool pierced plates	150	0,05	0.048 ÷ 0.037		non-combustible
Heat-insulating slabs of mineral wool on a synthetic binder	65	0.04	0.039 ÷ 0.03	From - 60 to + 400	non-combustible
	95	0,043	0.042 ÷ 0.031	From - 60 to + 400	non-combustible
	120	0,044	0.043 ÷ 0.032	From - 180 + 400
	180	0,052	0.051 ÷ 0.038	From - 180 + 400
Thermal insulation products made of foamed ethylene-polypropylene rubber Aeroflex	60	0,034	0,033	From - 55 to + 125	Slightly combustible
Semi-cylinders and mineral wool cylinders	50	0,04	0.039 ÷ 0.029	From - 180 to + 400	non-combustible
	80	0,044	0.043 ÷ 0.032
	100	0,049	0.048 ÷ 0.036
	150	0,05	0.049 ÷ 0.035
	200	0,053	0.052 ÷ 0.038
Thermal insulation cord made of mineral wool	200	0,056	0.055 ÷ 0.04	From - 180 to + 600 depending on the material of the mesh tube	In mesh tubes made of metal wire and glass thread - non-combustible, the rest are slightly combustible
Glass staple fiber mats with synthetic binder	50	0,04	0.039 ÷ 0.029	From - 60 to + 180	non-combustible
Glass staple fiber mats with synthetic binder	70	0,042	0.041 ÷ 0.03	From - 60 to + 180	non-combustible
Mats and wool made of superfine glass fiber without binder	70	0,033	0.032 ÷ 0.024	From - 180 to + 400	non-combustible
Mats and wool made of super-thin basalt fiber without a binder	80	0,032	0.031 ÷ 0.024	From - 180 to + 600	Non-combustible
Perlite sand, expanded, fine	110	0,052	0.051 ÷ 0.038	From - 180 to + 875	non-combustible
	150	0,055	0.054 ÷ 0.04
	225	0,058	0.057 ÷ 0.042
Thermal insulation products made of expanded polystyrene	30	0,033	0.032 ÷ 0.024	From - 180 to + 70	combustible
	50	0,036	0.035 ÷ 0.026
	100	0,041	0.04 ÷ 0.03
Thermal insulation products made of polyurethane foam	40	0,030	0.029 ÷ 0.024	From - 180 to + 130	combustible
	50	0,032	0.031 ÷ 0.025
	70	0,037	0.036 ÷ 0.027
Thermal insulation products made of polyethylene foam	50	0,035	0,033	From - 70 to + 70	combustible

But for sure, an inquisitive reader will ask: where is the answer to one of the main questions that arise - what should be the thickness of the insulation?

This question is quite complex, and there is no single answer to it. If you wish, you can use cumbersome calculation formulas, but they are probably understandable only to qualified heating engineers. However, not everything is so scary.

Manufacturers of finished thermal insulation products (shells, cylinders, etc.) usually lay down the required thickness, calculated for a particular region. And if mineral wool insulation is used, then you can use the data of the tables that are given in a special Code of Rules, which is designed specifically for thermal insulation of pipelines and process equipment. This document is easy to find on the web by entering a search query "SP 41-103-2000".

Here, for example, is a table from this handbook regarding the above-ground placement of the pipeline in the Central region of Russia, using mats made of glass staple fiber grade M-35, 50:

Outer diameter pipeline, mm	Type of heating pipe
	innings	return line	innings	return line	innings	return line
	Average temperature regime coolant, °С
	65	50	90	50	110	50
	Required insulation thickness, mm
45	50	50	45	45	40	40
57	58	58	48	48	45	45
76	67	67	51	51	50	50
89	66	66	53	53	50	50
108	62	62	58	58	55	55
133	68	68	65	65	61	61
159	74	74	64	64	68	68
219	78	78	76	76	82	82
273	82	82	84	84	92	92
325	80	80	87	87	93	93

Similarly, you can find the desired parameters for other materials. By the way, the same Code of Rules does not recommend significantly exceeding the specified thickness. Moreover, the maximum values of the insulation layer for pipelines are also determined:

Outer diameter of the pipeline, mm	Maximum thickness of the thermal insulation layer, mm
	temperature 19 ° C and below	temperature 20 ° C or more
18	80	80
25	120	120
32	140	140
45	140	140
57	150	150
76	160	160
89	180	170
108	180	180
133	200	200
159	220	220
219	230	230
273	240	230
325	240	240

However, one should not forget important nuance. The fact is that any insulation with a fibrous structure inevitably shrinks over time. And this means that after a certain period of time, its thickness may become insufficient for reliable thermal insulation of the heating main. There is only one way out - even when installing insulation, immediately take into account this amendment for shrinkage.

To calculate, you can apply the following formula:

H = ((D + h) : (D + 2 h)) × h× Kc

H- the thickness of the mineral wool layer, taking into account the correction for compaction.

D- outer diameter of the pipe to be insulated;

h- the required thickness of insulation according to the table of the Code of Practice.

Ks- coefficient of shrinkage (compaction) of fibrous insulation. It is a calculated constant whose value can be taken from the table below:

Thermal insulation materials and products	Compaction factor Kc.
Mineral wool mats	1.2
Heat-insulating mats "TEHMAT"	1.35 ÷ 1.2
Mats and canvases made of super-thin basalt fiber when laying on pipelines and equipment with nominal diameter, mm:
Doo	3
	1,5
DN ≥ 800 at an average density of 23 kg/m3	2
̶ the same, with an average density of 50-60 kg/m3	1,5
Mats made of glass staple fiber on a synthetic binder brand:
M-45, 35, 25	1.6
M-15	2.6
Glass staple fiber mats "URSA" brand:
M-11:
̶ for pipes with DN up to 40 mm	4,0
̶ for pipes with DN from 50 mm and above	3,6
M-15, M-17	2.6
M-25:
̶ for pipes with DN up to 100 mm	1,8
̶ for pipes with DN from 100 to 250 mm	1,6
̶ for pipes with DN over 250 mm	1,5
Mineral wool boards on a synthetic binder brand:
35, 50	1.5
75	1.2
100	1.10
125	1.05
Glass staple fiber board grades:
P-30	1.1
P-15, P-17 and P-20	1.2

To help the interested reader, a special calculator is placed below, in which the indicated ratio is already included. It is worth entering the requested parameters - and immediately get the required thickness of mineral wool insulation, taking into account the amendment.

Thermal insulation of pipelines of heating networks is considered mandatory. This also applies to water supply and sewerage. After all, substances or liquids passing through pipes sometimes freeze during the cold season or gradually lose the energy they carry. Help prevent this different methods. This article will talk about some of them.

Ways to solve the problem

You can protect networks from changes in external temperature and other influences as follows:

Make heating with heating cables. Devices are mounted on top of household pipelines, or are brought inside the collector. Such devices work from the mains.

Note! In case of need for constant heating, self-regulating wires are used, which turn off and on automatically, preventing overheating of the structures.

Lay communications below the freezing level of the soil. As a result, they have minimal contact with cold sources.
Use closed underground trays. The air space here is relatively isolated, so the air around the pipelines cools slowly and does not allow their contents to freeze.
Create a heat-insulating contour from porous materials. This method of protection is used most often. With such insulation, a buffer zone is created that prevents the loss of heat from hot liquids and protects them from freezing.

Pipe heating with heating cable

This article will focus on the last way to protect communications.

Regulatory regulation

Thermal insulation of equipment and pipelines is based on SNiP 2.04.14-88. It contains information on materials and methods of their use, and outlines the requirements for protective circuits.

Regardless of the carrier temperature, it is necessary to insulate any system.
To create a heat-insulating layer, ready-made and prefabricated structures are equally used.
The metal parts of the networks must be protected from corrosion.
It is desirable to use a multilayer circuit design. It consists of insulation, vapor barrier and a protective layer of dense polymer, non-woven fabric or metal. Sometimes a reinforcing contour is mounted, which prevents porous materials from wrinkling and prevents pipe deformation.

The document contains formulas by which the thickness of each layer of a multilayer structure is calculated.

On a note! Most of the requirements for thermal insulation of pipelines apply to high-capacity trunk networks. However, when installing domestic water supply and sewerage systems on your own, you should familiarize yourself with the document and take into account its recommendations when designing and installing.

According to SNiP, thermal insulation is mandatory

Analysis of insulation materials

Polymer heaters

When choosing materials to protect pipelines from heat loss, they first of all turn to foamed polymers. With their assortment, you can choose a heater that will help solve the problem.

At the head of the list are the following compositions for isolation:

Polyethylene foam. The material is characterized by low density, porosity and low mechanical strength. Cylinders with a cut are made from it, which even non-professionals can mount. The disadvantage of pipe insulation is considered to be rapid wear and poor heat resistance.

Note! The diameter of the cylinders must match the diameter of the manifold. In this case, after mounting the casings, they cannot be removed spontaneously.

Styrofoam. The insulation is characterized by low elasticity and significant strength. Produced in the form of segments resembling a "shell". The parts are connected using locks with spikes and grooves, as a result of which “cold bridges” are eliminated and additional fasteners can be dispensed with.
Polyurethane foam. It is used for pre-installed thermal insulation, although it can also be used in everyday life. Available in the form of foam or "shell", consisting of two or four segments. The method of spraying provides reliable hermetic thermal insulation of communications, which are characterized by a complex configuration.

Important! In order to protect polyurethane foam from damage by ultraviolet light, it is covered with paint or non-woven fabric with good permeability.

Tubular polyethylene insulation

Fiber materials

Heaters based on mineral wool or its derivatives are popular at least (and sometimes more) polymer materials.

Fibrous insulation has the following advantages:

low coefficient of thermal conductivity;
resistance to acids, oils, alkalis and other external factors (heating, cooling);
the ability to maintain a given shape without the help of an additional frame;
moderate cost.

Note! When installing thermal insulation of equipment and pipelines using such materials, make sure that the fiber is not compressed and not exposed to moisture.

Mineral wool cylinders covered with foil

Casings made of polymer and mineral wool insulation are sometimes covered with steel or aluminum foil. This heat shield reduces heat dissipation and reflects infrared radiation.

Layered structures

Insulation according to the "pipe in pipe" method is done using an already mounted heat-shielding casing. The task of the installer in this case is to correctly connect the parts into a single structure. In the end, it looks like this:

Base in the form of a metal or polymer pipe. It is considered the supporting element of the entire device.
Thermal insulation layer made of foamed polyurethane (PPU). It is applied using pouring technology, when a special formwork is filled with molten mass.
Protective cover. It is made of pipes made of galvanized steel or polyethylene. The first are intended for laying networks in open space, and the second - in the ground using channelless technology.
In addition, copper conductors are often laid in polyurethane foam insulation, designed for remote control over the condition of the pipeline, including the integrity of the thermal insulation.

Pipes that arrive at the installation site already assembled are connected by welding. For the assembly of heat-protective circuits, special heat-shrink cuffs or overhead sleeves made of mineral wool, covered with a layer of foil, are used.

Laminated construction with galvanized steel outer coating

Do-it-yourself thermal insulation device

The technology for thermal insulation of equipment and pipelines depends on whether the collector is laid outside or mounted in the ground.

Insulation of underground networks

Work on the installation and thermal protection of buried household networks is carried out in the following order:

Lay sewer trays at the bottom of the trench.
Lay the pipes and make a thorough sealing of the joints.
Put heat-insulating casings on them and wrap the structure with vapor-proof fiberglass. For fixing, use special polymer clamps.
Close the tray with a lid and fill it with soil. Place a sand-clay mixture in the gap between the tray and the trench and carefully compact it.
In the absence of a tray, the pipes are laid on compacted soil, sprinkled with sand and gravel.

Insulation of pipes with laying in a tray

Thermal protection of the external pipeline

According to SNiP, thermal insulation of pipelines located on the surface of the earth is carried out in the following way:

Remove rust from all parts.
Process pipes anti-corrosion composition.
Install a polymer "shell" or wrap the pipe with a rolled mineral wool insulation.

On a note! You can cover the structure with a layer of polyurethane foam or apply several layers of heat-insulating paint.

Wrap the pipe as in the previous version. In addition to fiberglass, a foil film with polymer reinforcement is also used.
Secure the structure with steel or plastic clamps.

Compliance with the requirements for thermal insulation of pipelines is a guarantee that you will do it right. This means that the temperature hot water will be preserved along the route from the boiler room to the house, and the cold one will not freeze even in severe frosts.

Video briefing: the process of pipeline insulation

If you follow the standard execution scheme installation work and use the right materials, your plumbing and sewerage will function smoothly. Good luck!

Thermal insulation of pipelines is a set of measures aimed at preventing the heat exchange of the carrier 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 the 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 by means of infrared radiation.

The greatest application, expressed in numbers, is the thermal insulation of pipelines of heating networks. Unlike Europe, the centralized heating system dominates the entire post-Soviet space. Only 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 that have autonomous system heating. Only in a few northern regions, private houses are connected to the central heating main with heating pipes placed outside.

For some types of boilers, for example, powerful gas or diesel ones, the requirements of the set of rules SP 61.13330.2012 “Thermal insulation of equipment and pipelines” require a separate location from the building - in a boiler room several meters away from the heated object. In their case, the strapping fragment passing through the street necessarily needs to be insulated.

On the street, insulation of heating pipelines is required both for open ground placement and for hidden laying underground. The latter method is channel - a reinforced concrete gutter is first laid in the trench, and pipes are already placed in it. Channelless placement - directly in the ground. The insulating materials used differ not only in thermal conductivity, but also in vapor and water resistance, durability and installation methods.

The need to insulate cold water pipes is not so obvious. However, it cannot be dispensed with in the case when the water supply is laid in an open ground way - the pipes must be protected from freezing and subsequent damage. But inside buildings, it is also necessary to insulate water pipes - to prevent moisture condensation on them.

Glass wool, mineral wool

Proven insulating materials. They 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, similar in structure to crystals.

Glass wool is made from waste glass production, mineral wool from silicon-containing slag and silicate metallurgy waste. The differences in their properties are insignificant. They are produced in the form of rolls, stitched mats, plates and pressed cylinders.

It is important to be careful with materials and be able to handle them correctly. Any manipulations should be performed in protective overalls, gloves and a respirator.

Installation

The pipe is wrapped or lined with cotton wool, ensuring a uniform filling density over the entire surface. Then the insulation, without too much pressure, is fixed with a tie wire. The material is hygroscopic and easily gets wet, therefore, the 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 cover layer is placed on top of it, which prevents the penetration of precipitation - a casing made of roofing sheet, galvanized iron or sheet aluminum.

Basalt (stone) wool

Thicker than glass wool. The fibers are made from a melt of gabbro-basalt rocks. Absolutely non-combustible, briefly withstands temperatures up to 900 ° C. Not all insulating materials can, like basalt wool, be in long-term contact with surfaces heated to 700 ° C.

The thermal conductivity is comparable to polymers, ranging from 0.032 to 0.048 W/(m K). High performance indicators make it possible to use its thermal insulation properties not only for pipelines, but also for the arrangement of hot chimneys.

Available in several versions:

like glass wool, rolls;
in the form of mats (stitched rolls);
in the form of cylindrical elements with one longitudinal slot;
in the form of pressed cylinder fragments, the so-called shells.

The last two versions have different modifications, differing in density and the presence of a heat-reflecting film. The slot of the cylinder and the edges of the shells can be made in the form of a spike connection.

SP 61.13330.2012 contains an indication that the thermal insulation of pipelines must comply with safety and protection requirements environment. By itself, basalt wool fully complies with this indication.

Manufacturers often resort to tricks: to improve consumer performance - to give it hydrophobicity, greater density, 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 hygiene certificate.

Installation

Insulation fibers are stronger than those of glass wool, so the ingress of its particles into the body through the lungs or skin is almost impossible. However, when working, it is still recommended to use gloves and a respirator.

The installation of a roll web does not differ from the way in which glass wool heating pipes are insulated. Thermal protection in the form of shells and cylinders is attached to pipes using mounting tape or a wide bandage. Despite some hydrophobicity of basalt wool, pipes insulated with it also require a waterproof vapor-permeable sheath made of polyethylene or roofing felt, and an additional one made of tin or dense aluminum foil.

Foamed polyurethane (polyurethane foam, PPU)

Reduces heat loss by more than half 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; The operating temperature range is from -40 to +140 °С, the maximum withstand temperature for a short time is 150 °С.

The main brands of PPU belong to the combustibility group G4 (highly combustible). When changing the composition with the help of the addition of fire retardants, they are assigned G3 (normally combustible).

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-apartment residential buildings, and SP 2.13130.2012 limits their height to two floors.

The heat-insulating 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 protective sheath made of polyethylene.

Installation

The shells are fixed on the heating pipe with the help of ties, clamps, plastic or metal bandage. Like many polymers, the material does not tolerate long-term exposure to sunlight, therefore, an open above-ground pipeline, when using PU foam shells, needs a cover layer, for example, from galvanized steel.

For underground channelless placement, heat-insulating products are laid on waterproof and temperature-resistant mastics or adhesives, and are insulated from the outside with a waterproof coating. It is also necessary to take care of the anti-corrosion surface treatment. metal pipes– even glued shell joints are not tight enough to prevent condensation of water vapor from the air.

Expanded polystyrene (polystyrene, PPS)

It is produced in the form of shells, outwardly practically no different from polyurethane foam - the same dimensions, the same tongue-and-groove locking connection. But the temperature range of application, from -100 to +80 ° C, with all this external similarity, makes it impossible or limited to use it for thermal insulation of a heating pipeline.

SNiP 41-01-2003 "Heating, ventilation and air conditioning" states that in the case of a two-pipe heat supply system, the maximum supply temperature can reach 95 ° C. As for the return risers of heating, everything is not so simple here: 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 over other heaters with a higher allowable application temperature.

The material has a number of some disadvantages: highly flammable (even with the addition of fire retardants), does not tolerate chemical exposure(dissolves in acetone), crumbles with prolonged exposure to solar radiation.

There are other, non-polystyrene foams - formaldehyde, or shortly, phenolic. In fact, this is a completely different material. It is devoid of these shortcomings, is successfully used as thermal insulation of pipelines, but is not so widespread.

Installation

The shells are fixed on the pipe with a bandage or foil tape, it is allowed to glue them to the pipe and to each other.

Foamed polyethylene

The temperature range at which the use of foamed high-pressure polyethylene is allowed is from -70 to +70 °С. The upper limit is not combined with the maximum temperature of the heating pipe, usually taken into account in the calculations. This means that the material is of little use as a thermal insulation of pipelines, but can be used as an insulating layer over a heat-resistant one.

Polyethylene foam insulation has found practically no alternative application 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. The standard length is 2 meters. The color varies from white to dark gray. An IR reflective aluminum foil coating may be available. The differences relate to internal diameters (from 15 to 114 mm), wall thickness (from 6 to 30 mm).

The application ensures that the temperature on the pipe is above the dew point, which means it prevents the formation of condensate.

Installation

An easy way with worse vapor barrier results is to cut the foam material into a small indentation along the side surface, open the edges and put it on the pipe. Then wrap along the entire length with mounting tape.

More difficult decision(and far from always feasible) - turn off the water, completely disassemble the insulated sections of the water supply and put on solid sections. Then put everything back together. Secure the polyethylene with zip ties. In this case, only the junction of the segments will become a weak point. It can be glued or also wrapped with tape.

foamed rubber

Foamed synthetic rubber with a closed cell structure is the most versatile material for keeping warm and cold. Designed for temperature range from -200 to +150 °С. Conforms to all requirements of ecological safety.

Used as pipeline insulation cold water, insulation of heating pipes, 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.

Outwardly similar to polyethylene foam, it is also available in the form of sheets and flexible thick-walled pipes. Installation is also practically the same, except that such thermal insulation of pipes can be attached to glue.

Liquid heaters

A technology has been successfully applied that allows self-spraying foam from a polyurethane composition on already prefabricated structures. Excellent adhesive properties allow you to use it not only for insulating pipelines, but also to apply to other elements that need insulation: foundation, walls, roofing. The coating, in addition to thermal protection, provides hydro, vapor barrier, provides anti-corrosion resistance.

Conclusion

Properly performed installation of thermal insulation is a guarantee that the pipe will not lose heat, and the consumer will not freeze. Freezing of the cold water supply pipeline invariably leads to its rupture. Until recently, in hidden and open heating mains, glass wool was the usual insulating material. Its shortcomings stem from one another. Such coverage requires constant monitoring.

Even with a slight damage to the protective surface layer, vapor permeability and hygroscopicity nullify all savings. Moisture causes low thermal resistance and premature failure. Modern insulating materials with a cellular structure that are inert to the effects of steam and water will help to significantly improve the situation: polyurethane foam, foamed rubber, polyethylene foam.

Thermal insulation is the most important structural element of all links of DH systems - heat generating, transport links, heat consumption installations. By reducing heat losses and preventing coolants from drying out, it forms the technical and economic efficiency, reliability and durability of installations as a whole, the possibility of industrialization and is the main means of saving fuel resources. In channelless laying of heat pipelines, thermal insulation also performs the functions of a supporting structure.

For thermal insulation equipment, pipelines, air ducts, prefabricated or complete prefabricated structures are used, as well as pipes with thermal insulation of full factory readiness.

For pipelines of heating networks, including fittings, flange connections and compensators, thermal insulation must be provided regardless of the temperature of the coolant and the method of laying. Structurally, it is made of the following elements: heat-insulating layer; reinforcing and fasteners; vapor barrier layer; cover layer.

As a heat-insulating layer SNiP 41-03-2003 " Thermal insulation of equipment and pipelines» recommend for use more than 30 main types of materials, products, factory products of general purpose, providing: heat flow through the insulated surfaces of equipment and pipelines according to a given process mode or normalized heat flux density; exclusion of the release during operation of harmful, flammable and explosive, unpleasantly smelling substances in quantities exceeding the maximum permissible concentrations; exclusion of the release during operation of pathogenic bacteria, viruses and fungi.

Such effective materials traditionally used in heating networks include autoclaved reinforced foam concrete, bitumen perlite, expanded clay asphalt concrete, gas silicate, phenolic foam plastics, thermal insulation mats and slabs of mineral wool, volcanic and some other materials (Fig. 1). Basic average data thermal insulation materials and products are presented in table. 1.

Picture 1.

Table 1. Basic data of heat-insulating materials and products

Materials or products	Maximum coolant temperature, °C	Thermal conductivity, W/(m°С), at 20°С and humidity, %	Density, kg / m 3
Materials or products	Maximum coolant temperature, °C		Density, kg / m 3
Mineral wool
Insulation:
mineral wool
continuous fiberglass			170*
staple fiberglass

covelite			400*
volcanic			400*
calc-silica			225*
Monolithic:
armored concrete
bitumen perlite
asphalt-ceramsite-concrete
foam concrete
fluoroplast
Self-sintering asphaltoizol
Peat slabs			220*

* Maximum value.

As materials for the cover layer thermal insulation in new construction, prefabricated structures are used:

1) from metal (sheets and tapes from aluminum and its alloys, sheet steel for roofing and galvanized, corrugated shells, metal-layers, etc.);

2) based on synthetic polymers (structural fiberglass, rolled fiberglass, reinforced plastic materials, etc.);

3) based on natural polymers (roofing material, glass roofing material, roofing felt, roofing glassine, etc.);

4) mineral (glass cement, asbestos-cement plaster, etc.);

5) duplicated with foil (duplicated aluminum foil, foil isol, etc.).

As anti-corrosion and waterproofing coatings, barrier and protective coatings are used - polymer, metallization, silicate and organosilicate, as well as protective coatings based on bituminous binder.

For the channelless design of heat pipelines, materials with an average density of not more than 600 kg / m 3 and thermal conductivity of not more than 0.13 W / (m ° C) should be used. In this case, the design of thermal insulation must have a compressive strength of at least 0.4 MPa. Estimated specifications materials used to insulate pipelines during channelless laying are presented in table. 2.

Table 2

Material	Conditional passage of the pipeline, mm	Average density ρ, kg / m 3	Thermal conductivity of dry material λ, W/(m °С), at 20°С	Maximum substance temperature, °C
Armored concrete
Bitumoperlite				130*
Bitumen expanded clay				130*
Bitumovermiculitis				130*
Foam polymer concrete
polyurethane foam
Phenolic foam FP monolithic

* It is allowed to use up to a temperature of 150 "C with a high-quality method of heat release.

On fig. 2, 3 shows several options for traditional industrial designs of heat pipelines.

Figure 2. 1 - pipe; 2 - anti-corrosion coating; 3 - mineral wool mat; 4 - steel mesh; 5 - asbestos cement plaster

Figure 3 1 - pipe; 2 - anti-corrosion coating; 3 - bitumen perlite; 4 - waterproof coating of fiberglass over varnish

Foam concrete insulation is a light insulating material obtained by preparing foam mass and then curing it in a cassette autoclave at a steam pressure of 8-10 kgf / cm 2 for 11-14 hours.

Given the significant fragility of foam concrete insulation, it is reinforced with a spiral frame located in the outer third of the insulation thickness.

After the autoclave, foam concrete is dried with hot gases at t = 200 °C during the day.

This design has been widely used in the laying of distribution and yard networks.

Starting from the 1970s, in the Moscow region (Dmitrov and Vladimir heating networks), polyurethane foam (PPU) insulation of heating network pipelines began to be used, originally made in a primitive way, manually, in repair and procurement workshops.

Pre-cleaned from scale steel pipe was placed in a trough-shaped chute (a pipe of larger diameter cut along) and covered with the same chute from above, then liquid polymer composition, consisting of a mixture of resin "polyisocyanate" (component "A") and hardener - "pol-iol" (component "B"). This composition within a few minutes, reacting, foamed, filling the entire volume, then solidified and turned into a porous spongy mass with open pores. Depending on the selected proportions of the components, it was possible to obtain insulation of various densities - from a soft structure - foam rubber, to a stone-like hard spongy mass, firmly grasping with metal surface pipes. After the completion of the exothermic reaction, the mixture of components and the cooling of the structure of the gutter were removed, and the pipe insulated in this way was put into installation.

The described manual technology formed the basis of the factory one, with the difference that instead of home-made boxes, factories began to use tubular-type shells made of specially processed - extruded (for better adhesion to the porous mass of polyurethane foam) polyethylene or thin-walled metal pipes. The process of preliminary mechanical cleaning (to a metallic sheen) of the outer surface of the main pipe has also improved, and input and output factory quality control of products has been established.

The main difficulty in making such isolation Until now, there is an acute shortage of starting components, since the domestic chemical industry is not able to meet the needs of the national economy (industry, transport, energy, military-industrial complex) and they have to be purchased at expensive prices abroad. This is reflected in the price of polyurethane foam insulation.

Despite this, modern factory technologies have begun to develop in the country, taking into account both domestic and foreign experience in insulating pipes and equipment using PPU.

The modern production facility (CJSC MosFlowline), provided by the Russian side, was designed and staffed by leading Western European companies, taking into account the technologies available on the market. Technological equipment allows to produce 2400 m of insulated pipe and 60 pcs. insulated fittings per day. Products are produced in two types: in a polyethylene sheath for underground laying and in a galvanized metal sheath for above-ground laying of heating networks.

For pipelines of hot and cold water supply, galvanized pipes d y \u003d 32-219 mm are used as a working pipe. The assembly of galvanized fittings in the factory is carried out by a non-zinc destructive method - soldering.

For heating networks, products with a diameter of 32-1220 mm are supplied with all fittings. CJSC MosFlowline is so far the only domestic company that provides a full range of services from design to commissioning and issuance of a 5-year guarantee for factory elements, work on sealing joints and the operability of the remote control system (ODC) of pipelines. This is an example of the development and implementation of new technologies of the XXI century.

On fig. Figures 4 and 5 show finished products of thermally insulated pipelines of CJSC MosFlowline, which are a rigid structure of the "pipe in pipe" type, consisting of a steel (working) pipe, an insulating layer of rigid polyurethane foam (PPU) and an outer protective sheath of polyethylene low pressure or galvanized steel.

NOTE. At polyurethane foam insulation there is a significant drawback that must always be remembered - this organic material is flammable and in the process of burning it releases potent toxic substances (SDYAV), which during fires are the main cause of death. Therefore, in underground structures of heat networks with PPU insulation every 300 m in thermal insulation arrange non-combustible inserts from mineral insulation.

Figure 4. The design of PPU - insulation of the pipeline according to the technology of CJSC "MosFlowline"

Figure 5. Thermally insulated PPU pipes for channelless (in a polyethylene sheath) and above-ground laying of heat networks (in a metal sheath)