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Requirements for pipeline insulation. Thermal insulation of industrial equipment. Insulation of underground networks

Thermal insulation is the most important structural element all links of district heating systems - heat generating, transport links, heat consumption installations. By reducing heat losses and preventing cooling of coolants, it creates 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 ductless heat pipe installations, thermal insulation also serves as a supporting structure.

For thermal insulation equipment, pipelines, and air ducts use fully prefabricated or complete factory-made structures, as well as pipes with thermal insulation that are fully prefabricated.

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

As a thermal insulation layer SNiP 41-03-2003 " Thermal insulation of equipment and pipelines» more than 30 main types of materials, products, and industrial products are recommended for use general purpose providing: heat flow through isolated surfaces equipment and pipelines in accordance with a given technological regime or normalized heat flux density; elimination of the release during operation of harmful, flammable and explosive, unpleasant-smelling substances in quantities exceeding the maximum permissible concentrations; eliminating the release of pathogenic bacteria, viruses and fungi during operation.

Such effective materials traditionally used in heating networks include autoclaved reinforced foam concrete, bitumen perlite, asphalt expanded clay concrete, gas silicate, phenolic foams, thermal insulation mats and slabs from mineral wool, vulcanite 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 thermal insulation materials and products

* Maximum value.

As materials for the cover layer thermal insulation For new construction, factory-made structures are used:

1) made of metal (sheets and strips of aluminum and its alloys, thin-sheet roofing and galvanized steel, corrugated shells, metal-plastics, etc.);

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

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

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

5) duplicated with foil (laminated aluminum foil, folgoizol, etc.).

Barrier and tread type coatings are used as anti-corrosion and waterproofing coatings - polymer, metallization, silicate and organosilicate, as well as protective coatings on bitumen binder.

For the ductless design of heat pipelines, materials with an average density of no more than 600 kg/m 3 and a thermal conductivity of no more than 0.13 W/(m °C) should be used. The thermal insulation design must have a compressive strength of at least 0.4 MPa. Calculated specifications materials used for insulation of pipelines for channelless installation are presented in table. 2.

Table 2. Estimated technical characteristics of materials used for insulation of pipelines for channelless installation

* Allowed for use up to a temperature of 150 "C at qualitative method release of heat.

In Fig. 2, 3 show 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 fiberglass coating over varnish

Foam concrete insulation represents a lightweight 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.

Considering 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 for 24 hours.

This design received wide application in laying distribution and yard networks.

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

Pre-cleaned from scale steel pipe placed in a trough-shaped trench (a pipe of a larger diameter cut lengthwise) and covered with the same trench on top, then liquid was poured into the resulting annular gap at an angle polymer composition, consisting of a mixture of “polyisocyanate” resin (component “A”) and a hardener - “pol-iol” (component “B”). Within a few minutes, this composition reacted, 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 varying densities - from a soft structure - foam rubber, to a stone-like hard spongy mass that firmly adheres to metal surface pipes. After the completion of the exothermic reaction of the mixture of components and the cooling of the gutter structure, they were removed, and the pipe thus insulated was sent for installation.

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 treated - extruded (for better adhesion to the porous mass of polyurethane foam) polyethylene or thin-walled metal pipes. The pre-production process has also improved mechanical cleaning(to metallic shine) outer surface main pipe and installed input and output factory quality control of products.

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 National economy(industry, transport, energy, military-industrial complex) and they have to be purchased at high prices abroad. This is also reflected in the price of polyurethane foam insulation.

Despite this, modern factory technologies began to develop in the country, taking into account both domestic and Foreign experience insulation of pipes and equipment using polyurethane foam.

The modern production base (JSC MosFlowline), provided by the Russian side, was designed and equipped by leading Western European companies, taking into account the technologies currently on the market. Technological equipment allows you to produce 2400 m of insulated pipe and 60 pcs. insulated shaped products per day. The products are available in two types: in a polyethylene shell for underground laying and in a galvanized metal shell for overhead laying heating networks.

For hot and cold water supply pipelines, galvanized pipes with d y = 32-219 mm are used as a working pipe. Assembly of galvanized shaped products in a factory is carried out using a zinc-non-destructive method - soldering.

For heating networks, products with a diameter of 32-1220 mm are supplied with all shaped products. MosFlowline CJSC is so far the only domestic enterprise that provides a full range of services from design to commissioning and issuing a 5-year warranty on factory elements, work on insulating joints and the operability of the operational remote monitoring (ODC) system of pipelines. This is an example of the development and implementation of new technologies of the 21st century.

In Fig. 4 and 5 shown finished goods thermally insulated pipelines of MosFlowline JSC, which are a rigid “pipe-in-pipe” type structure consisting of a steel (working) pipe, an insulating layer of rigid polyurethane foam (PPU) and an outer protective shell of polyethylene low pressure or galvanized steel.

NOTE. U polyurethane foam insulation There is significant drawback, which must always be remembered - this organic material is flammable and during its combustion, highly toxic substances (TDS) are released, which in fires are the main cause of death. Therefore, in underground structures heating networks with polyurethane foam insulation every 300 m thermal insulation arrange non-flammable inserts from mineral insulation.

Figure 4. Design of PPU - pipeline insulation using the technology of JSC MosFlowline

Figure 5. Thermally insulated polyurethane foam pipes for ductless (in a polyethylene shell) and above-ground installation of heating networks (in a metal shell)

To reduce the level of heat loss in heating systems that occurs during the cold period, pipes are insulated. Thermal insulation materials help maintain the required temperature in the network, eliminating the occurrence of condensation on the pipeline surface and insulation. The use of these types of products prevents water from icing during stagnation, and slows down the corrosion process that forms over time on pipeline components made of metal, extending their service life.

When choosing insulation, you must first decide on the place where it will be used, outside or inside the house. The choice of thermal insulation material is influenced by:

• diameter of the located pipes;
• heating temperature of the coolant;
• conditions under which the heating system is operated.

The types of insulation used differ depending on the diameter of the existing pipes. Manufacturing companies offer half-cylinders, soft roll insulation and cylinders with a certain rigid shape.

For pipelines with small diameters, half-cylinders and cylinders with characteristic rigidity are suitable. This type design has grooves that greatly simplify installation work. This material has an excellent level of resistance to high temperatures, with minimal water absorption. The rigid heat insulator constantly retains its original shape, providing additional safety from possible mechanical damage.

When choosing, you need to pay attention to the following characteristics of the heat insulator:

• flammability class, which should be especially taken into account for further placement inside residential and industrial buildings;
• the level of water absorption, on which the service life of the material directly depends, because with a high level of moisture absorption, the insulation succumbs to rotting, beginning to decompose, subsequently not representing any effectiveness;
• the degree of resistance to ultraviolet radiation, because material with a low index that is located outside the house will begin to succumb to destruction by sunlight;
• the level of thermal conductivity should be as low as possible, because with a low indicator, the heat insulator saves heat better, allowing the use of insulation with a smaller layer thickness.

Types of insulation materials

Thermal insulation of heating pipes is carried out after purchasing the material, but before this moment it is necessary to learn about the characteristics and advantages of the insulation, as well as its scope. After this data, you will be able to select the most suitable and effective option.

This insulation consists of ribs and walls that form a solid solid structure. It creates a heat-insulating shell that has high level strength, while quite effectively retaining heat inside the heating network. Polyurethane foam has the following positive qualities:

• odorless and non-toxic;
• does not rot;
• it is environmentally harmless to the human body;
• has excellent dielectric properties;
• material is resistant to different kinds climatic influences, favorably suitable for outdoor use;
• sufficiently strong insulation, eliminating the possibility of pipeline breakdowns under the influence of mechanical loads from the outside.

Its only noticeable drawback is its high cost.

Minvata

Possessing a significant level of efficiency, it is quite popular among heat insulators. It consists of mineral wool and has a number of its own features:

• cotton wool has low moisture absorption due to treatment with special compounds during the manufacturing process;
• high degree of thermal stability, which, when heated, ensures the preservation of thermal insulation and mechanical parameters at the primary level;
• is environmentally friendly and does not contain toxic substances;
• it is not afraid of exposure to acids, solvents and other chemical solutions.

Mineral wool is excellent for use as a heat insulator for heating pipes. It is quite often installed on pipelines that are subject to continuous heating of great force.

Foamed polyethylene

Does not harm the human body. It is not afraid of significant temperature changes and is resistant to moisture. The insulation is quite popular among buyers. It has the shape of a tube with a specific thickness in which an incision is made. It is used as a heat-insulating material for heating network pipes, and also for insulating warm and cold water pipes.

It retains its properties when used together with other building materials, including concrete, lime and others.

This insulation for heating pipes has appeared on the market quite recently, being a reflective heat insulator, which consists of aluminum foil and cellular polyethylene. Thanks to 2 layers, the material has excellent thermal performance, which is why it is quite in demand among buyers. Folgoizol has a number of features:

• enough easy installation, not requiring special means protection;
• it is environmentally friendly and does not emit toxic substances;
• has a long service life;
• has a wide range of uses, suitable for both indoor and outdoor use.

Penofol is distributed in rolls with varying levels of density of the polyethylene layer. When choosing thickness, you should take into account the future conditions of use of the heat insulator. The double layer helps retain heat in a closed space, achieving the maximum permissible efficiency.

Stages of thermal insulation of heating pipes

Mineral wool

Processes for insulating a heating pipeline with mineral wool must be carried out while wearing gloves.

1. First of all, the material is cut according to the required dimensions.
2. It is wound onto the pipe without the need to tighten it too much.
3. At intervals you should stop, fixing it with electrical tape, wire or a solid rope.
4. Having finished covering the pipeline with mineral wool, it is necessary to prepare a protective sheathing, which is made of roofing felt or corrugated foil, which is pre-cut into pieces.
5. Having installed a shell of foil or roofing felt, it is secured using plastic ties or ropes.

Polyurethane foam shell

For small diameters, you can use a cylindrical or semi-cylindrical shell shape.

1. Thermal insulation material is placed on the pipeline.
2. It is fixed using glue, tape, wire or self-adhesive tape.

If the pipes have large diameter, then you need to select a shell that consists of several parts. This type of material is fixed using the tongue-and-groove principle.

Having produced high-quality insulation heating networks, it will be possible to retain a significant amount of heat indoors. Therefore, the choice of insulation should be approached responsibly, having weighed all the advantages of those available on the market thermal insulation building materials before making a purchase.

One of the most important tasks of modern energy in the Russian Federation is energy saving. Great importance In this we play a role in reducing heat loss through heating networks, heating mains and housing and communal services pipes. The scale of losses is enormous: more than 70% of heat is lost annually. Of these, about 60% are in heating plants, and 40% in residential buildings. Thermal insulation of most pipes is done the old fashioned way, using glass wool or other lining materials, protected from the outside with insulation, polymer tapes, brizol or reinforced foam concrete. Heating mains with this type of insulation do not provide reliable and economical heat supply to consumers due to the higher frequency of pipe damage due to moisture and destruction.

And although in Europe, America, and Canada, reliable and reliable thermal insulation has been used for more than 50 years durable material- foamed polyurethane foam; this technology came to Russia only in 1994. The number of companies involved in PPU insulation is still small, despite the fact that a long period of time has passed.

CMETHODS OF THERMAL INSULATION OF PIPES USING POLYURETHANE FOAM There are three main methods of insulating pipelines:

PPU shells

Pipe-in-pipe method

Spraying polyurethane foam

Also called half cylinders. They are manufactured in a factory by pouring polyurethane foam into molds. The resulting half-cylinders and blanks for bends are fastened together at the pipeline laying site different ways(ties, clamps, polypropylene tapes, wire).

Half-cylinders can be either without additional insulation or with it. This method is used to insulate oil pipelines, gas pipelines, network engineering chemical plant, etc.

High-quality thermal insulation material reduces heat losses by two and a half times. Hidden in durable, moisture-resistant packaging, protected from corrosion and mechanical stress, the pipes last much longer.Labor intensity installation work shell installation is very low. Almost every business can install thermal insulation.

Although the process of installing the shell is not very labor-intensive, some technological rules should be followed:

Firstly, the installation of thermal insulation must be carried out using mounting locks perpendicular to the pipe. If you do not follow this rule, then a kind of tray will form at the bottom of the pipe, which will contain condensate, which will form one way or another. The longitudinal locks must be in a vertical position.

Secondly, to join the ends of the insulation, it is necessary to use composite glue and clamps. The clamps should be inserted into the shells in 3 places: at the beginning, in the middle and at the end. If the installation process conditions are followed, the thermal insulation will last for decades.

"Pipe-in-pipe" technology. This is the name given to pipes pre-insulated with polyurethane foam. Used to insulate pipes made of stainless and galvanized steel, polypropylene and polyethylene. The essence of the method is as follows: on the pipe through which the substance will be transported, another, larger in diameter, is put on. Polyurethane foam is poured into the resulting cavity between the pipes, which, foaming and hardening, forms a heat-insulating layer.

There are important requirements in the application of pipe-in-pipe technology:

Firstly, the insulated pipe must be perfect quality(after all, in case of damage, it will have to be changed along with the insulation).

Secondly, the pipe must be fully prepared for pre-insulation. In addition, “the pipe in the pipe must be equipped with electronic monitoring devices (every 200 meters of length), otherwise it is impossible to establish “sore” areas of the heat pipeline.

The third method of thermal insulation is spraying polyurethane foam using special equipment. has the lowest thermal conductivity coefficient of all currently used thermal insulation materials. For comparison: it is 25 times more effective sand-lime brick, 4.5 times - expanded clay gravel, 2 times - slabs of mineral wool and glass staple fiber, and 1.5-1.7 times more effective than expanded polystyrene. A 45 mm layer of polyurethane foam coating is sufficient for air laying, even if the coolant temperature is up to +1100 C, and outside temperature up to -250 C.

In many houses (from buildings that have been standing for decades to recently built cottages), people overpay considerable sums for heating only because the heating system wastes a significant part of the energy (in particular, those networks that run along the street).

Very often this happens due to errors made during the installation of heating network pipelines - in this case, losses can reach 40-60%, which, of course, is a lot.

Moreover, this situation not only increases your costs, but in addition also reduces the service life of heating network equipment, which would have worked longer under lower loads.

For this reason, thermal insulation of heating network pipelines is sufficient current solution which should not be neglected. Let's look at how heating pipelines are insulated, what material is used and how exactly this procedure is carried out.

Why insulate pipelines?

To begin with, let’s take a closer look at whether the material should be used for insulation of heating pipes or for thermal insulation of heating networks, and if necessary, why and where exactly.

The heating system of any building is designed as follows: the air inside the room heats the coolant (water) circulating through pipelines to the radiators.

Giving off its heat through the walls of the pipes, the water returns back to the boiler, which heats it again. This is in general terms.

However, heat transfer is not necessary over the entire length of the pipe. For example, if the boiler room in your house is located far from residential premises (or even in a separate building on the street) that need heating.

During transportation from the boiler to the area requiring heating, the water will lose some of its heat. As a result, to warm up the air for living rooms you will have to spend more energy (fuel), and therefore more money.

Often boiler rooms are located in basements, where the temperature is significantly lower than in a living room. So Energoflex insulation for heating pipes in the basement will give serious results in saving fuel.

But thermal insulation for heating pipes for an apartment is no longer so important and irreplaceable. The only caveat is that it is important to insulate the heating risers: in this case, more heat will reach the battery.

In addition, the pipeline also needs mechanical protection from possible damage. First of all, this concerns areas along the street - it is their isolation that needs to be thought about first of all.

How to isolate?

Now let’s look at how to insulate heating network pipes most effectively. There are several options (according to application method):

1. Roll materials.
2. "Shell".
3. Liquid (sprayed) insulation.

As an option (by the way, the most successful and convenient) you can buy pre-insulated heating pipes. It is most convenient to use pre-insulated pipes because it saves time: You are installing the networks of a system that is already insulated.

The disadvantages of this solution are the following nuances:

• working with segments is not always convenient (we are talking about laying pipes through hard-to-reach places);
• the junctions of the segments will be unprotected - which means they will still have to be insulated (and this will be a small section of pipe for which it is unlikely to be able to select a standard-sized insulator);
• the price of pre-insulated heating pipes is 15-50% higher than the price of the same products without insulation (depending on the insulating material and its thickness).

Now let's take a closer look at the above variations.

The simplest, but ineffective option. It is good when there is no need to obtain significant heat savings, or (which is better) when combined with some other insulator.

Material for insulating heating networks of this type is represented by the following products:

1. Butacryl is a heat-saving paint. Its price is $5 per 1 kg.
2. Liquid ceramic thermal insulation. Brands – “Akterm”, “Korund”, “Teplomet”. Costs about $3.5-5 per 1 kg.
3. Thermal insulating paint "Armor". The composition is similar to the above-mentioned ceramic products. It costs about the same.

The advantage of using such materials is the simplicity and speed of application. The material is applied to the surface, hardens, forming a dense crust - which will retain heat.

Roll materials

Rolled insulation material for heating networks began to be used more than a decade ago - for industry and for housing and communal services. The most common material is mineral wool.

The pipeline was simply wrapped in rolls of this material, after which it was tied with wire on top, and with a galvanized casing on top. The resulting design retained heat and, in addition, was not “afraid” of mechanical damage.

This solution is still common today due to its low cost.

However, there is also important nuance: for thin pipes (which are used in homes) this material is not suitable - there are more successful and convenient solutions on sale.

In addition, the mineral wool material does not tolerate moisture very well - condensation makes the structure heavier and contributes to caking of the material.

So, thermal insulation of heating network pipelines in the basement (if it’s humid) or outside is not a very good solution (unless you take care of additional protection - like galvanizing or a fiberglass casing).

Such an insulator costs on average $1.5 (with a thickness of 5 cm) per 1 “square”.

"Shell"

Among modern solutions for household insulation - by far the most successful option.

The product is made in the form of a cylinder, which is placed on top of the pipe - this, in principle, is the entire insulation process. However, this option is only possible when creating a pipeline system.

But for insulation existing structure You can use another option - a cylinder cut into 2 parts. In this case, the segments are put on the pipe and connected together (we will discuss how exactly below).

The “shell” can be made from several materials:

Now let's mention specific manufacturers.

Mineral wool products are now represented in the largest quantities on the market. This is insulation for heating pipes “Energoflex”, “TechnoNIKOL”, “Ursa”, “Knauf”, “Rockwool”.

On average, you can buy thermal insulation for heating pipes from the above manufacturers for around $1.5-2 per meter (for a pipe with a diameter of 25 mm and a wall thickness of 50 mm).

The products of the presented brands are produced in both in the usual form(i.e. only a mineral wool cylinder), and with additional protection - galvanized, fiberglass or foil.

Protected options are relevant when waterproofing of heating pipes is also needed - since mineral wool itself, as mentioned above, does not “tolerate” moisture well.

By the way, with their help, soundproofing of the heating riser is also carried out.

Now let’s mention the manufacturers of polyurethane foam “shells”. In this category you should know about the following brands: “Thermoplex”, “TIS”.

The price of insulation for heating pipes in this case will be slightly higher than the above figures - about $2 will have to be paid for 1 meter of a product suitable for a pipe with a diameter of 22 mm.

"Shell" for insulation with foil

The thickness of the insulation will be 40 mm. However, it should be taken into account that polyurethane foam is an order of magnitude more effective than mineral wool and polystyrene foam, which means it can be used with a smaller insulator thickness.

In addition to the advantages, moisture resistance should also be included - thanks to which the thermal insulation of heating network pipelines in the basement or outdoors using polyurethane foam can be carried out without problems.

Liquid insulation

This option is not suitable for “home” insulation - the application is carried out using special expensive installations, and for thin pipes (which are used in apartments or houses) the method is not very convenient.

Most often it is used in industry, less often in public utilities (for insulating large-diameter pipelines).

The process consists of spraying a composition (liquid polyurethane foam) onto the surface of the pipe, which hardens on it in a matter of seconds.

The advantage of the technique is that in this way a pipe section of any complexity can be insulated without any problems - regardless of the angle of rotation. Prices for insulating heating pipes of this type range from $3-4 per meter (depending on the complexity of the work and diameter).

About insulation methods (video)

Nuances of shell installation

We figured out how much you can buy insulation for heating pipes. Now we will describe the procedure for installing the “shell” (of two segments) - as the most good option for independent work.

The stages are as follows:

1. The edges of one segment are coated with glue for better adhesion.
2. The “shell” segment is placed on the pipe.
3. A second one is applied on top and pressed - so that glue"grabbed."
4. You can use tape or wire on top - to increase reliability or to press the insulation more tightly to the pipe.