The choice of the route of thermal networks and laying methods. Pipelines and types of their laying
6.1*. The choice of the route of heating networks and the method of laying should be provided in accordance with the instructions of SNiP 1.02.01-85 and SNiPII-89-80.
Laying of heating networks on embankments highways common network I, II, and III categories is not allowed.
Heat networks, regardless of the laying method and heat supply system, should not pass through the territory of cemeteries, landfills, animal burial grounds, radioactive waste disposal sites, agricultural irrigation fields, filtration fields and other areas that pose a risk of chemical, biological and radioactive contamination.
6.2*. In settlements, for heating networks, as a rule, underground laying is provided (without channels, in channels or in city and intra-quarter tunnels together with other engineering networks).
When justified, it is allowed to lay overground heating networks except for the territories of children's and medical institutions.
For heating networks D at 400 mm, it is necessary to provide, mainly, channelless laying.
6.3. The laying of heat networks on the territory not subject to development outside settlements should be provided above ground on low supports.
6.4. When choosing a route for heating networks, it is allowed to cross residential and public buildings with water networks with a diameter of 300 mm or less, provided that networks are laid in technical undergrounds, technical corridors and tunnels (at least 1.8 m high) with a drainage well at the lowest point at the exit from the building .
The intersection of heating networks with preschool, school and medical institutions is not allowed.
6.5. The laying of heat networks at a working steam pressure above 2.2 MPa and a temperature above 350 ° C in impassable channels and general city or intra-quarter tunnels is not allowed.
6.6. The slope of heat networks, regardless of the direction of movement of the coolant and the method of laying, must be at least 0.002. With roller and ball bearings, the slope should not exceed
where r - radius of the roller or ball, see
Slope of heating networks to individual buildings at underground laying should be taken from the buildings to the nearest camera.
On the separate sections(when crossing communications, laying on bridges, etc.) it is allowed to accept the laying of heat networks without a slope.
6.7*. Underground laying of heat networks is allowed to be accepted together with the listed engineering networks:
in channels - with water pipelines, compressed air pipelines with a pressure of up to 1.6 MPa, fuel oil pipelines, control cables intended for servicing heating networks;
in tunnels - with water pipes up to 500 mm in diameter, communication cables, power cables voltage up to 10 kV, compressed air pipelines with pressure up to 1.6 MPa, pressure sewer pipelines. Laying of pipelines of heating networks in channels and tunnels with other engineering networks other than those indicated is not allowed.
The laying of water pipelines together with heating networks in tunnels should be provided in the same row or under the pipelines of heating networks, while it is necessary thermal insulation plumbing to prevent condensation.
6.8*. Horizontal and vertical distances from the outer edge of the building structures of channels and tunnels or the pipeline insulation shell in case of channelless laying of heat networks to buildings, structures and engineering networks should be taken according to the mandatory Appendix 6, and on the territory of industrial enterprises - according to SNiPII-89-80.
6.9. The crossing of rivers, highways, tram lines, as well as buildings and structures by heating networks should, as a rule, be provided at a right angle. When justified, it is allowed to cross at a smaller angle, but not less than 45, and for subway and railway structures - at least 60.
6.10. The crossing of tram tracks by underground heating networks should be provided at a distance of at least 3 m from the arrows and crosses (clearly).
6.11. At underground crossing by heating networks railways the smallest horizontal distances in the light should be taken, m:
up to the points and crosses of the railway track and the places where suction cables are connected to the rails of electrified railways - 10;
to arrows and crosses of the railway track with heaving soils - 20;
to bridges, pipes, tunnels and other artificial structures on railways - Z0.
6.12*. The laying of heat networks at the intersection of railways of the general network, as well as rivers, ravines, open drains, should be provided, as a rule, above ground. In this case, it is allowed to use permanent road and railway bridges.
The laying of heat networks at the underground intersection of railways, highways, main roads and streets of city and district significance, as well as streets and roads of local importance, tram tracks and metro lines should be provided for:
in channels - if it is possible to carry out construction, installation and repair work open way;
in cases - if it is impossible to perform work in an open way, the length of the intersection is up to 40 m and the provision on both sides of the intersection of straight sections of the route up to 10-15 m long;
in tunnels - in other cases, as well as when deepening from the surface of the earth to the overlap of the channel (case) of 2.5 m or more.
When crossing streets and roads of local importance, highways of category V. as well as on-farm highways of category IIIc, channelless laying of heat networks is allowed.
When laying heating networks under water barriers, as a rule, siphons should be provided.
The intersection of heating networks with metro station structures is not allowed.
At underground crossing of metro lines by heating networks, channels and tunnels should be provided from monolithic reinforced concrete with waterproofing.
6.13*. The length of channels, tunnels or cases at intersections must be taken in each direction by at least 3 m more sizes crossed structures, including subgrade structures of railways and highways.
When heating networks cross railways of the general network, motor roads of categories I, II, III, main roads of cities, metro lines, rivers and reservoirs, shut-off valves should be provided on both sides of the intersection, as well as devices for draining water from pipelines of heating networks, channels, tunnels or cases at a distance of no more than 100 m from the border of the structures being crossed.
6.14. When laying heat networks in cases, enhanced anti-corrosion protection of pipes of heat networks and cases should be provided, and at the intersections of electrified railways and tram tracks, additionally active electrochemical protection, electrically insulating supports and control and measuring points.
A gap of at least 100 mm must be provided between the thermal insulation and the case.
6.15. At the intersections during the underground laying of heat networks with gas pipelines, it is not allowed to pass gas pipelines through the building structures of chambers, impassable channels and niches of heat networks.
6.16*. When heating networks intersect existing water supply and sewerage networks located above pipelines of heating networks, as well as when crossing gas pipelines, it is necessary to provide for the installation of cases on pipelines of water supply, sewerage and gas at a length of 2 m on both sides of the intersection (in the light). Cases should include protective covering from corrosion.
6.17. At the intersections of heating networks during their underground laying in channels or tunnels with gas pipelines, devices for sampling for gas leakage should be provided on heating networks at a distance of no more than 15 m on both sides of the gas pipeline.
When laying heating networks with associated drainage at the intersection with the gas pipeline, drainage pipes should be provided without holes at a distance of 2 m on both sides of the gas pipeline with hermetically sealed joints.
6.18*. At the inlets of pipelines of heating networks into buildings in gasified areas, it is necessary to provide devices that prevent the penetration of water and gas into buildings, and in non-gasified areas - water.
6.19*. At the intersection of ground heat networks with overhead power lines and electrified railways, grounding of all electrically conductive elements of heat networks (with a resistance of grounding devices of not more than 10 Ohms) located at a horizontal distance of 5 m in each direction from the wires should be provided.
6.20*. The laying of heat networks along the edges of terraces, ravines, slopes, artificial excavations should be provided outside the prism of soil collapse from soaking. At the same time, when buildings and structures are located under a slope for various purposes measures should be taken to remove emergency water from heating networks in order to prevent flooding of the building area.
A heat network is a complex engineering and construction structure that serves to transport heat using a coolant (water or steam) from a source (CHP or boiler house) to heat consumers.
From collectors direct network water CHPP or from district boiler houses with the help of main heat pipelines, hot water is supplied to the urban area. The main heat pipelines have branches, to which the intra-quarter wiring is connected to the central heating points (CHPs). The CTP is heat exchange equipment with regulators, providing apartments and premises with hot water.
Heat pipelines can be underground and aboveground.
Above-ground heat pipelines are usually laid in territories industrial enterprises and industrial zones not subject to development, at the intersection a large number railway tracks, i.e. everywhere, where either the not quite aesthetic appearance of heat pipelines does not play a big role, or access to the revision and repair of heat pipelines is difficult. On underground heat pipelines, they are more durable and better suited for repairs.
Rice. The main types of above-ground laying of heat pipelines a-on free-standing supports (masts), b-on flyovers, c - on suspended (wa - D) ntovye) structures, 1 - metal "/ top, 2 - suspended supports, 3 - thrust
In residential areas, for aesthetic reasons, underground laying of heat pipelines is used, which can be channelless and channeled.
With channelless laying, sections of the heat pipeline are laid on special supports directly at the bottom of dug soil channels, joints are welded together, they are protected from the effects of an aggressive environment and covered with soil. Channelless laying is the cheapest, but heat pipes are tested external load from soil pressure (the depth of the heat pipeline should be 0.7 m), are more susceptible to aggressive environments (soil) and less maintainable.
Rice. Types of channelless heat pipelines "A - in a prefabricated and monolithic shell; b - cast and prefabricated cast; c - filling
During channel laying, heat pipes are placed in channels made of prefabricated reinforced concrete elements manufactured at the factory. With such a laying, the heat pipeline is unloaded from the hydrostatic action of the soil, is located in more comfortable conditions, more available for repair.
According to the possibility of access to heat pipelines, the channels are divided into
through, semi-through and impassable.
Rice. Placement of pipelines and cables in the communication manifold: 1- plumbing; 2- electrical cables; 3- lamp; 4- technological pipelines; 5- heat pipes
In the passage channels, in addition to pipelines for supply and return network water, they place water pipes drinking water, power cables, etc. These are the most expensive channels, but also the most reliable, as they allow you to organize constant easy access for revisions and repairs, without disturbing road surfaces and pavements. Such channels are equipped with lighting and natural ventilation.
The internal dimensions of the collectors are determined by the following requirements:
A) the width of the passage must be at least 800 mm, height 1800 mm;
B) the distance in the light from the surface of the insulation of the heat pipes to the wall and floor of the collector - 200 mm with a pipeline diameter of 500 ... 700 mm and 220 mm with a pipeline diameter of 800 ... 900 mm and before the overlap of the collector, respectively - 120 and 150 mm;
B) distance between the insulation surfaces of heat pipelines - 200 mm (with a pipeline diameter of 500.. .900 mm);
D) the distance from the surface of the water pipes, pressure sewerage and air ducts to the building structures of the collector and to the cables is at least 200 mm;
E) vertical distance between consoles for laying power cables - 200 mm, for control cables and communication cables - 150 mm;
E) horizontal clear distance between power cables should be equal to the cable diameter, but not less than 35 mm.
Rice. 3.2. Laying a heat supply network in an impassable channel: a - prefabricated from iron concrete slabs; b - vaulted with a support frame;
1- iron concrete base: 2- wall block; 3- hinged thermal insulation; 4- floor block; 5- pillow; 6- reinforced concrete vault
Non-passable channels allow you to place only the supply and return heat pipes, to access which it is necessary to tear off the soil layer and remove the upper part of the channel. Most of the heat pipelines are laid in impassable channels and channelless. Impassable channels are used for pipes with a diameter of 500-700 mm. Channels can be reinforced concrete, asbestos-cement and metal. Outside, the channels are isolated from moisture with bitumen and pasted over with a waterproofing material.
Semi-through channels are constructed in cases where constant, but rare access is required to the heat pipes. Semi-through channels have a height of at least 1400 mm, which allows a person to move in it in a half-bent state, performing inspection and minor repairs of thermal insulation.
Section content
Thermal networks according to the method of laying are divided into underground and aboveground (air). Underground laying of pipelines of heating networks is carried out: in channels of impassable and semi-passage cross-section, in tunnels (passage channels) with a height of 2 m or more, in common collectors for the joint laying of pipelines and cables for various purposes, in intra-quarter collectors and technical undergrounds and corridors, channelless.
Above-ground laying of pipelines is carried out on free-standing masts or low supports, on overpasses with a solid span structure, on masts with pipe suspension on rods (cable-stayed structure) and on brackets.
A special group of structures includes special structures: bridge crossings, underwater crossings, tunnel crossings and transitions in cases. These structures, as a rule, are designed and built according to separate projects with the involvement of specialized organizations.
The choice of the method and designs for laying pipelines is determined by many factors, the main of which are: the diameter of pipelines, the requirements for the operational reliability of heat pipelines, the cost-effectiveness of structures and the method of construction.
When placing a heat network route in areas of existing or prospective urban development, for architectural reasons, underground pipelines are usually accepted. In the construction of underground heating networks, the laying of pipelines in impassable and semi-passage channels has received the greatest application.
The channel design has a number of positive properties that meet the specific operating conditions of hot pipelines. Channels are a building structure that protects pipelines and thermal insulation from direct contact with the soil, which exerts both mechanical and electrochemical effects on them. The design of the channel completely unloads the pipelines from the action of the mass of soil and temporary transport loads, therefore, when calculating their strength, only stresses arising from the internal pressure of the coolant, their own weight and temperature elongations pipelines that can be determined with a reasonable degree of accuracy.
Laying in channels provides free temperature movement of pipelines both in the longitudinal (axial) and transverse directions, which makes it possible to use their self-compensating ability at the corner sections of the heating network route.
The use of natural flexibility of pipelines for self-compensation in channel laying makes it possible to reduce the number or completely abandon the installation of axial (gland) expansion joints that require the construction and maintenance of chambers, as well as bent expansion joints, the use of which is undesirable in urban conditions and leads to an increase in pipe costs by 8- fifteen%.
The design of the channel lining is universal, as it can be applied under various hydrogeological soil conditions.
With sufficient tightness of the building structure of the channel and properly functioning drainage devices, conditions are created that prevent the penetration of surface and ground water, which provides non-moisturizing thermal insulation and protects the outer surface of steel pipes from corrosion. The route of heat networks laid in channels (unlike channelless) can be chosen without significant difficulties along the passable and impassable territory of the city together with other communications, bypassing or with a slight approximation to existing structures, and also taking into account various planning requirements (promising changes in the terrain, the purpose of the territory, etc.).
One of the positive properties of the channel lining is the possibility of using light materials (mineral wool, fiberglass, etc.) with a low coefficient of thermal conductivity as a suspended thermal insulation of pipelines, which makes it possible to reduce heat loss in networks.
By performance the laying of heating networks in impassable and semi-passage channels has significant differences. Obstructed canals inaccessible for inspection without opening pavement, excavation and disassembly of the building structure, do not allow to detect the damage to the thermal insulation and pipelines, as well as to eliminate them prophylactically, which leads to the need for repair work at the time of emergency damage.
Despite the disadvantages, laying in impassable channels is a common type of underground laying of heat networks.
In semi-passage channels accessible for the passage of operating personnel (with disconnected heat pipelines), inspection and detection of damage to thermal insulation, pipes and building structures, as well as their current repairs can be performed in most cases without opening and disassembling the channel, which significantly increases reliability and service life. thermal networks. However, the internal dimensions of semi-through channels exceed the dimensions of non-through channels, which naturally increases their construction cost and material consumption. Therefore, semi-through channels are mainly used when laying pipelines of large diameters or in certain sections of heating networks when the route passes through a territory that does not allow excavation, as well as at a large depth of the channels, when the backfill above the ceiling exceeds 2.5 m.
As operating experience shows, pipelines of large diameters laid in impassable channels inaccessible for inspection and current repair, are most susceptible to accidental damage due to external corrosion. These damages lead to a long-term interruption of heat supply to entire residential areas and industrial enterprises, the production of emergency and restoration work, disruption of traffic, disruption of landscaping, which is associated with high material costs and danger to operating personnel and the public. The damage caused as a result of damage to pipelines of large diameters cannot be compared with damage to pipelines of medium and small diameters.
Considering that the rise in the cost of construction of single-cell semi-passage channels compared to impassable channels with a diameter of heating networks of 800 - 1200 mm is insignificant, their use should be recommended in all cases and throughout the heating mains of the indicated diameters. Recommending the laying of pipelines of large diameters in semi-through channels, one cannot fail to note their advantages over non-passage channels in terms of maintainability, namely, the ability to replace worn pipelines in them over a considerable distance without opening and disassembling the building structure using closed method production of installation works.
The essence of the closed method of replacing worn pipelines is to remove them from the channel by horizontal movement simultaneously with the installation of new insulated pipelines using a jacking installation.
The need for the construction of tunnels (passage channels) arises, as a rule, at the head sections of the main heat networks that branch off from large CHPPs, when it is necessary to lay a large number of pipelines hot water and couple. In such heating tunnels, the laying of cables of high and low currents is not recommended due to the practical impossibility of creating the required constant temperature regime in it.
Heating tunnels are built mainly on the transit sections of large-diameter pipelines laid from thermal power plants located on the periphery of the city, when the above-ground laying of pipelines cannot be allowed for architectural and planning reasons.
Tunnels should be located in the most favorable hydrogeological conditions to avoid the installation of deep associated drainage and drainage pumping stations.
Common collectors, as a rule, should be provided in the following cases: if it is necessary to simultaneously place two-pipe heating networks with a diameter of 500 to 900 mm, a water supply system with a diameter of up to 500 mm, communication cables 10 pcs. and more, electrical cables voltage up to 10 kV in the amount of 10 pcs. and more; during the reconstruction of urban highways with a developed underground economy; with a lack of free space in the cross profile of streets for placing networks in trenches; at intersections with main streets.
In exceptional cases, upon agreement with the customer and operating organizations, it is allowed to lay pipelines with a diameter of 1000 mm and water lines up to 900 mm, air ducts, cold pipelines, circulating water supply pipelines and other engineering networks in the collector. The laying of all types of gas pipelines in common urban sewers is prohibited [1].
Common collectors should be laid along city streets and roads in a straight line, parallel to the axis of the carriageway or the red line. It is advisable to place the collectors on the technical strips and under the strips of green spaces. The longitudinal profile of the collector must provide gravity drainage of emergency and groundwater. The slope of the collector tray should be taken at least 0.005. The depth of the collector must be assigned taking into account the depth of the intersected communications and other structures, bearing capacity structures and temperature regime inside the collector.
When deciding whether to lay pipelines in a tunnel or sewer, consideration should be given to ensuring that drainage and emergency water can be diverted from the sewer to existing storm drains and natural water bodies. The placement of the collector in plan and profile in relation to buildings, structures and parallel communications should ensure the possibility of construction work without compromising the strength, stability and working condition of these structures and communications.
Tunnels and collectors located along city streets and roads are usually built in an open way using standard prefabricated reinforced concrete structures, the reliability of which must be checked taking into account the specific local conditions of the route (characteristics of hydrogeological conditions, traffic loads, etc.).
Depending on the number and type of engineering networks laid together with pipelines, a common collector can be one- or two-section. The choice of design and internal dimensions of the collector should also be made depending on the availability of laid communications.
The design of common collectors should be carried out in accordance with the scheme of their construction for the future, drawn up taking into account the main provisions of the master plan for the development of the city for the estimated period. During the construction of new areas with green streets and free planning of residential development, heating networks, together with other underground networks, are placed outside the carriageway - under technical lanes, green spaces, and in exceptional cases - under sidewalks. It is recommended to place engineering underground networks in undeveloped areas near the right of way of streets and roads.
The laying of heat networks on the territory of newly constructed areas can be carried out in collectors constructed in residential areas and microdistricts to accommodate engineering communications serving this development [2], as well as in technical undergrounds and technical corridors of buildings.
Laying of distribution heating networks with a diameter of up to D 300 mm in technical corridors or basements of buildings with a clear height of at least 2 m is allowed, subject to the possibility of their normal operation (ease of maintenance and repair of equipment). Pipelines should be laid on concrete supports or brackets, and compensation for temperature elongations should be carried out by U-shaped bent expansion joints and corner sections of pipes. Technical underground must have two entrances that do not communicate with the entrances to the living quarters. Electrical wiring should be carried out in steel pipes, and the design of fixtures should exclude access to lamps without special devices. It is forbidden to arrange storage or other premises in the places where the pipeline passes. The laying of heating networks in microdistricts along routes coinciding with other engineering communications should be provided combined in common trenches with the placement of pipelines in channels or without channels.
The method of overground (air) laying of heat networks has limited application in the conditions of the existing and prospective development of the city due to the architectural and planning requirements for structures of this type.
Above-ground laying of pipelines is widely used in industrial areas and individual enterprises, where they are placed on overpasses and masts together with industrial steam pipelines and technological pipelines, as well as on brackets fixed on the walls of buildings.
The above-ground method of laying has a significant advantage over the underground one in the construction of heating networks in areas with a high level of standing groundwater, as well as in subsiding soils and in permafrost areas.
It should be taken into account that the design of thermal insulation and the actual pipelines during air laying are not exposed to the destructive action of ground moisture, and therefore their durability is significantly increased and heat losses are reduced. The cost-effectiveness of the above-ground laying of heat networks is also essential. Even under favorable soil conditions, in terms of capital costs and the consumption of building materials, air laying of pipelines of medium diameters is more economical than underground laying in channels by 20–30%, and for large diameters, by 30–40%.
In connection with the increased design and construction of out-of-town CHPPs and nuclear heat supply plants (NPPs) for centralized heat supply of large cities, issues of increasing the operational reliability and durability of transit heating mains of large diameter (1000 - 1400 mm) and length while reducing their metal consumption and spending material resources. The existing experience in design, construction and operation of elevated heating mains of large diameter (1200-1400 mm) with a length of 5-10 km gave positive results, which indicates the need for their further construction. Aboveground laying of heating mains is especially advisable under adverse hydrogeological conditions, as well as on sections of the route located on an undeveloped territory, along highways and at the intersection of small water barriers and ravines.
When choosing methods and designs for laying heat networks, special construction conditions in areas should be taken into account: with seismicity of 8 points or more, the spread of permafrost and subsidence from soaking soils, as well as in the presence of peat and silty soils. Additional requirements for heat networks under special construction conditions are set out in SNiP 2.04.07-86*.
Channel laying satisfies most of the requirements, however, its cost, depending on the diameter, is 10-50% higher than channelless. Channels protect pipelines from the impact of ground, atmospheric and flood waters. Pipelines in them are laid on movable and fixed supports, while organized thermal elongation is ensured.
The technological dimensions of the channel are taken based on the minimum clear distance between the pipes and structural elements, which, depending on the diameter of the pipes 25-1400 mm, respectively, is taken equal to: to the wall 70-120 mm; to overlap 50-100 mm; to the surface of the insulation of the adjacent pipeline 100-250 mm. Channel depth
are taken based on the minimum volume of earthworks and the uniform distribution of concentrated loads from vehicles on the floor. In most cases, the thickness of the soil layer above the ceiling is 0.8-1.2 m, but not less than 0.5 m.
At district heating for laying heating networks, impassable, semi-through or through channels are used. If the laying depth exceeds 3 m, then in order to be able to replace pipes, semi-through or through channels are constructed.
impassable channels used for laying pipelines with a diameter of up to 700 mm, regardless of the number of pipes. The design of the channel depends on the moisture content of the soil. In dry soils, block channels with concrete or brick walls or reinforced concrete single- and multi-cell channels are more often arranged. AT soft soils First, a concrete base is made, on which a reinforced concrete slab is installed. At high level groundwater for their removal at the base of the channel, a drainage pipeline is laid. The heating network in impassable channels, if possible, is placed along the lawns.
At present, channels are mainly arranged from prefabricated reinforced concrete tray elements (regardless of the diameter of the pipelines being laid) of types KL, KLs, or wall panels KS types, etc. The channels are covered with flat reinforced concrete slabs. The bases of channels of all types are made of concrete slabs, lean concrete or sand preparation.
If it is necessary to replace pipes that have failed, or when repairing a heating network in impassable channels, it is necessary to break the soil and disassemble the channel. In some cases, this is accompanied by the opening of the bridge or asphalt pavement.
semi-through channels. AT difficult conditions crossings of pipelines of the heating network of existing underground utilities, under the roadway, with a high level of standing groundwater, semi-passage channels are arranged instead of impassable ones. They are also used when laying a small number of pipes in places where, according to operating conditions, the opening of the roadway is excluded, as well as when laying pipelines of large diameters (800-1400 mm). The height of the semi-through channel is assumed to be at least 1400 mm. Channels are made of prefabricated reinforced concrete elements - bottom slabs, wall block and floor slabs.
through channels. Otherwise they are called collectors; they are built in the presence of a large number of pipelines. They are located under bridges of large highways, on the territory of large industrial enterprises, in areas adjacent to the buildings of thermal power plants. Together with heat pipelines, other underground communications are also placed in these channels: electrical and telephone cables, water supply, low pressure gas pipeline, etc. For inspection and repair in collectors, free access of maintenance personnel to pipelines and equipment is provided.
Collectors are made of reinforced concrete ribbed slabs, links frame structure, large blocks and bulk elements. They are equipped with lighting and natural supply and exhaust ventilation with triple air exchange, providing air temperature no more than 30°C, and a device for removing water. Entrances to the collectors are provided every 100-300 m. To install compensating and locking devices on the heating network, special niches and additional manholes should be made.
Channelless laying. To protect pipelines from mechanical influences, with this method, the gaskets arrange reinforced thermal insulation - a shell. The advantages of channelless laying of heat pipelines are the relatively low cost of construction and installation work, a small amount of earthwork and a reduction in construction time. Its disadvantages include the increased susceptibility of steel pipes to external soil, chemical and electrochemical corrosion.
With this type of laying, movable supports are not used; pipes with thermal insulation are laid directly on a sand cushion, poured onto a previously leveled bottom of the trench. Fixed supports for channelless pipe laying, as well as for channel laying, are reinforced concrete shield walls installed perpendicular to the heat pipes. These supports, with small diameters of heat pipes, are usually used outside the chambers or in chambers with a large diameter at high axial forces. To compensate for thermal elongation of pipes, bent or stuffing box compensators are used, located in special niches or chambers. At the turns of the route, in order to avoid clamping the pipes in the ground and to ensure their possible movement, impassable channels are constructed.
For channelless laying, backfill, prefabricated and monolithic types of insulation are used. A monolithic shell made of autoclaved reinforced foam concrete has become widespread.
Above ground lining. This type of gasket is the most convenient in operation and repair and is characterized by minimal heat loss and ease of detection of accident sites. Supporting structures for pipes are free-standing supports or masts that ensure that the pipes are located at the right distance from the ground. With low supports, the clear distance (between the surface of the insulation and the ground) with a group of pipes up to 1.5 m wide is assumed to be 0.35 m and not less than 0.5 m for a larger width. The supports are usually made of reinforced concrete blocks, the masts and flyovers are made of steel and reinforced concrete. The distance between the supports or masts for above-ground laying of pipes with a diameter of 25-800 mm is assumed to be 2-20 m. Sometimes one or two intermediate suspension supports are arranged using stretch marks to reduce the number of masts and reduce capital investments in the heating network.
For maintenance of fittings and other equipment installed on the pipelines of the heating network, special platforms with fences and stairs are arranged: stationary at a height of 2.5 m or more and mobile - at a lower height. In places of installation of main valves, drain, drainage and air devices, insulated boxes are provided, as well as devices for lifting people and fittings.
5.2. Drainage of thermal networks
When laying underground heat pipes, in order to avoid water penetration to thermal insulation, an artificial lowering of the groundwater level is provided. For this purpose, together with heat pipelines, drainage pipelines are laid below the base of the channel by 200 mm. The drainage device consists of a drainage pipe and a filtration material of sand and gravel. Depending on the working conditions, various drainage pipes are used: for non-pressure drainage - bell-shaped ceramic, concrete and asbestos-cement pipes, for pressure pipes - steel and cast iron diameter not less than 150 mm.
At bends and with differences in pipe laying, manholes are arranged like sewer wells. In straight sections, such wells are provided for at least 50 m. drainage pipes. Pumping stations They are built, as a rule, from reinforced concrete rings with a diameter of 3 m. The station has two compartments - a machine room and a reservoir for receiving drainage water.
5.3. Buildings on thermal networks
Heating chambers designed to service equipment installed on heating networks with underground laying. The dimensions of the chamber are determined by the diameter of the pipelines of the heating network and the dimensions of the equipment. In the chambers, shutoff valves, stuffing box and drainage devices etc. The width of the passages is taken at least 600 mm, and the height - at least 2 m.
Heating chambers are complex and expensive underground structures, therefore they are provided only in places where shut-off valves and stuffing box expansion joints are installed. The minimum distance from the ground surface to the top of the chamber ceiling is assumed to be 300 mm.
At present, heat-extraction chambers made of prefabricated reinforced concrete are widely used. In some places, the chambers are made of brick or monolithic reinforced concrete.
On heat pipelines with a diameter of 500 mm and above, electric gate valves with a high spindle are used, therefore, an above-ground pavilion with a height of about 3 m is built above the recessed part of the chamber.
Supports. To ensure organized joint movement of the pipe and insulation during thermal elongation, movable and fixed supports are used.
fixed supports, designed to fix pipelines of heating networks at characteristic points, they are used for all laying methods. Characteristic points on the route of the heating network are considered to be the places of branches, the installation sites of valves, stuffing box compensators, mud collectors and the installation sites of fixed supports. The most widespread are shield supports, which are used both for channelless laying and for laying pipelines of heating networks in impassable channels.
The distances between the fixed supports are usually determined by calculating the strength of the pipes at the fixed support and depending on the magnitude of the compensating capacity of the accepted expansion joints.
Movable supports installed with channel and channelless laying of pipelines of the heating network. There are the following types of different designs of movable supports: sliding, roller and suspended. Sliding supports are used for all laying methods, except channelless. Rollers are used for above-ground laying along the walls of buildings, as well as in collectors, on brackets. Suspension supports are installed with above-ground laying. In places of possible vertical movements of the pipeline, spring supports are used.
The distance between the movable supports is taken based on the deflection of the pipelines, which depends on the diameter and wall thickness of the pipes: the smaller the pipe diameter, the smaller the distance between the supports. When laying pipelines with a diameter of 25-900 mm in the channels, the distance between the movable supports is assumed to be 1.7-15 m, respectively. When laying above ground, where a slightly larger pipe deflection is allowed, the distance between the supports for the same pipe diameters is increased to 2-20 m.
Compensators used to relieve thermal stresses that occur in pipelines during elongation. They can be flexible U-shaped or omega-shaped, articulated or stuffing box (axial). In addition, the existing pipeline turns at an angle of 90-120 ° are used, which work as compensators (self-compensation). The installation of expansion joints is associated with additional capital and operating costs. Minimum costs are obtained in the presence of self-compensation sections and the use of flexible compensators. When developing projects for heating networks, they take the minimum number axial expansion joints, making maximum use of the natural compensation of heat pipes. The choice of the type of compensator is determined by the specific conditions for laying pipelines of heating networks, their diameter and parameters of the coolant.
Anti-corrosion coating of pipelines. To protect heat pipelines from external corrosion caused by electrochemical and chemical processes under the influence of the environment, anti-corrosion coatings are used. Coatings made in the factory are of high quality. The type of anti-corrosion coating depends on the temperature of the coolant: bituminous primer, several layers of isol on insulating mastic, wrapping paper or putty and epoxy enamel.
Thermal insulation. For thermal insulation of pipelines of heating networks use various materials: mineral wool, foam concrete, armo-foam concrete, aerated concrete, perlite, asbestos cement, sovelite, expanded clay concrete, etc. For channel laying, suspension insulation from mineral wool is widely used, for channelless - from autoclaved armo-foam concrete, asphalt-toizol, bitumoperlite and foam glass, and sometimes and backfill insulation.
Thermal insulation consists, as a rule, of three layers: heat-insulating, integumentary and finishing. The cover layer is designed to protect the insulation from mechanical damage and moisture ingress, i.e. to preserve the thermal properties. For the device of the cover layer, materials are used that have the necessary strength and moisture permeability: roofing felt, glassine, fiberglass, foil insulation, sheet steel and duralumin.
As a cover layer for channelless laying of heat pipelines in moderately humid sandy soils apply reinforced waterproofing and asbestos-cement plaster on a wire mesh frame; for channel laying - asbestos-cement plaster on a wire mesh frame; for above-ground laying - asbestos-cement semi-cylinders, sheet steel casing, galvanized or painted aluminum paint.
Suspension insulation is a cylindrical shell on the surface of the pipe, made of mineral wool, molded products (plates, shells and segments) and autoclaved foam concrete.
The thickness of the thermal insulation layer is taken according to the calculation. As the design temperature of the coolant, the maximum is taken if it does not change during the working period of the network (for example, in steam and condensate networks and hot water pipes), and the average for the year if the temperature of the coolant changes (for example, in water networks). The ambient temperature in the collectors is assumed to be +40°C, the soil on the axis of the pipes is the average for the year, the outside air temperature for above-ground laying is the average for the year. In accordance with the norms for designing heat networks, the maximum thickness of thermal insulation is taken based on the laying method:
For above-ground laying and in collectors with a pipe diameter of 25-1400
mm insulation thickness 70-200 mm;
In channels for steam networks - 70-200 mm;
For water networks - 60-120 mm.
Fittings, flange connections and other fittings of heating networks, as well as pipelines, are covered with a layer of insulation with a thickness equal to 80% of the thickness of the pipe insulation.
With channelless laying of heat pipelines in soils with increased corrosive activity, there is a danger of corrosion of pipes from stray currents. To protect against electrical corrosion, measures are taken to prevent the penetration of stray currents to metal pipes, or arrange the so-called electrical drainage or cathodic protection (cathodic protection stations).
The plant of information technologies "LIT" in the city of Pereslavl-Zalessky produces flexible heat-insulating products made of polyethylene foam with a closed pore structure "Energoflex". They are environmentally friendly, as they are made without the use of chlorofluorocarbons (freon). During operation and processing, the material does not release toxic substances into the environment and does not have harmful effects on the human body upon direct contact. Working with it does not require special tools and increased security measures.
"Energoflex" is designed for thermal insulation of engineering communications with a coolant temperature from minus 40 to plus 100 °C.
Energoflex products are manufactured in following form:
Tubes 73 standard sizes with an internal diameter from 6 to 160 mm and
wall thickness from 6 to 20 mm;
Rolls 1 m wide and 10, 13 and 20 mm thick.
The coefficient of thermal conductivity of the material at 0°C is 0.032W/(m-°C).
Mineral wool heat-insulating products are produced by the enterprises of JSC "Termosteps" (Tver, Omsk, Perm, Samara, Salavat, Yaroslavl), AKSI (Chelyabinsk), JSC "Tizol", Nazarovsky ZTI, plant "Komat" (Rostov -on-Don), CJSC " Mineral wool"(Zheleznodorozhny, Moscow Region), etc.
Imported materials from ROCKWOLL, Ragos, Izomat, etc. are also used.
The performance properties of fibrous heat-insulating materials depend on the composition of the used by various manufacturers raw materials and technological equipment and vary over a fairly wide range.
Technical thermal insulation made of mineral wool is divided into two types: high-temperature and low-temperature. CJSC "Mineralnaya vata" produces thermal insulation "ROCKWOLL" in the form of fiberglass mineral wool boards and mats. More than 27% of all fiber products produced in Russia thermal insulation materials falls on the share of URSA thermal insulation, produced by JSC "Fleiderer-Chudovo". These products are made of staple glass fiber and are characterized by high thermal and acoustic characteristics. Depending on the brand of the product, the coefficient of thermal conductivity
such insulation ranges from 0.035 to 0.041 W/(m-°C), at a temperature of 10°C. Products are characterized by high environmental performance; they can be used if the temperature of the coolant is in the range from minus 60 to plus 180°C.
CJSC Izolyatsionny Zavod (St. Petersburg) produces insulated pipes for heating systems. Here, reinforced concrete is used as insulation, the advantages of which include:
High limiting temperature of application (up to 300°С);
High compressive strength (not less than 0.5 MPa);
Can be used for channelless laying at any depth
bin laying of heat pipelines and in all soil conditions;
The presence of a passivating protective layer on the insulated surface
a film that occurs when foam concrete comes into contact with pipe metal;
The insulation is non-combustible, which allows it to be used in all
types of laying (aboveground, underground, channel or channelless).
The thermal conductivity coefficient of such insulation is 0.05-0.06 W/(m-°C).
One of the most promising ways Today is the use of pre-insulated channelless pipelines with polyurethane foam (PPU) insulation in a polyethylene sheath. The use of pipelines of the "pipe in pipe" type is the most progressive way of energy saving in the construction of heating networks. in the USA and Western Europe, especially in the northern regions, these designs have been used since the mid-60s. In Russia - only from the 90s.
The main advantages of such structures:
Increasing the durability of structures up to 25-30 years or more, i.e. in
2-3 times;
Reduction of heat losses up to 2-3% compared to existing ones
20^40% (and more) depending on the region;
Reducing operating costs by 9-10 times;
Reducing the cost of repairing heating mains by at least 3 times;
Decreased capital costs in the construction of new heating pipelines in
1.2-1.3 times and a significant (2-3 times) reduction in construction time;
A significant increase in the reliability of heating mains constructed according to
new technology;
The possibility of using a system of operational remote control
control over the moisture content of the insulation, which allows timely response
to violate the integrity steel pipe or polyethylene guide
insulation coating and prevent leaks and accidents in advance.
On the initiative of the Government of Moscow, Gosstroy of Russia, RAO UES of Russia, CJSC MosFlowline, TVEL Corporation (St. Petersburg) and a number of other organizations, the Association of Manufacturers and Consumers of Industrial Polymer Insulation Pipelines was established in 1999.
CHAPTER 6. CRITERIA FOR SELECTING THE BEST OPTION
Channel laying satisfies most of the requirements, however, its cost, depending on the diameter, is 10-50% higher than channelless. Channels protect pipelines from the impact of ground, atmospheric and flood waters. Pipelines in them are laid on movable and fixed supports, while organized thermal elongation is ensured.
The technological dimensions of the channel are taken based on the minimum clear distance between the pipes and structural elements, which, depending on the diameter of the pipes 25-1400 mm, respectively, is taken equal to: to the wall 70-120 mm; to overlap 50-100 mm; to the surface of the insulation of the adjacent pipeline 100-250 mm. Channel depth
are taken based on the minimum volume of earthworks and the uniform distribution of concentrated loads from vehicles on the floor. In most cases, the thickness of the soil layer above the ceiling is 0.8-1.2 m, but not less than 0.5 m.
With district heating, impassable, semi-through or through channels are used for laying heating networks. If the laying depth exceeds 3 m, then in order to be able to replace pipes, semi-through or through channels are constructed.
impassable channels used for laying pipelines with a diameter of up to 700 mm, regardless of the number of pipes. The design of the channel depends on the moisture content of the soil. In dry soils, block channels with concrete or brick walls or reinforced concrete single- and multi-cell channels are more often arranged. In weak soils, a concrete base is first made, on which a reinforced concrete slab is installed. At a high level of groundwater, a drainage pipeline is laid at the base of the canal to drain it. The heating network in impassable channels, if possible, is placed along the lawns.
At present, channels are predominantly made of prefabricated reinforced concrete tray elements (regardless of the diameter of the pipelines being laid) of types KL, KLs, or wall panels of types KS, etc. The channels are covered with flat reinforced concrete slabs. The bases of channels of all types are made of concrete slabs, lean concrete or sand preparation.
If it is necessary to replace pipes that have failed, or when repairing a heating network in impassable channels, it is necessary to break the soil and disassemble the channel. In some cases, this is accompanied by the opening of the bridge or asphalt pavement.
semi-through channels. In difficult conditions where pipelines of the heating network intersect existing underground utilities, under the roadway, with a high level of standing groundwater, semi-passage channels are arranged instead of impassable ones. They are also used when laying a small number of pipes in places where, according to operating conditions, the opening of the roadway is excluded, as well as when laying pipelines of large diameters (800-1400 mm). The height of the semi-through channel is assumed to be at least 1400 mm. Channels are made of prefabricated reinforced concrete elements - bottom slab, wall block and floor slab.
through channels. Otherwise they are called collectors; they are built in the presence of a large number of pipelines. They are located under bridges of large highways, on the territory of large industrial enterprises, in areas adjacent to the buildings of thermal power plants. Together with heat pipelines, other underground communications are also placed in these channels: electric and telephone cables, water supply, low-pressure gas pipeline, etc. For inspection and repair in the collectors, free access for maintenance personnel to pipelines and equipment is provided.
Collectors are made of reinforced concrete ribbed slabs, frame structure links, large blocks and bulk elements. They are equipped with lighting and natural supply and exhaust ventilation with triple air exchange, providing an air temperature of not more than 30 ° C, and a device for removing water. Entrances to the collectors are provided every 100-300 m. To install compensating and locking devices on the heating network, special niches and additional manholes must be made.
Channelless laying. To protect pipelines from mechanical influences, with this method, the gaskets arrange reinforced thermal insulation - a shell. The advantages of channelless laying of heat pipelines are the relatively low cost of construction and installation work, a small amount of earthwork and a reduction in construction time. Its disadvantages include the increased susceptibility of steel pipes to external soil, chemical and electrochemical corrosion.
With this type of laying, movable supports are not used; pipes with thermal insulation are laid directly on a sand cushion, poured onto a previously leveled bottom of the trench. Fixed supports for channelless pipe laying, as well as for channel laying, are reinforced concrete shield walls installed perpendicular to the heat pipes. These supports, with small diameters of heat pipes, are usually used outside the chambers or in chambers with a large diameter at high axial forces. To compensate for thermal elongation of pipes, bent or stuffing box compensators are used, located in special niches or chambers. At the turns of the route, in order to avoid clamping the pipes in the ground and to ensure their possible movement, impassable channels are constructed.
For channelless laying, backfill, prefabricated and monolithic types of insulation are used. A monolithic shell made of autoclaved reinforced foam concrete has become widespread.
Above ground lining. This type of gasket is the most convenient in operation and repair and is characterized by minimal heat loss and ease of detection of accident sites. Supporting structures for pipes are free-standing supports or masts that ensure that the pipes are located at the right distance from the ground. With low supports, the clear distance (between the surface of the insulation and the ground) with a group of pipes up to 1.5 m wide is assumed to be 0.35 m and not less than 0.5 m for a larger width. The supports are usually made of reinforced concrete blocks, the masts and flyovers are made of steel and reinforced concrete. The distance between the supports or masts for above-ground laying of pipes with a diameter of 25-800 mm is assumed to be 2-20 m. Sometimes one or two intermediate suspension supports are arranged using stretch marks to reduce the number of masts and reduce capital investments in the heating network.
For maintenance of fittings and other equipment installed on the pipelines of the heating network, special platforms with fences and stairs are arranged: stationary at a height of 2.5 m or more and mobile - at a lower height. In places of installation of main valves, drain, drainage and air devices, insulated boxes are provided, as well as devices for lifting people and fittings.
5.2. Drainage of thermal networks
When laying underground heat pipes, in order to avoid water penetration to thermal insulation, an artificial lowering of the groundwater level is provided. For this purpose, together with heat pipelines, drainage pipelines are laid below the base of the channel by 200 mm. The drainage device consists of a drainage pipe and a filtration material of sand and gravel. Depending on the working conditions, various drainage pipes are used: for non-pressure drainage - socketed ceramic, concrete and asbestos-cement pipes, for pressure pipes - steel and cast iron pipes with a diameter of at least 150 mm.
At bends and with differences in pipe laying, manholes are arranged like sewer wells. In straight sections, such wells are provided for at least 50 m. If the drainage of drainage water into reservoirs, ravines or sewers by gravity is not possible, pumping stations are built, which are placed near the wells at a depth depending on the mark of the drainage pipes. Pumping stations are built, as a rule, from reinforced concrete rings with a diameter of 3 m. The station has two compartments - a machine room and a reservoir for receiving drainage water.
5.3. Buildings on thermal networks
Heating chambers designed to service equipment installed on heating networks with underground laying. The dimensions of the chamber are determined by the diameter of the pipelines of the heating network and the dimensions of the equipment. Shut-off valves, gland and drainage devices, etc. are installed in the chambers. The width of the passages is taken to be at least 600 mm, and the height - at least 2 m.
Heating chambers are complex and expensive underground structures, therefore they are provided only in places where shut-off valves and stuffing box expansion joints are installed. The minimum distance from the ground surface to the top of the chamber ceiling is assumed to be 300 mm.
At present, heat-extraction chambers made of prefabricated reinforced concrete are widely used. In some places, the chambers are made of brick or monolithic reinforced concrete.
On heat pipelines with a diameter of 500 mm and above, electric gate valves with a high spindle are used, therefore, an above-ground pavilion with a height of about 3 m is built above the recessed part of the chamber.
Supports. To ensure organized joint movement of the pipe and insulation during thermal elongation, movable and fixed supports are used.
fixed supports, designed to fix pipelines of heating networks at characteristic points, they are used for all laying methods. Characteristic points on the route of the heating network are considered to be the places of branches, the installation sites of valves, stuffing box compensators, mud collectors and the installation sites of fixed supports. The most widespread are shield supports, which are used both for channelless laying and for laying pipelines of heating networks in impassable channels.
The distances between the fixed supports are usually determined by calculating the strength of the pipes at the fixed support and depending on the magnitude of the compensating capacity of the accepted expansion joints.
Movable supports installed with channel and channelless laying of pipelines of the heating network. There are the following types of different designs of movable supports: sliding, roller and suspended. Sliding supports are used for all laying methods, except channelless. Rollers are used for above-ground laying along the walls of buildings, as well as in collectors, on brackets. Suspension supports are installed with above-ground laying. In places of possible vertical movements of the pipeline, spring supports are used.
The distance between the movable supports is taken based on the deflection of the pipelines, which depends on the diameter and wall thickness of the pipes: the smaller the pipe diameter, the smaller the distance between the supports. When laying pipelines with a diameter of 25-900 mm in the channels, the distance between the movable supports is assumed to be 1.7-15 m, respectively. When laying above ground, where a slightly larger pipe deflection is allowed, the distance between the supports for the same pipe diameters is increased to 2-20 m.
Compensators used to relieve thermal stresses that occur in pipelines during elongation. They can be flexible U-shaped or omega-shaped, articulated or stuffing box (axial). In addition, the existing pipeline turns at an angle of 90-120 ° are used, which work as compensators (self-compensation). The installation of expansion joints is associated with additional capital and operating costs. The minimum costs are obtained in the presence of self-compensation sections and the use of flexible expansion joints. When developing projects for heating networks, a minimum number of axial expansion joints is adopted, making maximum use of the natural compensation of heat pipes. The choice of the type of compensator is determined by the specific conditions for laying pipelines of heating networks, their diameter and parameters of the coolant.
Anti-corrosion coating of pipelines. To protect heat pipelines from external corrosion caused by electrochemical and chemical processes under the influence of the environment, anti-corrosion coatings are used. Coatings made in the factory are of high quality. The type of anti-corrosion coating depends on the temperature of the coolant: bituminous primer, several layers of isol on insulating mastic, wrapping paper or putty and epoxy enamel.
Thermal insulation. For thermal insulation of pipelines of heating networks, various materials are used: mineral wool, foam concrete, armored foam concrete, aerated concrete, perlite, asbestos cement, sovelite, expanded clay concrete, etc. For channel laying, suspension insulation from mineral wool is widely used, for channelless - from autoclaved armored foam concrete, asphalt -toisol, bitumen perlite and foam glass, and sometimes backfill insulation.
Thermal insulation consists, as a rule, of three layers: heat-insulating, integumentary and finishing. The cover layer is designed to protect the insulation from mechanical damage and moisture ingress, i.e. to preserve the thermal properties. For the device of the cover layer, materials are used that have the necessary strength and moisture permeability: roofing felt, glassine, fiberglass, foil insulation, sheet steel and duralumin.
As a cover layer for channelless laying of heat pipelines in moderately moist sandy soils, reinforced waterproofing and asbestos-cement plaster over a wire mesh frame are used; for channel laying - asbestos-cement plaster on a wire mesh frame; for above-ground laying - asbestos-cement semi-cylinders, sheet steel casing, galvanized or painted aluminum paint.
Suspension insulation is a cylindrical shell on the surface of the pipe, made of mineral wool, molded products (plates, shells and segments) and autoclaved foam concrete.
The thickness of the thermal insulation layer is taken according to the calculation. As the design temperature of the coolant, the maximum is taken if it does not change during the working period of the network (for example, in steam and condensate networks and hot water pipes), and the average for the year if the temperature of the coolant changes (for example, in water networks). The ambient temperature in the collectors is assumed to be +40°C, the soil on the axis of the pipes is the average for the year, the outside air temperature for above-ground laying is the average for the year. In accordance with the norms for designing heat networks, the maximum thickness of thermal insulation is taken based on the laying method:
For above-ground laying and in collectors with a pipe diameter of 25-1400
mm insulation thickness 70-200 mm;
In channels for steam networks - 70-200 mm;
For water networks - 60-120 mm.
Fittings, flange connections and other fittings of heating networks, as well as pipelines, are covered with a layer of insulation with a thickness equal to 80% of the thickness of the pipe insulation.
With channelless laying of heat pipelines in soils with increased corrosive activity, there is a danger of corrosion of pipes from stray currents. To protect against electrical corrosion, measures are taken to prevent the penetration of stray currents to metal pipes, or arrange the so-called electrical drainage or cathodic protection (cathodic protection stations).
The plant of information technologies "LIT" in the city of Pereslavl-Zalessky produces flexible heat-insulating products made of polyethylene foam with a closed pore structure "Energoflex". They are environmentally friendly, as they are made without the use of chlorofluorocarbons (freon). During operation and processing, the material does not release toxic substances into the environment and does not have harmful effects on the human body upon direct contact. Working with it does not require special tools and increased security measures.
"Energoflex" is designed for thermal insulation of engineering communications with a coolant temperature from minus 40 to plus 100 °C.
Energoflex products are produced in the following form:
Tubes 73 standard sizes with an internal diameter from 6 to 160 mm and
wall thickness from 6 to 20 mm;
Rolls 1 m wide and 10, 13 and 20 mm thick.
The coefficient of thermal conductivity of the material at 0°C is 0.032W/(m-°C).
Mineral wool heat-insulating products are produced by the enterprises of JSC "Termosteps" (Tver, Omsk, Perm, Samara, Salavat, Yaroslavl), AKSI (Chelyabinsk), JSC "Tizol", Nazarovsky ZTI, plant "Komat" (Rostov -on-Don), CJSC Mineralnaya Vata (Zheleznodorozhny, Moscow Region), etc.
Imported materials from ROCKWOLL, Ragos, Izomat, etc. are also used.
The performance properties of fibrous heat-insulating materials depend on the composition of the feedstock and process equipment used by various manufacturers and vary over a fairly wide range.
Technical thermal insulation made of mineral wool is divided into two types: high-temperature and low-temperature. CJSC "Mineralnaya vata" produces thermal insulation "ROCKWOLL" in the form of fiberglass mineral wool boards and mats. More than 27% of all fibrous heat-insulating materials produced in Russia fall on the share of URSA heat-insulation produced by Fleiderer-Chudovo JSC. These products are made of staple glass fiber and are characterized by high thermal and acoustic characteristics. Depending on the brand of the product, the coefficient of thermal conductivity
such insulation ranges from 0.035 to 0.041 W/(m-°C), at a temperature of 10°C. Products are characterized by high environmental performance; they can be used if the temperature of the coolant is in the range from minus 60 to plus 180°C.
CJSC Izolyatsionny Zavod (St. Petersburg) produces insulated pipes for heating systems. Here, reinforced concrete is used as insulation, the advantages of which include:
High limiting temperature of application (up to 300°С);
High compressive strength (not less than 0.5 MPa);
Can be used for channelless laying at any depth
bin laying of heat pipelines and in all soil conditions;
The presence of a passivating protective layer on the insulated surface
a film that occurs when foam concrete comes into contact with pipe metal;
The insulation is non-combustible, which allows it to be used in all
types of laying (aboveground, underground, channel or channelless).
The thermal conductivity coefficient of such insulation is 0.05-0.06 W/(m-°C).
One of the most promising methods today is the use of pre-insulated channelless pipelines with polyurethane foam (PUF) insulation in a polyethylene sheath. The use of pipelines of the "pipe in pipe" type is the most progressive way of energy saving in the construction of heating networks. In the USA and Western Europe, especially in the northern regions, these designs have been used since the mid-60s. In Russia - only from the 90s.
The main advantages of such structures:
Increasing the durability of structures up to 25-30 years or more, i.e. in
2-3 times;
Reduction of heat losses up to 2-3% compared to existing ones
20^40% (and more) depending on the region;
Reducing operating costs by 9-10 times;
Reducing the cost of repairing heating mains by at least 3 times;
Decreased capital costs in the construction of new heating pipelines in
1.2-1.3 times and a significant (2-3 times) reduction in construction time;
A significant increase in the reliability of heating mains constructed according to
new technology;
The possibility of using a system of operational remote control
control over the moisture content of the insulation, which allows timely response
check for violation of the integrity of the steel pipe or polyethylene guide
insulation coating and prevent leaks and accidents in advance.
On the initiative of the Government of Moscow, Gosstroy of Russia, RAO UES of Russia, CJSC MosFlowline, TVEL Corporation (St. Petersburg) and a number of other organizations, the Association of Manufacturers and Consumers of Industrial Polymer Insulation Pipelines was established in 1999.
CHAPTER 6. CRITERIA FOR SELECTING THE BEST OPTION