In the event that the thermal insulation of pipelines is carried out correctly, this will significantly increase the life of the system and ensure the most efficient operation. The thermal insulation of heating pipelines itself must be carried out in accordance with all established norms and standards.
Basic rules of thermal insulation
So, in general, there are several basic requirements (recommendations, rules) that should be observed when installing thermal insulation:- For thermal insulation, high quality materials should be used, the characteristics of which are suitable for the operating conditions.
- Installation of thermal insulation is carried out exclusively by specialists - this is the only way to guarantee the correct and high-quality performance of all work.
- Completion of all plumbing and welding work;
- Checking the density and strength of the surface;
- Coating of the pipeline with anti-corrosion agents.
Installation of thermal insulation: cylinder design
Thermal insulation of process pipelines will be most effective if it is a prefabricated or prefabricated system. In other words, it will be a cylinder structure. The essence of the work is quite simple - laying thermal insulation on the pipe with its further adjustment and strengthening.When performing work, some requirements for thermal insulation of pipelines should be observed:
- Installation should start from the flange connections, while the thermal insulation cylinders should be mounted as tightly as possible;
- Seams should not form one continuous horizontal line;
- Special bandages are used as fasteners - two per cylinder (in increments of 40-50 cm);
- The bandage is fastened with buckles, which are made of aluminum or packing tape.
It should be noted that often, as thermal insulation, such heaters as perlite cement, foam diatomite and silica lime segments are used. After the volume of thermal insulation of the pipeline has been calculated, the material in the form of mats should be laid in such a way that all seams are closed - then the insulation is fixed to the pipes using wire hangers in increments of 50 cm.
Remarkably, in case of failure of the heat-insulating structural element, you can easily selectively dismantle the thermal insulation of pipelines and replace the damaged element with a new one.
Thermal insulation and structural temperature - features
It should be remembered that the calculation of the thickness of the thermal insulation of pipelines depends on some important factors, for example, the temperature of the substance transported through the pipes. If the substance has a very high temperature, then thermal insulation is carried out using cylinders that are laminated with aluminum foil. For this type of thermal insulation, a protective coating is not applied. As a bandage, it is recommended to use a material made on the basis of aluminum.In the event that water passes through the pipeline, the temperature of which does not exceed 12 ° C, the thickness of the thermal insulation of the pipelines can be increased, and hydrofiberized cylinders are used as an insulator. As an additional protection, a vapor barrier is installed, while the seams of the structure must be insulated (glued) with high quality.
Attention! In case of damage to the vapor barrier layer, it should be properly glued or completely replaced with a new one.
In general, it becomes clear that the calculation of the thermal insulation of pipelines is made depending on the type of insulation, climatic factors and the liquid that is transmitted through the pipes.
Thermal insulation of pipelines is a set of measures aimed at preventing the heat exchange of the carrier transported through them with the environment. Thermal insulation of pipelines is used not only in heating systems and hot water supply, but also where technology requires the transportation of substances with a certain temperature, for example, refrigerants.
The meaning of thermal insulation is the use of means that provide thermal resistance to heat transfer of any kind: contact and carried out by means of infrared radiation.
The greatest application, expressed in numbers, is the thermal insulation of pipelines of heating networks. Unlike Europe, the centralized heating system dominates the entire post-Soviet space. Only in Russia alone, the total length of heating networks is more than 260 thousand kilometers.
Much less often, insulation for heating pipes is used in private households with an autonomous heating system. Only in a few northern regions, private houses are connected to the central heating main with heating pipes placed outside.
For some types of boilers, for example, powerful gas or diesel ones, the requirements of the set of rules SP 61.13330.2012 “Thermal insulation of equipment and pipelines” require a separate location from the building - in a boiler room several meters away from the heated object. In their case, the strapping fragment passing through the street necessarily needs to be insulated.
On the street, insulation of heating pipelines is required both for open ground placement and for hidden laying underground. The latter method is channel - a reinforced concrete gutter is first laid in the trench, and pipes are already placed in it. Channelless placement - directly in the ground. The insulating materials used differ not only in thermal conductivity, but also in vapor and water resistance, durability and installation methods.
The need to insulate cold water pipes is not so obvious. However, it cannot be dispensed with in the case when the water supply is laid in an open ground way - the pipes must be protected from freezing and subsequent damage. But inside buildings, it is also necessary to insulate water pipes - to prevent moisture condensation on them.
Glass wool, mineral wool
Proven insulating materials. They meet the requirements of SP 61.13330.2012, SNiP 41-03-2003 and fire safety standards for any installation method. They are fibers with a diameter of 3-15 microns, similar in structure to crystals.
Glass wool is made from waste glass production, mineral wool from silicon-containing slag and silicate metallurgy waste. The differences in their properties are insignificant. They are produced in the form of rolls, stitched mats, plates and pressed cylinders.
It is important to be careful with materials and be able to handle them correctly. Any manipulations should be performed in protective overalls, gloves and a respirator.
Mounting
The pipe is wrapped or lined with cotton wool, ensuring a uniform filling density over the entire surface. Then the insulation, without too much pressure, is fixed with a tie wire. The material is hygroscopic and easily gets wet, therefore, the insulation of external pipelines made of mineral or glass wool requires the installation of a vapor barrier layer made of a material with low vapor permeability: roofing material or polyethylene film.
A cover layer is placed on top of it, which prevents the penetration of precipitation - a casing made of roofing sheet, galvanized iron or sheet aluminum.
Basalt (stone) wool
Thicker than glass wool. The fibers are made from a melt of gabbro-basalt rocks. Absolutely non-combustible, briefly withstands temperatures up to 900 ° C. Not all insulating materials can, like basalt wool, be in long-term contact with surfaces heated to 700 ° C.
The thermal conductivity is comparable to polymers, ranging from 0.032 to 0.048 W/(m K). High performance indicators make it possible to use its thermal insulation properties not only for pipelines, but also for the arrangement of hot chimneys.
Available in several versions:
- like glass wool, rolls;
- in the form of mats (stitched rolls);
- in the form of cylindrical elements with one longitudinal slot;
- in the form of pressed cylinder fragments, the so-called shells.
The last two versions have different modifications, differing in density and the presence of a heat-reflecting film. The slot of the cylinder and the edges of the shells can be made in the form of a spike connection. 
SP 61.13330.2012 contains an indication that the thermal insulation of pipelines must comply with safety and environmental protection requirements. By itself, basalt wool fully complies with this indication.
Manufacturers often resort to tricks: to improve consumer performance - to give it hydrophobicity, greater density, vapor permeability, they use impregnations based on phenol-formaldehyde resins. Therefore, it cannot be called 100% safe for humans. Before using basalt wool in a residential area, it is advisable to study its hygiene certificate.
Mounting
Insulation fibers are stronger than those of glass wool, so the ingress of its particles into the body through the lungs or skin is almost impossible. However, when working, it is still recommended to use gloves and a respirator.
The installation of a roll web does not differ from the way in which glass wool heating pipes are insulated. Thermal protection in the form of shells and cylinders is attached to pipes using mounting tape or a wide bandage. Despite some hydrophobicity of basalt wool, pipes insulated with it also require a waterproof vapor-permeable sheath made of polyethylene or roofing felt, and an additional one made of tin or dense aluminum foil.
Foamed polyurethane (polyurethane foam, PPU)
Reduces heat loss by more than half compared to glass wool and mineral wool. Its advantages include: low thermal conductivity, excellent waterproofing properties. The service life declared by the manufacturers is 30 years; The operating temperature range is from -40 to +140 °С, the maximum withstand temperature for a short time is 150 °С.
The main brands of PPU belong to the combustibility group G4 (highly combustible). When changing the composition with the help of the addition of fire retardants, they are assigned G3 (normally combustible).
Although polyurethane foam is excellent as an insulating material for heating pipes, keep in mind that SP 61.13330.2012 allows the use of such thermal insulation only in single-family residential buildings, and SP 2.13130.2012 limits their height to two floors.
The heat-insulating coating is produced in the form of shells - semicircular segments with tongue-and-groove locks at the ends. Ready-made steel pipes insulated from polyurethane foam with protective sheath made of polyethylene.
Mounting
The shells are fixed on the heating pipe with the help of ties, clamps, plastic or metal bandage. Like many polymers, the material does not tolerate prolonged exposure to sunlight, so an open above-ground pipeline using PU foam shells needs a cover layer, for example, made of galvanized steel.
For underground channelless placement, heat-insulating products are laid on waterproof and temperature-resistant mastics or adhesives, and are insulated from the outside with a waterproof coating. It is also necessary to take care of the anti-corrosion treatment of the surface of metal pipes - even the glued shell joint is not tight enough to prevent condensation of water vapor from the air.
Expanded polystyrene (polystyrene, PPS)
It is produced in the form of shells, outwardly practically no different from polyurethane foam - the same dimensions, the same tongue-and-groove locking connection. But the temperature range of application, from -100 to +80 ° C, with all this external similarity, makes it impossible or limited to use it for thermal insulation of a heating pipeline.
SNiP 41-01-2003 "Heating, ventilation and air conditioning" states that in the case of a two-pipe heat supply system, the maximum supply temperature can reach 95 ° C. As for the return risers of heating, everything is not so simple here: it is believed that the temperature in them does not exceed 50 ° C.
Foam insulation is more often used for cold water and sewer pipes. However, it can be used over other heaters with a higher allowable application temperature.
The material has a number of some disadvantages: it is highly combustible (even with the addition of fire retardants), it does not tolerate chemical influences (it dissolves in acetone), it crumbles with balls during prolonged exposure to solar radiation.
There are other, non-polystyrene foams - formaldehyde, or shortly, phenolic. In fact, this is a completely different material. It is devoid of these shortcomings, is successfully used as thermal insulation of pipelines, but is not so widespread.
Mounting
The shells are fixed on the pipe with a bandage or foil tape, it is allowed to glue them to the pipe and to each other.
Foamed polyethylene
The temperature range at which the use of foamed high-pressure polyethylene is allowed is from -70 to +70 °С. The upper limit is not combined with the maximum temperature of the heating pipe, usually taken into account in the calculations. This means that the material is of little use as a thermal insulation of pipelines, but can be used as an insulating layer over a heat-resistant one.
Polyethylene foam insulation has found practically no alternative application as protection against freezing of water pipes. Very often it is used as a vapor barrier and waterproofing.
The material is produced in the form of sheets or in the form of a flexible thick-walled pipe. The latter form is more often used, as it is more convenient for insulating water pipes. The standard length is 2 meters. The color varies from white to dark gray. An IR reflective aluminum foil coating may be available. The differences relate to internal diameters (from 15 to 114 mm), wall thickness (from 6 to 30 mm).
The application ensures that the temperature on the pipe is above the dew point, which means it prevents the formation of condensate.
Mounting
An easy way with worse vapor barrier results is to cut the foam material into a small indentation along the side surface, open the edges and put it on the pipe. Then wrap along the entire length with mounting tape.
A more complex solution (and by no means always feasible) is to turn off the water, completely disassemble the insulated sections of the water supply and put on solid sections. Then put everything back together. Secure the polyethylene with zip ties. In this case, only the junction of the segments will become a weak point. It can be glued or also wrapped with tape.
foamed rubber
Foamed synthetic rubber with a closed cell structure is the most versatile material for keeping warm and cold. Designed for temperature range from -200 to +150 °C. Conforms to all requirements of ecological safety.
It is used as insulation for cold water pipelines, insulation for heating pipes, often found in refrigeration and ventilation systems. Heating pipes laid inside buildings and insulated with rubber do not require the installation of a vapor barrier layer.
Outwardly similar to polyethylene foam, it is also available in the form of sheets and flexible thick-walled pipes. Installation is also practically the same, except that such thermal insulation of pipes can be attached to glue.
Liquid heaters
A technology has been successfully applied that allows self-spraying foam from a polyurethane composition onto ready-made structures. Excellent adhesive properties allow it to be used not only for insulating pipelines, but also applied to other elements that need insulation: foundation, walls, roofing. The coating, in addition to thermal protection, provides hydro, vapor barrier, provides anti-corrosion resistance.
Conclusion
Properly performed installation of thermal insulation is a guarantee that the pipe will not lose heat, and the consumer will not freeze. Freezing of the cold water supply pipeline invariably leads to its rupture. Until recently, in hidden and open heating mains, glass wool was the usual insulating material. Its shortcomings stem from one another. Such coverage requires constant monitoring.
Even with a slight damage to the protective surface layer, vapor permeability and hygroscopicity nullify all savings. Moisture causes low thermal resistance and premature failure. Modern insulating materials with a cellular structure that are inert to the effects of steam and water will help to significantly improve the situation: polyurethane foam, foamed rubber, polyethylene foam.
Mats with a one-sided lining can be used, while the mats are installed with the lining towards the frame (inside the structure). Fully prefabricated structures based on stitched mats in linings can also be used. 4.6. Thermal insulation of cold drinking water storage tanks in water supply systems. For thermal insulation of cold water storage tanks in water supply systems, it is recommended, first of all, to use stitched mats in fiberglass linings on both sides. The design of thermal insulation is similar to that given in paragraphs 4.5.4 - 4.5.5 (with a frame made of wooden bars) and is distinguished by the presence of a vapor barrier layer. Stitching mats manufactured by CJSC ISOROK are installed in one or two layers, depending on the estimated thickness of the insulation, between the posts of a wooden frame, fastened with pins with tying of galvanized wire along the pins (Fig. 59 - 64).
Technologies for installing thermal insulation of pipelines
FIELD OF APPLICATION OF HEAT-INSULATING MATS OF MINERAL WOOL PLUGGED PRODUCTION OF CJSC "ISOROK" 1.1. Heat-insulating pierced mineral wool mats are designed for use in industrial thermal insulation at temperatures of insulated surfaces from minus 180°С to plus 700°С and in accordance with the recommendations of sections 2 and 3. service mats piercing is significantly reduced.
1.2. Stitched mats can be used to insulate industrial equipment of industrial and housing facilities, including:
- vertical and horizontal cylindrical technological apparatuses of enterprises of chemical, oil refining, gas, metallurgical, etc.
Sewn mats made of mineral wool - so that the pipes live longer!
Info
CUTWOOL®MP stitched mats are made of mineral basalt wool on a synthetic binder with carpet stitching with glass roving, lined with fiberglass on both sides of the mat, according to TU 5762-002-89646568-2013. Marking: CUTWOOL®MP2 M50-2400.100.1000, TU 5762-002-89646568-2013, where: MP is a symbol for stitched mats; 2 - lining with fiberglass on both sides; M50 - brand of product; 2400 - mat length (mm); 100 – mat thickness (mm); 1000 - mat width (mm). Specifications: Length (mm) 2400 Width (mm) 1000 Thickness (mm) from 50 to 120; Density, kg/m3 from 30 to 100; Compressibility, % no more than 20 Humidity, % no more than 0.5 Thermal conductivity, W/mK 0.033 Flammability group NG Application temperature* from -180 to +600; * standard application temperature +4000C, more on special order.
Benefits of embroidered mineral wool mats
They are characterized by low smoke generation, and also effectively prevent the spread of fire, providing additional time for the rescue of personnel and equipment.
- Excellent soundproofing. Stitched mats guarantee excellent sound insulation of both residential premises and industrial workshops.
- Ability to withstand high temperatures. Mineral wool stitched mats are a material that can withstand loads up to 700°C! And some types of material, for example, having a combined composition, with the addition of mullite-silica, operate at temperatures up to 1100°C!
- Chemical resistance.
Mineral wool mats pierced are not afraid of the effects of such organic substances as oils, alkalis, solvents. - Low water absorption. An important ability of pierced mineral wool mats is to resist the influence of moisture.
Heat-insulating products CJSC "izorok". part 2
To compensate for temperature deformations, serration of coating elements or other design solutions can be applied. 4.3.14. The design of the protective coating of the vertical apparatus is shown in fig. 47 and 48. The protective coating of vertical apparatuses is also fastened with self-tapping screws 4x12 with anti-corrosion coating or rivets.
Attention
Screw (rivet) installation step: vertically 150 - 200 mm, horizontally - no more than 300 mm. 4.3.15. In the protective coating of the apparatus, expansion joints must be provided in height, in which the elements of the protective coating rest on unloading devices or hinged brackets (Fig. 79) and are not fixed horizontally (circumferences). Hinged brackets can be installed on the sheets of the previous row.
Unloading devices are installed along the height of the apparatus with a step in height of not more than 3-4 meters.
403 forbidden
By density mats are produced grade 100. 2.3. The limiting temperature of application is determined by the temperature resistance of mineral wool and lining materials. The limiting temperature for the use of mats, depending on the type of facing material, is given in Table 2.1. Table 2.1. Application temperature of piercing mats.
Name of lining material Without lining material or with fiberglass lining on one side (install with fabric facing outward) 600-700 (see clause 1.1.) Cloth, mesh, fiberglass canvas (with lining material sewn on both sides) 450 2.4. Mineral wool mats grade 100 with and without facings belong to the group of non-combustible materials (NG) according to GOST 30244. 2.5. Nominal dimensions of mats with indication of limit deviations are given in Table 2.2. Table 2.2.
Permissible temperature difference (to - tk) Air temperature, t0 , °С Relative air humidity, φ, % 50 60 70 80 90 Calculated difference, (to - tk) °С 10 9.8 7.3 5.1 3.1 1.5 12 9.9 7.3 5.1 3.1 1.5 14 10.1 7.4 5.2 3.2 1.5 16 10.2 7.6 5.3 3.3 1, 5 18 10.4 7.7 5.4 3.3 1.5 20 10.5 7.8 5.4 3.4 1.5 22 10.7 7.9 5.5 3.4 1.5 24 10.9 8.0 5.6 3.5 1.6 26 11.0 8.2 5.7 3.5 1.6 28 11.2 8.3 5.8 3.6 1.6 30 11, 4 8.4 5.9 3.6 1.6 5.3.4. The heat transfer coefficient, (αn), should be taken in accordance with Appendix 2.1. 5.3.5. When designing, it is necessary to take the thickness of thermal insulation in the structure, a multiple of 10 mm, taking into account the current range of pierced mineral wool mats produced by ZAO ISOROK, while rounding up only.
5.3.6.
Unloading devices are also installed at the upper and lower bottoms of the apparatus. To make the structure of the protective coating rigid, the elements of the coating can be zigzag. 4.4. Thermal insulation of gas ducts and air ducts of rectangular section. 4.4.1. Heat-insulating stitched mats are recommended to be used for insulation of gas ducts of thermal power plants, objects of ferrous and non-ferrous metallurgy, etc., and rectangular air ducts. A variant of the design of the thermal insulation of a gas duct with a rectangular cross section is shown in fig. 49. Fastening of the heat-insulating layer is provided with the help of pins (welded, plug-in) and bandages. At the corners of the thermal insulation of rectangular gas ducts, metal linings made of the coating material are installed under the bandages or wire rings replacing them.
Thermal insulation of pipelines with pierced mats
Temperature regimes of water heating networks, ºС 95-70 150-70 180-70 Pipeline Estimated coolant temperature, ™ ºС Supply 65 90 110 Return 50 50 50 : - for year-round operation of the heating network - the average annual temperature of the outside air; - when working only during the heating period - the average for the heating period; c) with a depth of laying the top of the channel more than 0.7 m - the average annual temperature of the soil at the depth of laying the axis of the pipelines. 5.4.3. The recommended thickness of insulation from heat-insulating pierced mineral wool mats grade 100, which meets the norms of heat flux density for pipelines of heating networks of two-pipe underground channel laying, located in the European region of Russia, is given in Table 5.4.2.
Thermal insulation of pipelines with stitched mats
The calculated thickness of thermal insulation from pierced mineral wool mats produced by ISOROK CJSC at an air temperature in the room of 20ºС and relative humidity of 60, 70 and 80% is given in Table 5.3.2. 5.3.7. If the temperature and humidity in the room differ from those indicated, the thickness of the insulation should be determined by formulas (6) or (7), since with an increase in the relative humidity of the air in the absence of ventilation, the thickness of the insulation increases significantly. Table 5.3.2. The recommended thickness of thermal insulation from pierced mineral wool mats, which prevents condensation of moisture from the air on the surface of the insulation of pipelines and equipment located in the room.
Outer diameter, mm Relative humidity of the ambient air.
With the greatest effect in the construction of thermal insulation of industrial equipment and pipelines with positive and negative temperatures, the products shown in Table. 1 and 2.
Thermal insulation structures for pipelines
For pipelines with outer diameter from 15 to 159 mm incl. for the heat-insulating layer of embroidered mats of glass staple fiber on a synthetic binder, embroidered mats of mineral and basalt wool, mats of basalt or superfine glass fiber, fastening is used:
for pipelines with an outer diameter of the heat-insulating layer of not more than 200 mm - fastening with a wire with a diameter of 1.2–2 mm in a spiral around the heat-insulating layer (Fig. 1), while the spiral is fixed on wire rings along the edges of the mats. If mats are used in facings, then the edges of the facings of the mats are sewn together with glass thread, silica thread, roving or wire with a diameter of 0.8 mm; for pipelines with an outer diameter of 57 - 159 mm: when laying mats in one layer - bandages from a tape of 0.7x20 mm. The bandage installation step depends on the size of the products used, but not more than 500 mm.
When laying mats with a width of 1,000 mm, bandages are recommended to be installed in increments of 450 mm with an indent of 50 mm from the edge of the product. Two bandages should be installed on a product with a width of 500 mm (Fig. 2); when laying mats in two layers - with rings of wire with a diameter of 2 mm for the inner layer of two-layer structures, bandages - for the outer layer of two-layer heat-insulating structures. Bandages made of tape 0.7x20 mm are installed along the outer layer in the same way as in a single-layer construction.
Black steel bands must be painted to prevent corrosion.
The edges of the plates are sewn together, as indicated above. With two-layer insulation, the edges of the linings of the inner layer are not stitched together.
When using molded products, cylinders or segments for thermal insulation of pipelines, they are fastened with bandages. Two bandages are installed when insulated with cylinders. When insulating with segments, it is recommended to install bandages with a pitch of 250 mm with a product length of 1,000 mm.
For pipelines with an outer diameter of 219 mm or more, for a heat-insulating layer of mats, fastening is used:
- when laying products in one layer- bandages made of tape 0.7x20 mm and pendants made of wire with a diameter of 1.2 mm. Hangers are evenly spaced between the bandages and are attached to the pipeline. Fiberglass linings are installed under the hangers when using mats without lining (Fig. 3).
When using mats in linings, linings are not installed. Fiberglass linings are sewn together;
–when laying products in two layers- rings made of wire with a diameter of 2 mm and pendants made of wire with a diameter of 1.2 mm for the inner layer of two-layer structures. Hangers of the second layer are attached to the hanger of the first layer from below. Bandages made of tape 0.7x20 mm are installed along the outer layer in the same way as in a single-layer construction.
The heat-insulating layer keeps within with consolidation on thickness.
In two-layer constructions, the mats of the second layer must overlap the seams of the inner layer.
For pipelines with an outer diameter of 273 mm or more, in addition to mats, mineral wool slabs with a density of 35-50 kg / m 3 can be used, although the optimal scope is for pipelines with an outer diameter of 530 mm or more. When insulating with plates, the heat-insulating layer can be fastened with bandages and suspensions (Fig. 4).
The location of fasteners - bandages, hangers and rings (with two-layer insulation) is selected taking into account the length of the plates used. Linings made of rolled fiberglass or roofing felt are installed under the pendants. When using boards laminated with fiberglass, glass wool, fiberglass, linings are not installed. The plates are laid with the long side along the pipeline.
In heat-insulating structures with a thickness of less than 100 mm, when using a metal protective coating on horizontal pipelines, support brackets should be installed.
Brackets are installed on horizontal pipelines with a diameter of 108 mm or more with a step of 500 mm along the length of the pipeline.
For pipelines with an outer diameter of 530 mm or more, three brackets are installed in diameter in the upper part of the structure and one at the bottom.
Support brackets are made of aluminum or galvanized steel (depending on the material of the protective coating) with a height corresponding to the thickness of the insulation.
Support rings are installed in horizontal heat-insulating structures of pipelines with a diameter of 219 mm or more with positive temperatures and an insulation thickness of 100 mm or more.
For pipelines with negative temperatures, the supporting structures should have gaskets made of fiberglass, wood or other low-heat-conducting materials to eliminate "cold bridges".
When insulating with dimensionally stable thermal insulation materials such as cylinders, segments of mineral wool or fiberglass, as well as mats such as KVM-50 with vertical grain orientation (manufactured by Isover) or Lamella Mat, support structures on horizontal sections are not required.
On vertical pipelines with outer diameter up to 476 mm incl. fastening of the heat-insulating layer is carried out with bandages and wire rings. To prevent slipping of rings and bandages, wire strings with a diameter of 1.2 or 2 mm should be installed (Fig. 5).
On vertical pipelines with an outer diameter of 530 mm or more, the heat-insulating layer is fastened on a wire frame with the installation of wire strings that prevent the fastening elements (rings, bandages) from slipping.
Rings made of wire with a diameter of 2-3 mm are installed along the length of the pipeline on its surface in increments of 500 mm for plates 1,000 long and 500 mm wide and mats 500 and 1,000 mm wide. Bundles of ties made of wire with a diameter of 1.2 mm are attached to the rings with a step along the arc of the ring of 500 mm (Fig. 6).
There are four ties in the bundle for one-layer insulation and six for two-layer insulation. When using mats with a width of 1,000 mm, the ties pierce the heat-insulating layers and are fixed crosswise. When using mats with a width of 500 mm and plates with a width of 500 mm, the ties pass at the joints of the products.
Bandages from a tape 0.7x20 mm with buckles are installed in increments depending on the width of the product, 2-3 pcs. on the product (plate or mat 1,000–1,250 mm wide) with single-layer insulation and along the outer layer with two-layer insulation. Instead of bandages, rings made of wire with a diameter of 2 mm can be installed along the inner layer of two-layer insulation.
When using mats with a width of 500 mm, two bandages (or rings) should be installed on the product.
The edges of the mats in the facings are sewn with 0.8 mm wire or glass fiber, depending on the type of lining.
The strings can be attached to unloading devices, which are installed in height increments of 3-4 m, or to rings made of wire with a diameter of 5 mm, welded to the surface of the pipeline or its other elements.
Unloading devices are installed on vertical pipelines with a step of 3-4 m in height.
When insulating cold water pipelines, pipelines transporting substances with negative temperatures, as well as pipelines of underground heating networks, galvanized wire, galvanized steel or painted bandages should be used to fasten structural elements.
Designs of thermal insulation of fittings and flange connections
To insulate fittings and flange connections, depending on the material of thermal insulation of the pipeline, both cylinders and pierced mats made of mineral, basalt or glass wool or super-thin basalt fiber can be used.
Plates for insulation of reinforcement, as a rule, are not used.
To isolate fittings and flange connections of pipelines, mats can be used in the form of mattresses with linings made of fiberglass, basalt or silica fabric on all sides. The type of fabric is determined by the temperature of the insulated surface.
A removable metal casing is installed over the mattresses, which can be fastened with locks welded directly to the casing, or bandages with locks installed over the casing (Fig. 7 and 8).
Mattresses are fastened to the surface to be insulated with bandages with buckles and tied with wire on hooks.
Cylinders and mats pierced in linings made of metal mesh or fiberglass are used as a heat-insulating layer as part of prefabricated heat-insulating structures (cases or half-cases) for insulating fittings and flange connections of pipelines (Fig. 9).
In this case, the mats are installed in a case, pinned on cotter pins or fastened with glue. The case is equipped with bandages or locks. Cases are mounted on flange connections or flange fittings.
Constructions of thermal insulation of industrial equipment
To insulate equipment, depending on its geometry, slabs of mineral, basalt or glass wool, or super-thin basalt fiber or stitched mats in linings of fiberglass and metal mesh can be used.Superfine basalt fiber scrims or uncovered mats for insulating equipment should only be used in exceptional cases where no other material can be provided.
Mats are recommended for insulating horizontal and vertical equipment with an outer diameter of 530-1420 mm.
Plates for insulation of equipment with a large radius of curvature and for flat surfaces.
For horizontal and vertical units with outer diameter from 530 to 1420 mm incl. (tanks, heat exchangers, etc.), KVM-50 brand mats and other products with a corrugated structure can be used as a heat-insulating layer, since this does not require the use of supporting structures (on horizontal devices).
Fastening of the heat-insulating layer on horizontal apparatus with an outer diameter of 530 - 1420 mm can be provided by bandages and hangers similar to fastening pipelines (Fig. 10).
To insulate vertical apparatus with an outer diameter of up to 1420 mm, the fastening of the heat-insulating layer is mainly provided for on a wire frame using wire strings (Fig. 11).
Rings installed on the surface of the apparatus are recommended to be made of wire with a diameter of 2-3 mm with a step of 500 or 600 mm, depending on the size and type of heat-insulating material used. Bundles of ties made of wire with a diameter of 1.2 mm are attached along the perimeter of the rings at a distance of 400 or 600 mm from each other when insulated with plates and 500 mm when insulated with pierced mats. The number of ties is determined by the number of heat-insulating layers: 4 - for single-layer insulation, 6 - for two-layer insulation.
After fixing the heat-insulating layer with screeds, it is planned to install bandages from a 0.7x20 mm tape. Three bandages are installed for insulation with plates and two bandages for insulation with mats 1,000 mm wide.
Fastening the heat-insulating layer on devices with a diameter of more than 1,020 mm
On the surface of apparatus with an outer diameter of more than 530 mm, as a rule, staples or bushings must be welded to fasten the heat-insulating layer. Staples and bushings are welded to the surface of vessels and apparatuses at the equipment manufacturer. The location of the brackets is established by the requirements of GOST 17314-81 “Devices for fastening the thermal insulation of steel vessels and apparatus. designs and dimensions. Technical requirements". Removable parts are installed during the installation of thermal insulation.
As a rule, welded parts on vessels and apparatuses are placed:
a) on vertical objects: in vertical and horizontal directions with a step of 500 mm. The distance of welding of fastening elements from anchor bolts of flange joints or welded joints or welds connecting the bottoms (lids) and bodies of vessels and apparatuses can be 70-250 mm. On surfaces (bottoms, covers) facing down, brackets or bushings are welded in increments of 250x250mm;
b) on horizontal objects:
- in the horizontal direction with a step of 500 mm, stepping back from the flange joints or welds connecting the bottoms (lids) and bodies of vessels and apparatuses, at a distance of 70-250 mm;
– in the vertical direction: on the upper half of the object with a step of 500 mm; on the lower half of the object with a step of 250 mm. The step is measured from the plane of the horizontal diameter.
Such an arrangement of fasteners causes difficulties when using products with dimensions different from 500x500, 1,000x1,000 or 1,000x500 mm, typical for plates and mats of domestic production, since it requires the use of additional fasteners to fix the heat-insulating material.
It is recommended to fasten the heat-insulating layer of fibrous materials in the insulation structures of vertical and horizontal devices with an outer diameter of more than 1,020 mm using wire pins with a diameter of 4-5 mm, which are inserted into brackets or bushings welded at the factory.
Heat-insulating products are pricked on pins, which are then bent. Further fixation of the heat-insulating layer can be carried out by bandaging along the bent pins with wire strings with a diameter of 1.2-2.0 mm and bandages, usually installed with a step of 500 mm (Fig. 12).
Another step of installing bandages may be provided.
It can be provided for fastening with bandages (without bandaging with strings) and bandages and rings with two-layer insulation (Fig. 13 and 14).
At the same time, on horizontal devices, rings and bandages are installed in the intervals between the pins with a step of 500 mm when insulated with pierced mats and soft plates. When insulating with canvases made of super-thin basalt fiber, bandages are recommended to be installed in increments of 250 mm.
When insulating vertical devices with bandages and rings located in the gaps between the pins, strings made of wire with a diameter of 2 mm are provided for their fixation (Fig. 15).
If the bandages are installed on the pins, then the strings are not provided.
For single-layer insulation, single pins are used; when insulating in two layers - double pins. Mats and slabs of the inner layer are pierced on pins, one end of which is bent. Then the inner layer is fastened with rings of wire with a diameter of 2 mm. The outer heat-insulating layer is fixed with pins and bandages made of 0.7x20 mm tape.
The dimensions of welded brackets, single and double pins are regulated by GOST 17314.
In the thermal insulation structures of the bottoms of vertical and horizontal apparatus, depending on their diameter and configuration, the heat-insulating layer of fibrous heat-insulating materials can be fastened using wire ties and bandages or strings made of wire with a diameter of 2 mm or pins, bandages or strings.
The fastening of the heat-insulating layer on the bottoms of apparatus with a diameter of more than 1,020 mm is carried out with pins installed in brackets or bushings, and bandages or strings.
Removable structures can be fully assembled - in the form of half-cases or cases, and complete - in the form of mattresses and casings, according to the type used for reinforcement insulation (see Fig. 11, 15).
Unloading devices (rings, brackets) with diaphragms are installed at the flange connections and bottoms of vertical apparatuses and in increments of 3-3.6 m along the apparatus height. The installation step of the unloading devices is determined by the dimensions of the heat-insulating material.
Unloading devices can be welded or bolted to structural elements.
For fixing the plates to the surface of the insulation, pins are provided. Additionally, the plates can be fastened with a wire with a diameter of 1.2-2 mm (ligation by pins).
In the designs of thermal insulation of the bottoms of vertical and horizontal apparatuses using heat-insulating mats and plates, depending on their diameter and configuration, the fastening of the heat-insulating layer from mats or plates can be carried out using wire ties and bandages or strings made of wire with a diameter of 2 mm, or pins, bandages or strings.
As a rule, at one end, bandages and strings are attached to a wire ring welded or tied around the branch pipe, and at the other - to a wire or support ring (unloading device) that are installed at the bottoms (see Fig. 11).
Manholes and flange connections of the apparatus are subject to periodic inspection and therefore removable heat-insulating structures are used for them.
Removable structures can be fully assembled - in the form of half-cases or cases, and complete - in the form of mattresses and casings.
As a heat-insulating layer in the composition of fully assembled structures (half-cases), it is recommended to use stitched mats in linings made of metal mesh or fiberglass.
In this case, as a rule, mats of the brand MM-50, MM-75 or MS-50, MS-75 are attached with cotter pins to the metal surface of the casing. The edges of the metal mesh or fiberglass are sealed inside the metal casing and sewn with a wire with a diameter of 0.8 mm.
The half-case is equipped with locks or bandages. Half-cases are installed on the flanges over the thermal insulation of the apparatus and fastened together. The dimensions and number of half-cases are determined by the dimensions of the flange connection.
With a flange diameter of more than 1.5 m, it is preferable to use a complete design of thermal insulation in the form of mattresses and removable casings.
As part of complete structures, it is recommended to use mats in the form of mattresses with linings on all sides made of fiberglass or silica fabric. For the manufacture of mattresses, it is recommended to use mats without covers, which are wrapped with fiberglass (basalt, silica), the edges of the fiberglass are sewn together. Mattresses are stitched with glass thread, silica thread or wire with a diameter of 0.8 mm. When using mats in fiberglass facings, the edges of the mats are additionally sheathed with fiberglass.
Mats in silica fabric with a stitching of silica thread or wire can be used at the temperature of the insulated surface up to 750 °C.
Mattresses are attached to the insulated surface with bandages with buckles.
When insulating flange connections of large-diameter devices, hooks are sewn to the mattresses. For flange connections of large diameter, two or more mattresses can be provided around the perimeter of the flange. When installing mattresses on a flange connection, the hooks are connected with wire (lacing), then bandages are installed over the mattresses.
The heat-insulating layer is closed with a removable metal casing, which can be fastened with locks welded directly to the casing, or bandages with locks installed over the casing.
For devices, as a rule, metal coatings are provided as a cover layer. For the manufacture of coating elements (cover layer), sheets or strips of aluminum and aluminum alloys, thin-sheet galvanized or roofing (with painting), or thin-sheet stainless steel, metal-layer are provided. The thickness of the coating sheets is from 0.8 to 1.2 mm.
Fastening of the cover layer of thermal insulation of horizontal devices is carried out with self-tapping screws 4x12 with anti-corrosion coating or rivets. Screw (rivet) installation pitch: horizontally 150 - 200 mm, circumferentially - 300 mm (Fig. 17).
To speed up the installation, the elements of the protective coating can be connected by recumbent folds 8–10 mm wide (section G-D) into large-sized paintings.
To make the structure of the coating of thermal insulation rigidity, the elements of the coating are zigzag along the ends horizontally and around the circumference with a zig radius of approximately 5 mm. The coating shall be supported by support rings or other welded support elements.
Support rings (section A-A) are made of tape 2x30, 3x30, 2x40 or 3x40 mm. When thermally insulating objects with positive surface temperatures, metal support structures must have low heat-conducting elements to reduce the temperature on the surface of the protective coating in contact with them. As a rule, supports or gaskets made of asbestos cardboard are used.
For vertical devices, as well as for horizontal ones, metal coatings are used. Metal sheets can be assembled into paintings. As a rule, the connection of sheets with a lying fold is used.
The cover layer of vertical apparatuses is also fastened with 4x12 self-tapping screws with anti-corrosion coating or rivets. Screw (rivet) installation step: vertically 150 - 200 mm, horizontally - no more than 300 mm (Fig. 2 and 18).
Thermal insulation of gas ducts and rectangular air ducts
It is recommended to use heat-insulating boards for thermal insulation of rectangular gas ducts. The fastening of the heat-insulating layer can be carried out using pins (welded, plug-in) and bandages (or wire rings) (Fig. 18 and 19).
At the corners of the thermal insulation of gas ducts of rectangular cross section, metal linings made of the coating material are installed under the bandages or wire rings replacing them.
As a rule, gas ducts have significant ribbing. If the height of the stiffeners is greater than the thickness of the thermal insulation, then they should be insulated. The design of the insulation depends on the configuration of the ribs. Pins, studs, brackets and other fastening elements of thermal insulation and coating can be welded to the ribs.
When insulating air ducts for supply ventilation, the heat-insulating layer of plates can be fastened with pins, wire rings and strings or by gluing with bituminous mastics.
As supporting elements under the coating, wooden blocks or structural fiberglass elements, which are attached to metal brackets, can be used.
Instead of metal brackets, a frame made of wooden bars installed on the surface of the duct can be used. In this case, the metal cover layer is attached to the frame with screws.
A vapor barrier layer is installed over the heat-insulating layer. The joints of the vapor barrier layer are also recommended to be placed on the bars (elements) of the frame.
When used as a heat-insulating layer of boards or mats coated with foil on one side, the joints of the heat-insulating products must be glued with adhesive-backed aluminum tapes. These tapes can also be used as bandages for fastening the thermal insulation layer of foil-coated boards and mats.
If welding of pins to the duct is not allowed, then a wire frame construction can be used, as in the case of pipe insulation. Metal bandages made of 2x30 or 3x30 mm tape with pins welded to them can be used. Such bandages are installed on the surface of the air duct and fastened together with bolts and nuts.
When insulating air ducts for supply ventilation, a vapor barrier layer is installed.
To prevent damage to the vapor barrier layer made of polyethylene film or aluminum foil when using a metal coating with screw fastening, it is recommended to install a protective layer 15-20 mm thick made of fibrous materials (Fig. 20).
Can be used canvas-stitched or needle-punched fiberglass or other materials having a small thickness. Other constructive solutions can be used, for example, fastening the cover with planks.
Thermal insulation of steel vertical cylindrical tanks
For thermal insulation of tanks for storing oil and oil products, it is recommended to use heat-insulating plates made of mineral and glass wool. The plates are attached to the tank wall with pins welded with a pitch of 600x600 or 400x400 mm.For fixing the metal coating, support structures made of vertically arranged steel angles or strips can be provided. The protective cover is attached with screws. Protective coating elements can be combined into paintings.
A frame made of wooden blocks can also be provided. In this case, the cover layer is fastened with screws to the frame of wooden bars vertically and with screws horizontally (Fig. 20).
The installation step of the supporting structures is determined by the dimensions of the elements of the protective coating and heat-insulating plates.
Additional fastening of the plates by tying the pins with wire (in the form of rings or crosswise) can be provided.
Support shelves must be provided along the height of the tank to prevent slipping of the heat-insulating layer. At the place of installation of the supporting shelves, expansion joints in the cover layer are also provided.
Mats in metal mesh linings can also be used to insulate tanks. The step of welding the pins is 500x500 mm.
If bandages are welded to the surface of the tank with a step of 3 m, then a construction of hinged mattresses made of mats with a heat-insulating layer of stitched mats in linings on both sides of fiberglass or fiberglass can be used (Fig. 21).
On hinged mattresses, hooks should be provided for fastening to bandages (Fig. 22).
The mattresses are suspended from the bandages and attracted to the surface of the tank by rings of wire with a diameter of 2 mm. The installation step of the rings should be taken as 500 mm along the length of the mattress (along the height of the tank).
Joints of mattresses are recommended to be sewn together with a wire with a diameter of 0.8 mm.
In this case, the tank roof must be insulated with mats that are laid between the steel angle guides welded to the roof. Instead of a corner, strings made of wire with a diameter of 5 mm can be provided, while the mats are fastened to the strings with a wire with a diameter of 2 mm, and the cover layer is fastened with clamps.
When insulating cold water tanks, the insulation structure made of fibrous materials must have a vapor barrier layer made of polyethylene film, aluminum foil or foil materials.
When using materials with a closed-cell structure (foam glass, foamed rubber), the vapor barrier layer is not installed.
Insulation of pipelines with pierced mineral wool mats
For this type of work, mats are used either without lining, or in linings made of metal mesh (up to a temperature of 700 ° C), glass cloth (up to a temperature of 450 ° C) and cardboard (up to a temperature of 150 ° C).
Coverless mats can also be used for low-temperature insulation (up to -180 °C).
Scope of work
1. Cutting products to a given size.
2. Laying products with fitting in place.
3. Fastening products with wire rings.
4. Seal of seams with waste products.
5. Stitching joints (mats in facings).
6. Additional fastening of products with wire rings or bandages (along the top layer).
Lined mats are used to insulate pipelines with a diameter of 57-426 mm, and mats with linings are used on pipelines with a diameter of 273 mm or more.
Products are laid on the surface of pipelines in one or two layers with overlapping seams and fixed with bandage rings made of packing tape with a cross section of 0.7x20 mm or steel wire with a diameter of 1.2-2.0 mm, installed every 500 mm.
The heat-insulating layer on pipelines with a diameter of 273 mm or more must have additional fastening in the form of wire hangers (Fig. 1).
Fig.1. Insulation with mineral wool pierced mats:
but- pipelines: 1 - wire suspension with a diameter of 2 mm (used for pipelines with a diameter of 273 mm or more); b- gas ducts: 1 - fixing pins with a diameter of 5 mm; 2 - heat-insulating product; 3 - stitching with wire with a diameter of 0.8 mm; 4 - wire with a diameter of 2 mm (fastening of the lower layer); in- flat surfaces: 1 - mineral wool mats; 2 - pins before laying the insulating layer; 3 - pins after laying the insulating layer; 4 G- spheres: 1 - stitching with wire with a diameter of 0.8 mm; 2 - wire ring; 3 - wire bandages; 4 - mineral wool products; 5 - fixing pins
When insulating pipelines with products in metal mesh linings, longitudinal seams should be stitched with wire with a diameter of 0.8 mm. For pipes with a diameter of more than 600 mm, transverse seams are also stitched.
Mineral wool stitched mats are compacted during installation and reach the following density (according to GOST in the design), kg / m; mats brand 100-100/132; grades 125-125/162.
Insulation of pipelines with mineral wool boards on a synthetic binder
Products are applied taking into account their density (brand) on surfaces with a temperature from -60 to +400 °C.
It is not allowed to use plates of grade 50 for thermal insulation of pipelines with a diameter of less than 217 mm, grade 75 - with a diameter of less than 325 mm. Plates of grades 125 and 175 are used for insulation of pipelines and equipment with a diameter of more than 529 mm.