Each, at least indirectly, is familiar with such a concept as "calorie". What is it and ...
When assembling transport networks of various purposes, for example, heating communications or highways intended for distillation of oil and gas until recently used mainly conventional pipes made of steel. With its work, this type of product is not bad for most and today. However, such pipes still have one pretty serious drawback. Whatever the thickness of their walls, protect the distilled fluid from the cold during the winter period they cannot.
The result of freezing of water or coolant in the highways is usually the output of the latter. At the same time, in utility steel networks during the cold season, there is also significant heat loss, which makes their exploitation much more expensive.
What is PPU pipes
To eliminate the movement of the transported on the highways of liquids, the latter during the assembly of the network on the street or are paving very deeply underground, or further insulate with the use of special materials. And the one and other techniques are characterized by consideration and technological complexity. Therefore, the pipes of special design are becoming increasingly popular - pre-insulated.
Products of this type are insulated at the stage of production using a modern insulator, which is characterized by a very low degree of thermal conductivity - polyurethane foam. There are such pipes more expensive. However, the highways collected from them can be served subsequently without the need to repair decades.
PPP pipe design
Externally, such products are very similar to well known to many sandwich chimneys. That is, they consist of three main layers:
the actual steel pipe, according to which liquid pumping will be carried out in the future;
polyurethane foam layer;
external protective shell.
In layer of polyurethane foam in such pipes, special signal cables pass. Thanks to their presence, you can always determine the place of the accident on the highway and quickly make repair work.
What specific specifications may have
The pre-insulated pipes are supplied to the market today in a wide range. Those products can be distinguished by:
diameter;
wall thickness;
the thickness of the insulating layer;
the number of laid signal cables, etc.
The cost of products of this variety directly depends on their diameter and the thickness of the insulating layer. According to the latter, the PPU is chosen with the climate of the region in which the network is assembled, as well as the depth of the latter. In warm areas, highways with a thickness of the insulation layer in 5 cm are usually collected. In the northern regions, pipes with an insulating layer of 10 cm and more are used.
Signal cables in the insulation layer of such products, depending on the diameter, can be laid two or three.
Regulations GOST
Pre-insulated pipes in our country with strict observance of the GOST regulations are made. The insulation used in the manufacture of such products, in any case, must meet the following requirements:
water absorption in volume - 10%;
elasticity of compression is at least 0.3 MPa (deformation in all directions - up to 10%);
density - up to 60 kg / m 3.
When heated to 110 ° C, the length of the insulator is used when assembling pipes, the insulator should not exceed 3%.
Polyurethane foam for insulation pipes can according to various technologies. But most often such material is based on carbon dioxide and freon. In most cases, in the manufacture of pipes, the PPU uses polyurethane foam of such well-proven marks, like "Dow", "Isolan", Hantsman, "Eloostokam".
Types of construction
At the moment, there are two main varieties of pre-insulated pipes on the market:
The first varieties are made of conventional or galvanized steel with insulation of polyurethane foam. Outside, such pipes are trimmed with stainless steel sheets or stainless steel.
Flexible products of this type are manufactured by similar technology. However, such pipes are covered with a shell not from steel, but from corrugated plastic. Of course, too large flexibility such products do not differ. After all, polyurethane foam - the material itself is quite tough and not too elastic. However, a little bending the pipes of this variety during laying is still possible.
Of course, in the manufacture of plastic shells of pre-insulated pipes, GUTs are also complied with mandatory. Used for their assembly usually the highest quality light-stabilized material.
Sometimes protective shells with a warming layer can be supplied separately from the pipes themselves. In this case, before they are assembly, it is pre-checked for tightness, and then coated with an anti-corrosion composition.
How the insulation layer is applied on the PPU pipe
Many domestic factories produce such products. Pre-insulated pipes supply to the Russian market as well, of course, and foreign companies.
If you judge by reviews, the domestic products of this type of quality today at a lower cost are practically no extent inferior to imported. For example, there are simply excellent reviews from consumers such products issued by the "Novosibirsk Plant of Precision Pipe", An Ollovsky Trupping Plant, Stroyzolation Plant (Seversk), etc.
In any case, in the manufacture of such products, specialists are mandatory, among other things, it is also monitored that the adhesion between polyurethane foam and steel pipe is as strong as possible. So that the insulation does not slide along the steel and kept as closely as possible, before applying it, it is carefully cleaned before the formation of a rough surface with the simultaneous removal of rust.
When foaming the most polyurethane foam should be accurately supported by the specified thermal mode. Improve the adhesion between the inner shell with the foam filler can also be processed by the latest discharge.
In order not to have a frozen insulator, a special metal plug is fixed from the end of the pipe. After hardening the material, this element from the pipe preized PPU is removed. For sale such products come with nothing closed by the end of the polyurethane foam layer.
Usal scope
The most widespread PPU pipe was currently received, of course, first of all in industry. These products are used in the assembly mainly:
oil pipelines;
gas pipelines;
steam lines.
The preized pipes and for heat networks intended for pumping heated liquids are very often used. Such communications are usually mounted in hot workshops of enterprises of different specialization.
Recently, the pre-insulated pipes began to conquer enormous popularity and communal services. Organizations of such specialization use these products when laying centralized heating systems and water pipes of cities and towns. The use of such pipes in this case can significantly improve the quality of the service of the population.
Main advantages
Pre-insulated pipes for heat pipes, water pipes, oil pipelines, etc., or rather, for from the assembly, we use in our country, therefore, quite often. But what is explained by such popularity of modern products of this type?
The unconditional pluses of PPU pipes, in comparison with the usual, can be attributed:
the possibility of mounting any communications to the maximum deadlines and with minimal labor costs;
reducing heat loss (usually from 40% to 2%);
significant increase in pipeline efficiency;
increase the timing of the network operation of 2-5 times;
reducing the cost of repairing pipelines.
Due to the presence of a protective shell, such highways are practically not afraid of the effects of aggressive media. PUPP pipelines are allowed without grounding and preliminary improvement of drainage. Polyurethane foam differs, among other things, and by the fact that he does not miss moisture. Consequently, steel pipes isolated using this material are much less affected by rust.
disadvantages
There are practically no minuses of PPU pipes. Perhaps the only drawback of such products is their rather high cost. However, this minus is more compensated by the long service life of the PPU highways and the lack of need for their frequent repairs.
FEATURES OF MONTAGE
PUP pipes are made, therefore, from high-quality steel. Consequently, the installation is made using welding. Of course, the laying of pre-insulated pipes in assembling of various types of industrial and utility networks is performed according to special technology. Polyurethane foam - material, unfortunately, not tolerant of too high temperatures. Therefore, when welding such pipes, special protective screens are used.
After connecting the segments of the wizard, performing the assembly of the PPU highway, it is mandatory to check the quality of the seams. After a complete cooling of the metal in the connecting places on the pipes, among other things, special coupling are superimposed. A feature of such elements of the design of PPU highways is that they are made of heat shrink material. After cooling, such a coupling decreases in size and fits tightly welded, thereby ensuring complete tightness. When using the connecting elements of this type, a small cavity remains in places of pipe connection, into which the mounting foam is subsequently poured or polyurethane foam.
The technology described above is used both when assembling large industrial highways and small household engineering communications networks.
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Pre-insulated heating mains: what are the advantages?
Pre-insulated pipes are a special type of product that is used in layers of large heat mains and heating systems. Unique features such products give not only materials, but also the availability of a technical control system that does not apply to other types of pipes.
Pipeline scheme
1 - pressure corrugated stainless steel pipe; 2 - Explorer indicators (when producing pipes with a system of ADC); 3 - thermal insulation of polyurethane foam;
4 - corrugated protective sheath of polyethylene.
When laying such highways, heat loss is reduced at times, they constitute a value of up to 2%, which was previously considered impossible even when using insulation. Pre-insulated pipes are already fully finished products that do not require additional work when installing, which significantly reduces all costs for installation and further maintenance.
Feature of pre-insulated pipelines
The preserved pipeline is a special system that is created for laying the heating industry. Such pipes possess numerous advantages and features, the main thing is that the pipe consists of several layers, each of which has its own characteristics.
So, part of the pipes, which is intended for underground gasket, is made of steel and polyurethane shell, between which the heat-insulating layer is laid, and for the surfaces of the above-ground system, the outer shell is made of galvanized, which makes it possible to effectively protect the track from corrosion, negative weather conditions, other influences .
Specificity of production
Steel pre-insulated products are designed for laying the heating paints, while the pipelines in the steel or polyethylene sheath are laid in the infantal underground method, and in galvanized - in the passing channels or tunnels above the surface of the Earth.
The pipes themselves are a "sandwich" design, consisting of such layers: pressure steel inner pipe, special SCROS signal wire (technical control), thermal insulation layer (usually from foamed polyurethane), protective shell. A special pipe is obtained consisting of two separate pipes with thermal insulation, which is located between them.
It is the peculiarities of the production that provide stability of pipes to corrosion, which is very important for the constituent elements of any heating industry.
Before starting isolation, the pipe passes a special processing in a shotgun. This gives the surface with light roughness, which improves the adhesion of the thermal insulating layer to the base of the inner tube.
Polyethylene shell is also processed from its inner side using coronary discharges, which guarantees excellent grip between insulation and pipe. All the pipes previously treated in this way acquire their unique properties, allowing them to use them in the most unfavorable conditions.
Technical quality control
Today, insulated pipes are offered that can have shells from various materials. Most often it is a shell of polyethylene and galvanized steel, which can be suitable for laying underground and overhead routes.
The casing from such materials provides protection against any mechanical damage, moisture impacts, corrosion. In addition, the diffusion of polyurethane is prevented, which is the main material for the production of the pipe itself.
Spike pipe connections.
Most often, high density polyethylene is used for the manufacture of an insulating shell, which is considered to be the most effective in underground gaskets. Polyethylene itself is a heat-stabilized, its color is black, it is produced strictly according to GOST 16330, but in some cases GOST 18599 can be used.
It is used for isolation and polyurethane foam, which is perfectly suitable for steel pipes.
All pre-insulated pipes are mandatory undergo technical control, which allows you to guarantee the quality of the product. During laboratory tests, such characteristics of the pipe are determined as:
- density;
- compressive strength at 10 percent deformation;
- volume fraction of all closed pores;
- water absorption during boiling;
- shift strength;
- thermal conductivity.
Welded joints take one hundred percent test with the help of a modern method of ultrasound control, which is a mandatory requirement before implementing.
Advantages of use
The assembly scheme of the details of the pre-insulated flexible system of pipelines.
All prefoliated steel products differ from others to lay the heat mains with such advantages:
- The system of operational remote control makes it possible to significantly increase the strength and reliability of such pipes, reduce all costs for the repair of laid heating parts.
- The deadlines of the service are about 30 years, while simple uninsulated pipelines serve only 10-15 years. This reduces the cost of replacing unsuitable pipes, the maintenance of the route, repair.
- A similar pipe reduces heat loss when used to 2%, although, when laying uninsulated pipelines, such losses are quite significant - from 25%.
- Steel isolated tracks are stacked much easier and faster than ordinary, construction time is reduced by about two or three times, since there is no need to arrange channels and wells, and it becomes the reason for the decline and all costs.
- All steel pipes do not require an additional anti-corrosion coating, as they already have all the necessary properties. This reduces the cost of laying many times.
- The heat resistance of pipes is up to 150 degrees.
You can make such conclusions: all prefoliated pipelines are much more profitable for the heat maintenance device, as they are more modern and less costly. Their durability is more than two times, the operating costs and repair costs reduced. In a word, it is a profitable and promising option.
Materials of the preized pipeline thermal network
For the construction of heat networks used preized pipes and parts
according to the catalogs of manufacturers.
The steel pipe material must comply with the requirements of the rules of the device and
safe operation of steam and hot water pipelines approved
Ministry of Emergency Situations and Ministry of Labor of the Republic of Belarus
(3.1.1 and 3.1.2).
Changing the direction of the heat network pipeline route is performed using
pre-insulated taps with an angle of 15, 30, 45, 60, 75, 90 ° factory manufacture.
Turns of the track at an angle of 15 ° and less carried out by trimming separate
plots of the pipeline by an angle of not more than 5 °.
Armature - prefoliated ball valves (valves).
Compensation of temperature lengthening of pipelines is carried out by
applications L, Z, U-systems, disposable compensators, preheating
pipeline when installing.
The connection of steel pipelines of different diameters is made welding with
using typical transitions.
The connection of the joints of the outer polyethylene pipes is performed using
special shell worn on the pipeline made of low polyethylene
magnifier pressure 273-79, 273-80, 273-81 according to GOST 16338 or high pressure polyethylene
Sealing butt connections are performed using a shrink bracket
or heat shrinking bandage.
For thermal insulation of the butt compounds, PPU-317M polyurethane foam is applied (
6355-55-221-1472), consisting of component A 317M / 1 to TU 6.55.221.14.71 and component
(polyisocyanate) on TU 113.03.38-106.
5.10
For thermal and hydraulic insulation at the ends of the pipeline
a special end nozzle is applied, polyurethane foam components, as well as
shrink braid or sleeve.
Transportation and storage of pre-insulated elements
When transporting, loading and unloading pre-insulated pipes and their elements
it is necessary to follow the precautions to not damage the outdoor
polyethylene shell pipe.
Loading and unloading operations must be performed using soft
wide sling and sling with end grip. It is impossible to use steel steel
cables, cords, etc., causing the deformation of the surface of polyethylene pipes. Throw
pipes are prohibited.
Transportation of pipes by motor transport and loading and unloading
allowed at the outdoor temperature to minus 20 ° C. Pipes should be stored in
stacks on a flat platform equipped with liters located in 2 m increments.
The height of the stack should not exceed 1 m. Stacks should be located under a canopy,
protecting pipes from the effects of sun rays and precipitation.
The duration of the storage of pre-insulated products should be negotiated
manufacturer.
5.15
Liquid components of polyurethane foam should be stored in heated rooms
at temperatures from 15 to 30 ° C.
Earth and auxiliary work
Earth, auxiliary and preparatory work should be performed according to
requirements of the SNB 5.01.01 and SNiP 3.05.03.
The depth of the trench is determined by the project according to the longitudinal profile on the basis of
permissible depths of the attachment of pipelines, taking into account the leveling sandy subtype
thickness of at least 100 mm. The density of the dumping soil after the tumble should
located within 1700 to 1800 kg / m "
The minimum width of the trench sole depends on the values \u200b\u200bof the corresponding
pipe diameters and regulated distances horizontally between pipes and wall
trenches. The distance from the pipe to the wall of the trench should be at least 100 mm. Distance
between the pipes, mm, is accepted for pipes with a diameter:
from 250 to 780 mm - 250;
more than 900 mm - 350.
In places of compounds of pre-insulated elements, trench must be
expand and deepen on the basis of the convenience of work.
The bottom must be smooth and made with a bias in accordance with the project.
The tolerance for irregularities should not exceed 3 cm at a length of 1 m.
6.1
Thermal networks from pre-insulated pipes are mounted in compliance with the requirements.
supervision from representatives of the project organization and the customer. The work should be carried out under favorable weather conditions. Welding pipeline performs at a temperature not lower than ° C, and insulation and sealing of connections are not lower than 10 ° C. With atmospheric precipitation, the sealing of the compounds must be carried out under the shelter (tent from the film, tarpaulin, etc.).
Laying pipelines
6.2 Preized pipeline should be laid on the leveling layer of sandthick at least 10 cm.
Lowering the pre-insulated pipes to the trench by the outer diameter of up to 160 mm is allowed manually or using a winch (crane). At the same time, it is necessary to follow the precautions in order not to damage the shell pipe.
Pre-insulated pipes containing detection alarm devices
pipeline isolation malfunctions, must fit so that the control
wires were at the top of the pipes.
The pipeline should be laid with a slope of at least 2% 0.
6.5 Welding of joints and taps of pre-insulated pipelines
directly to the trench. In some cases, welding pipeline is allowed over
trench, which is stipulated by the project.
In this case, the pre-insulated pipes must be put on wooden lining with a cross section of 100x100 mm, which have a step from 2 to 3 m.
Before laying pre-insulated pipes and elements in the trench is necessary for the ends
pipes to wear temporary plugs.
All connections of steel pipes and their elements should be performed by electric welding.
Gas welding for pipes with a diameter of up to 50 mm is allowed.
Welded operations when connecting pre-insulated pipes should be performed according to
requirements of existing regulatory documents.
During gas welding, it is necessary to use protective screens for preservation and shell pipes from the burner flame action.
Before starting welding, the ends of steel pipes must be carefully cleaned from
anti-corrosion oil with active degreasers, without solvents, as well as
from polyurethane foam, because With its combustion, toxic gases are distinguished.
After performing welded joints and testing pipelines for tightness
embed to execute alarm system device.
If you need to shorten the preized pipe, you must perform
the following operations:
measure the specified segment and mark the case of the cut;
measure from the place of the cut on the remaining pipe 200 mm and mark the circular line;
so as not to damage the wires of alarm;
Remove the sliced \u200b\u200bportion of the polyethylene shell;
remove polyurethane foam insulation in the removation zone of the shell pipe with
knife or other cutting equipment carefully not to damage the wires
alarm;
thoroughly clean the surface of the steel pipe so that during welding it is not allowed
burning residues of polyurethane foam excreasing toxic gases;
Installation of butt connections
6.13
On the sandy base, wooden lining is stacked, the distance between
which should be no more than 3.0 m. The coaxiality of the pipes is ensured.
Before the start of the connection to one of the ends of the pipe is put on the coupling. If a
thermoft rings are used, it is necessary to wear them.
After controlling the alignment, pipe welding is performed.
If the pipes are mounted with signal wires, it is necessary that the wires be at the top in the position "without 10 minutes for 14 hours."
When installing the transition, two coupling of various diameters are required, which are pre-put on the ends of the pipes. When installing a thermosooping seal, it is necessary to carry out the following activities:
finish if necessary, installation of alarm;
stretching the signal wires through a heat shrinking seal, and if there is
need to connect the signal wires to each other;
clean the steel tube with a metal brush from rust;
clear outdoor polyethylene tube from foreign objects and clean;
heat steel and polyethylene pipes up to 60 ° C;
After checking the coupling on tightness in the coupling hole, components are flooded
polyurethane foam. After hardening the foam, the hole is sealed with a plug.
Alarm system
6.14
To control the condition (moisturizing) of the thermal insulation layer of the pipeline
the alarm system is mounted.
The system consists of two copper wires (hereinafter referred to as the wires) of a cross section of 1.5 mm 2, mounted into polyurethane foam insulation at a distance of 15 to 20 mm from the steel pipe in the "no 10 minutes of 14 hours" position.
Installation of butt connections
Sealing the end of the pipeline
6.26 Before sealing the end of the pipeline, it is necessary to close the hole of the steel pipe.
After the positive results of tightness tests at the end of the pipeline
wear a final clutch in such a way that between the bottom of the coupling and the end of the steel pipe
the thickness of thermal insulation was 5 cm for pipes with a diameter of up to 200 mm and 7.5 cm for pipes
with a diameter of more than 250 mm.
For hydraulic insulation of the end of the preserved pipeline, heat shrinking sleeves are used.
Failure of pipelines soil
6.27 Failure begins with sandy sprinkles.
Sand overflow should be performed by two layers. The first layer is to fall asleep space between pipelines, as well as between the pipeline and the wall of the trench, and then lay the layer. The second layer is placed horizontally, not less than 10 cm above the pipeline and seal.
After performing sandy sprinkles, the remaining part of the trench is soiled, first selected from the trench (the removal of large stones and solid boulders from it) and compact it with a mechanical manner.
Special requirements
In case of laying pre-insulated pipelines in places exposed
dynamic loads (exceeding 5.0 t / axis), as well as with a covering layer less
50 cm, in places stipulated by the project, at an altitude of at least 30 cm above the surface
pipeline must be putting a reinforced concrete slab, or pipeline pave into
protective pipes or reinforced concrete channels.
The thermal network indicate a warning ribbon laid at a distance of 30 cm
above the pipeline.
7.1 Tests and flushing heat lines are made in accordance with the requirements
SNiP 3.05.03 and "rules of device and safe operation of steam pipelines and
hot water ", ed. 1994
Heat pipelines must be subjected to preliminary and final tests for strength and tightness.
The preliminary test of pipelines should be made by individual areas as the installation and welding work is completed before installing equipment of start-up, bellows compensators, shut-off reinforcement, but after the welded section of the heat pipe is laid and the ends of the test plot are harvested by plugs. The use of shut-off valves to disable the test area is not allowed.
Acts are drawn up on the results of testing and flushing.
Acceptance of pipelines to operation must be made in accordance with
requirements of the SNB 1.03.04, taking into account the indications of SNiP on 3.05.03.
The customer and general contractor represent the acceptance commission except
stipped SNiP 3.05.03 documents, optionally:
passports of manufacturers for equipment and certificates for pipelines;
acts on spending compensators and preheating areas
heat lines;
7.5 In the operating organization, information on the heating sections laid with preheating thermal conductors should be kept in the exploiting organization.
8 Safety Requirements for Work Production
In the work of work, it is necessary to comply with the requirements of SNIP W-4-80 *.
To work on the device of thermal networks from pipes with thermal insulation from
polyurethane foam in a polyethylene shell allowed persons who have reached 18 years old,
past medical examination, special training, introductory instruction
and briefing in the workplace on safety.
8.3 When sunbathing thermal insulation of pipes, fittings, parts and items should
use conventional fire extinguishing tools; With a fire in a closed room follows
use the BKF brand gas masks.
When dried or welding the ends of steel pipes, free from thermal insulation, the ends of thermal insulation should be protected by tin plug-in screens with a thickness of 0.8 to 1 mm to prevent fire from the flame of the propane burner, the spark of electric arc welding.
With a heat shrinking of polyethylene couplings and cuffs with a flame of propane burner
it is necessary to monitor the heating couplings, cuffs and polyethylene shells of pipes, not
allowing the facing of polyethylene or its fire.
Polyurethane foam and polyethylene waste when cutting insulated pipes and
the release of steel pipes from isolation should be immediately after the end of the working
operations are collected and stored in the place specifically reserved on the construction site
distance at least 2 meters from heat insulated pipes and parts.
Thermal insulation of pipes and parts (foamed polyurethane foam and polyethylene)
explosive, under normal conditions, does not release toxic substances into the surrounding medium
and it does not have a harmful effect on the human body with direct contact. Her appeal does not require special precautions (danger class 4 according to GOST 12.1.007).
(Preparation of a mixture of polyurethane foam, filling the mixture into the joint) should be made using special protection equipment (cotton costume, footwear,
rubber gloves, cotton mittens, protective glasses).
When pouring polyurethane foam of joints of pipelines paved in the passing channels (tunnels), it is necessary to use the respirator of the RU-60M type respirator.
8.8 In place of the fill of the joints of the polyurethane foam should be the means for the degassing of the substances used (10% solution of ammonia, 5% solution of hydrochloric acid), as well as the first-aid kit with medicines (1.3% solution of the cooking salt, 5% boric acid solution, 2% drinking solution Soda, iodine solution, bandage, wool, harness). It must be remembered that the component "b" of the mixture of polyurethane foam (polyisocyanate) refers to poisonous substances.
9 Environmental Protection
When laying thermal networks, the requirements of SNiP 3.05.03 must be respected
environmental protection.
Not allowed without obtaining permission in the prescribed manner
work on the construction of the heating network.
Washing pipelines should be performed with reuse of water.
Draining water from pipelines after washing (disinfection) to produce
provided PPR.
The territory after the end of work on the heat network must be
cleared of waste of construction and installation work and restored in accordance with
project requirements.
Waste thermal insulation from polyurethane foam and polyethylene should be collected for
the subsequent export of them to the plant for disposal or burial in permitted places.
The use of pipelines pre-isolated with a device for the insulation control system allows you to stop the process of damage to the pipelines from the outer corrosion. More than the undoubted advantages of the pre-insulated pipelines, in providing smaller heat losses due to polyurethane foam isolation, in comparison with the conventional channel laying, heat loss decrease in approximately 3-3 , 8 times.
The laying of pre-insulated pipelines, in addition, has significant advantages compared to the traditional, it does not require the use of reinforced concrete products and structures, has a significantly lower depth of pipelines and reduces construction time by 3-4 times.
Ready pre-insulated pipelines and shaped products are manufactured by Sarmat SCTB according to TU RB 14739482.130-97.
The pre-insulated pipes and parts are made from the pipe steel with a thermal insulation coating of industrial polyurethane foam (imprection and ozone-headed) with a hydraulic protection coating of polyethylene or galvanized tin.
Isolation is made of rigid polyurethane foam. The thermal conductivity is not more than 0.033 W \\ MK.
Total density-80 kg \\ m 3.
Resistance to compression is not less than 0.3MP.
Resistance to the section- (0.15-0.4) MPa.
The shell pipe is made of polyethylene. The thermal conductivity of thermal conductivity is not more than 0.43W / MK.
Density-950kg \\ m.
Lifetime-50 years.
Polyethylene pipes made without a seam, resistant to strike, corrosion, as well as to the action of ultraviolet rays. For air gasket there is a shell of galvanized tin in the form of a spiral tube TU RB 00012262-166-9.
Pre-insulated pipelines are used in thermal networks both with a non-free underground gasket and overhead gasket. In the practice of the construction of thermal networks, pipelines with polyurethane foam insulation type "pipe in a pipe" (PPU pipes) are used. The pipeline consists of a pipe, polyurethane foam thermal insulation and a protective shell (Fig. 3). Steel or polymer (for DHW) pipes are used. Between the pipe and the shell are installed centering supports from polyethylene.
Pre-insulated pipelines provide the following advantages over existing structures:
Increase in durability (pipeline resource) by 2-3 times;
Reducing heat losses by 2-3 times;
Reducing operating costs 9 times (specific damage is reduced 10 times);
Reducing capital costs in the construction of 1.3 times;
The presence of a system of operational remote control over the moistening of thermal insulation.
Pre-insulated pipes are successfully used for construction:
Heat supply networks;
Hot water systems;
Technological pipelines;
Oil pipelines.
The thermal insulation is applied to the entire length of steel pipes and shaped products with the exception of end areas of 150 mm with a diameter of pipes up to 219 mm, and 210 mm with a diameter of 273 mm and more. The locations of the joints are insulated at the construction site, after welding and testing the pipeline. Insulation of pipes with welded joints can be made according to one of the methods: installation of insulating shells from rigid polyurethane foam with applying waterproofing material; Installation of polyethylene couplings with fill to the cavity of the Polyurethane Foam Coupling.
Protective shells are manufactured in the form of thin-walled pipes from high density polyethylene. They are intended for pipelines directly located in the ground, providing their waterproof and mechanical protection.
For pipelines located above the ground surface, a protective shell of galvanized steel with a thickness of a zinc coating of at least 70 microns is used.
Pipelines made of steel pipes are equipped with a system of operational remote control of the wetting of insulation consisting of two copper wires (one of which is electrically insulated, and the second without isolation) and the electronic block of alarm. With wetting of insulation due to corrosion of the pipe or disorders of the integrity of the protective shell, the ohmic resistance of the system changes, which is fixed by the alarm unit.
The service life of thermal insulation of pipes and shaped products should be at least 25 years. Polyurethane foam does not adversely affect the environment and provides high-quality operation of insulation at temperatures up to 130 ° C.
Very often, when creating water supply systems or transporting various industrial liquids, the question of protecting pipelines is faced.
It is necessary to protect them from mechanical damage, atmospheric influences, but first of all protection is needed from the effects of cold. Be that as it may, it is too low the temperature on the street most seriously affects the state of the pipes, as well as their carrier.
The heat insulated pipes are performed by their functions at any air temperature, which distinguishes them from ordinary. Realizing the popularity of pipeline thermal insulation, the developers decided to go further and created the so-called pre-insulated samples.
What is it and what are they? We will enlighten you in this matter.
Building articles
What are the difference between simple pipes?
Ordinary pipe for transporting a certain kind of substances, what is she? Most likely, the pipe is called a steel or plastic oblong segment of the hollow cylinder.
The pipe can have the walls of different thickness, a certain diameter, may even bend. The walls are both very subtle, for domestic use, and quite thick, up to 10-15 mm or even more.
In the latter case, we are talking about high pressure lines mounted at industrial enterprises, where you need to have the ability to distinguish between communications systems under huge pressure and temperatures.
No matter how the thick wall of the pipe was, it still will not be able to protect its insides from the freezing. Metal is very well conducting heat, as well as plastic, although the latter thermal conductivity is still slightly lower.
At zero temperatures, the pipe without protection can still function properly, but at -10 no longer. The carrier is either completely freezed, or it will begin to slowly postpone on the walls. Sooner or later, all this will affect the functioning of the system, completely blocking it.
That is why it is necessary. Without it, any pipeline laid down the street, during the winter simply freezes. The exception will not be a system of warm water supply or heating.
Even if the heating pipe does not freeze due to the conflict of high and low temperatures, there is a discrepancy in the temperature of the media at the entrance and outlet of the highway.
A rather impressive part of thermal energy The carrier will lose free of charge, which is also not very good. After all, the efficiency is reduced, and resources for his artificial increase will have to spend more.
Alternative option
Protect the heating pipes or water sufficiently easy. We just need to consider the system of thermal insulation. Materials are used from the same ruler as the raw material for isolating the supporting structures of the house.
Most often apply:
- mineral wool;
- polystyrene foam;
- foamizole;
- polyethylene foamed.
Each option is good in its own way. But all of them, one way or another, suggest additional processing of the pipe, which time and money takes place. This process can be simplified.
Unlike the supporting structures of the house, which, by the way, have recently began to be preserved in recently, the pipes are pre-processing very easily.
After all, all samples are unified, manufacturers know what models to navigate and what exactly needs to be the buyer, and therefore they act on key areas.
So there were pre-insulated pipes - that is, those that were treated with thermal insulation still at the production stage at the factory.
Technology and design
Most often, the pre-insulated pipes produce large sizes. This is explained by the fact that household pipelines are paving mainly inside buildings or underground.
That is, they do not have access to air, and therefore there is no danger of freezing. If some site is still laid on the surface, then due to a low length, it will not be isolated for the owner of the labor.
While in the industry all pipeline lines are trying to keep on the surface so that if necessary, have access to any area.
This in turn generates the need to qualitatively protect the pipes from exposure to low temperatures, which means automatically increases the demand for industrial pre-insulated pipes.
The design of them is very simple. In fact, we have a conventional pipe with a coaxial shell. That is, the outer shell is satisfied with the inner, solid body of the pipe. They are satisfied with the coincidence of the axes, that is, the axes do not intersect and keep in parallel to each other.
The gap between the body of the pipe and its protective sheath is filled with heat insulator. At the very beginning, they used different materials, now preference is given to Penosol.
So it turns out that the heat-insulated products are analogues of the usual, only in a two-layer protective casing. The first layer is functioning directly as thermal insulation, and the second as an additional mechanical protection.
As an external shell use:
- tin Steel;
- plastic (including corrugated).
Properties of foamizol
Penosol manufacturers of pre-insulated pipes chose not just like that. It has a lot of useful properties, but at the same time has disadvantages.
From useful properties allocate:
- Low thermal conductivity.
- High strength.
- Efficiency.
- Low weight.
- Parry permeability.
- Zero reaction to moisture.
- Lack of corrosion.
- Durability.
Excellent material, isn't it? It has all those properties that is needed for high-quality insulation. The problem here is only that foamizol is applied as a finished foam.
The process is largely similar to applying a mounting foam, only in a much large scale.
And this, let's say straight, not always comfortable. For normal interaction, expensive equipment will be required, ingredients to knead the composition, as well as some experience, since foamizol has the property to be seated, and uneven, depending on many factors.
For self-use, and even on the pipes, this option is unacceptable. The result will be shapeless, inesticatory, and the time for the process will leave the process itself.
Another thing is processing at the factory, where all the steps are automated and calculated until a second. Here, the pipes preparaled by foaming became a real breakthrough.
They are easy to produce (you need to collect the coaxial basis and fill the gap between the shell and the protective casing) they are extremely effective and rather cheap (the price falls due to the unification and acceleration of production).
At the exit, the pipes are obtained with hardly the best, additional mechanical protection and good value.
Note that the pipes can be found on the market, isolated without foamizol. For example, foam-processed, flexible models with a shell filled with foam polyethylene, etc.
But they are almost always inferior to the above-described samples in all indicators, including economic, and therefore there were no such popularity.
Types of pre-insulated pipes
There are two main varieties of pre-insulated pipes. There are pipes:
- hard;
- flexible.
Hard pipes - standard option. There is an inner segment of a certain diameter pipe, treated with foam and layer. The thickness of the layer depends on the tasks that are set before the specific system.
In the cold regions, it can be equal to 10 or more centimeters, and in warmer it is enough isolation with a thickness of 5 cm.
The outer protective layer is made of tin steel, in rare cases of stainless steel. Such products are perfectly suitable for assembling the main water supply systems, pressure industrial pipelines, central wiring, etc.
Flexible variations are produced by similar technology, only instead of the outer shell made of metal, corrugated plastic framework is made. It cannot be called extremely flexible, and the foamizol inside the bending is not so easy, but nevertheless some degree of freedom is allowed.
The segment can be paved along a small radius, if you wish, bend and twisted as you want. Even if the insulation inside and damaged, no significant consequences on the functioning of the water supply system you do not feel.
Connection of pre-insulated pipes (video)
Additional variations
Pre-insulated pipes are produced mainly in single and monolithic. But it happens not always. For narrower tasks, models with combined wiring are produced.
That is, they can be inside the casing can be not one large segment, but several. Of course, they are much thinner, and not so effective, but it is well isolated and strengthened. Any damage or freezing of this design does not threaten.
A variant with several small pipes is interesting in that it is possible to lay entire clusters of communications, while forming a compact, aesthetic and extremely convenient system.
Its only minus is the need to open the casing in the event of a breakthrough of one of the pipes. Yes, and moreover, it is not so easy to understand what exactly it broke through.
Also, any self-respecting manufacturer of pre-isolated pipes is engaged in the manufacture of protected photos, which would be suitable for their products. The most frequent options are -, quadruple wiring, angular fittings, locking elements, etc.
