Features of laying pipelines

By Admin | Building Materials
23 May 2016
Such extravagance is estimated at 84-112 billion dollars in lost revenues from oil and gas exports.The Russian economy is one of the most energy intensive in the world.According to the IFC (International Finance Corporation), Russia could save 45%.Such extravagance is estimated at 84-112 billion dollars in lost revenues from oil and gas exports.Meanwhile, resource extraction drops, power is no longer cope with the provision of domestic demand: in some regions recorded a deficit of electricity during peak load in winter.

In June 2008, Dmitry Medvedev signed a decree "On some measures to improve energy and environmental efficiency of the Russian economy", including a reduction in energy intensity by 2020, Russia's GDP by at least 40% compared with 2007, however, systemic measures for its implementationIt has not yet been taken.

most deplorable state of affairs in our country has developed in the field of housing."Communal infrastructure - a" black hole "where disappear vast energy resources ... Lost in t
he heating system up to 60%", - said Russian President Dmitry Medvedev.

Solving the problem of reducing the heat loss, the focus is usually insulation walling.However, more than half of the named president 60% heat escapes through walls and no roof, and through the pipes heating and hot water.Thus, solving the problem of energy conservation in engineering networks, you can achieve double savings.

The higher the temperature of the coolant, the more important is the use of efficient thermal insulation.If the hot water temperature often exceeds 60 degrees, for the quarter heating networks it already comes to 95 years of age, and the main road from the TSC to the CHP can reach 150 degrees.Using

inadequate or insufficient insulation, particularly in the latter two cases, it causes that just the air (or ground) ejected tremendous amount of heat and thus money.The share of heat losses are now reaches 17% of the total heat consumption in the country, said CENEF, representing more than 170 million Gcal, or at least 50 billion rubles a year.

similar state of affairs is due to two objective reasons:

first - physical deterioration of insulation.According to the Ministry of Industry and Energy, Russia's average per year for every hundred kilometers of communication falls 200 accidents.Wear heating systems in some regions sometimes reaches 75%.Much earlier steel pipes and processing units fails traditional insulation made of outdated glass according to GOST 10499-78, with above-ground and underground channel routing, as well as armopenobetona or bitumoperlita - with channel-free laying.The average service life of these materials is only 10 years old.At the same time provided for the life of the pipeline is 25 years.

As a relatively hydrophilic old materials absorb moisture and thus further accelerate the corrosion of the metal.Considerable additional costs are inevitable: either the unscheduled replacement of a heating or permanent patching individual sections with concurrent elimination of the flood and fountains.

second reason is the mismatch modern requirements of thermal insulation.Coatings used for underground laying, by modern standards, are rather simple protective than the thermal insulation.Thermal conductivity and armopenobetona bitumoperlita even in the dry state is about 0.1 W / m * deg., And the inevitable and rapid hydration increases even 3-5 times.At the same time, effective materials, the figure does not exceed 0.05 W / m * deg.

Anyone familiar snow-free and dry track, thawed, "denoting" winter heating ducts.Glass wool, produced by the Soviet guests, does not satisfy the requirements of not only durability, but also security - especially for installers.
When using modern types of insulation there is another problem.Provide the necessary thickness of the shell some materials is too expensive.Therefore, despite the low thermal conductivity of the insulating layer, heat losses are high.


piping insulation is made not only to reduce heat loss, but also to reduce the surface temperature for safe operation.In particular, in accordance with paragraph. 2.1.8 of the "Rules of construction and safe operation of steam and hot water '(PB-10-573-03)," ... all the elements of pipelines with the outer wall surface temperature above 55 degrees, located in accessiblefield service personnel must be coated with thermal insulation, the temperature of the outer surface of which does not exceed 55 degrees. "Therefore, the calculation of insulation thickness when laying in the room can be made as according to the norms of the heat flow and for a given temperature on the surface of the insulation.



It is clear that in the latter case insulation performs both functions, but in practice the thickness of the calculated temperature on the surface, does not provide the necessary energy-saving features.

Unfortunately, focus on safe surface temperature is often more attractive because it allows to manage more than a thin layer of thermal insulation and thus "save" money.In addition, many popular types of modern insulation simply does not produce enough thickness.For example, products made of foamed polymers (polyethylene, synthetic rubber) issued a thickness not exceeding 13-25 mm - technology features make the production of greater thickness unnecessarily costly.Such insulation copes with the task of ensuring a safe surface temperature, but does not meet the modern standards of energy efficiency.

Putting the problem of energy saving, thermal insulation should be carried out on the calculation of the heat flux density standards, regulated SNIP 41-03-2003.The required insulation thickness is determined according to the formula presented in the joint venture 41-103-2000.As an example, consider the heating pipe diameter of 42 mm, the coolant temperature 90 degrees extending in the room with an air temperature of 10 degrees more than 5000 hours per year.The thermal conductivity of the insulation is taken as 0.04 W / m * °, which roughly corresponds to the value of this parameter for advanced materials (polymer and fiber) at elevated temperature.The result of this rough calculation shows that the minimum thickness of the insulation in this case is 38 mm.

required thickness - from 30 mm - are mineral wool products.Their application allows to ensure that the heat loss modern requirements for energy efficiency.Cylinders - the most convenient form of products for mounting on pipes - produced sufficiently large diameters.For example, rock wool is produced with an inner diameter of 273 mm.

However, the necessary thickness of insulation - is not a guarantee of energy efficiency.Common errors can lead to a significant increase in heat loss.Among them distinguish the two:

Application of thermal insulation without mounting seal fibrous materials.SNIP 41-03-2003 establishes that the thickness of the thermal insulation product to be installed on insulated surface should be determined taking into account the compaction factor Kc.For the cylindrical surface of the formula is used



where:
  • δ1 - the thickness of the thermal insulation product to be installed on an isolated surface (without compression) m;
  • δ - thickness of the insulation layer design with a seal in the design, m;
  • d - outer diameter of the insulated equipment, pipe, m;
  • Kc - coefficient of seal insulation products.

The same document lists the compaction factor for different materials.For example, kamennovatnyh products ROCKWOOL TECH MAT, the figure is 1,35-1,2, and some mats of glass staple fiber comes to 3.6, due to the different orientation of the fibers within the material.In the first case, they are arranged randomly, and in the second - preferably along the base of the mat.Therefore, fiberglass insulation is more susceptible to compaction.If you do not take into account this factor, the actual thickness of the thermal insulation of the pipeline will soon be significantly less than estimated, which would cause unforeseen power losses.And, accordingly, to provide a design parameter, it is necessary to use a larger amount of thermal insulation.

Improper installation

When installing steel sheeting should provide no load on the layer of insulation.For this purpose, a special attachment, taking the weight of the coating itself and redistributes the supports.For example, tires and suspension system, the options available for the different diameters of the pipes and the thickness of the insulation.Ignoring this approach leads to serious distortions of insulation and a further increase in heat loss.


impossible not to mention another error that often occurs even with all the rules of design and technology.If thermal insulation of pipelines of all suitable materials are selected the cheapest - with the obvious aim to save money.But, as is usually the case, unjustified additional cost savings turns.In this case - on the installation.The actual resource saving, not only in operation but also in the installation may be provided using the highest quality materials.For example, mineral fiber mats are manufactured by many companies, have a thermal conductivity reaching the limit specified in GOST 21880-94 - 0.044 W / m * deg.The figure of 0.036 W / m * °, which is characterized by high-quality products, enables the products of smaller thickness and thus reduce costs for installation.



clearly see all the articles of the budget savings can-compare.It contains data on the thermal insulation pipe having an outer diameter of 273 mm, with the water temperature of 100 degrees, which is located outdoors, the number of hours per year, more than 5000. The heat flux density according to snip 41-03-2003, should be no more than 57W / m.On this basis, calculates the thickness of the insulation: ROCKWOOL mat MAT TECH (lambda = 0.036 W / m * degree) - 90 mm mats in accordance with GOST 21880-94 proshivnymi - 110 mm (due to higher heat conductivity), mats made of fiberglass - 120 mm(due to a larger mounting seal).Accordingly, the amount of insulation in the 100 meters length of the pipeline is: 10.25, 13.22 and 14.80 m3 respectively.It is evident that due to the lower volume of insulation costs are reduced for all positions and installation work (labor workers and drivers, installing retaining rings, motor vehicles), as well as the consumption of steel in the protective coating.As a result, despite the greatest cost TECH MAT, final costs for their application are the lowest.

Thus, energy efficiency in housing in general and in pipeline networks in particular, is inextricably linked to the effective use of insulation.Already at the design stage is necessary to provide the thickness of the insulating layer, which provides compliance with the heat flux density.Further, for the fibrous thermal insulation materials should take into account the compaction factor, and the installation is mandatory to use the items to prevent strain on the insulation from the protective coating.Finally, it should be applied only modern, high-quality and durable materials, by which not only reduces the cost of operation, but also for the construction of pipelines.