Currently, due to the rising cost of energy heat loss try to minimize, so often the insulation system are included in the complex of tools to achieve energy efficiency.
With proper selection of technical parameters, and transport speed vapor condensation in the steam line will depend on the efficiency and reliability of insulation. To ensure optimal transport of gas through pipelines in various environments, cylindrical design made to isolate. According to DBN V. 2.6-31:2016 "thermal isolation Budivel" set specific requirements to thickness of insulation.
The process of calculating the thickness of the insulating layer to a steam pipe is very difficult and time consuming. The most common method is the determination of this parameter in the normalized indicators of heat loss. Losses are also installed in DBN V. 2.6-31:2016 and depend on the methods of laying pipes of different diameters:
- outdoor on the street
- outdoor indoor
- ductless method
- impassable channels
The essence of the calculation is reduced to the selection of this thickness of the insulating material to the value of the actual heat losses do not exceed the specified in the parameters. The correct selection of insulation and its thickness is very important as its insulating characteristics change in the direction of reducing the thermal resistance. As a result, improperly selected insulation increases heat loss and the surface temperature of the equipment. In the presence of an efficient, well-installed insulation the heat savings of the steam line will be much higher than that of the pipes of the steam line without isolation, and will be 80-85%.
The condensation process occurs when the movement of steam through the steam line due to cooling it in contact with the walls of the pipe. Properly selected and installed heat insulation reduces condensation. The presence of condensate in steam line can lead not only to loss of the heat contained in the pair, but also to more disastrous consequences to the system steam line. Condensation is also dangerous because of the possibility of water hammer in the movement of condensate drops with high velocity through fittings and valves.
Depending on the destination of the pipeline is selected the type of insulation material with appropriate characteristics. So, the choice of material and technology installation on cold piping will differ significantly from the materials for the insulation of hot pipelines. For cold piping apply to all underground metal pipes, and communication networks, where the temperature does not exceed 40-50°C, and the hot - heat networks and steam lines where the temperature can reach 500°With.
Pipelines and steam pipelines teploizolirovat to prevent them from losing their heat. The reason for this is the heat transfer at the tube wall and heating of the surrounding space, resulting in lost a significant amount of heat.
Besides the increased steam flow, loss of heat pipelines entails a number of undesirable effects. So, due to the cooling of the steam in vapor and it accumulates when large quantities of accumulated condensate inside the pipe interferes with the normal passage of steam through the steam line.
Special attention in the choice of material should be paid to the insulation of steam fresh steam protoporoi and control valves, piping steam to the turbine pump and ejectors operating at a coolant temperature of 500°C and above. Thermal insulation of these parts of the steam pipelines should be made of high temperature materials.
For the decision of problems of thermal insulation of steam pipelines to avoid heat losses using various types of materials:
- stitched mats are
- lamella mats
- basalt cylinders galvanized casing
- polyurethane foam galvanized casing
- insulation made of foam rubber in the zinc shell or in a special protective coating
For these thermal insulation materials disadvantages is the low thermal stability at high temperatures for insulation of polyurethane foam and foam rubber, as well as hydration and high shrinkage for basalt cylinders and lamella and wired mats, with subsequent loss of their insulating properties.
Data insulation materials require protection from moisture with constant control of humidity of the material, as the lack of the latter leads to deterioration of the insulating properties of the material, the condensation and further corrosion of steel pipes, which in turn adversely affects the reliability of thermal networks and steam lines.
All instructions for designing and basalt mineral wool insulation is recommended to use to a temperature of 400°C. Despite the fact that the manufacturers guarantee that the phenolic binder burnout occurs at temperatures above 250°C, it is not always the case. In fact, burnout occurs at a temperature of 190-200°C, which leads to the destruction of the structure of the material and accordingly the heat loss. Manufacturers also often ensure that the polyurethane foam operates at a temperature of 150°C. However, in fact, already at a temperature of 120°C is its destruction. Insulation foam rubber can withstand many manufacturers stated temperature to 90-110°C, high temperature rubber up to 175°. Stitched mats can withstand temperatures up to 750°C and, accordingly, can be applied to any high temperature steam lines. When the coolant temperature reaches 400 to 600°C, steam line teploizolyatsiya with two layers of different structure materials. The first material acts as a protective layer from the hot surface to the second layer, which serves to protect the steam line from the low temperature outside.
For protection against mechanical influences and from natural phenomena insulation of the steam pipe is additionally coated with a protective sheath – galvanized steel sheet or other protective coatings depending on temperature and destination Arma-chek Silver Guard 1000, FSS-insulation, foil with fiberglass.
The thickness of the insulation layer, depending on the diameter of the steam line and temperature averages from 30 to 220 mm. Flange connections of pipelines is usually not isolated.
The following is a selection table insulation thickness depending on the diameter of the steam pipe and the temperature of the media:
|
Diameter, mm |
The insulation thickness mm depending on the working temperature °C duct |
|||||||
|
100 |
150 |
200 |
250 |
300 |
350 |
400 |
450 |
|
|
25 |
30 |
40 |
50 |
75 |
85 |
100 |
125 |
140 |
|
40 |
30 |
40 |
50 |
75 |
85 |
100 |
125 |
140 |
|
50 |
30 |
40 |
50 |
75 |
85 |
110 |
130 |
140 |
|
65 |
30 |
40 |
50 |
75 |
85 |
110 |
140 |
150 |
|
75 |
30 |
40 |
60 |
80 |
90 |
115 |
140 |
150 |
|
100 |
30 |
40 |
75 |
80 |
100 |
115 |
145 |
160 |
|
150 |
40 |
50 |
75 |
80 |
115 |
120 |
150 |
175 |
|
200 |
40 |
50 |
75 |
90 |
115 |
125 |
160 |
180 |
|
250 |
40 |
50 |
75 |
90 |
120 |
130 |
170 |
190 |
|
300 |
40 |
50 |
75 |
100 |
125 |
140 |
180 |
200 |
|
350 |
50 |
50 |
75 |
100 |
125 |
150 |
190 |
210 |
|
400 |
50 |
60 |
75 |
115 |
125 |
150 |
190 |
210 |
|
450 |
50 |
60 |
85 |
120 |
140 |
160 |
200 |
220 |
The calculation of the thickness of the insulation pipe can be done using the formula:
ln B = 2πλ [K*(tT — to)/qL — RH]
where:
- λ — coefficient of thermal conductivity of insulation (reference)
- K — coefficient of additional heat losses through the mountings or supports
- tT is the temperature of the transported medium (annual average)
- to — outdoor air temperature (annual average)
- qL — heat flux
- RH — the resistance to heat transfer on the outer surface of the insulation (table.index)
* The value of the index ln can be found in the table of logarithms. The thermal insulation shall be of such thickness at which the right and left side of the equation will be equal.
The value of is calculated using the formula:
In = (dиз 2δ) / dтр
where:
- δ — the thickness of the insulation structure
- dиз — outer diameter of the tubing
- dтр — outer diameter of insulated pipe
Or another option, you can use the calculator on our website.
The company's products "Sanpreis" has certificates of quality, protocols for the determination of groups of combustibility, certificates of SES and other permits, and meets the basic criteria when choosing insulation for steam lines:
- meet the requirements of fire safety
- group of combustibility NG G1 and
- high maximum working temperature
- excellent performance of thermal resistance
- good conductivity at high temperatures
- simple and convenient, which facilitates and accelerates installation
- a wide range of sizes and thicknesses
Solutions with the correct insulation and protective materials are working throughout the service life of the equipment, while retaining its specifications without additional repairs and maintenance. Please contact us and we will help you to pick them up!
