Thermal insulation for polyethylene foam pipes

On the territory of our country there are many regions with severe winters. The temperature at this time drops to significant negative levels. If in such conditions the pipe does not have thermal insulation, then it is unlikely that it has a chance to remain safe and sound for further operation. In order for the pipeline to serve properly, its surface must be covered with a layer of heat-insulating material. Polyethylene insulation is used as a modern insulation.

The use of such material has advantages in terms of installation and cost. There are many other positives as well. That is what will be discussed in this review.

Where is polyethylene foam insulation used?

Foamed polyethylene insulation for metal pipes is mainly used for plumbing and sewer systems, with an underground laying method. It is not necessary that they should be laid on the street. This is relevant for rooms with insufficient heating or its complete absence. Insulation ensures that such pipes do not freeze in winter. Engineering communications are carried out by pipes, the material of which has a high thermal conductivity. This applies to steel pipes, fiberglass and polymer communications. Therefore, such pipes, of course, need to be insulated.

In severe frost, the liquid in the gas pipeline and pipeline will simply freeze with the formation of a plug. The movement of water through the system stops. Moreover, the ice can expand and break the pipe. She just can’t handle the pressure from within. Among all the causes of accidents on the central highways, the main ones are the lack or lack of thermal insulation. This leads to the conclusion that saving a heat insulator in this case is inappropriate. A plumbing accident will cost more.

Usually, with the underground method, the highway is laid to a depth that is lower than the soil freezes through. But hot water and heating pipes must be insulated to help prevent heat loss. In this case, water and heat will be supplied to the consumer in accordance with the specified parameters.

In addition, one should not forget about the protection against noise, which is created by water moving through the pipe. If an air conditioning system is used, then the pipes in it must also be insulated. This will help to avoid a situation in which excessive condensation forms. It is formed due to the temperature difference inside the pipe and the outside air. Excessive formation of condensate prematurely wears out the system and disables its components. It is easy to see that such a material has a fairly wide range of applications.

What is such a thermal insulator?

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For whatever purposes this heat insulator is intended, it always has one manufacturing technology. It is available in various densities and thicknesses. If it is produced for pipes, then it has the shape of a cylinder, the diameter of which is from 57 to 1420 mm and a length of up to 12.4 m. These dimensions are regulated by GOST 9.602 standards. The release in this form greatly facilitates the installation work.

The production technology involves foaming molten polyethylene while passing hydrocarbons through it. The output is a web having a bubble structure, with good technical characteristics of elasticity and elasticity. In this case, a significant increase in the size of the material occurs. This figure can reach 20 times. After that, the canvas goes to the extruder to give it the desired shape.

The insulator is available as:

• canvas that can be rolled up;
• shells (cylinder);
• harnesses.

Production is carried out in two ways, as a result of which the final product is represented by cross-linked and non-cross-linked polyethylene.

In the first version, the material is passed on special equipment through molten polyethylene of a propane-butane mixture. Or at the same time, freons allowed for use are used. Inside the extruder, the pressure is artificially increased, and at the exit it is reduced. As a result, the material acquires a bubble structure. Inside the resulting bubbles is gas. Then the material cools and becomes solid, while maintaining its shape.

This type has a lower density than in the case of cross-linked polyethylene. When viewed externally, it has larger cells. If such material is compressed, then a characteristic crack occurs, but it no longer returns to its original form.

You can get cross-linked polyethylene by radiation and chemical methods. This name he received due to the formation of cross-links. Thermal insulation made from polyethylene foam in a non-crosslinked manner is characterized by the presence of only linear chains. Cross-links and represent a kind of «crosslinking».

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The chemical method involves a process that uses high pressure. The process is very complex. There is a «crosslinking» with the help of initiators, due to which the formation of cross-links. The process takes place with the presence of high temperature. Radicals are formed that take a hydrogen atom from polyethylene. It is replaced by carbon to form a spatial structure.

Pipe insulation, carried out with extruded polyethylene by the radiation method, involves the formation of macromolecules under the action of directed energy beams. Cross-linked polyethylene has greater strength and elasticity. It is characterized by high density. Under the influence of pressure, it contracts, and when it ceases to act, it quickly returns to its original state.

Shapes and sizes of pipes with insulation

The length of the polyethylene foam cylinder is usually up to 2000 mm. The diameter inside it must correspond to the outer diameter of the pipe, which is to be insulated. Sometimes they are produced with the presence of an adhesive composition. In this case, the pipe can be insulated without dismantling it. If the pipeline is exposed to ultraviolet rays, then pipes with a special polymer coating are used. This protects the heat insulator from the harmful effects of ultraviolet radiation.

There may be a foil-coated cylinder. There is a foil on the outer surface of such material. It protects the insulation from overheating or hypothermia. Roll materials are used to insulate complex structures. This also applies to pipes with large diameters.

Sleeves may be used. They are especially relevant for cable systems. Such material has small cells and in addition plays the role of a waterproofing agent. In this case, we can talk about the universality of the material.

Polyethylene coatings

The structure of the tape-reinforced type coating for pipe insulation compares favorably with extruded polystyrene foam. Tape has a number of advantages:

• high adhesion rates;
• resistance to mechanical stress;
• low hydroscopic indicators.

Adhesive tape coatings are applied at the factory, on mechanized production lines.

Coating construction based on bituminous mastic is used for external insulation. A rubber or bituminous primer is used, which is applied to the prepared pipe surface. After it, an outer layer of polyethylene foam is applied. Such a structure is able to retain heat at temperatures below -20 degrees.

Positive and negative aspects of polyethylene foam insulation

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The material has certain advantages:

1. It has a lower coefficient of thermal conductivity than other types. With the right choice of thickness, it will be a reliable protection of the pipe from frost.
2. The heat insulator is safe for people and animals. It has no negative impact on the environment. It is allowed to be used in medical institutions, as well as those intended for children and adolescents.
3. The material is chemical resistant. With regard to mortars, it shows inertness. Laying through the foundation or laying in the ground is not an obstacle to its use.
4. The insulation is resistant to moisture.
5. The material exhibits good sound insulation properties. When moving in pipes, water is not perceived by the human ear at all, in other words, it flows completely silently.

   

6. The insulation is quite well tolerated by low temperatures. Even in a frost of 60 degrees, it will not lose its elasticity.
7. The affordability of the price makes it widely used. It will cost almost two times cheaper than another type of insulation.
8. Installation work with such material is simple and usually does not cause any problems. There is no need to use any special tools.

Unfortunately, there are also disadvantages, although the positive aspects easily cover them:

• Such material has a high flammability. It can not be used in those rooms to which increased fire safety requirements are imposed. Such a material cannot withstand a flame for a long time. It supports combustion well, and when it melts, it can itself cause a fire.
• The material is not resistant to ultraviolet light. If they plan to insulate pipes located on the street, then a view with a protective coating should be used. Otherwise, under the influence of ultraviolet radiation, it will lose its properties.
• Foamed polyethylene is unstable to mechanical impact. It can get damaged easily.

At the same time, this material has much more advantages than disadvantages.

Application features

When insulating, the surface of the pipe should be cleaned of dirt, and if the pipe is made of metal, then rust. The glue «QUICK-BOND», «88-NP», «Neoprene 2136», other types is used. It is applied to the surface, after which it is fixed until completely dry.

The glued joint must be additionally fixed with adhesive tape. You can also use building brackets for this.

Using foamed polyester for insulation, you can avoid problems with rupture and freezing of pipelines even in severe frosts.