Properties and scope of insulation for expanded polystyrene pipes

The characteristics of cold and hot water transported through pipes depend on many factors. With a large distance from the source to the consumer, the liquid inevitably cools. At low temperatures, this happens so quickly that it is not possible to solve the problem by simply increasing the heating. Insulation for pipes made of expanded polystyrene keeps the temperature of the coolant.

Expanded polystyrene and its types

Styrofoam is a type of polystyrene. The feedstock is polystyrene, but polydichlorostyrene, polymonochlorostyrene and other styrene copolymers can also be used. The manufacturing technology is simple: a gas is dissolved in the polymer mass, which fills the styrene granules. The mass is heated with steam. Under the influence of temperature, the granules grow many times over until they fill the mold.

Most often, natural gas is dissolved in polystyrene. But if they want to get a fire-resistant version, the mass is filled with carbon dioxide. There is also vacuum expanded polystyrene: no air or gas is needed during its production.

Finished polystyrene foam consists of fine cellular granules. Inside they contain micropores, between them - voids. The presence of numerous small cavities ensures high thermal insulation properties of the material.

The characteristics of expanded polystyrene are determined not only by the composition, but also by the manufacturing method.

Pressless

The polymer granules are dried, then foamed at +80 C. The blowing agent is isopentane. The operations are repeated twice. The material is dried in the form, since even with a good density - up to 37 kg / cubic meter. m, it is fragile. However, its manufacture requires almost 2 times less isopentane, which provides an affordable cost.

Pressless expanded polystyrene is more often used for insulating building structures than pipes. The pores in it are open, it is sensitive to moisture.

Press

The prepared raw material is put into a mold and heated to + 120–145 С under a pressure of 8–12 MPa. In this case, the particles of the mixture are sintered together, and the gas former releases gas. After cooling, the workpiece is removed from the mold and heated in chambers for 90–120 minutes. The polymer softens slightly when heated and the released gas is evenly distributed throughout the volume.

The pressed material has higher noise and heat insulation qualities. It belongs to electrical insulators and is used in the electrical and radio industries.

Extruded

Extruded polystyrene foam for piping is the best option. The structure of the material is fine-celled, very uniform, the cells are closed, so the insulation is not afraid of water. It is much stronger than the previous options and is actively used in construction.

Foaming agate is introduced into the polymer melt under a pressure of 10–20 MPa. The melt is quickly cooled to + 130–140 C and extruded. The material is produced in the form of plates and films and is used for thermal insulation of a wide variety of structures.

Specifications

Of great interest for pipe thermal insulation is pressed and extruded polystyrene foam. Its pores are closed, which significantly reduces moisture absorption. Since it is necessary to insulate the external pipeline, unprotected from the weather, this is an important property.

Pressless is more often used for thermal insulation of walls, foundations, floors - structures, where its greater fragility and moisture absorption is less important than the press version.

The characteristics of the foam press, non-press and extruded insulation for pipes are shown in the table.

Resistance to mold and mildew depends on the type of material. With high humidity and violation of the integrity of the pores, conditions for the reproduction of microorganisms arise. Special grades - PS1, PS4, PVC, have antiseptic properties.

Soundproofing properties are possessed only by closed cell polystyrene foam. Insulation PSB does not absorb noise.

Advantages and disadvantages

The obvious advantage of the material is the ability to give it different shapes. If the insulation does not fit tightly to the structure, there is no point in it. Insulation of the required shape and volume is made of expanded polystyrene.

Insulation pipe expanded polystyrene has other advantages:

• very low thermal conductivity - any brand guarantees heat preservation, 12.5 cm of expanded polystyrene replaces 53 cm of laminated veneer lumber;
• polystyrene does not rot, is not susceptible to fungi;
• the materials used for pipe insulation are not afraid of rain, frost, since they practically do not absorb water;
• the shell is operated in the temperature range from -70 to +65 C, temperature destruction begins when heated to more than +160 C;
• minimal weight facilitates installation;
• the service life varies from 40 to 60 years - it depends mainly on the action of sunlight.

The disadvantages of pipe insulation are related to the characteristics of the polymer material:

• All types of foam are to some extent afraid of the sun's rays. This affects the duration of operation.
• The material is treated with fire retardants, but remains combustible. Special fire-resistant brands also burn, but their ignition temperature is higher - +490 C.
• When burning, polystyrene foam emits harmful substances. The risk of poisoning is high.
• Expanded polystyrene is somewhat resistant to acids and alkalis. However, concentrated solutions, solvents, and even most paints destroy the structure of the material. It is prohibited to paint the thermal insulation.

Disadvantages of PS or PSB limit the scope. More often, expanded polystyrene is used to insulate the external pipeline.

Features of the manufacture of insulation for polystyrene pipes

Insulation from expanded polystyrene for pipes is cut with a heated string from polymer plates. It is a prefabricated cylinder of 2 or 4 segments with different bending radii. The well cylinder is assembled from 8 segments. Spikes and grooves are formed at the edges of the halves. For additional fixation, use glue or tape.

Insulation features:

• A shell is used to insulate pipes with a surface temperature of up to +80 C. If an additional gasket is installed between the thermal insulation and the pipe, it is allowed to thermally insulate pipes with a surface temperature of up to +110 C.
• The expanded polystyrene casing for the external pipeline is treated with UV protection compounds.
• The minimum segment circumference is 17 mm, the maximum is 1220 mm. The standard length is 1 m.
• Execution of shells to order according to individual sizes is possible. In some modifications, a groove is formed in the thickness of the material for the heating cable.

For thermal insulation of inner pipes, PSB is used. For outdoor use - pressed or extruded polystyrene foam.

Applications

Expanded polystyrene plates are used to insulate a wide variety of objects:

• thermal insulation of internal and external water supply systems, heating, including the main one;
• insulation of the foundation, roof, walls;
• production of household and industrial refrigerators, refrigerators;
• frost protection - roads, sites, underground highways;
• packaging for fragile and valuable items;
• production of insulated wagons and vans.

High density options are the most durable and tough thermal insulators. They are used as a structural material.

Correct insulation of the pipe with expanded polystyrene

Thermal insulation of pipes, especially of large diameter, is a difficult job. With a small volume of the pipeline, you can handle it yourself. In other cases, you need to invite a team of specialists.

Technology:

1. Dig a trench up to the level of soil freezing. This data can be found in the reference book.
2. 10–20 cm of sand is compacted to the bottom of the ditch.
3. The pipes are treated with anti-corrosion compounds and laid on the bottom of the trench so that a gap remains equal to the thickness of the shell between the pipe and the bottom.
4. To mount the shell, 2 people are needed: one supports the lower segment, the second installs the upper one, tightly joins and fixes the shell with tape.
5. The corner pieces are cut in place with a knife and fixed in the same way.
6. The casing is treated with a protective compound or covered with a film. Fill up the trench.

Adhesion with glue is considered less reliable and takes longer.