Types and technology of laying insulated pipes for water supply

Poor-quality insulation of the pipeline leads to freezing of the system and the complete cessation of its performance. At the same time, heat losses in the system increase and efficiency decreases. Insulated prefabricated pipes for water supply will not only save the time required for their installation, but also improve the quality of the entire system and reduce other labor costs.

The main types of thermal insulation

Manufacturers of finished pipelines use materials for their products that differ from each other in price, quality and durability. Before proceeding to the laying of insulated pipes, you should consider the description, pros and cons of each insulation.

Fibrous insulation

Most often it is mineral wool or glass wool — materials with an ideal ratio of productivity, durability and price. The main advantages of mineral wool in comparison with other materials:

• High tensile strength;
• Low thermal conductivity;
• Light weight, which greatly simplifies transportation.

But, in addition to its positive qualities, there are also disadvantages:

• Mineral wool is highly flammable and may cause a fire. Especially if there are wooden floors or plasterboard structures nearby;
• Susceptibility to moisture. Mineral wool must be additionally covered with a layer of durable foil, or it quickly gains moisture and loses its positive qualities.

Due to the above disadvantages, it is not worth doing the insulation of water pipes with mineral wool in the ground.

Polyurethane foam, expanded polystyrene and cross-linked polyethylene

Heaters of this class are used very often because of their positive qualities. For example, expanded polystyrene is a heat-insulating material that has a low cost, but is environmentally friendly and resistant to sudden temperature changes. It can be used when digging into the ground or underground. Unfortunately, expanded polystyrene is susceptible to various kinds of mechanical damage and it should be very carefully wrapped around pipes.

Polyurethane foam is a modern high quality heat insulator. To insulate water pipes in a private or multi-storey building, it is used in various forms:

• Spraying with a thin layer;
• Installation of cylinders on the finished pipeline;
• Production of polyurethane foam pipelines.

Polyurethane foam retains heat qualitatively, it is an environmentally friendly material that is immune to moisture. But this heat insulator has a significant drawback — high cost.

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More expensive, but high-quality material is cross-linked polyethylene. Cross-linked polyethylene is one of the most modern heat insulators, differing from others in resistance to mechanical stress and durability. Even the high price is not able to overshadow the technical characteristics of cross-linked polyethylene.

Thermal insulation paint

Heat-insulating paints for pipe insulation have been used relatively recently. Its price is at an average level, but such material has a number of advantages.

• Lies evenly on the surface of the pipeline. It turns out high-quality thermal insulation, a warming layer, which is suitable, for example, for plumbing in the country;
• Can be applied through a sprayer;
• Service life (depending on the manufacturer) varies from 15 to 40 years;
• Operates in conditions from -70°C to +260°C;
• Universal. It can be used both for the insulation of the pipeline, and for the protection of buildings from heat loss.

Heat-insulating paint is immune to direct sunlight and harmful microorganisms, it is waterproof and has increased resistance to mechanical damage. With the use of heat-insulating paint, the question immediately disappears, how to insulate water pipes in a barn or basement.

Pipes with heating cable

The heating electric cable provides high-quality internal heating of the water supply inside the pipe and is an actual solution, provided that the pipes are laid below the freezing level of the soil. In some soil conditions, for example, with an excess level of moisture, the use of a simple heater is not possible, due to its high susceptibility to such an environment. And the use of expensive material is irrelevant — this will entail unnecessary costs.

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How to properly install the electrical cable:

1. There are 2 ways to install the heating cable: laying it along the pipe or winding it around it. Both methods provide high-quality heating of pipes, subject to the integrity of the cable.
2. When laying along the pipe, the cable is attached with adhesive aluminum tape to its lower part.
3. When wrapping the cable around the pipeline, an adhesive tape is also used, which is applied in rings with a uniform pitch throughout the entire pipe. The laying step will be the shorter, the lower the cable power.
4. After laying the cable and fixing it, it is necessary to apply an additional heat-insulating layer, which serves more to protect the heating cable from mechanical damage and contact with the soil. At the same time, the cost of thermal insulation can be chosen inexpensively.

Such a heating element is used not only from freezing, but also when it is necessary to defrost frozen pipes. The power of the cable is selected within 10-15 W, this is quite enough for high-quality heating even at a depth of half a meter.

The sequence of correct laying of heat-insulating pipes

Pipes, in prefabricated thermal insulation shells, require careful handling, not only when laying under the floor or on the ground, but also during transport. Improper handling leads to mechanical damage, which significantly reduces the efficiency of the pipeline during operation.

Stage 1: Material preparation

Before laying individual pipes and welding them into a common structure, each of them should be carefully prepared. The first thing to do is to clean the edges of the insulation on each pipe. The raw edge will cause a poor quality joint in the future.

After insulation, the edges of the pipe itself should also be slightly cleaned, for a better weld. In addition to stripping, it is also necessary to thoroughly wipe the junction and dry it. Debris or foreign liquids will not give the quality of welding that is required when installing water pipes.

Stage 2: Laying pipes on pre-prepared brackets

After processing the material, all pipes on the surface must be laid in one common pipeline, fitting the joints closely. After laying, the system should be checked again, especially in the horizontal plane.

The pipeline prepared for welding must be covered with asbestos cloth, otherwise the insulation may ignite. After welding, asbestos strips can be removed, but some crews leave them as an additional protective material.

Stage 3: Welding the joints

A serviceable and tested welding machine is a guarantee of the durability of the pipeline. When laying water supply systems, the work usually reaches enormous volumes, so welding devices can function without interruption.

High-quality welding of an external water supply pipe is achieved only after the joints are completely melted. This requirement is spelled out in the corresponding GOST. With careful execution, the weld can be additionally not processed or cleaned. After welding, all seams should be checked with a flaw detector. If the parameters do not correspond to GOST, then the seam must be welded.

Stage 4: Insulation of pipeline joints

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After welding, all seams must be covered with a heat-insulating layer. What materials are used for this:

• Special sealant with adhesive tape. It is very convenient to use, provided that the surface is clean, without debris or plaque. Suitable if you need to insulate a water pipe from the outside, on the street;
• Casing made of galvanized steel. It looks like a simple clamp, which is tightened with a bolted connection;
• Expanded polystyrene adapter. Versatile and very convenient, but has a high price, as well as a heat insulator for a pipeline made of this material.

The above types of insulating materials are ideal for protecting the joints of insulated pipes. Joints should be covered carefully and accurately, leaving no open spaces.

Step 5: Sealing

The final stage of the installation of insulated pipes is the treatment with a special sealant or mounting foam of all open places remaining after the insulation of the joints. While the sealant or foam is curing, the seals, shrouds, or adapters can be adjusted to add more sealing designs.

If a prefabricated thermal insulation is provided for the pipeline, consisting of polystyrene half-cylinders, then metal clamps or steel tape, ordinary wire, and foil tape as the last protective layer should be used to fix it. The joints between the shells can also be sealed with sealant or polyurethane foam. For greater reliability, some craftsmen put an additional half-cylinder on such a joint and process its edges with a sealant.