Cable for heating a gas pipe: device, selection according to parameters, installation methods

In the cold season, unpleasant interruptions in the operation of gas pipelines occur. They arise not only due to low temperatures. You can get a problem with a high degree of probability if the installation of communications was of poor quality. Then freezing with stopping movement in the pipeline becomes commonplace.

To solve the problem, it is necessary to install a cable for heating the gas pipe, and preferably - before the onset of frost. Next, we will tell you how to choose the right heating cable and share the intricacies of its installation.

The structure of the heating cable

The device for heating wires includes up to 5 elements - the presence of a particular part depends on the type of product, and there are only two of them, except for rarely used ones:

• self-regulating;
• resistive.

Self-adjusting cable has two conductors with different phases. It is through these copper conductors that electricity is supplied. They are located inside the conductive matrix, which heats the cable and acts as the brain of the system.

Each part of this inside consists of an electrical circuit with an arrangement exactly in the middle between the conductors. The supply cores are heated and regulated precisely by the matrix.

In addition to its own heat-insulating layer, wires are used in tandem with external insulation. This is necessary to protect the cable from environmental influences.

The main part of the cable is always threaded into the insulating layer, which is also called thermal protection or insulating coating. Thermal insulation is enveloped with a shielding mesh of flat copper plates. This braid is used to protect against electromagnetic waves from the outside, and also for grounding. The outer shell located on the grid is a shield against mechanical damage.

Resistive cables are single and two-core. Accordingly, they are distinguished by the number of conductors.The device resembles a self-regulating option, but only without a matrix system. Instead, make anotherthermal protective layer.

Self-regulating heating wire

Such a cable works like an ordinary conductor of electricity. Heating leads to an increase in resistance and, by a simple physical law, to a decrease in current strength. In cold places of the pipe, the temperature of the wire is lower and the resistance is less, and due to the greater current strength at these points, the heater is working more intensively.

When the cable is turned on, it gradually builds up power and at some point begins to work at full capacity. It turns out that heating the gas pipe accelerates this process.

Self-regulating cable does not stop working. Do not worry, because heating continues only until the desired temperature is reached, and then the cable functions with less power. The heater is built around a predetermined temperature.

The self-regulating version of the heating cable has a variable resistance with a direct dependence on temperature, so the power of the wire can grow by itself

AT gas pipes not the gas itself freezes, but moisture, as a result of which it ceases to flow. It is necessary to choose such a pipe temperature to make probability freezing inconsequential. The peculiarity of self-regulating models is that the heating will not turn off or on as soon as the gas pipeline becomes warmer or colder than the optimal indicator. Just the intensity of the work will greatly change in the direction of decrease or increase.

In turn, the cost of power should not hit the wallet, because the cables consume about 10 watts per 1 meter of length. There are weak models with energy costs within 5 W and powerful ones with an indicator of up to 150. Given the large selection, you can always find an acceptable option to allow yourself to keep the equipment turned on all the time.

Resistive heating cable model

With a single-core variety, everything is more complicated, because you need food from two ends with subsequent restrictions in the design. The second end is returned to the connection point or additional power is laid to the same far end. This is the essence of the inconvenience. Single conductor in sheath ofthermoplastics occupies a niche in the market for the most affordable heaters.

Based on the principle of a single-core cable, an HT modification was created with 50 watts per 1 meter. The scope of its application extends not only to pipelines. Simultaneously with high energy consumption, the HT wire solves the issue of saving material itself.

Resistive heating cables produce only a specific length that cannot be shortened or extended in any way - such a wire cannot be cut

Based on the name, a two-core heater consists of 2 cores. They do not perform similar functions, as is the case with matrix cables. The heating core is paired withconductiveon which an auxiliary role is assigned. On the one hand, power is supplied to the cable, and on the opposite, an airtight sleeve is mounted.

The design and installation of the wire will not be difficult, but the coupling often becomes a problem. Practice has shown the connection of breakdowns with this part in more than half of the cases. For the gradual replacement of problem products, manufacturing companies began to producecouplingless options.

HT flat single-core cable makes it possible to reduce material consumption by 1 m² of gas pipeline area that needs heating

Resistive heating cables have the following advantages:

• stability characteristics over the life of the product;
• high heat dissipation;
• low prices.

But in terms of reliability, they are somewhat inferior to self-regulating models, because in the event of a breakdown, you have to replace the entire section with a problem place, and they often have local overheating.The inconvenience lies in the fact that it will take time to select sections of optimal length.

Choosing the perfect option for the parameters

For all outdoor models, the benefit is determined by the power and uniformity of the heat distribution. In theory, both types of cables are approximately the same, because the weaknesses of the resistive can be compensated by the type of installation.

Depending on the minimum temperatures in the region, a cable is selected that is sufficiently resistant to extreme ambient temperatures. It may be that the rate at which occursfreezingturns out to be too low for the heater itself.

There are more unambiguous situations. Only self-regulating wire cover pipelines with an underground location, because it is more profitable and convenient. Thin gas pipes should not be protected with a resistive wire - sometimes it happens that the communication melts, and a hole forms at the contact point.

Thanks to this diagram, it becomes clear how much self-regulating cables have a big advantage: the parameters of the length of the cable line and the temperature of the heating object are indicated

It will be nice if there is a table at handheat loss. In it, heat loss is determined by the difference between the temperature of the pipe and the environment in combination with the ratio of the diameter of the pipe and the thickness of the heat-insulating layer.

Information is available in a convenient format - watts per 1 linear meter.

For a clear example of energy efficiency, you need to look at the table of heat losses of pipelines - it will help in determining the required cable power for the planned thickness of insulation on the pipe

Rules and recommendations for installation

Operational problems will not occur if the general rules are followed. In accordance with the rules for installing electrical appliances (PUE), the frost protection system must be equipped with a residual current device (RCD) Mount onnon-conductive surfaces and units perform only with a protective braid. The cables finished with this coating are also installed on synthetic pipes.

During installation, air temperature matters: work is carried out if it is not colder than -15 ° C. After installation, they arrange mandatory thermal insulation. To reduce heat loss, the thickness of this layer is adjusted exactly to the diameter of the pipe. Moreover, exceeding this indicator will not lead to anything bad, but it will only get better.

The heating wire is considered functional if the bending radius reaches at least 3 product diameters. That is, if the radius of the imaginary circle, the center of which is located directly on the edge of the cable bending zone, is at least three times the diameter and 6 times the radius of the wire itself.

In the figure, R is the bending radius, dh is the cable diameter, A is the length of the bent part, L is the length of the straight part, α is the flat angle between two imaginary straight lines that intersect in the center of the conditional circle

After work, the insulation and the cable itself are checked for resistance. Then, marks are made on the trench and the pipeline with a warning about the presence of a heating element. Additionally install a plate.

Cable installation allows designers to place the pipe in a convenient location. In this case, there is no need for laying taking into account the level of freezing of the soil.

Installation methods for heating cables

There are four main options for placing a heating cable, but the first two are most often used:

• longitudinal laying of one cable;
• cable fixing with a spiral around the gas pipeline;
• placing several heating wires along the pipe;
• Installation by a wavy contour.

The cable is usually run along the bottom of the pipe at the level of the 4th or 8th hour, if you imagine that its cross section is a round dial of a mechanical watch. At the junction - raise 60 °.In a sense, this is a precaution: place the heating cable away from the mounting bracket.

There are separate ways of laying in different nodes of the system. Near the valve, the core is bent, laid below the movable part and fixedfiberglass tape. With a wavy or spiral mount, the step of the turn is done more where there is a turn in one direction. For example, on the knee joints.

When installing a heating cable near the nodes and connections, the most important thing is to leave convenient access to all controls

The essence of installation is extremely simple. It is only necessary to select the path for the cable and fix it on top with aluminum tape. First of all, the wire is fixed in fragments. After - press to the pipe until tight contact. It’s not worth putting a lot of effort, minimum tension is enough, especially since the cable has the ability to stretch unnecessarily.

In the future, you need to fix the tape along the entire length of the cable:

• to improve heat dissipation;
• for durability;
• to avoid contact with thermal insulation.

Aluminum tape or foil is used to process plastic pipes. In this way, excessive heating of the plastic is avoided and a more even distribution of heat is achieved over the entire area and length of the pipeline. No matter what material the pipe is made of, a sleeve is mounted on it and the supply cold end and the heating wire are fastened.

There, on the gas pipeline, a temperature regulator sensor is also placed - ideally exactly in the middle between the laid lines. In the future, warming of the site will be required, after which the work can be considered finished.

Longitudinal installation of a heating cable

Technically, this is an easier way. At the same time, one should not expect the same effect as with spiral mounting, when the gas pipeline is covered with a "mesh" of twisted cable. Fixation is performed parallel to the pipe closer to the bottom. Safety rules do not prohibit higher laying, but the probability of damage from above will, by definition, be higher.

The straight-line installation of a heating cable is often used for gas, as well as water pipelines, sewer and drainage pipes

The distribution pattern of heating cables on a gas pipe directly depends on their number. One line is laid at the bottom, respectively, 4 hours, if, again, imagine a dial instead of a slice. Adding a second will mean placement at the same level, but on the other hand.

In the variant with three branches, they are put into an imaginary triangle on the lower half of the pipe, and it should look a little to the right or left. Of the four cables, the correct square pattern is already made, and then two wires will be on top.

Spiral fixation around the pipe

The method is preferred in the northern regions. The probability of freezing moisture in the gas pipes there is much higher, so the contact area is increased. The contact zone in the spiral method covers the pipe at different angles, according to a principle similar to a wavy gasket, but even more efficient.

For spiral mounting produce long cables. So manufacturers provide an option for choosing the step between the turns. In practice, the interval is sometimes adjusted to 5 cm or less. The cable will then exceed the length of the pipeline itself by about 2 times.

The spiral installation method has more advantages: in difficult situations and at extreme temperatures, it is preferred to him

In some places, laying the cable is difficult. The way out of this situation is precisely screw-shaped installation, but using a different technology. The core is first wound with a margin, and then tightened with a change in the direction of the loops.

Important Installation Nuances

A successful installation includes several components. The first fiddle is played by an algorithm of actions. The pipeline must first be tested and painted, and for installation, you should choose a suitable day when there will be no precipitation.Moreover, the laying of some cables is possible only on one side. It is enough to miss this one nuance - and all work will have to be started anew.

Practical points about using heating cables:

• the lower the wire, the better the heat transfer processes;
• the adhesive layer accelerates heating;
• thin metal pipes must be additionally insulated with foil or tape, as well as plastic.

Do not rush the process of fastening to valves and threaded parts. The wire should be laid in such a way that then it is easy to service, repair and replace pipe elements without dismantling the heating system.

The cable must be shaped like a loop near the connection, and then rolled up to a state of light tension and secured with tape.

Conclusions and useful video on the topic

Overview of the self-regulating heating cable, including the principle of operation, applications and tests:

A good example of a longitudinal installation on a thin pipe, also with a gasket near the valve:

Cables for installation on the gas pipeline are of 2 types: self-regulating and resistive. It is unlikely that one will have to puzzle over the choice, because the first option is clearly better in the sum of characteristics. Installation of the heating system is carried out longitudinally, with a spiral or a wavy line.

Before that, they select the length and power of the heater, make calculations with a large number of physical indicators. After all, you need to understand what happens when a gas pipe is heated with specific types of heating cable, and what you should refuse. After installation, discomfort and problems with gas supply will be a thing of the past.

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