It is released on the market in two forms. In the first one it looks like a hollow cylinder with a slot. In the second - consists of two components, which are joined with each other. Some of the precast elements of the shell are equipped with a so-called "groove-comb" system, and some have usual flat edges. 
To begin with, let's talk about the shell in the form of a whole cylinder with a slot, which includes foamed polyethylene. She gained confidence due to her flexible material, and also because she could be mounted on a pipe with different diameters. The operating temperature ranges from minus 40 to plus 95 degrees. Naturally, there are some drawbacks. The first is a similar polyethylene absorbs moisture. In this regard, it will have to be covered with a means for waterproofing. The second - the shell requires additional fastening( as a rule, use adhesive tape on the surface of the pipe).In addition to fixing, it performs a function of a kind of waterproofing.
The second kind of shell consists of foam. It is a little more expensive, but it is justified. The material is more rigid, the constituent elements have both a lock and an endless edge. It practically does not absorb moisture and can withstand the operating temperature in the range from minus 50 to plus 80 degrees. It is this shell that is insulated by city highways. 
Shell of PPU - is used in extreme conditions. It has better characteristics and, of course, is much more expensive. Basically, it is used in production plants because of the operating temperature, which ranges from minus 180 to plus 130 degrees.
In addition to simplicity of installation and installation without additional fasteners, the shell of polyurethane foam and polystyrene is positively distinguished in terms of its specific gravity. It is light, so it does not make the design too heavy. Reliable and good thermal insulation of pipes ensures the lowest coefficient of thermal conductivity and minimum moisture absorption. Plus, the PPU shell does not attract different rodents, which means that the risk of damage is minimal. The material is not peculiar to infection with mold and fungus. Such a heater can last for more than fifty years, and there is a possibility of its secondary use.
Assembly of the shell for the insulation of pipes.
Before proceeding with the installation of the shell, make sure that the pipeline is intact. If any leaks are found, repair, eliminate the cause of the problem and then proceed with installation. 
Do not forget that the surface of the pipeline must be treated with an anti-corrosion agent or painted with a primer. On small pipes, mount a heater of two parts. For better fixation, we want to advise you to let the joints in the runaway. On a medium-sized pipeline, mount the shell, which consists of several parts, and you can not leave a gap between the elements of the insulation. Best of all, glue the joints with adhesive tape. A large diameter pipe is additionally fitted with wire, steel tape or clamps.
Today, it is customary to assume that this particular method of insulation of pipes is considered the most popular not only in Krasnoyarsk, but also in the country as a whole. He confirmed his effectiveness and expediency. 
If you want to simplify the installation work on the insulation of pipes, be sure to use the shell of PPU.
How much can I buy shells for insulation pipes.
The main advantage of such insulation is low cost, including in the city of Krasnoyarsk. The price depends on the thickness of the shell and the diameter of the pipe. Below is a table of indicative prices.
| Pipe diameter, mm | Wall thickness 50mm, price per 1 mp, rub. | Wall thickness 100mm, price per 1 mp, rub. |
| 25 | 65 | 209 |
| 30 | 75 | 219 |
| 32 | 77 | 222 |
| 40 | 85 | 238 |
| 50 | 88 | 258 |
| 57 | 95 | 277 |
| 60 | 100 | 279 |
| 62 | 104 | 284 |
| 73 | 111 | 308 |
| 76 | 115 | 315 |
| 80 | 121 | 324 |
| 89 | 125 | 345 |
| 102 | 145 | 377 |
| 110 | 160 | 392 |
| 133 | 195 | 458 |
| 140 | 220 | 477 |
| 159 | 230 | 532 |
| 203 | 265 | 670 |
| 250 | 390 | 836 |