The metalplastic pipe is the integral, welded by the laser "end-to-end" or ultrasound "with an overlap" aluminum pipe protected from within and outside by polyethylene layers. The inside protective layer does a pipe of much more equal, than metal. Therefore it is difficult for rust, lime and other deposits "to be hooked" for plastic. So, the internal surface of a pipe remains pure longer, it is less than danger that will begin to flow. The external polyethylene layer protects a pipe from external influences and serves as a metal insulator from moisture condensate. Often experts call such pipe five-layer, meaning two more layers of special glue.
Five layers of a metalplastic pipe:
- 1 - polyethylene;
- 2 - the sticking together layer for strong compound of plastic and metal;
- 3 - an aluminum tube with a longitudinal welded seam "with an overlap";
- 4 - the sticking together layer;
- 5 - polyethylene.
For connection of components of a metalplastic pipe producers use the special gluing structure. At each firm - the, its formula is kept a secret. And it is clear: plasticity, and respectively and durability of a pipe depends on its quality. By the way, this glue - the most weak spot of a pipe. If glue loses elasticity, the pipe begins to be stratified and proceed in places of connections.
One of important requirements: though the pipe and multilayered, it should not be thick (and respectively and less flexible) therefore some producers try to make aluminum part thinner. Sometimes she on thickness reminds a foil.
Coefficient of thermal expansion and other difficulties
One more important nuance: the metalplastic pipe can have initially smaller diameter, than steel. If for a steel pipe when calculating system 1 inch is put, then for a metalplastic pipe 3/4 inches are enough. It increases possibilities of its application. At desire it is possible to make absolutely thin pipe - with a diameter of 10 mm and even 8 mm. For example, the heating of a floor was widely adopted only after emergence of metalplastic pipes. To make thin pipes of steel and plastic it is difficult, and for metalplastic - there are no problems. Steel pipes for this purpose were no good - they are insufficiently flexible; plastic flexible, but they carry badly out heat. Copper pipes, of course, too suit for installation of system of heat-insulated floors, but it is unfairly expensive.
One more advantage: metalplastic pipes are universal, they can be used both indoors, and outside. The main thing and the only condition at their operation - free access to pipes in places of connections that is where there is fitting. It in case the pipe "will begin to cry".
And she can begin to cry, alas, too. And the cause is - coefficient of thermal expansion. The matter is that plastic and metal differently carry out heat. The metal layer is thinner, the more considerably metal reacts to differences of temperatures. In other words, if on a pipe long time there was only a hot water, and cold, then aluminum foil went then will decrease in sizes (will be narrowed) more, than plastic, connection will weaken. In this "weak" place water can also filter.
This feature of metalplastic pipes (in other words, big coefficient of thermal expansion) - their main shortcoming.
This nuance should be considered during installation. The main thing governed - at installation of a metalplastic pipe it should be stacked with a stock. That is in places of bends of a pipe have to "lie" freely, but not end-to-end. Experts call this surplus of material compensation loops. By the way, only the expert can calculate the necessary length of metalplastic pipes.
There is also one more reason why the metalplastic pipe can leak. There is an example. Let's present an aluminum wire: it easily bends in all directions, but it is very difficult to return it to a former, initial state, it can just break. And pipe. Of course, polyethylene gives to aluminum plasticity, but all the same it is impossible to bend a pipe at an acute angle. It will break, and it will not be possible to restore it any more, it is necessary to change.
But even by means of these devices it is impossible to bend metalplastic pipes more often than through each 5 centimeters. And especially they cannot be twisted. And fasteners (which pipes fix to walls, a floor etc.) have to be installed freely, without pressing and dents, only in the places corresponding to the project. That is why it is better to bend such pipes manually or by means of the special tool - the pipe bender. On the pipe bender there is an arch regulated on radius. The pipe is stacked on this arch and softly bent under the set corner. If it is necessary to bend a pipe manually, then it is necessary to insert previously into it a steel spring or to fill a pipe with dry sand - then it will be bent more evenly and will not become torn.
So than they are good?
And still metalplastic pipes - more flexible in comparison with pipes from other materials. Besides, do not need additional connecting corners and knees. Bent a pipe - and all. More nothing is necessary.
Let's remind that metalplastic pipes can be used practically in all systems of communications: heating, hot and cold water supply, heating of a floor, at supply of compressed air and chemical liquids (including aggressive). Even electric wires can be hidden in metalplastic pipes or to lay heating pipes in one system with an electrical wiring. They are suitable also for capital repairs in multi-storey buildings when connection from a strut when replacing all system of the pipeline is required, and for usual "cosmetic" apartment renovation or private doma among themselves connect very easily: to connect or connect them to the pipeline, the welding machine or a blowtorch is not necessary. It is enough to cut off a pipe of the necessary size (a photo 1), to calibrate, that is to level a circle (a photo 2), to note a junction with a fitting, to put on and fix a fitting (a photo 3).
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