And we have gas in the cottage. And you?

Connecting parts made of polyethylene
Polyethylene gas pipes PE-100 produced by «AND GAZTRUBPLAST» in bays
Polyethylene pipes U-shaped molds are used to repair the gas pipeline

Above and below— replacement of worn steel pipes according to technology U-LinerScheme of gas input to the house with the transition from a polyethylene pipe to a steel one:
1. Steel pipe with compensator
2. Ball valve DU.25 (DU.20)
3. Rubber ring or sealant
4. One-piece connection «polyethylene-steel»
5. Bracket with sliding collar
6. Steel case DU.403.0
7. Case made of heat-resistant plastic
8. Polyethylene pipe 32(thirty)
9. Polyethylene curved case
10. Electrofusion polyethylene coupling
11. Rubber ring or sealant

How to answer this childish, but far from idle question? We also have gas in our houses, but quite often it is imported, in cylinders. BUTthe local gas industry either cannot or does not want to build a quarterly gas pipeline from the main line: they say, the conditions of the area do not allow, and it is expensive. A familiar situation, isn’t it?

The laying of any communications, including the installation of a traditional metal gas pipe to the settlement, requires serious material costs. There is also an alternative— instead of steel, use a special polyethylene pipe for gas supply. You simply wonder why, with the obvious benefits of using polyethylene pipes in the construction of inter-settlement underground gas pipelines, obsolete steel prototypes are still used in the gas industry.

If we calculate the benefits during installation and operation, the comparison will not be in favor of the metal at all (according to the data provided by Lenoblgaz OJSC).

Metal pipes in the ground are subject to intense electrochemical and chemical corrosion, which eventually leads to their partial or complete destruction. Maintaining communications from metal pipes in working order entails high operating costs. The maximum service life of a metal pipe in a gas industry, provided that cathodic protection is installed on the pipeline and the pipe insulation is not damaged, is calculated 20for years. FROMover time, the operation of a steel gas pipe becomes more dangerous than a polyethylene pipe of the same service life.

In the USA, Canada, Great Britain, Japan, they understood the advantages of using polyethylene pipes in gas supply earlier than others and advanced further than others in the field of technologies and practices of gas transportation and distribution. AT1998in Russia out of 36thousandkm of gas pipelines 5517.2km were laid using polyethylene pipes.

What are the advantages of polyethylene pipes over steel pipes? They have much higher frost resistance, plasticity, resistance to aggressive chemical compounds, they are not afraid of electrochemical corrosion, the action of stray currents. Polyethylene pipes are laid directly into the ground without the special protection and insulation that steel pipes need. They weigh at 7times smaller than steel ones of the same diameter and are supplied in coils (with a diameter of up to160mm), wound on drums (with a diameter of63mm and more) up to1200m, or in segments (diameter 110 and 160mm). Pipes are easy to cut and weld. The complexity of their installation 2-3 times below steel. The high plasticity of polyethylene pipes and tensile strength allow them to be laid in heaving soils and in regions with increased seismic activity. But most importantly, the warranty period of their service— 50 years at low installation and operating costs!

In Russia, polyethylene pipes for the needs of the gas industry today produce 14enterprises. Among them are two plants in Kazan— «ORGSINTEZ» and «GAZPLAST», the enterprise «LIVNYPLASTIC» in the city of Livny, Oryol region, «AGRIGAZPOLYMER» in the city of Obninsk, «SIBGAZAPPARAT» in Tyumen. ToUnfortunately, domestic pipes are still equipped with foreign-made fittings. However, for 1999It is planned to implement a large-scale project for the joint production of polyethylene fittings using the technology of the English company FUSION.

The first manufacturer of plastic gas pipes that meet progressive European standards was the Moscow plant «ANDGAZTRUBPLAST. Its pipes are made of polyethylene of the type PE-80 and PE-100 comply with the standards GOST R 50838-95,TU 6-49-04719662-120-94. The plant produces pipes with a diameter of20 to225mm with wall thickness from3 to20.5mm, designed for rated working pressure up to12atm. All pipes are completed with the necessary connecting elements manufactured by FUSION— saddles, couplings, bends, tees, various adapters, couplings for connecting polyethylene pipes with steel and brass products, etc.

Is it possible to mount a gas distribution system on your own? After all, they do the same with water supply and heating systems? ATIn the case of gas, things are much more complicated. The gas distribution network, like the electrical one, belongs to the means of increased danger. To carry out any work with gas, a license from the Gorgostekhnadzor of Russia is required, issued to companies whose personnel have been trained in specialized training centers and have the necessary practical experience.

All this means that in the field of gas distribution, amateur activity is strictly prohibited. You can supply gas to the village and to your house only officially, with the participation of licensed specialists. ATfirst of all, for connection to the gas main in the regional (city, district) operational service, technical conditions must be obtained, after which a project is developed by a licensed organization. At this stage, with your participation, an optimal gas supply scheme for a village or cottage can be developed. Andonly then will a licensed construction company implement the project using technologies that can also be agreed with you. The completed work is accepted by the acceptance committee, which includes the customer, contractor, representative of the gas management service and the Gosgortekhnadzor body.

Cabinet regulators can be installed to reduce gas pressure at the inlets to consumer homes. This makes it possible to reduce the length of the underground gas pipeline by eliminating the network of low-pressure pipelines and parallel laying, which provides significant cost savings.

Gas is supplied to the house through an individual cabinet point(SHP) directly from the gas distribution network of medium pressure. Construction of the main distribution point(HF) is not required at the entrance to the settlement, hundreds of meters of pipes are saved. ATIn general, such a scheme costs the consumer40% cheaper than a traditional low pressure gas distribution network with hydraulic fracturing.

The question “what if gas communications have long been laid using metal pipes?” is appropriate, because the moment will come when they will need to be replaced. Oddly enough, the problem in this case is solved much easier. There is a technology for pulling polyethylene pipes inside worn out pipelines. As the diameter of your gas pipeline decreases, the gas supply system will be switched from low pressure to medium pressure. According to another technology for the repair of a gas pipeline, instead of polyethylene pipes of a smaller diameter, special, longitudinally folded in the shape of the letter U, pipes made of polyethylene grade PE-100. Pulled into a steel pipe, under the influence of pressure and temperature, they become round (technology U Liner). At the same time, the pressure in the restored gas pipeline will remain the same.

Another technology— «Phoenix»— allows you to restore a worn-out steel gas pipeline by pulling a synthetic fabric hose through it, glued to the pipe walls with a special two-component adhesive. At the same time, the diameter of the pipe practically does not change and the same pressure is maintained in it. It should be noted that this technology is quite expensive.

There is an important nuance to be aware of. Gas can be supplied to the house through a polyethylene pipe laid in the ground, but gas can be supplied to the house and wiring inside it only using a steel pipe of the appropriate diameter. Those who have been abroad will object: they say, you can do the wiring using copper pipes. This is of course true, only Russian SNIPs and GOSTs are still far from perfect, but no one has canceled them. Andalthough in some places in Russia, on the basis of departmental permits, copper wiring is already being done today, due to the lack of regulatory documents, it is not officially allowed by the local authorities of Gosgortekhnadzor. It is allowed to connect gas stoves to the pipe using special flexible reinforced hoses with yellow markings, the length of which does not exceed 1.5meters.

Welding of polyethylene pipes is possible both with the use of parts with embedded electric heaters, and end-to-end. For these purposes, welding machines and machines of domestic («Protva-4») and foreign production (firms FUSION, VIDOS, SORON, FRIATECK, UPONOR, GEORGE FISCHER, etc.). The machine for electrofusion welding operates both in automatic and manual modes and is used for welding pipes with diameters from16 to315mm. The device has a built-in device that automatically controls the quality of welding. The pipe butt welding machine is an automated machine controlled by a computer that controls all welding operations. It is used for welding pipes with diameters from63 to250mm.

The use of polymeric materials in the gas supply of the village and the cottage will ensure a safe life for all its residents for a long time and will eventually save a very substantial amount.

The editors thank the administration of CJSC «POLYMERGAZ», the plant «ANDGAZTRUBPLAST» and JV FIT-PLAST— FUSION GROUP» for the materials provided

• Source: Ideas for Your Home Magazine#21

Material prepared

Petr Nikolaev