in our country for the internal piping hot and cold water and heating until now mainly used steel pipes, only for flexible podvodok to sanitary devices used polyethylene (cold water) and copper alloys (hot water).However, long experience has shown that the steel pipes corrode, their life is less than the period before the overhaul of the building, corrosion of pipe materials degrade water quality and clog the inner cavity of the pipes, reducing their capacity and degrade the performance of valves and automatic control system devices.The rate of corrosion of steel pipes regulated SNIP 41.02.-2003 "Thermal networks" and RD 153-34.20.599-99 "Standard instruction for periodic inspection of heating networks in operation."In these documents
Options transporting hot water supply systems and heating normalized GOST R 52134 "pressure pipes and fittings of thermoplastics to them for water supply and heating," harmonized with ISO / FDIS 10508: 2005 (E).
Temperature-time modes of pipelines are shown in Table., Where the following notation: Truby - operating temperature or a combination of the temperature of the transported water that defines the area of application;Tmax - maximum operating temperature, the effect of which is limited in time;Tawara - emergency temperature that occurs in emergency situations in violation of regulatory systems.
maximum service life of the pipeline for each class of operation is determined by the total time of his work at Trabia, Tmax, Tawara and is 50 years old.If a shorter life all of temporal characteristics but Tawara should proportsionalnoumenshit.
may establish other classes of operation, but temperatures must not exceed the specified class 5.
It should be noted that the data table.do not contradict the norms and made up for the average climatic zone.When designing systems for other climates duration of the working temperature of the transported water is recalculated according to the statistical data for the respective climatic zone.Pipes made of polymeric materials have some characteristics compared to steel.They pay attention when choosing the material of the pipeline.For prepara- tion of pipes is polypropylene (PPR), crosslinked polyethylene (PEX), polybutene (PB), chlorinated polyvinyl chloride (PVC-C) and the new material - a heat resistant polyethylene (PERT).
One of the requirements for the pipe material is resistant to chlorine, which has become over the last 100 years, almost universal remedy for the treatment of drinking and waste water.Schemes of cleaning and disinfection of drinking water are based on the criteria set out in SanPiN 2.14.1074-01 "Drinking Water" in accordance with the requirements of which are certified and plastic pipes for water transportation.Practice confirms polymeric pipe materials are not exposed to the chlorine dissolved in the water, while the water quality meets the sanitary norms.
Rules of construction and safe operation of steam and hot water boilers are regulated following the maximum permissible concentration of oxygen in the make-up water for indoor heating systems: for boilers with a working pressure up to 39 MPa and a steam capacity of 2 tons / hour or more, without economizers and iron economizers - notmore than 100 mg / kg;in the presence of steel economizer - less than 300 mg / kg;Boiler - no more than 50 mg / kg.Increasing the oxygen content in the water make-up and network accelerates the corrosion of boiler heated surfaces.Its requirements for the content of oxygen in the coolant radiators and impose various kinds.
In this regard, in IEC 52134 (para. 5.1.13) set the maximum allowable rate of oxygen permeability for grades 3-5 operation (Sec. 5.2.1), is not more than 0.1 g (m3 · d).
For protection against oxygen diffusion wall plastic pipes made with the introduction of multi-layered as the diffusion preventing barrier layers of aluminum (Al), or ethylene vinyl alcohol (EVOH).The marking of pipes usually specified notional scope.For example: 70 ° C - 10 bar (hot water);90 ° C - 6 or 10 bars (heating).
One of the most common materials for the transportation of hot water is a cross-linked polyethylene (PEX) and composite materials on its basis.Volumes use PEX pipes and metal-based on them are rising mainly due to the decrease in the use of steel and copper pipes.
Most pipe systems XLPE can withstand Operating temperature class 5. Also produced only pipes for hot water, which is usually reflected in their labeling.
in Russia PEX pipes without diffusion barrier made of "Bir Pecs" and "Van Tubo."Pipes cross-linked polyethylene with the diffusion preventing layer of ethylene vinyl alcohol (EVOH PEX) supplied by foreign companies Rehau, Comap, Giacomini, Golan Plastic Products, KAN, Hewing, Purmo, Pipe Life, Tiemme Raccorderie, Uponor, Viega, Wavin, Wirsbo, and others.In our country, we began the production of such pipes (with thermal insulation for underground installation) of "Polyplastic" and "TVEL-PAX."
cross-linked polyethylene pipes with the diffusion preventing layer of aluminum (PEX-Al-PEX), or as they are called metal-polymer (MP-Multilayer PE / Al), produced in Russia several companies ("Kazanorgsintez", "Rubber-Plast"" Metallopolimer "NGOs" plastic "," Mayak-93 "," Omskvodprom ", LLC" Valtek ") mainly from imported components and zarubezhnomoborudovanii.At the same time the domestic market is no shortage in the offer on the basis of metal-PEX pipes produced by European (CoES, Comap, Ennetiemme, Frankishe, Geberit, Henco, Hewing, Kisan, Oventrop, Prandelli, Rehau, TECE, Valsir, and others.)and Asian (LG Chemical, and others.) enterprises.
Since cross-linked polyethylene is not welded or glued, the connection of pipes among themselves and with fittings made mechanical couplings to crimp the pipe on the fitting collet with union nut, slip-clutch or clutch Compression (press fitting).The last two types of compounds are more cheap and used for large scale installation.The fasteners and fittings for pipes of PEX, PEX-EVOH, PEX-Al-PEX installation tool in Russia is mostly imported.Design and installation of pipelines made of SP 40-103-98 "Design and installation of hot and cold water using a metal-pipe" and SP 41-102-98 "Design and installation of heating systems using metal-pipe".
composition PEX-Al-PEX - the most common for metal pipes, but not the only one.There are other options.For example, the polymer layers can be made of high density polyethylene (PEHDAlPEHD), polyethylene of raised temperature resistance (PERT-Al-PERT).Known combinations and when the inner and outer polymeric layers are made of different materials: PEX-Al-PE (outer layer material - linear polyethylene) and PEX-Al-PEHD.And such companies as Aquatherm, Wefa Plastic (Germany), Prandelli (Italy), Dizayn Group (Turkey) produce multilayer pipes based on polypropylene, the primarily-means of which is the possibility of connection by welding.
new product on the market of engineering equipment - polyethylene pipes with high thermal stability PERT (Polyethelene of Raised Temperature Resistance), not included in the GOST R 52134-2003, but is widely used in Russia and abroad.
This material - ethylene-octene - was developed by The Dow Chemical Company and is available under the trademark Dowlex.His advantage over cross-linked polyethylene pipe extrusion was the opportunity without further cross-linking, as well as welding.Pipes from PERT cheaper and smarter in production.They are suitable for use in the negative (up to -40 ° C) temperatures.For the recently introduced modification Dowlex 2388 point Vicat softening material is +124,5 ° C.
pipes PERT available for hot and cold water and for underfloor and radiator heating.Thus, the German company produces Cronatherm pipe material Dowlex 2343E diameter of 12 to 25 mm with an anti-diffusion coating of EVOH for heating and without - to water (diameter - 18 mm and 25 mm).The pipes of the first of these types are designed for nominal pressure of 12.5 atm and designed for use in central heating systems with a pressure of 6 bar and a temperature of 90 ° C.On the Russian market, this product delivers the Polish company KAN.
PERT - a promising material for the production of composite pipes.As an example of composition pipe based on it can cause the tube Unipipe, proposed on the market concern Uponor.At present, the annual production volume of the tube (diameter - from 14 to 110 mm) complete with connector parts is 55 million cubic meters.
Fatherland petrochemical enterprises Organization heat-resistant polyethylene production is not planned.In 2006, the NGO "Stroypolimer" (Moscow) were produced pilot batch of the PERT pipe deliveries abroad.Production passes certification tests.
To transport hot water in the hot water and heating systems GOST R 52134 2003 normalized use of pipes of polybutene for grades 1-5 operating conditions (see. Table.).
polybutene is characterized by a high resistance to stress cracking, low creep under prolonged mechanical loads, high wear resistance, heat resistance and resistance to ultraviolet rays.
The polybutene pipes for heating provides protivodiffuzi-onny layer of EVOH.The most widely used polybutene in England, Germany, Scandinavia and North America.Major manufacturers of raw materials for the production of these pipes - companies Shell, Basell and Mitsui;European leader in the production of polybutene pipes - the company Georg Fischer.Pipes and fittings of polybutene for hot water and heating in the Russian market offers German companies and Gabotherm Aquatherm.
pipes made of polypropylene in Russia began to be used since the mid-1970s.and they were normalized to the CH 478-75.In the mid-1980s it was mastered the production of propylene-ethylene copolymer (PPR).The peculiarity of this material is its high resistance to hot water, so he began to be used in heating systems.An additional advantage of polypropylene pipes - the ability to create reliable welds.Details for socket fusion also significantly cheaper choke and mechanical.Further, when laying pipelines can be repeated polypropylene trace piping similar conventional steel.
Today, polypropylene pipes and fittings - one of the most common types of products on the market of equipment for engineering systems.They offer European, Asian and domestic companies: Dizayn Group, Pilsa (Turkey), Wavin Ecoplastik, FV Plast (Czech Republic), Wefa Plastic (Germany) and others.
In our country, the release of parts of the PPR was first mastered the NGO "Stroypolimer."During the period of 1995-2006.It was installed 1,200 kilometers of its pipelines.From manufacturers entered the market in recent years, it should be noted the company "Aquatech-Plast" sold under the brand name Aquatech polypropylene pipes and fittings for cold and hot water as well as heating systems with water temperature to 75 ° C.
addition of polypropylene produced in Russia, domestic manufacturers of piping systems are widely used imported raw materials: PPR-80 companies Borealis (Brand RA 130E), Basell (Brand N5416), Hyosung (grade R 200P).
in Russia in the next decade, a significant increase in the planned release of the material.Specifications for pipes and the details are regulated in the GOST R 52134-2003, and recommendations for the design and installation - in SP 40-101-96 "Design and installation of pipes made of polypropylene" Random copolymer ".Russian companies supply parts and pipes with outer diameters up to 125 mm with a nominal pressure of 10 and 20 atm.
As resistance to the perception of stress in the pipe wall materials considered are located in the following sequence: polybutene;a crosslinked polyethylene;resistant polyethylene;polypropylene;chlorinated polyvinyl chloride.
Currently of these materials in our country is massively used PEX pipes and plastic pipes based on it, as well as pipes made of polypropylene.Pipes made of other materials is not yet play a significant role in the domestic market of pipe products.
"Aqua-Therm" № 6 (34) 2006