Trubnyiy a choice

The choice of pipes for systems of local water supply, heating and the water drain to which concern and podvodka a building and distributing in it, is rather great presently. And after all more recently for these purposes almost exclusively steel and pig-iron pipes were used. Possibly, exclusiveness of steel pipes also was a basis of belief in their high durability and reliability. These pipes and methods of work with them (welding, carving cutting) have played not the last role in creation of an image of the sanitary technician.
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The first factory on production of steel pipes has started to work in England in 1842, and in Russia only in the eighties XIX century But already in the beginning of XX century steel pipes became a principal view of pipes for water-and pipeline networks. However in a number of the countries of Europe they and could not supersede copper pipes used still from XVII century.

Exclusive existence metal (steel and copper) pipes has infringed occurrence of polymers and plastic. Industrial production and application of polymeric pipes has begun practically simultaneously in Europe, the USA and Japan in the early fifties of the XX-th century. These pipes thanks to a number of positive properties have started to supersede the steel actively. They it is easier (in 3-5 times), not korrodirovali and easily incorporated in systems. The basic scopes - water and sewer systems in inhabited and public buildings. By 2000 polymeric pipes have taken dominating items in the Western Europe: in Switzerland the volume of their use in new building and at overhaul has made 70 %, in Finland — 51 %, in Germany — 46 % from total amount of use of pipes.

In Russia still mainly apply metal, more precisely, steel pipes. However appreciable shifts in the Russian market of building materials are already visible: the diversified pipes (metal, polymeric, ceramic, asbestotsementnyie, etc.) are offered.

To orient in this variety and to choose the necessary type of a pipe, it is necessary to know pipeline appointment, parametres of its work (temperature, pressure, character of environment, etc.), required durability and, naturally, to consider the financial possibilities.

The durability often is a stumbling-block as the consumer faces to a dilemma: if a pipe cheap, it short-lived and on the contrary. However it is necessary to remember, that replacement of pipelines in buildings — the serious problem interfaced to the big expenses. But the big single expenses during building will help in further to save money for repair. One more not less important problem — complexity (or, on the contrary, simplicity) installation of system of the pipeline and the expenses interfaced to it. And at last, purely aesthetic requests as they are an interior element.

To consider properties of pipes expediently by the form a material from which they are produced as it defines pipe field performances, its durability, methods of installation and, naturally, cost.

METAL PIPES

For manufacturing of pipes the steel, pig-iron and copper are really used. Pig-iron pipes in local networks are used practically only for the water drain. To waterpipes and a heat supply apply steel and copper pipes.

Steel pipes in Russia and in many other things the countries are applied till now in building more often others. It speaks not only and not so much adherence of Russians to all thorough: walls at the house — brick, pipes — steel zinced, but also serious raw our country serious raw and technological base for their production.

For local systems use so-called water gas pipes. Them receive a bend of a steel sheet of the corresponding width with the subsequent welding are so-called shovnyie pipes. Diameter of such pipes («conditional pass») from 8 to 150 mm. More often than others pipes with diameter of conditional pass 15, 20 and 25 mm are applied. A thickness of a wall at these pipes — 2,8 mm. So big thickness of a wall not desire to supply high durability, and absolutely other reasons speaks. First, steel pipes connect on a carving or welding that requires a certain thickness of metal, and, secondly, a steel pipe fast korrodiruet and for maintenance of its durability the big thickness is necessary.

Corrosion of steel pipes — their basic defect. For its delay use zinc cover («the zinced pipes»), that slows down, but does not prevent corrosion.

Positive property of steel pipes is the low temperature factor of linear expansion (0,012 mm/m·k). It means, that at rise in temperature on one degree each metre of a pipe is extended on 0,012 mm.

Steel pipes have enough the big weight, that speaks in high density of a steel (r=7,85 g/sm і) and the big thickness of a wall.

At steel pipes high heat conductivity — 74 Vt/m·K. It is good, when they are used in heating system, but at transportation of cold water becomes defect: pipes "moisten", korrodiruyut outside, becomes wet and the wall adjoining to them collapses. To avoid it, it is possible to take advantage of tubes from the made foam polyethylene or the rubber, put on a pipe.

One more small, but at times rather annoying defect: steel pipes "sing", though as a noise source malfunctions serve in armature (cranes, siphons, etc.), and pipes only transmit and strengthen this sound.

Throughput of steel pipes at equal internal diameter more low, than at copper and polymeric because an internal surface at them rough, that causes turbulences in a stream of a liquid and hinders its advancement. In due course, when pipes acquire products of corrosion and other adjournment (as an old teapot — a scum), their throughput decreases very essentially. It can be one of the replacement reasons still whole by sight pipes.

Service life of the steel pipes used for water supply and heating, about 30-40 years.

Installation of system from steel pipes — labour-consuming enough business. Steel pipes connect on a carving to the help muft, sgonov, squares and other fasoninyi or weldings. Decorative effect steel systems not bleschut and consequently require the colouring masking their presence at a premise.

It is necessary to notice, that the zinced pipes to weld does not follow, as in a place of realisation of welding protective zinc cover completely disappears, because zinc at heating to 900°S (and welding temperature considerably above) evaporates and burns down. The welded joint becomes the most vulnerable for corrosion by a plot factory. At installation of systems zinc cover can be restored.

Pig-iron pipes — thick-walled, concerning the big diameter (50-500 mm), but shorter, than steel. Them receive casting from grey pig-iron. Pig-iron pipes for the account bolshey thickness of a wall and bolshey corrosion stability of the material have high durability and reliability, but their weight several times above, than steel the same diameter.

Connect pig-iron pipes by means of the bells condensed with stamping by the tarred rope, extending cement, or ancient and very reliable reception — lead. By the way, last has entitled a trade of the sanitary technician in Europe — plumber (from an armour. Plumbum — lead).

More reliable methods of fastening are developed also. For pipes with bells — tension bolts. For the pipes not having bells and connected end-to-end, it is developed and with success system SMU (France) with rubber germetiziruyuschey a cuff and a fixing collar from stainless steel is used. In this system the pipes painted outside akrilovoy by a paint of red colour and having a sheeting, raising stability to corrosion from within are used.

The pig-iron pipes applied to a lining of intraquarter water supply systems and for the water drain, are manufactured complete with shaped details. Networks from them work long years without repair and replacement. For example, in the centre of Moscow there are networks from the pig-iron pipes, laid in the end of XIX century.

Copper pipes have started to be used in building in 20-30th years of the XX-th century. The peak of their popularity has fallen to 70th years. During same time wide introduction in building of polymeric pipes has begun. As a result of competition between copper and polymeric pipes have emerged their strong and weaknesses.

Copper is known for a long time as in the pure state, and in the form of brass alloys (an alloy with zinc) and bronze (an alloy with tin).

The name copper (an armour. Cuprum) — soft and plastic (in the technician speak «kovkiy» metal, has received from the island Cyprus name where copper ore was extracted. It it is very good (in 5 times better steels) are conducted by heat and an electric current and almost is not exposed to corrosion. In the neutral water environment (for example, in water water) it is dissolved in insignificant doses and practically is not oxidised. As acknowledgement following facts can serve it: copper as gold and silver, meets in the nature in a native kind and more than 80 % of the copper melted by mankind, is in operation (the steel on 8-10 % "is annually eaten" by corrosion).

There is an opinion, that water in which copper connections are dissolved, is harmful to an organism and even is poisonous. In this case it is useful to recollect words of the well-known doctor of Renaissance of Paracelsus: «the Substance can be poison and a medicine: all depends on concentration». It to the full concerns copper: on the one hand, it is heavy metal, and with other — a vital element. Really, the human body contains on the average about 100 mg of copper. And as it in an organism is not accumulated, and constantly removed, the person should consume with food of copper of 2-3 mg a day. These quantities at 10-50 time above, than contain in one litre of the water which are passing through copper pipes.

For manufacturing of pipes use copper of very high cleanliness (99,9 %), that is the quantity of impurity in it does not exceed 0,1 %. Such copper differs especially high corrosion firmness and plasticity, thus not losing plasticity and at negative temperatures (to-100°S). At water freezing in a copper pipe the last does not burst, and extends only a little and after thawing is again ready to work.

At machining (vyityagivanii, punching, etc.) copper partially loses plasticity and becomes more rigid and strong. This phenomenon in metallurgical science name «naklep». It is possible to return copper in an initial plastic condition «otzhigom», that is heating to 600-700°S and the subsequent slow cooling. For comparison we will result two figures: neotozhzhennaya copper has durability 280-300 MPa and lengthening at rupture of 10-15 %, and otozhzhennaya, accordingly, — 210-220 MPa and 50-60 %.

About decorative qualities of copper and to speak it is not necessary.

Copper pipes manufacture in neotozhzhennom a condition (in the form of switches in length 5) and in otozhzhennom in curtailed into bays (25 and 50). The largest manufacturers of copper pipes: German firm KME and ESENCO, entering into the Italian firm SILMET.

Pipes are manufactured the standard sizes: diameter from 10 to 28 mm at a thickness of a wall of 1 mm (!) and diameter from 35 to 54 mm at a thickness of a wall of 1,5 mm (manufacture pipes and bolshego diameter). It is necessary to notice, that in comparison with steel copper pipes have very small thickness of a wall and accordingly increased internal diameter. So, a copper pipe with internal diameter 20 mm have walls in the thickness of 1 mm and weight of one metre of a pipe only 0,59 kg, that is almost in 3 times it is easier steel. At so small thickness of a wall copper pipes are calculated for higher, than at steel, working pressure.

Copper pipes have very smooth walls. Their roughness in 100 times more low, than at steel, and in 4-5 times more low, than at the polymeric. With allowance for smoothnesses of a surface of copper pipes their throughput will be much more above, than at steel, and there is constantly high all term of its operation (not korrodiruet and "does not acquire").

Prochnostnyie parametres and durability of copper pipes practically do not depend on pressure and temperature of a transported liquid (the allowed interval of temperatures from +250 to-100°S). This one of essential advantages of copper pipes before polymeric, at which the durability depends on parametres (temperature and pressure) a transported liquid. Besides, the problem of protection against Uf-radiation and oxygen penetration through a wall of a pipe for copper pipes unlike polymeric simply is not present.

Thanks to plasticity of a material copper pipes are not afraid of freezing of water being in them.

However it is necessary to name our century polymeric. Even copper pipes "have asked" the help for polymers. Some firms have begun issue of copper pipes with outside cover from polymers. Basically covers from PVC and polyethylene polyvinylchloride (including made foam) are applied. Such covers execute protectively-decorative functions:

Give to pipes desirable colour;
Reduce heat losses at transportation of hot water;
Interfere with condensate formation at transportation of cold water;
Reduce «shumnost» pipes;
Protect pipes from abrasive deterioration (a scratch, the tease) and corrosion at their lining in the earth and in walls.

Copper pipes can be recommended as for heating (here the positive role is played by high heat conductivity of copper), and for water supply. In all cases of transportation of water it is necessary to adhere to the rule: not to put in system downstream water after copper pipes the steel zinced. Intensive destruction of zinc cover in this case will go.

Installation of copper pipes is made fast. The big set fitingov from copper is manufactured. In it the leading part belongs to firm SANHA (Germany). Copper pipes easily are cut and bend. The system is mounted with the help fitingov the soldering or zapressovkoy with sealing rings.

ASBESTOTSEMENTNYIE PIPES

In the XX-th century beginning the new material — asbestotsement was born, and, accordingly, have appeared asbestotsementnyie pipes. They have received a wide circulation in the Western Europe and the USA.

As the material for pipes asbestotsement has conclusive dignities. It is not subject to corrosion, including by the most dangerous to metal pipes — electrochemical. Contact to water, especially hot, causes not destruction, and hardening asbestotsementa — as cement hardens at interaction with water. Asbestotsement has considerably smaller heat conductivity, therefore water freezing in such pipes less possibly, than in the metal. Does not occur also characteristic for metals «otpotevaniya» at transportation of cold water.

The domestic industry manufactures asbestotsementnyie pipes in diameter from 100 to 500 mm and length to 5 m in two variants: not pressure head — for the organisation of drains, ventilation, a lining of cables, etc.; strengthened, pressure head — for water supply systems and gas pipelines. For distributing of water in premises them do not use.

Connection of pipes is carried out without a carving and welding with the help muft and rubber sealants. Such connection is very reliable and simple in performance. Besides, the system of a mobile joint with rubber sealants removes problems of deformations thermal and from ground procorfs.

Application asbestotsementnyih pipes for networks of hot and cold water supply at water delivery in cottages, for the water drain and ventilation system is rational. They in 3-5 times are cheaper, than similar steel, pig-iron and polymeric pipes. But there are also restrictions. It is impossible to apply asbestotsementnyie pipes to furnaces, fireplaces, etc., smoke tap on those plots where heating of a material to 400-500°S is possible, that is actually in fire operative range. In this case pipes rastreskivayutsya (boys specially throw slate in a fire and wait when it "will blow up").

About harmlessness of asbestos for the person or, on the contrary, to its ecological cleanliness separate, almost detective history. We hasten to certify only you (rely on our competence), that asbestotsementnyie pipes are harmless to the person. Acknowledgement to that experience of Austria, Holland and other European countries where for water supply such pipes are used. They work without repair and failures many tens years.
POLYMERIC PIPES

The polymeric materials named usually plastic, have appeared in human life rather recently — in the middle of the XX-th century.

To understand positive and negative properties of polymeric pipes, it is necessary to begin with polymers. Unlike metals and asbestotsementa polymers — organic substances with all their merits and demerits, consisting in close relationship with natural high-molecular — wood, a skin and a wool.

Polymers have variety of dignities: they have universal chemical firmness and are not subject to corrosion. Despite the ease (their density in 5-8 times below steel density), they strong enough and elastic. Polymers are easily processed in items, that is accept the set form and are well painted. Heat conductivity of polymers much more low, than at metals, that, in particular, reduces teplopoteri at transportation of hot liquids.

Along with these positive properties polymers are not deprived also essential defects. At heating durability of polymers decreases. As well as all organic substances, they burn, and under the influence of ultra-violet beams grow old (are done fragile and collapse). It is necessary to carry To defects and big (in 10 times more, than at a steel) factor of temperature expansion; the truth, elasticity of polymers partially compensates this defect.

The technologists making items from polymers, try, and not without success, to strengthen their dignities and to reduce defects.

The chemical industry in second half of XX-th century has run in production of tens polymers, but mass application including by production of pipes, have found 5-7 of pivotal of them. Unconditional leaders are polyethylene (RE), polypropylene (RR) and polyvinylchloride (PVC). The indicated polymers concern group of the thermoplastic. They are capable to pass at heating in an is plastic-viscous condition, and at cooling to harden.

Pipes from such polymers receive a method ekstruzii (expression) by means of warmed shneka (an example of the elementary ekstrudera, but only without heating — a house meat grinder). Pipes are received with very smooth surface (a roughness of polymeric pipes approximately in 10 times more low, than steel).

The greatest distribution was received by pipes from polyethylene. Originally them did of usual polyethylene (recollect a transparent polyethylene film). Such pipes lost durability at heating to 50-60°S and fast grew old. They could be used for giving only cold water. In 80th chemists have learnt to connect with one another linear molecules of polyethylene — to "sew". Such "sewed" polyethylene has the raised durability, temperature constancy and firmness to Uf-radiation. On them transportation of water in temperature to 95°S is admissible. Having received the raised temperature constancy, the "sewed" polyethylene has lost ability to cook. In marks of items the "sewed" polyethylene is designated RE (letter H indicates that polymer "is sewed"). Pipes make of the sewed polyethylene more than half from the general issue of polymeric pipes. Pipes of German firm REHAU are most known. In Russia such pipes are made, in particular, by firm «Bir Peks» in Saratov.

Pipes from the "sewed" polyethylene RE can be used not only for cold, but also hot water supply and heating (central and floor). For example, in a building of the Moscow mayoralty on New Arbate 113 m in water supply and heating systems steel pipes have been replaced by height with pipes from the sewed polyethylene.

Polypropylene (RR) on use in production of pipes takes the second place. Physicomechanical and thermal properties of this polymer are close to the sewed polyethylene, but unlike last it more rigid. Therefore polipropilenovyie pipes are manufactured in the form of measured sections that is a little less convenient at transportation and requires a considerable quantity of connecting elements at installation. On large firms this problem is decided: different variants of complex systems of connection — nizkotemperaturnoy by welding and by means of metal accessories are offered.

The largest firm delivering on the Russian market polipropilenovyie pipes, (Germany) is «Akvaterm». For manufacturing of pipes this firm uses a polypropylene copolymer «Random», having the raised temperature constancy. Pipes from «Randoma» can be applied to giving of hot water to 75°S.

Polyvinylchloride (PVC) — polymer very widely used in building, in production of pipes goes after polyethylene and poliipropilenom. Usually it is used in neplastifitsirovannom a kind (rigid PVC — «viniplast»). Presence of chlorine at PVC causes vigilance of ecologists and limits application of such pipes for water supply. Positive property of polyvinylchloride is its lowered combustibility and the raised chemical firmness in comparison with other polymers. It also is less sensitive to Uf-radiation, therefore the basic scopes of PVC-PIPES are water waste systems and the water drain.

Polibuten (RV) — polymer the same as both polyethylene and polypropylene from group poliolefinov. It is biologically harmless. Pipes from polibutena are more elastic, than from polypropylene. Polibuten it is characterised high prochnostnyimi by indicators, firmness to the Uf-irradiation and the raised temperature constancy, coming nearer in this respect to the "sewed" polyethylene. Pipes from polibutena have proved in networks of hot water supply and heating (in particular, for the system of warm floors). At 70°S and working pressure in system 0,3 MPa 50-year-old service life of Rv-pipes is guaranteed. The maximum temperature of operation of such pipes +95°S. As well as polipropilenovyie, polibutenovyie pipes can be welded, that facilitates and makes cheaper installation of systems from Rv-pipes, having built up a reputation for these pipes perspective for internal distributing.

Along with many positive properties of a pipe from polymers in due course grow old. This quality is characteristic for all polymers for they are on the verge «live and lifeless» and are subject to many laws of the live world. For example, speed of "ageing" of polymeric pipes depends first of all on temperature and pressure. Ageing process is accompanied by decrease in elasticity, durability, increase of fragility and spontaneous rastreskivaniem. Distinctive feature of polymeric pipes that they grow old on all weight while corrosion of steel pipes begins with a surface. Plastic pipes collapse as though "suddenly" and completely, and in metal — fistulas which can be closed up, for example, are formed by welding.

Depending on an operation mode (temperature and pressure of water) are established admissible terms of their operation (the tab. see).

Dependence of durability of pipes from PE-X
From temperature and pressure

Temperature 0S

Service life of years 1 5 10 25 50 20 1,37 1.33 1.32 1.31 1.25 40 1.10 1.08 1.07 1.06 1.04 60 0.87 0.84 0.83 0.81 0.80 80 0.65 0.64 0.63 0.63 - 95 0.57 0.55 0.54; - -

Polymeric pipes mark by the form polymer (RE, RE, RR, etc.), on outside diameter and nominal pressure (PN). Outside diameters of pipes () for internal distributing are presented to mm by following number: 10; 12; 16; 25; 32; 40; 50 etc. Except diameter, pipes are marked on a thickness of a wall. Nominal pressure usually express in bars: 1 bar = 0,1 MPa. By nominal pressure mean constant internal pressure of water at 20°S which the pipe can smoothly maintain within 50 years (for example, PN=10, PN=12,5 or RM=20). For an estimation of level of these parametres it is possible to recollect, that working pressure of water in water system no more than 0,6 MPa (6 bar). The maximum pressure which the pipe can sustain short time, several times above the nominal. At temperature above 20°S term of non-failure operation of polymeric pipes at invariable pressure is reduced or can remain the same — 50 years, but under condition of smaller working pressure.

METALLOPOLIMERNYIE PIPES

Telling about polymeric pipes, as the standard, as a rule, choose the traditional steel. On their background modern polymeric pipes seem centre of dignities. Defects, as a rule, are ignored. And they, certainly, are. And it is clear — is not present in the perfection world, and each "improvement" bears with itself and «new defects».

Universal pipes, equally suitable for high-rise houses, cottages and the industrial purposes, no and to aspire to it it is not necessary.

The decision of many problems has been found thanks to composite materials. Each element entering into composites executes the functions, and the material as a whole acquires a new set of properties. It is possible to carry ferro-concrete, fibreglass to the elementary composites, etc. Thus, the multilayered pipe which wall consists at least of three layers has been created: very thin metal, being between two layers of polymer.

Metallopolimernyie pipes are manufactured two types. The first — the aluminium layer — is possessed between two, approximately identical layers of polymer. Coupling of aluminium with polymer is supplied with a glutinous layer. At such decision as polymer the "sewed" polyethylene is used, and the pipe in this case is designated PEX-AI-PEX.

The second — the aluminium layer — places on an outside surface of a polymeric pipe. From above aluminium is protected by a thin layer of polymer. Coupling in this case is supplied or glutinous layers (pipe REH-Stabil), or by means of the polymer which is becoming numb in punching on an aluminium pipe (the Rr-pipe fuzioterm SHtabi). The aluminium pipe in the considered variants metallopolimernyih pipes is received from a strip of the aluminium foil turned off round the polymeric core and welded by means of the laser.

As a whole metallopolimernyie pipes have saved basically all positive properties of polymeric pipes. Feature is ability easily to bend and save the necessary form. For the account bolshey rigidity they do not require serious measures on fastening at open posting. However it is necessary to consider, that the aluminium core has brought with itself fear of such pipes to freezing in the condition filled in with water as destruction of solidity of an aluminium part of a pipe in this case is probable. Besides, it is necessary to exclude contact of aluminium to other metals in places of connections.

Other composit pipes are manufactured also. For example, a pipe from the polypropylene, reinforced by the high-strength fibre, manufactured under mark fuzioterm-Fazer.

It is necessary to notice, that metallopolimernyie pipes in Russia use the big popularity which part, possibly, it it is necessary to charge some "metal" (affect our big attachment and belief in reliability metal, that is steel pipes).
To. PRIESTS, the prof. (MGSU)
NTS «Stroyinform» Source: "the Building Season" #3, 4 (2003)

It is introduced: on February, 05th, 2003

Trubnyiy a choice

The choice of pipes for systems of local water supply, heating and the water drain to which concern and podvodka a building and distributing in it, is rather great presently. And after all more recently for these purposes almost exclusively steel and pig-iron pipes were used. Possibly, exclusiveness of steel pipes also was a basis of belief in their high durability and reliability. These pipes and methods of work with them (welding, carving cutting) have played not the last role in creation of an image of the sanitary technician.
/>
The first factory on production of steel pipes has started to work in England in 1842, and in Russia only in the eighties XIX century But already in the beginning of XX century steel pipes became a principal view of pipes for water-and pipeline networks. However in a number of the countries of Europe they and could not supersede copper pipes used still from XVII century.

Exclusive existence metal (steel and copper) pipes has infringed occurrence of polymers and plastic. Industrial production and application of polymeric pipes has begun practically simultaneously in Europe, the USA and Japan in the early fifties of the XX-th century. These pipes thanks to a number of positive properties have started to supersede the steel actively. They it is easier (in 3-5 times), not korrodirovali and easily incorporated in systems. The basic scopes - water and sewer systems in inhabited and public buildings. By 2000 polymeric pipes have taken dominating items in the Western Europe: in Switzerland the volume of their use in new building and at overhaul has made 70 %, in Finland — 51 %, in Germany — 46 % from total amount of use of pipes.

In Russia still mainly apply metal, more precisely, steel pipes. However appreciable shifts in the Russian market of building materials are already visible: the diversified pipes (metal, polymeric, ceramic, asbestotsementnyie, etc.) are offered.

To orient in this variety and to choose the necessary type of a pipe, it is necessary to know pipeline appointment, parametres of its work (temperature, pressure, character of environment, etc.), required durability and, naturally, to consider the financial possibilities.

The durability often is a stumbling-block as the consumer faces to a dilemma: if a pipe cheap, it short-lived and on the contrary. However it is necessary to remember, that replacement of pipelines in buildings — the serious problem interfaced to the big expenses. But the big single expenses during building will help in further to save money for repair. One more not less important problem — complexity (or, on the contrary, simplicity) installation of system of the pipeline and the expenses interfaced to it. And at last, purely aesthetic requests as they are an interior element.

To consider properties of pipes expediently by the form a material from which they are produced as it defines pipe field performances, its durability, methods of installation and, naturally, cost.

METAL PIPES

For manufacturing of pipes the steel, pig-iron and copper are really used. Pig-iron pipes in local networks are used practically only for the water drain. To waterpipes and a heat supply apply steel and copper pipes.

Steel pipes in Russia and in many other things the countries are applied till now in building more often others. It speaks not only and not so much adherence of Russians to all thorough: walls at the house — brick, pipes — steel zinced, but also serious raw our country serious raw and technological base for their production.

For local systems use so-called water gas pipes. Them receive a bend of a steel sheet of the corresponding width with the subsequent welding are so-called shovnyie pipes. Diameter of such pipes («conditional pass») from 8 to 150 mm. More often than others pipes with diameter of conditional pass 15, 20 and 25 mm are applied. A thickness of a wall at these pipes — 2,8 mm. So big thickness of a wall not desire to supply high durability, and absolutely other reasons speaks. First, steel pipes connect on a carving or welding that requires a certain thickness of metal, and, secondly, a steel pipe fast korrodiruet and for maintenance of its durability the big thickness is necessary.

Corrosion of steel pipes — their basic defect. For its delay use zinc cover («the zinced pipes»), that slows down, but does not prevent corrosion.

Positive property of steel pipes is the low temperature factor of linear expansion (0,012 mm/m·k). It means, that at rise in temperature on one degree each metre of a pipe is extended on 0,012 mm.

Steel pipes have enough the big weight, that speaks in high density of a steel (r=7,85 g/sm і) and the big thickness of a wall.

At steel pipes high heat conductivity — 74 Vt/m·K. It is good, when they are used in heating system, but at transportation of cold water becomes defect: pipes "moisten", korrodiruyut outside, becomes wet and the wall adjoining to them collapses. To avoid it, it is possible to take advantage of tubes from the made foam polyethylene or the rubber, put on a pipe.

One more small, but at times rather annoying defect: steel pipes "sing", though as a noise source malfunctions serve in armature (cranes, siphons, etc.), and pipes only transmit and strengthen this sound.

Throughput of steel pipes at equal internal diameter more low, than at copper and polymeric because an internal surface at them rough, that causes turbulences in a stream of a liquid and hinders its advancement. In due course, when pipes acquire products of corrosion and other adjournment (as an old teapot — a scum), their throughput decreases very essentially. It can be one of the replacement reasons still whole by sight pipes.

Service life of the steel pipes used for water supply and heating, about 30-40 years.

Installation of system from steel pipes — labour-consuming enough business. Steel pipes connect on a carving to the help muft, sgonov, squares and other fasoninyi or weldings. Decorative effect steel systems not bleschut and consequently require the colouring masking their presence at a premise.

It is necessary to notice, that the zinced pipes to weld does not follow, as in a place of realisation of welding protective zinc cover completely disappears, because zinc at heating to 900°S (and welding temperature considerably above) evaporates and burns down. The welded joint becomes the most vulnerable for corrosion by a plot factory. At installation of systems zinc cover can be restored.

Pig-iron pipes — thick-walled, concerning the big diameter (50-500 mm), but shorter, than steel. Them receive casting from grey pig-iron. Pig-iron pipes for the account bolshey thickness of a wall and bolshey corrosion stability of the material have high durability and reliability, but their weight several times above, than steel the same diameter.

Connect pig-iron pipes by means of the bells condensed with stamping by the tarred rope, extending cement, or ancient and very reliable reception — lead. By the way, last has entitled a trade of the sanitary technician in Europe — plumber (from an armour. Plumbum — lead).

More reliable methods of fastening are developed also. For pipes with bells — tension bolts. For the pipes not having bells and connected end-to-end, it is developed and with success system SMU (France) with rubber germetiziruyuschey a cuff and a fixing collar from stainless steel is used. In this system the pipes painted outside akrilovoy by a paint of red colour and having a sheeting, raising stability to corrosion from within are used.

The pig-iron pipes applied to a lining of intraquarter water supply systems and for the water drain, are manufactured complete with shaped details. Networks from them work long years without repair and replacement. For example, in the centre of Moscow there are networks from the pig-iron pipes, laid in the end of XIX century.

Copper pipes have started to be used in building in 20-30th years of the XX-th century. The peak of their popularity has fallen to 70th years. During same time wide introduction in building of polymeric pipes has begun. As a result of competition between copper and polymeric pipes have emerged their strong and weaknesses.

Copper is known for a long time as in the pure state, and in the form of brass alloys (an alloy with zinc) and bronze (an alloy with tin).

The name copper (an armour. Cuprum) — soft and plastic (in the technician speak «kovkiy» metal, has received from the island Cyprus name where copper ore was extracted. It it is very good (in 5 times better steels) are conducted by heat and an electric current and almost is not exposed to corrosion. In the neutral water environment (for example, in water water) it is dissolved in insignificant doses and practically is not oxidised. As acknowledgement following facts can serve it: copper as gold and silver, meets in the nature in a native kind and more than 80 % of the copper melted by mankind, is in operation (the steel on 8-10 % "is annually eaten" by corrosion).

There is an opinion, that water in which copper connections are dissolved, is harmful to an organism and even is poisonous. In this case it is useful to recollect words of the well-known doctor of Renaissance of Paracelsus: «the Substance can be poison and a medicine: all depends on concentration». It to the full concerns copper: on the one hand, it is heavy metal, and with other — a vital element. Really, the human body contains on the average about 100 mg of copper. And as it in an organism is not accumulated, and constantly removed, the person should consume with food of copper of 2-3 mg a day. These quantities at 10-50 time above, than contain in one litre of the water which are passing through copper pipes.

For manufacturing of pipes use copper of very high cleanliness (99,9 %), that is the quantity of impurity in it does not exceed 0,1 %. Such copper differs especially high corrosion firmness and plasticity, thus not losing plasticity and at negative temperatures (to-100°S). At water freezing in a copper pipe the last does not burst, and extends only a little and after thawing is again ready to work.

At machining (vyityagivanii, punching, etc.) copper partially loses plasticity and becomes more rigid and strong. This phenomenon in metallurgical science name «naklep». It is possible to return copper in an initial plastic condition «otzhigom», that is heating to 600-700°S and the subsequent slow cooling. For comparison we will result two figures: neotozhzhennaya copper has durability 280-300 MPa and lengthening at rupture of 10-15 %, and otozhzhennaya, accordingly, — 210-220 MPa and 50-60 %.

About decorative qualities of copper and to speak it is not necessary.

Copper pipes manufacture in neotozhzhennom a condition (in the form of switches in length 5) and in otozhzhennom in curtailed into bays (25 and 50). The largest manufacturers of copper pipes: German firm KME and ESENCO, entering into the Italian firm SILMET.

Pipes are manufactured the standard sizes: diameter from 10 to 28 mm at a thickness of a wall of 1 mm (!) and diameter from 35 to 54 mm at a thickness of a wall of 1,5 mm (manufacture pipes and bolshego diameter). It is necessary to notice, that in comparison with steel copper pipes have very small thickness of a wall and accordingly increased internal diameter. So, a copper pipe with internal diameter 20 mm have walls in the thickness of 1 mm and weight of one metre of a pipe only 0,59 kg, that is almost in 3 times it is easier steel. At so small thickness of a wall copper pipes are calculated for higher, than at steel, working pressure.

Copper pipes have very smooth walls. Their roughness in 100 times more low, than at steel, and in 4-5 times more low, than at the polymeric. With allowance for smoothnesses of a surface of copper pipes their throughput will be much more above, than at steel, and there is constantly high all term of its operation (not korrodiruet and "does not acquire").

Prochnostnyie parametres and durability of copper pipes practically do not depend on pressure and temperature of a transported liquid (the allowed interval of temperatures from +250 to-100°S). This one of essential advantages of copper pipes before polymeric, at which the durability depends on parametres (temperature and pressure) a transported liquid. Besides, the problem of protection against Uf-radiation and oxygen penetration through a wall of a pipe for copper pipes unlike polymeric simply is not present.

Thanks to plasticity of a material copper pipes are not afraid of freezing of water being in them.

However it is necessary to name our century polymeric. Even copper pipes "have asked" the help for polymers. Some firms have begun issue of copper pipes with outside cover from polymers. Basically covers from PVC and polyethylene polyvinylchloride (including made foam) are applied. Such covers execute protectively-decorative functions:

Give to pipes desirable colour;
Reduce heat losses at transportation of hot water;
Interfere with condensate formation at transportation of cold water;
Reduce «shumnost» pipes;
Protect pipes from abrasive deterioration (a scratch, the tease) and corrosion at their lining in the earth and in walls.

Copper pipes can be recommended as for heating (here the positive role is played by high heat conductivity of copper), and for water supply. In all cases of transportation of water it is necessary to adhere to the rule: not to put in system downstream water after copper pipes the steel zinced. Intensive destruction of zinc cover in this case will go.

Installation of copper pipes is made fast. The big set fitingov from copper is manufactured. In it the leading part belongs to firm SANHA (Germany). Copper pipes easily are cut and bend. The system is mounted with the help fitingov the soldering or zapressovkoy with sealing rings.

ASBESTOTSEMENTNYIE PIPES

In the XX-th century beginning the new material — asbestotsement was born, and, accordingly, have appeared asbestotsementnyie pipes. They have received a wide circulation in the Western Europe and the USA.

As the material for pipes asbestotsement has conclusive dignities. It is not subject to corrosion, including by the most dangerous to metal pipes — electrochemical. Contact to water, especially hot, causes not destruction, and hardening asbestotsementa — as cement hardens at interaction with water. Asbestotsement has considerably smaller heat conductivity, therefore water freezing in such pipes less possibly, than in the metal. Does not occur also characteristic for metals «otpotevaniya» at transportation of cold water.

The domestic industry manufactures asbestotsementnyie pipes in diameter from 100 to 500 mm and length to 5 m in two variants: not pressure head — for the organisation of drains, ventilation, a lining of cables, etc.; strengthened, pressure head — for water supply systems and gas pipelines. For distributing of water in premises them do not use.

Connection of pipes is carried out without a carving and welding with the help muft and rubber sealants. Such connection is very reliable and simple in performance. Besides, the system of a mobile joint with rubber sealants removes problems of deformations thermal and from ground procorfs.

Application asbestotsementnyih pipes for networks of hot and cold water supply at water delivery in cottages, for the water drain and ventilation system is rational. They in 3-5 times are cheaper, than similar steel, pig-iron and polymeric pipes. But there are also restrictions. It is impossible to apply asbestotsementnyie pipes to furnaces, fireplaces, etc., smoke tap on those plots where heating of a material to 400-500°S is possible, that is actually in fire operative range. In this case pipes rastreskivayutsya (boys specially throw slate in a fire and wait when it "will blow up").

About harmlessness of asbestos for the person or, on the contrary, to its ecological cleanliness separate, almost detective history. We hasten to certify only you (rely on our competence), that asbestotsementnyie pipes are harmless to the person. Acknowledgement to that experience of Austria, Holland and other European countries where for water supply such pipes are used. They work without repair and failures many tens years.
POLYMERIC PIPES

The polymeric materials named usually plastic, have appeared in human life rather recently — in the middle of the XX-th century.

To understand positive and negative properties of polymeric pipes, it is necessary to begin with polymers. Unlike metals and asbestotsementa polymers — organic substances with all their merits and demerits, consisting in close relationship with natural high-molecular — wood, a skin and a wool.

Polymers have variety of dignities: they have universal chemical firmness and are not subject to corrosion. Despite the ease (their density in 5-8 times below steel density), they strong enough and elastic. Polymers are easily processed in items, that is accept the set form and are well painted. Heat conductivity of polymers much more low, than at metals, that, in particular, reduces teplopoteri at transportation of hot liquids.

Along with these positive properties polymers are not deprived also essential defects. At heating durability of polymers decreases. As well as all organic substances, they burn, and under the influence of ultra-violet beams grow old (are done fragile and collapse). It is necessary to carry To defects and big (in 10 times more, than at a steel) factor of temperature expansion; the truth, elasticity of polymers partially compensates this defect.

The technologists making items from polymers, try, and not without success, to strengthen their dignities and to reduce defects.

The chemical industry in second half of XX-th century has run in production of tens polymers, but mass application including by production of pipes, have found 5-7 of pivotal of them. Unconditional leaders are polyethylene (RE), polypropylene (RR) and polyvinylchloride (PVC). The indicated polymers concern group of the thermoplastic. They are capable to pass at heating in an is plastic-viscous condition, and at cooling to harden.

Pipes from such polymers receive a method ekstruzii (expression) by means of warmed shneka (an example of the elementary ekstrudera, but only without heating — a house meat grinder). Pipes are received with very smooth surface (a roughness of polymeric pipes approximately in 10 times more low, than steel).

The greatest distribution was received by pipes from polyethylene. Originally them did of usual polyethylene (recollect a transparent polyethylene film). Such pipes lost durability at heating to 50-60°S and fast grew old. They could be used for giving only cold water. In 80th chemists have learnt to connect with one another linear molecules of polyethylene — to "sew". Such "sewed" polyethylene has the raised durability, temperature constancy and firmness to Uf-radiation. On them transportation of water in temperature to 95°S is admissible. Having received the raised temperature constancy, the "sewed" polyethylene has lost ability to cook. In marks of items the "sewed" polyethylene is designated RE (letter H indicates that polymer "is sewed"). Pipes make of the sewed polyethylene more than half from the general issue of polymeric pipes. Pipes of German firm REHAU are most known. In Russia such pipes are made, in particular, by firm «Bir Peks» in Saratov.

Pipes from the "sewed" polyethylene RE can be used not only for cold, but also hot water supply and heating (central and floor). For example, in a building of the Moscow mayoralty on New Arbate 113 m in water supply and heating systems steel pipes have been replaced by height with pipes from the sewed polyethylene.

Polypropylene (RR) on use in production of pipes takes the second place. Physicomechanical and thermal properties of this polymer are close to the sewed polyethylene, but unlike last it more rigid. Therefore polipropilenovyie pipes are manufactured in the form of measured sections that is a little less convenient at transportation and requires a considerable quantity of connecting elements at installation. On large firms this problem is decided: different variants of complex systems of connection — nizkotemperaturnoy by welding and by means of metal accessories are offered.

The largest firm delivering on the Russian market polipropilenovyie pipes, (Germany) is «Akvaterm». For manufacturing of pipes this firm uses a polypropylene copolymer «Random», having the raised temperature constancy. Pipes from «Randoma» can be applied to giving of hot water to 75°S.

Polyvinylchloride (PVC) — polymer very widely used in building, in production of pipes goes after polyethylene and poliipropilenom. Usually it is used in neplastifitsirovannom a kind (rigid PVC — «viniplast»). Presence of chlorine at PVC causes vigilance of ecologists and limits application of such pipes for water supply. Positive property of polyvinylchloride is its lowered combustibility and the raised chemical firmness in comparison with other polymers. It also is less sensitive to Uf-radiation, therefore the basic scopes of PVC-PIPES are water waste systems and the water drain.

Polibuten (RV) — polymer the same as both polyethylene and polypropylene from group poliolefinov. It is biologically harmless. Pipes from polibutena are more elastic, than from polypropylene. Polibuten it is characterised high prochnostnyimi by indicators, firmness to the Uf-irradiation and the raised temperature constancy, coming nearer in this respect to the "sewed" polyethylene. Pipes from polibutena have proved in networks of hot water supply and heating (in particular, for the system of warm floors). At 70°S and working pressure in system 0,3 MPa 50-year-old service life of Rv-pipes is guaranteed. The maximum temperature of operation of such pipes +95°S. As well as polipropilenovyie, polibutenovyie pipes can be welded, that facilitates and makes cheaper installation of systems from Rv-pipes, having built up a reputation for these pipes perspective for internal distributing.

Along with many positive properties of a pipe from polymers in due course grow old. This quality is characteristic for all polymers for they are on the verge «live and lifeless» and are subject to many laws of the live world. For example, speed of "ageing" of polymeric pipes depends first of all on temperature and pressure. Ageing process is accompanied by decrease in elasticity, durability, increase of fragility and spontaneous rastreskivaniem. Distinctive feature of polymeric pipes that they grow old on all weight while corrosion of steel pipes begins with a surface. Plastic pipes collapse as though "suddenly" and completely, and in metal — fistulas which can be closed up, for example, are formed by welding.

Depending on an operation mode (temperature and pressure of water) are established admissible terms of their operation (the tab. see).

Dependence of durability of pipes from PE-X
From temperature and pressure

Temperature 0S

Service life of years 1 5 10 25 50 20 1,37 1.33 1.32 1.31 1.25 40 1.10 1.08 1.07 1.06 1.04 60 0.87 0.84 0.83 0.81 0.80 80 0.65 0.64 0.63 0.63 - 95 0.57 0.55 0.54; - -

Polymeric pipes mark by the form polymer (RE, RE, RR, etc.), on outside diameter and nominal pressure (PN). Outside diameters of pipes () for internal distributing are presented to mm by following number: 10; 12; 16; 25; 32; 40; 50 etc. Except diameter, pipes are marked on a thickness of a wall. Nominal pressure usually express in bars: 1 bar = 0,1 MPa. By nominal pressure mean constant internal pressure of water at 20°S which the pipe can smoothly maintain within 50 years (for example, PN=10, PN=12,5 or RM=20). For an estimation of level of these parametres it is possible to recollect, that working pressure of water in water system no more than 0,6 MPa (6 bar). The maximum pressure which the pipe can sustain short time, several times above the nominal. At temperature above 20°S term of non-failure operation of polymeric pipes at invariable pressure is reduced or can remain the same — 50 years, but under condition of smaller working pressure.

METALLOPOLIMERNYIE PIPES

Telling about polymeric pipes, as the standard, as a rule, choose the traditional steel. On their background modern polymeric pipes seem centre of dignities. Defects, as a rule, are ignored. And they, certainly, are. And it is clear — is not present in the perfection world, and each "improvement" bears with itself and «new defects».

Universal pipes, equally suitable for high-rise houses, cottages and the industrial purposes, no and to aspire to it it is not necessary.

The decision of many problems has been found thanks to composite materials. Each element entering into composites executes the functions, and the material as a whole acquires a new set of properties. It is possible to carry ferro-concrete, fibreglass to the elementary composites, etc. Thus, the multilayered pipe which wall consists at least of three layers has been created: very thin metal, being between two layers of polymer.

Metallopolimernyie pipes are manufactured two types. The first — the aluminium layer — is possessed between two, approximately identical layers of polymer. Coupling of aluminium with polymer is supplied with a glutinous layer. At such decision as polymer the "sewed" polyethylene is used, and the pipe in this case is designated PEX-AI-PEX.

The second — the aluminium layer — places on an outside surface of a polymeric pipe. From above aluminium is protected by a thin layer of polymer. Coupling in this case is supplied or glutinous layers (pipe REH-Stabil), or by means of the polymer which is becoming numb in punching on an aluminium pipe (the Rr-pipe fuzioterm SHtabi). The aluminium pipe in the considered variants metallopolimernyih pipes is received from a strip of the aluminium foil turned off round the polymeric core and welded by means of the laser.

As a whole metallopolimernyie pipes have saved basically all positive properties of polymeric pipes. Feature is ability easily to bend and save the necessary form. For the account bolshey rigidity they do not require serious measures on fastening at open posting. However it is necessary to consider, that the aluminium core has brought with itself fear of such pipes to freezing in the condition filled in with water as destruction of solidity of an aluminium part of a pipe in this case is probable. Besides, it is necessary to exclude contact of aluminium to other metals in places of connections.

Other composit pipes are manufactured also. For example, a pipe from the polypropylene, reinforced by the high-strength fibre, manufactured under mark fuzioterm-Fazer.

It is necessary to notice, that metallopolimernyie pipes in Russia use the big popularity which part, possibly, it it is necessary to charge some "metal" (affect our big attachment and belief in reliability metal, that is steel pipes).
To. PRIESTS, the prof. (MGSU)
NTS «Stroyinform» Source: "the Building Season" #3, 4 (2003)

It is introduced: on February, 05th, 2003

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