Classification of the main types of water pipes and features of their operation


Water sup­ply is the most impor­tant com­mu­ni­ca­tion for pro­vid­ing house­hold, drink­ing and indus­tri­al needs of a per­son, extin­guish­ing fires. Water qual­i­ty and oper­at­ing para­me­ters large­ly depend on the com­po­nents of the sys­tem. Water pipes are the main ele­ment for trans­port­ing flu­id in the net­work from the source to the con­sumer. There are many types of prod­ucts on sale, dif­fer­ing in mate­r­i­al, char­ac­ter­is­tics and price. Instal­la­tion of each of them involves the use of cer­tain tech­nolo­gies.

Plumb­ing is the most impor­tant com­mu­ni­ca­tion

Types of water pipes and basic requirements

Water is sup­plied for var­i­ous pur­pos­es:

  • drink­ing, cook­ing;
  • for water­ing;
  • fire extin­guish­ing;
  • hot water sup­ply;
  • ensur­ing the pro­duc­tion and tech­no­log­i­cal cycle.

Pipes are used for exter­nal or inter­nal water sup­ply net­works:

  • steel straight-line seam accord­ing to GOST 10704;
  • cop­per for water and gas GOST 52318;
  • pres­sure pipes made of poly­eth­yl­ene accord­ing to GOST 18599;
  • pres­sure pipes made of ther­mo­plas­tics accord­ing to GOST 52134;
  • mul­ti­lay­er from met­al and poly­mers accord­ing to GOST 53630;
  • asbestos-cement accord­ing to GOST 539–73;
  • cast iron accord­ing to GOST 21053.

The stan­dards nor­mal­ize the inner and out­er diam­e­ter of the pipe, wall thick­ness, mass per meter, strength, com­po­si­tion and prop­er­ties of mate­ri­als. Struc­tures must be resis­tant to con­stant pres­sure, with­stand the oper­at­ing tem­per­a­ture of the medi­um. Dam­age, defor­ma­tion, cracks or shells are not allowed on the inner and out­er sur­faces.

The exter­nal water sup­ply is laid under­ground, the inter­nal net­work is locat­ed in the build­ing along or in the thick­ness of the walls, under the base­boards or under the floor.

Scheme of inter­nal plumb­ing in a two-sto­ry house

The high­est require­ments for the qual­i­ty of pipes for sup­ply­ing drink­ing water to the house. Haz­ardous sub­stances can enter the liq­uid and harm human health. So an excess of cop­per leads to liv­er cir­rho­sis, and an increased con­cen­tra­tion of iron leads to the depo­si­tion of tox­ic com­pounds in human organs.

The main char­ac­ter­is­tics are out­er (Dn), con­di­tion­al or nom­i­nal (Dn or DN) diam­e­ters, wall thick­ness. Prod­ucts with a diam­e­ter of 5–102 mm are clas­si­fied as small, 103–427 — medi­um, over — large.

Pipe para­me­ters


Water net­works rely on a cer­tain pres­sure indi­ca­tor:

  • up to 12 atmos­pheres — low pres­sure;
  • 12–25 — medi­um;
  • over 25 — high.

In apart­ments or pri­vate hous­es, pipes must with­stand a pres­sure of at least 2 atm. The pres­sure in the inter­nal fire water sup­ply sys­tem is high­er — up to 10 atm.

To trans­fer cold water, pipes with a tem­per­a­ture sta­bil­i­ty lim­it of up to + 46 ° are used. Trans­porta­tion of a high­er tem­per­a­ture medi­um is car­ried out by “hot” pipelines.

The ques­tion of which pipes are best used for plumb­ing can be answered by con­sid­er­ing all the options and weigh­ing the advan­tages or dis­ad­van­tages of each.

Steel water pipes

Steel pro­files are a tra­di­tion­al mate­r­i­al for the man­u­fac­ture of exter­nal and inter­nal plumb­ing. They have mechan­i­cal strength and wear resis­tance, per­ceive mul­ti­ple loads from pres­sure or tem­per­a­ture drops in the net­work.

Pro­files are made of car­bon steel by rolling (cold or hot), fold­ing or weld­ing. The sheet is cut into strips, aligned, weld­ed in a straight or spi­ral line. Pipes are test­ed for strength under flat­ten­ing and increased hydraulic pres­sure.

The need for steel pipes is great. More than 10% of all pro­duced met­al is spent on the pro­duc­tion of these prod­ucts.

Pipes steel elec­trow­eld­ed

Steel pipes are used:

  • for lay­ing water or gas pipelines;
  • in indus­tri­al and civ­il con­struc­tion;
  • when lay­ing high­ways;
  • in the pro­duc­tion of ships, air­craft, auto­mo­biles;
  • in the met­al­lur­gi­cal indus­try.

In hous­ing and com­mu­nal ser­vices, struc­tures are used to orga­nize sys­tems for exter­nal and inter­nal water sup­ply, heat­ing. For exter­nal lay­ing, prod­ucts with a cross sec­tion of up to 150 mm are used. When choos­ing the diam­e­ter of a pipe for a cold water sup­ply in a pri­vate house, one should be guid­ed by the length of the com­mu­ni­ca­tion:

  • up to 10 m — 20 mm;
  • up to 30 m — 25 mm;
  • more than 30 m — 32 mm.

The sys­tem is assem­bled by weld­ing or using fit­tings. For thread­ed con­nec­tions, a vari­ety of com­po­nents are pro­duced.

The main dis­ad­van­tage of steel com­mu­ni­ca­tions is the insta­bil­i­ty to elec­tro­chem­i­cal cor­ro­sion.

The aggres­sive action of soil mois­ture or trans­port­ed liq­uid grad­u­al­ly destroys the met­al, leads to the for­ma­tion of holes in the walls, through ulcers or pit­ting.

Cor­ro­sion of met­al


The stan­dard ser­vice life of a water sup­ply sys­tem — a ris­er or an eye­lin­er — made of steel pipes does not exceed 15 years. In fact, the action of destruc­tive fac­tors that short­en the dura­tion of oper­a­tion is pos­si­ble. For exam­ple, cold water tends to cor­rode faster than hot water. The for­ma­tion of con­den­sate on the sur­face of the pipeline is accel­er­at­ed due to the tem­per­a­ture dif­fer­ence, which leads to the destruc­tion of the met­al.

To avoid con­tact with water and oxy­gen, the effects of stray cur­rents, the sur­face of the mate­r­i­al is cov­ered with a pro­tec­tive lay­er of zinc or poly­mers. Pro­tec­tive cathod­ic pro­tec­tion is used in out­door net­works.

Galvanized pipes

Longer ser­vice life of gal­va­nized pro­files. This is due to the fact that the coat­ing pre­vents the inter­ac­tion of steel with mois­ture, and when water pass­es through, less deposits form on the inner smooth walls.

Gal­va­nized — coat­ed steel

In the sys­tem itself, there is prac­ti­cal­ly no scale or pieces of rust, lead­ing to the for­ma­tion of irreg­u­lar­i­ties in the lumen. This increas­es the capac­i­ty of the gal­va­nized water pipe, so for a home sys­tem it is enough to use bends with a diam­e­ter of 20 mm.

The stan­dards deter­mine the ser­vice life of a gal­va­nized water pipe at 30 years. In real­i­ty, this peri­od is high­er — up to 50–70 years.

Gal­va­niza­tion is car­ried out in three ways:

  • gal­van­ic — apply­ing a pro­tec­tive lay­er to the prod­uct, placed in the elec­trolyte, by elec­trol­y­sis;
  • hot gal­va­niz­ing — the coat­ing is fixed on the sur­face when the part is immersed in the met­al melt;
  • cold gal­va­niz­ing — a pro­tec­tive com­po­si­tion is sprayed or applied by stain­ing;
  • dif­fuse — treat­ment with zinc vapor occurs at ele­vat­ed pres­sure and tem­per­a­ture.

The high­est qual­i­ty pro­tec­tion is formed in the lat­ter case.

Diam­e­ters of gal­va­nized steel pipes accord­ing to the range of 6–150 mm (nom­i­nal bore). The out­er sec­tion of the prod­ucts is 10.2–165 mm. The length of the pro­files is 4–12 m. The wall thick­ness varies from 1.8 to 5.5 mm. At the same time, the mass of coat­ed struc­tures exceeds black steel ones by 3%.

The assem­bly of the water sup­ply sys­tem is car­ried out main­ly by thread­ed con­nec­tions with fit­tings. When using weld­ing, the pro­tec­tive lay­er is dam­aged. Sub­se­quent­ly, cor­ro­sion cen­ters form in these places. Thus, the mean­ing of the device of the gal­va­nized sys­tem is lost, since the dura­bil­i­ty is reduced to that of sim­ple black pipes.

To pre­vent dam­age to the coat­ing dur­ing weld­ing, zinc com­po­si­tion is sprayed onto the weld area, spe­cial flux­es or rutile-coat­ed elec­trodes are used.



Pipes made of alloyed cor­ro­sion-resis­tant steel are durable, not sub­ject to the destruc­tive action of water. They can last up to 400 years. Oxi­da­tion prod­ucts do not accu­mu­late on the wall, do not enter the house­hold water sup­ply. Increas­ing­ly, stain­less steel prod­ucts are replac­ing con­ven­tion­al car­bon steel despite the high­er cost of the mate­r­i­al and the com­plex­i­ty of instal­la­tion.

Pro­files of their stain­less steel

Stain­less steel struc­tures com­ply with san­i­tary and hygien­ic stan­dards, tol­er­ate water ham­mer well, and are resis­tant to crit­i­cal tem­per­a­tures. Water with exces­sive chlo­rine con­tent can dam­age stain­less steel, so it is rec­om­mend­ed to thor­ough­ly rinse the sys­tem after dis­in­fec­tion.

Stain­less pipes are used in var­i­ous areas:

  • water, heat and gas sup­ply;
  • fire­fight­ing;
  • arrange­ment of chan­nels for air con­di­tion­ing;
  • lay­ing “warm floor”;
  • for pro­tec­tion of pow­er elec­tric cables.

The water sup­ply is assem­bled using press fit­tings, also made of stain­less steel, by weld­ing with a tung­sten elec­trode in an inert atmos­phere. In indus­tri­al con­di­tions, laser weld­ing is used.

The device of a water sup­ply sys­tem from flex­i­ble cor­ru­gat­ed pipes is becom­ing more and more wide­spread. Their advan­tages are the pos­si­bil­i­ty of lay­ing in hard-to-reach places, instal­la­tion of long lines, resis­tance to dynam­ic or vibra­tion loads.


Cop­per plumb­ing is much more com­mon in Europe than in our coun­try. They are time-test­ed and deserve atten­tion due to the long peri­od of trou­ble-free oper­a­tion.

Advan­tages of cop­per pipes:

  • cor­ro­sion resis­tance — cop­per is insen­si­tive to chlo­rine, dilute acids or alka­lis;
  • resis­tance to tem­per­a­ture drops with­in ‑100°С…+250°С, pres­sure fluc­tu­a­tions;
  • growths do not form on the walls, bac­te­ria do not set­tle, since cop­per ions are detri­men­tal to them;
  • with reg­u­lar main­te­nance, the ser­vice life exceeds 50 years.

Cop­per pipes for plumb­ing in an apart­ment are sub­ject­ed to addi­tion­al pro­cess­ing — anneal­ing. This gives soft­ness and elas­tic­i­ty to prod­ucts, they are easy to bend and cut. Such com­mu­ni­ca­tions look very dec­o­ra­tive. Addi­tion­al paint­ing with pro­tec­tive struc­tures is not required.

Cop­per pip­ing is dec­o­ra­tive

The dis­ad­van­tages include:

  • high­er price com­pared to steel ana­logues;
  • for join­ing, only cop­per fit­tings can be used, since the met­al forms a gal­van­ic cou­ple with steel, con­tribut­ing to its destruc­tion;
  • the assem­bly of the sys­tem is car­ried out with spe­cial equip­ment, which increas­es the price of instal­la­tion.

Pipes are con­nect­ed by high-tem­per­a­ture sol­der­ing or using fit­tings, which must be com­bined. Cut­ting soft met­al is not allowed.

Polymer pipes


The rev­o­lu­tion in the chem­i­cal indus­try was marked by the emer­gence of new mate­ri­als in con­struc­tion. Var­i­ous types of poly­mer­ic water pipes are made from ther­mo­plas­tics or ther­mo­plas­tics:

  • poly­eth­yl­ene PE;
  • polyvinyl chlo­ride PVC;
  • polypropy­lene PP;
  • polyamide PA;
  • poly­buty­lene PB;
  • fiber­glass;
  • fiber­glass;
  • epoxy or poly­ester.

The diam­e­ter of poly­eth­yl­ene pres­sure pro­files is 16–1600 mm. The wall thick­ness is designed to with­stand a work­ing pres­sure of 4–20 bar. Prod­ucts with a cross sec­tion of up to 40 mm are used for domes­tic plumb­ing, up to 160 — for ris­ers or sew­ers. Larg­er ones are used in the field of pro­duc­tion.

Poly­eth­yl­ene pro­file

Poly­eth­yl­ene pipes are marked by den­si­ty — from 63 to 100 (kg / m³). Less dense mate­ri­als are mechan­i­cal­ly unsta­ble. Non-pres­sure struc­tures are made from them — an out­door show­er, water­ing, sew­er drains. PE 80 is stronger, they are used to install a cold pipeline inside the house. PE 100 is used to sup­ply hot water and heat­ing.

Poly­eth­yl­ene pipelines are mount­ed using com­pres­sion or ther­mis­tor fit­tings, butt weld­ing.

Fit­ting con­nec­tion

Exter­nal water sup­ply is laid from polyvinyl chlo­ride pipes. They are gray in col­or and are avail­able in lengths of 1, 2, 3 and 6 m. The nom­i­nal diam­e­ter of prod­ucts is 90–500 mm. Designed for pres­sure 6–16 bar. Mount them with­out cou­plings or weld­ing. At one end, a sock­et with an annu­lar seal is formed, where the oth­er part of the round pro­file is insert­ed. The con­nec­tion is com­plete­ly sealed, with­stands stan­dard loads.

Advan­tages of poly­mer pipes:

  • resis­tance to chem­i­cal and elec­tri­cal cor­ro­sion, expo­sure to aggres­sive envi­ron­ments;
  • harm­less­ness, absence of harm­ful emis­sions into the trans­port­ed liq­uid;
  • smooth­ness of the inner sur­face, on which dirt does not linger;
  • low ther­mal con­duc­tiv­i­ty, reduc­ing ener­gy loss­es and con­den­sa­tion;
  • light weight and plas­tic­i­ty, which sim­pli­fies trans­porta­tion and instal­la­tion;
  • poor sound per­me­abil­i­ty, reduc­ing the noise lev­el dur­ing the pas­sage of water.

Dur­ing recon­struc­tion, the sys­tem can be eas­i­ly redone by cut­ting com­mu­ni­ca­tions and con­nect­ing a new branch using a fit­ting. The con­struc­tion of water pipelines made of poly­mer pipes is 30–40% cheap­er than a sim­i­lar one made of steel.

Dis­ad­van­tages of prod­ucts com­mon to all plas­tics:

  • insta­bil­i­ty to ultra­vi­o­let;
  • high coef­fi­cient of lin­ear ther­mal expan­sion;
  • brit­tle­ness at low tem­per­a­ture;
  • most of them do not burn, but sup­port com­bus­tion, while emit­ting harm­ful sub­stances;
  • oper­at­ing pres­sure and tem­per­a­ture lim­its.

The most heat-resis­tant pipes are made of cross-linked PEX poly­eth­yl­ene, which is pro­duced under high pres­sure. Used for cold and hot water sup­ply. With­stands tem­per­a­tures up to +95° and pres­sure up to 20 atm.



Met­al-plas­tic pipes are pro­duced by extru­sion, apply­ing a melt of poly­mers to a frame made of mesh, wire or foil.

Met­al-plas­tic mate­ri­als com­bine the advan­tages of met­al and poly­mer types of pipes for heat­ing or plumb­ing:

  • resis­tance to cor­ro­sion, chem­i­cal attack;
  • small ther­mal expan­sion;
  • wear resis­tance;
  • sim­ple instal­la­tion using detach­able, crimp or press fit­tings;
  • oper­at­ing tem­per­a­ture range up to 95°-110° and pres­sure up to 10 bar, with­stand repeat­ed freez­ing;
  • ser­vice life up to 30 years.

Met­al-plas­tic retains its shape when bent, does not emit harm­ful com­pounds into the water.

Met­al-plas­tic pipe

Dis­ad­van­tages of water pipelines made of met­al poly­mers:

  • less mechan­i­cal strength than steel pipes;
  • not applic­a­ble at pres­sures exceed­ing 10 bar and tem­per­a­tures above 110°;
  • some types are sub­ject to fatigue fail­ure.

The com­bi­na­tion of pos­i­tive qual­i­ties makes this mate­r­i­al promis­ing for wide appli­ca­tion in var­i­ous areas of con­struc­tion.

Hydraulic calculation

To deter­mine the most eco­nom­i­cal sec­tions of the water sup­ply, a hydraulic cal­cu­la­tion is car­ried out. The con­di­tion for ensur­ing the required water flow, main­tain­ing pres­sure and min­i­miz­ing head loss must be met. Tak­en into account:

  • esti­mat­ed direc­tion of water move­ment;
  • con­sump­tion accord­ing to water con­sump­tion stan­dards;
  • char­ac­ter­is­tics of water fit­tings and the num­ber of points;
  • hous­ing over­crowd­ing rate;
  • head loss due to fric­tion along the entire length of the pipe.

Accord­ing to the results of the cal­cu­la­tion, the diam­e­ter of the water pipes is select­ed based on the size table and prod­uct range.

To deter­mine the pres­sure loss, Shevelev tables or online pro­grams are used.

The tables for the hydraulic cal­cu­la­tion of steel, cast iron, asbestos-cement, plas­tic and glass water pipes con­tain ready-made indi­ca­tors depend­ing on the diam­e­ter, mate­r­i­al, line length, net­work pres­sure. Loss­es are deter­mined in each sec­tion and sum­ma­rized. Accord­ing to the found val­ue, the required flow rate and pump pow­er are deter­mined.

An exam­ple of hydraulic cal­cu­la­tion accord­ing to Shevelev’s tables

The plumb­ing sys­tem is a com­plex engi­neer­ing com­mu­ni­ca­tion. It is impor­tant to choose pipes, tak­ing into account their tech­ni­cal, to per­form the instal­la­tion cor­rect­ly.


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