Choosing reinforced polypropylene pipes for heating


In almost any res­i­den­tial build­ing or in a city apart­ment, you can always find water heat­ing sys­tems. These are main­ly cen­tral­ized or autonomous heat­ing sys­tems, dou­ble-cir­cuit or sin­gle-cir­cuit, the dif­fer­ence is in pow­er, in details and in the tasks set. How­ev­er, one tech­no­log­i­cal aspect remains com­mon to all — this is the liq­uid type. The main work on the deliv­ery of heat to the heat­ing devices is per­formed by boil­er water or antifreeze.

The coolant cir­cu­lates along the cir­cuit, which are the “cir­cu­la­to­ry sys­tem” of heat­ing. The paten­cy of the pipelines, the dura­tion of the pipeline’s oper­a­tion depends on the qual­i­ty of the pipes and the mate­r­i­al of man­u­fac­ture. Today, new tech­nolo­gies in the field of heat­ing equip­ment have also touched on con­sum­ables, bring­ing to the fore rein­forced polypropy­lene pipes used for heat­ing sys­tems. This prod­uct appeared rel­a­tive­ly recent­ly, but has already man­aged to gain wide pop­u­lar­i­ty among con­sumers. What is the rea­son for such suc­cess of syn­thet­ic prod­ucts, what are the advan­tages of polypropy­lene pipes rein­forced with fiber­glass or alu­minum.

The main arti­cle about polypropy­lene pipes.

Reinforcement of polypropylene pipes — the main goal and objectives

We remem­ber well the met­al pipelines in our apart­ments or in pri­vate hous­es, through which hot water gur­gles, sup­ply­ing home bat­ter­ies with the desired warmth. It is not nec­es­sary to talk about the attrac­tive appear­ance of such high­ways, espe­cial­ly since the per­me­abil­i­ty of met­al high­ways dete­ri­o­rates sig­nif­i­cant­ly over time. Poor qual­i­ty of the coolant, fre­quent block­ages cause a decrease in the func­tion­al­i­ty of met­al heat­ing cir­cuits. Con­se­quent­ly, over time, the qual­i­ty of heat­ing of res­i­den­tial premis­es sharply dete­ri­o­rates.

In most cas­es, it was these fac­tors that caused the appear­ance on the mar­ket of con­sum­ables for heat­ing syn­thet­ic mate­ri­als. First, met­al-plas­tic pipes appeared, and a lit­tle lat­er, polypropy­lene con­sum­ables began to enter the mar­ket. High per­for­mance, tech­no­log­i­cal para­me­ters and afford­able price have made syn­thet­ics the most com­mon com­po­nents for heat­ing sys­tems today. Attempts to improve the tech­no­log­i­cal para­me­ters and char­ac­ter­is­tics of polypropy­lene led to the deci­sion to rein­force polypropy­lene.

Rein­force­ment is a tech­nol­o­gy, as a result of which the struc­ture of the base mate­r­i­al is sup­ple­ment­ed with rein­forc­ing com­po­nents. Due to the inclu­sion of an addi­tion­al inner lay­er in the polypropy­lene struc­ture, the lin­ear rigid­i­ty of the pipe is sig­nif­i­cant­ly increased, the strength and sta­bil­i­ty of the mate­r­i­al are increased. The rein­forc­ing lay­er plays a key role, sig­nif­i­cant­ly reduc­ing the coef­fi­cient of ther­mal expan­sion of syn­thet­ic pipelines. Unlike ordi­nary polypropy­lene, the rein­forced polypropy­lene pipe is 5 times less sus­cep­ti­ble to ther­mal elon­ga­tion, which has a pos­i­tive effect on the appear­ance of the pipeline and its func­tion­al para­me­ters.

For ref­er­ence: in a home heat­ing sys­tem, the tem­per­a­ture of the coolant in the cir­cuit is 50–700C. In the case of autonomous heat­ing, the tem­per­a­ture of the coolant may peri­od­i­cal­ly rise to a crit­i­cal lev­el of 950C. The oper­a­tion of an unre­in­forced poly­mer pipe at such tem­per­a­ture indi­ca­tors has an extreme­ly neg­a­tive effect on the phys­i­cal prop­er­ties of its mate­r­i­al of man­u­fac­ture.

For home heat­ing, when a sig­nif­i­cant part of the heat­ing cir­cuit lies out­side and is clear­ly vis­i­ble, the use of a con­ven­tion­al poly­eth­yl­ene pipeline is imprac­ti­cal. You will have to con­stant­ly solve the prob­lem of sag­ging high­ways by installing addi­tion­al fas­ten­ers and clamps. Which prod­uct is bet­ter to choose for the heat­ing cir­cuit is the next ques­tion, which should be con­sid­ered in more detail.

Types of reinforcement used in combination with polypropylene

Rein­force­ment is not a new phe­nom­e­non in engi­neer­ing mechan­ics. The very fact that rein­forc­ing ele­ments are includ­ed in the com­po­si­tion of mate­ri­als or in com­plex struc­tures indi­cates that this tech­nol­o­gy is aimed at increas­ing the strength char­ac­ter­is­tics of a mate­r­i­al or a fin­ished prod­uct. In ther­mal struc­tures and sys­tems, rein­force­ment has been used rel­a­tive­ly recent­ly. With the advent of rein­forced polypropy­lene con­sum­ables, the tech­no­log­i­cal capa­bil­i­ties of heat­ing equip­ment have increased sig­nif­i­cant­ly. Such chan­nels per­fect­ly inter­act with high tem­per­a­tures, are sta­ble, durable and easy to install.

Strength­en­ing in this case can have two ver­sions. Polypropy­lene pipes rein­forced with alu­minum or con­sum­ables, which include a rein­forc­ing lay­er of fiber­glass.

How to choose the most suit­able rein­forced polypropy­lene pipes for your own heat­ing sys­tem, with one or anoth­er rein­forc­ing lay­er, depends on a num­ber of aspects. To make it eas­i­er to make a choice, you should under­stand. What is the dif­fer­ence between the two options for rein­forc­ing polypropy­lene, and what are the tech­no­log­i­cal fea­tures of such equip­ment.

Varieties of reinforced products

In many heat­ing sys­tems, it is cus­tom­ary to use three or five-lay­er polypropy­lene prod­ucts. It is these con­sum­ables that are dis­tin­guished by the pres­ence of the high­est tech­no­log­i­cal char­ac­ter­is­tics that cor­re­spond to the con­di­tions and para­me­ters of oper­a­tion of heat­ing equip­ment.

Con­sid­er the dis­tinc­tive para­me­ters of var­i­ous types of polypropy­lene prod­ucts:

  • three-lay­er pipes are prod­ucts in which there is an inner, mid­dle rein­forc­ing lay­er. Alu­minum or fiber­glass are used as a rein­forc­ing com­po­nent;
  • five-lay­er polypropy­lene con­sum­ables are prod­ucts that have two, inner and out­er lay­ers of polypropy­lene. In the mid­dle of the mate­r­i­al there are two adhe­sive lay­ers (adhe­sive), between which there is a rein­forc­ing lay­er.

Note: two adhe­sive lay­ers are added so that the mate­r­i­al does not delam­i­nate dur­ing oper­a­tion. Three-lay­er prod­ucts often suf­fer from this dis­ad­van­tage, in which the alu­minum rein­forc­ing lay­er often begins to peel off from the poly­mer base.

Main arti­cle: Under­floor heat­ing from polypropy­lene pipes.

Both options are used with equal suc­cess in prac­tice, form­ing the basis of heat­ing cir­cuit lines. Three-lay­er and five-lay­er polypropy­lene pipes per­fect­ly cope with high work­ing pres­sure, work in the mode of expo­sure to high tem­per­a­tures of the coolant.

Accord­ing­ly, such prod­ucts have their own dis­tinc­tive mark­ing, on the basis of which it is pos­si­ble to draw a con­clu­sion about what mate­r­i­al the prod­uct is rein­forced with.

Fiberglass reinforced products

All polypropy­lene pipes are marked with the cor­re­spond­ing PP sym­bols. The addi­tion of a glass fiber rein­forced lay­er is indi­cat­ed in the mate­r­i­al mark­ing with the fol­low­ing sym­bols PPR-FB-PPR. It is imme­di­ate­ly clear that the prod­uct has three lay­ers, among which the mid­dle lay­er per­forms rein­forc­ing func­tions. This mark­ing indi­cates that you have polypropy­lene fiber­glass prod­ucts in front of you.

Out­ward­ly, such con­sum­ables are dis­tin­guished by the pres­ence of a col­ored lay­er inside. The rein­forc­ing lay­er can be made in dif­fer­ent col­ors, rang­ing from red, orange, end­ing with a green lay­er. The col­or does not affect the tech­no­log­i­cal para­me­ters in any way. The main struc­tur­al data are print­ed on the out­er sur­face of the pipe, indi­cat­ing the oper­at­ing con­di­tions, the diam­e­ter of the prod­uct.

Glass fiber rein­forced con­sum­ables offer the fol­low­ing ben­e­fits:

  • no need to clean and cal­i­brate indi­vid­ual pipe frag­ments dur­ing instal­la­tion;
  • the absence of the effect of delam­i­na­tion of prod­ucts, achieved as a result of a mono­lith­ic struc­ture.

How­ev­er, the advan­tages of fiber­glass lines in com­par­i­son with alu­minum-rein­forced polypropy­lene pipes are not so sig­nif­i­cant. Both options can be used for heat­ing cir­cuit equip­ment, but the fol­low­ing should be remem­bered:

Unlike alu­minum-rein­forced mate­ri­als, fiber­glass prod­ucts have a high­er coef­fi­cient of ther­mal elon­ga­tion (by 5–6%).

At a price, fiber­glass prod­ucts are slight­ly cheap­er than five-lay­er con­sum­ables. The instal­la­tion of such pipelines for heat­ing is quick and straight­for­ward. Using spe­cial scis­sors — a cut­ter and a sol­der­ing iron, it is pos­si­ble to lay a heat­ing cir­cuit through­out the entire res­i­den­tial build­ing with­in one or two days. As a result of dif­fuse sol­der­ing, the required strength of the joints is achieved.

Products reinforced with aluminum

As in the pre­vi­ous case, alu­minum rein­forced polypropy­lene pipes are also often used in prac­tice. Among pro­fes­sion­als, there is a con­di­tion­al divi­sion into those who pre­fer syn­thet­ic pipelines rein­forced with alu­minum and those who pre­fer fiber­glass con­sum­ables. Each cat­e­go­ry of mas­ters has its own argu­ments in favor of one or anoth­er type of con­sum­ables. Con­sid­er how pipes with a lay­er of alu­minum dif­fer from a tech­no­log­i­cal point of view.

Let’s start with label­ing. Prod­ucts of this kind usu­al­ly car­ry the fol­low­ing set of char­ac­ters, the abbre­vi­a­tion PPR-Al-PPR. As in the pre­vi­ous case, the mark­ing shows how many lay­ers the pipe has and what they con­sist of.

In turn, such con­sum­ables are divid­ed into sev­er­al sub­species:

  • the first option — the prod­ucts have per­fo­rat­ed alu­minum in the mid­dle part (a thin lay­er of alu­minum foil with small round holes);
  • the sec­ond option — the pipe has a mid­dle lay­er of sol­id alu­minum.

The fig­ures below show the first and sec­ond options for alu­minum-rein­forced con­sum­ables.

Both options have a three-lay­er struc­ture. The third option involves a polypropy­lene rein­forced pipe with five lay­ers. Here, two lay­ers of adhe­sive base are added to polypropy­lene and alu­minum. Due to the pres­ence of two addi­tion­al ther­mal lay­ers, con­sum­ables of this type have increased resis­tance to high tem­per­a­tures and dura­bil­i­ty.

Prod­ucts with alu­minum can also have dif­fer­ent col­ors, which do not have a spe­cial tech­no­log­i­cal sig­nif­i­cance.

Some­times on sale there are prod­ucts marked with the fol­low­ing des­ig­na­tions PEX-Al-PEX. Unlike pipes marked PPR-AL-PPR, in this case we are talk­ing about a dif­fer­ent lay­er struc­ture. The first let­ters des­ig­nate the out­er lay­er of cross-linked poly­eth­yl­ene. These con­sum­ables have slight­ly dif­fer­ent per­for­mance char­ac­ter­is­tics and deserve a sep­a­rate dis­cus­sion. There are no fun­da­men­tal dif­fer­ences in this case, there­fore, both of them can be safe­ly used for the instal­la­tion of heat­ing pipelines.

Impor­tant! In the process of prac­ti­cal use, polypropy­lene chan­nels with alu­minum must be cleaned to ensure the strength and tight­ness of the con­nec­tion.

Depend­ing on the man­u­fac­tur­er, the alu­minum lay­er may be locat­ed in dif­fer­ent ways. In some pipes, the rein­force­ment lay­er is in the mid­dle, between two oth­er lay­ers on both sides. There are prod­ucts in which alu­minum foil is locat­ed clos­er to the inner wall of the pipe.

In order to prop­er­ly lay the pipeline with such con­sum­ables, in addi­tion to spe­cial scis­sors and a sol­der­ing iron, you will need a shaver. This device is used to clean the edges of alu­minum foil on indi­vid­ual pipe frag­ments. Since alu­minum itself can­not be sol­dered, it is nec­es­sary to strip the chan­nel deep by 2–3 mm.

A prop­er­ly equipped heat­ing cir­cuit using rein­forced syn­thet­ic mate­ri­als can last a long time. Accord­ing to the instruc­tions, such sys­tems are oper­a­tional for 30–50 years, with­out loss of basic per­for­mance char­ac­ter­is­tics.

Rein­forced pipes are able to with­stand high tem­per­a­tures per­fect­ly. Con­sum­ables and acces­sories in which alu­minum is present have the low­est ther­mal expan­sion.

Technical parameters for the operation of reinforced polypropylene pipes

Now know­ing what rein­forced syn­thet­ic pipes are, we can draw some con­clu­sions. The advan­tages of rein­forced con­sum­ables include:

  • the low­est coef­fi­cient of ther­mal expan­sion among all cur­rent­ly known com­po­nents of this kind;
  • each prod­uct is designed for a cer­tain work­ing pres­sure (indi­cat­ed on the label);
  • wide oper­at­ing tem­per­a­ture range;
  • resis­tance to cor­ro­sion;
  • resis­tance of prod­ucts to a sharp decrease in tem­per­a­ture (the effect of defrost­ing does not threat­en such pipelines).

The main tech­no­log­i­cal para­me­ters of polypropy­lene con­sum­ables rein­forced with alu­minum or fiber­glass are as fol­lows.

Let’s go back to the coef­fi­cient of ther­mal expan­sion.

For ref­er­ence: For an ordi­nary plas­tic pipe, the ther­mal elon­ga­tion is 10 cm per 1 lin­ear meter of the pipe. Upon con­tact with a coolant whose tem­per­a­ture is 700FROM.

With polypropy­lene prod­ucts, in which there is a rein­forc­ing lay­er, the sit­u­a­tion looks dif­fer­ent. At high tem­per­a­tures, even reach­ing +950C, ther­mal elon­ga­tion is only 1 cm per 1 lin­ear meter of pipeline.

The oper­at­ing pres­sure also affects the func­tion­al­i­ty of the heat­ing cir­cuit and its dura­bil­i­ty. For clar­i­ty, just look at the table, which shows the mark­ings and indi­ca­tors of dif­fer­ent types of polypropy­lene prod­ucts used in home heat­ing sys­tems.

Prod­uct mark­ing


Heat car­ri­er tem­per­a­ture ˚С

Nom­i­nal coolant pres­sure MPa

PN 10

For cold water sys­tem

≤ + 20˚С

1 kgf/cm2

For low-tem­per­a­ture heat­ing sys­tems (heat-insu­lat­ed floors)

≤ + 45˚С

PN 16

For cold and hot water sys­tems

≤ + 60˚С

1.6 kgf/cm2

PN 20

Only for DHW sys­tems

≤ + 95˚С

2 kgf/cm2

PN 25 (rein­forced)

For cen­tral heat­ing and hot water sys­tems

≤ + 95˚С

2.5 kgf/cm2

Note: con­sum­ables and com­po­nents used in the instal­la­tion of polypropy­lene pipelines, rein­forced and in the usu­al ver­sion, can be made of prac­ticed, tra­di­tion­al mate­ri­als: brass, cop­per, nick­el-plat­ed inserts. The type of con­nec­tion is select­ed from the point of view of tech­no­log­i­cal neces­si­ty.


Polypropy­lene con­sum­ables rein­forced with spe­cial com­po­nents today have sig­nif­i­cant­ly expand­ed the per­for­mance of heat­ing sys­tems. Due to the afford­able price and ease of instal­la­tion, using such prod­ucts, it is pos­si­ble to lay a heat­ing pipeline of almost any length. Restric­tions can only be due to the pow­er of the heat­ing devices and the specifics of the heat­ing method. Do not for­get that poly­mer pipes are very con­ve­nient and prac­ti­cal to use. With such a pipeline, it is easy to car­ry out repair work. Sep­a­rate sec­tions of the pipeline are inter­change­able. Thanks to the sol­der­ing method, the nec­es­sary tight­ness, strength and sta­bil­i­ty of the joints are achieved.

In terms of man­u­fac­tura­bil­i­ty, syn­thet­ic pipes rein­forced with fiber­glass have great advan­tages, there­fore, over time, this type of con­sum­ables will take a dom­i­nant posi­tion in the mar­ket for ther­mal equip­ment.


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