How to fix a leak (hole, leak) in a heating pipe?


Leak­age of the heat­ing sys­tem is not uncom­mon, and in most cas­es it hap­pens unex­pect­ed­ly, except for test runs of equip­ment at the begin­ning of the heat­ing sea­son. What caused the leak is not always pos­si­ble to deter­mine reli­ably, and it is not always impor­tant, since in the fore­ground in such sit­u­a­tions is the restora­tion of the tight­ness of the heat­ing cir­cuit. As a rule, a thor­ough repair is post­poned for the warm sea­son, and if a leak is detect­ed, they choose how to cov­er up the leak in the heat­ing pipe tem­porar­i­ly.

Factors characterizing system depressurization

The heat­ing sys­tem con­sists of the fol­low­ing main ele­ments:

  • heat­ing boil­er;
  • pipeline;
  • radi­a­tors;
  • con­trol and mea­sur­ing and shut-off valves.

All of the list­ed ele­ments are mount­ed in a heat­ing cir­cuit, the tight­ness of which depends on the integri­ty of the con­stituent ele­ments and their con­nec­tions.

The choice of method for restor­ing the integri­ty of the heat­ing sys­tem depends on the fol­low­ing fac­tors:

  • acces­si­bil­i­ty of the dam­age site;
  • leak­age sta­tus (fis­tu­la, loss of tight­ness of a thread­ed con­nec­tion, etc.);
  • the mate­r­i­al of man­u­fac­ture of the dam­aged ele­ment;
  • the pos­si­bil­i­ty of shut­ting down the sys­tem.

Based on the com­bi­na­tion of the above cir­cum­stances, a method is cho­sen how to most effec­tive­ly close the leak in the heat­ing pipe in the cur­rent sit­u­a­tion.

Preparatory work

When spot repair­ing the heat­ing sys­tem, first of all, it is nec­es­sary to estab­lish a spe­cif­ic place for the leak­age of the coolant. If the pipeline is laid secret­ly (in the wall, in the floor), lined with dec­o­ra­tive ele­ments or equipped with ther­mal insu­la­tion, the task becomes more com­pli­cat­ed.

Impor­tant! In a sit­u­a­tion where a pipe or a joint embed­ded in a wall has leaked, it is advis­able to con­sid­er the pos­si­bil­i­ty of installing a new sec­tion of the pipeline, since it does not make sense to spoil the fin­ish of the room for repair­ing a pipe with a high degree of wear.

On the alleged emer­gency sec­tion of the cir­cuit, the dec­o­ra­tive trim and ther­mal insu­la­tion are dis­man­tled, the place of the leak is found, after which the nature and extent of the dam­age is assessed, as well as its avail­abil­i­ty for repair.

Spot repair of the heat­ing sys­tem can be of three types:

  • mechan­i­cal — with the use of com­press­ing and tight­en­ing devices, elec­tric weld­ing and oth­er means not based on the use of seal­ing solu­tions;
  • chem­i­cal — using var­i­ous kinds of seal­ing com­pounds that hard­en as a result of chem­i­cal reac­tions or dry­ing;
  • com­bined — seal­ing the cir­cuit using a com­bi­na­tion of mechan­i­cal and chem­i­cal meth­ods.

If a mechan­i­cal repair method is cho­sen, and the dam­age is not sig­nif­i­cant (nee­dle fis­tu­la or drip leak), the heat­ing sys­tem can be left in oper­a­tion before start­ing work to elim­i­nate the leak. If the dam­age is more seri­ous, then the heat­ing must be turned off:

  • the autonomous boil­er is turned off, the coolant is drained;
  • in the cen­tral heat­ing sys­tem, it is nec­es­sary to close the valve of the com­mon ris­er and hang a warn­ing sign on it, after which the water must also be drained from the sys­tem.

The tech­nol­o­gy of pro­cess­ing the base before seal­ing the con­tour depends on the mate­r­i­al of the pipeline, the sta­tus of the leak and the type of repair, but, in any case, the final result of the work is large­ly due to the qual­i­ty of the sur­face prepa­ra­tion.

Methods for performing repairs with reference to the place of leakage


In most cas­es, it is pos­si­ble to elim­i­nate the leak­age of the heat­ing sys­tem on your own, with­out the involve­ment of pro­fes­sion­als. To do this, con­sid­er the meth­ods for pro­duc­ing spot repair of the con­tour with the most com­mon dam­age.

Elimination of a fistula in a straight section of a steel pipeline by mechanical means

On a hor­i­zon­tal or ver­ti­cal sec­tion of a sol­id steel pipe, due to a num­ber of fac­tors (wear, cor­ro­sion, mate­r­i­al defect), a leak often occurs that can be elim­i­nat­ed inde­pen­dent­ly and with­out sig­nif­i­cant costs.

If a fis­tu­la with a jet cross sec­tion of approx­i­mate­ly a match has formed in a steel pipe with a diam­e­ter of up to 50 mm, then it can be elim­i­nat­ed even with­out spe­cial prepa­ra­tion of the base, but the thick­ness of the pipeline wall must be at least 3 mm. The area around the dam­age is cleaned of rust and scale with a file or grinder, after which a self-drilling screw with a seal­ing rub­ber wash­er is screwed into the hole with a drill. The length of the screw is select­ed in such a way that it pro­trudes min­i­mal­ly at the exit from the hole inside the pipe and in no case rests against the oppo­site wall.

Impor­tant! When using an elec­tric drill, the coolant in the pipe must not be under pres­sure so that the water jet does not hit the tool and cause an elec­tri­cal injury or break­age of the drill. For safe­ty rea­sons, it is bet­ter to use a drill with a built-in 12 V bat­tery, wrapped in a plas­tic bag with a slot for a chuck.

It is also bet­ter to know in advance how to close a hole in a heat­ing pipe with a diam­e­ter of 50 mm or more and with a larg­er fis­tu­la cross sec­tion, since the con­se­quences of dam­age to such a heat pipe are more seri­ous, and the prob­a­bil­i­ty of an acci­dent is no less.

The hole of the fis­tu­la is dri­ven with a drill of a slight­ly larg­er diam­e­ter in such a way that then a bolt thread can be cut in it. The wall thick­ness must also be suf­fi­cient for thread­ing. The table shows the cor­re­spon­dence of drills and threads (tap).

Stan­dard Pitch Met­ric Hole Diam­e­ters

Nom­i­nal diam­e­ter

thread (mm)

Drill diam­e­ter for the prod­uct,

made from:

brass, steel cast iron, bronze
3.0 2.5 2.5
3.5 2.9 2.9
4.0 3.3 3.3
5.0 4.2 4.1
6.0 5.0 4.9
7.0 6.0 5.9
8.0 6.7 6.6
9.0 7.7 7.7
10.0 8.4 8.3


After cut­ting the thread, a bolt with a wash­er and a rub­ber seal is screwed into the hole. The length of the bolt is select­ed depend­ing on the wall thick­ness — the part after screw­ing should not block the pipe lumen or rest against the oppo­site wall.

It is pos­si­ble to elim­i­nate the leak­age of a steel heat­ing pipe with­out thread­ed ele­ments — by caulk­ing and elec­tric weld­ing. The hole is drilled to the near­est diam­e­ter, after which a cone (chop) of a suit­able size, machined from steel, is ham­mered into it with a ham­mer. The part of the chop remain­ing out­side is ground down by a grinder to such an extent that a small pro­trud­ing hat remains, which is then scald­ed by elec­tric weld­ing. This method of elim­i­nat­ing leak­age is reli­able and durable, but it should be remem­bered that rutile-coat­ed elec­trodes must be used for weld­ing gal­va­nized pipes, and the pipe wall thick­ness must be suf­fi­cient (3 mm).

A sin­gle hole in the wall of a steel pipe can also be plugged with a nar­row clamp.

Such a clamp can also be made inde­pen­dent­ly from strip steel, but there is a large assort­ment of these devices on sale, the aes­thet­ics of which are much high­er. The clamp is select­ed accord­ing to the diam­e­ter of the pipe and, if there is no gas­ket includ­ed with it, such a seal­ing strip is cut out of rub­ber or paronite with a thick­ness of at least 3 mm. The device is put on the pipe, the gas­ket is com­bined with the fis­tu­la, and the clamp is crimped with the nec­es­sary force. This method of elim­i­nat­ing leak­age is also applic­a­ble to pipelines made of cop­per or poly­mer­ic mate­ri­als.

In a sit­u­a­tion where sev­er­al fis­tu­las have formed on a small area, it is impos­si­ble to use the above repair meth­ods — the pipe sec­tion is weak­ened, and it is not effec­tive to repair leaks indi­vid­u­al­ly and even fraught with the destruc­tion of the entire con­tour frag­ment. For dam­age to an oblong shape (crack), a nar­row clamp, like a chop, can­not be installed.

If at the moment it is not pos­si­ble to replace the entire emer­gency sec­tion, then clips are used to restore the tight­ness of the heat­ing pipeline — wide clamps, the prin­ci­ple of oper­a­tion of which is the same as that of nar­row devices.

Repair of a pipeline in a straight section or a turn by chemical and combined methods

To elim­i­nate the leak­age of the heat­ing pipeline, var­i­ous types of heat-resis­tant one- and two-com­po­nent sealants are pro­duced, used on both steel and poly­mer pipes. The most wide­spread are high-tem­per­a­ture sil­i­cone-based com­pounds, char­ac­ter­ized by a high degree of adhe­sion, plas­tic­i­ty and the abil­i­ty to with­stand tem­per­a­tures up to 350 degrees. These sealant mix­tures dif­fer from oth­er types of sil­i­cone adhe­sives by hav­ing a red­dish or brown tint.

Each of these com­po­si­tions has its own instruc­tions for use, set out on the pack­ag­ing and pro­vid­ing for the use of joints and mates for seal­ing. But, if rein­force­ment is applied, they can also be used on a plane, that is, on the sur­face of a pipeline, both steel and poly­mer.

Before start­ing work, the coolant is drained from the heat­ing sys­tem, and the area around the dam­age is cleaned of paint, degreased and dried.

Impor­tant! The adhe­sion of sil­i­cone sealants to smooth sur­faces is stronger than to rough ones, there­fore, the repaired sec­tion of the pipe should not be treat­ed with abra­sives.

Rein­force­ment of the sil­i­cone seal­ing coat­ing is made to increase the ten­sile strength of the shell and its resis­tance to mechan­i­cal dam­age. Ser­pyan­ka is used as rein­force­ment — fiber­glass mask­ing tape.


A sealant is applied to the pre­pared sur­face of the heat­ing pipe in a con­tin­u­ous lay­er 2–3 mm thick, on top of which a sick­le is screwed — in butt turns. A lay­er of sealant is again applied over the first lay­er of the mesh, and then a sick­le again, but with 5 mm over­lap­ping turns on each oth­er. In total, there should be 4 or 5 lay­ers of mesh with lay­ers of sil­i­cone. It is nec­es­sary that the turns fit into an inter­fer­ence fit, with­out folds with voids, like ban­dag­ing — with the tape turn­ing around the axis at the end of each lay­er to return in the oppo­site direc­tion. Such ban­dag­ing should cap­ture sec­tions of the pipeline 10–20 cm in both direc­tions from the dam­age. The last lay­er on the pipe is made of sealant, which is smoothed out with a hand dipped in soapy water. The end of the sick­le is tem­porar­i­ly attached to the pipe with a nylon clamp away from the repaired area — after the com­po­si­tion has cured, it is cut off flush with the sur­face of the sealant.

Depend­ing on the type of adhe­sive and the total thick­ness of the seal­ing lay­er, cur­ing, which occurs from the con­tact of the com­po­si­tion with atmos­pher­ic mois­ture, requires from sev­er­al hours to a day.

Using the same tech­nol­o­gy, using sick­le rein­force­ment, the heat­ing sys­tem is repaired using heat-resis­tant rub­ber sealants — also durable, but elas­tic com­pounds that are suc­cess­ful­ly used both in every­day life and in pro­duc­tion.

It should be borne in mind that sil­i­cone and rub­ber sealants are com­mer­cial­ly avail­able for use in auto­mo­tive engines. If the per­for­mance char­ac­ter­is­tics of such com­po­si­tions meet the require­ments of the heat­ing sys­tem, then the auto-sealant, designed for use in the repair of an inter­nal com­bus­tion engine, will cope even more with the seal­ing of the heat pipe in every­day life.

To fix a leak­ing pipe in a domes­tic heat­ing sys­tem, ready-made repair kits are often used, which include every­thing nec­es­sary for seal­ing. An exam­ple of such tools is the Silo­plast repair kit, even equipped with pro­tec­tive rub­ber gloves. The main ele­ment of the leak elim­i­na­tion in the kit is a tape with a spe­cial impreg­na­tion, which, upon con­tact with water (wet­ting dur­ing instal­la­tion), hard­ens and forms a strong her­met­ic shell on the pipe, which does not need to be addi­tion­al­ly coat­ed with any­thing.

The method of appli­ca­tion of Silo­plast is described in detail on the pack­ag­ing, and the suc­cess of the repair depends on the obser­vance of this tech­nol­o­gy, as well as the qual­i­ty of the base prepa­ra­tion. The repair kit can be used not only on straight, but also on curved sec­tions of the pipe, as well as over thread­ed con­nec­tions, the seal­ing mate­r­i­al of which has lost its prop­er­ties.

The mate­r­i­al is pro­duced for var­i­ous areas of pro­duc­tion, so when buy­ing, you need to choose exact­ly the type of repair kit you need, one of them is Silo­plast “For Home”.

To restore the tight­ness of the heat­ing sys­tem, spe­cial two-com­po­nent com­po­si­tions called “cold weld­ing” are also used — mix­tures based on epoxy resins with the addi­tion of met­al filler and addi­tives that are respon­si­ble for the spe­cif­ic char­ac­ter­is­tics of the adhe­sive under cer­tain con­di­tions.

The resin in the com­po­si­tion ensures the plas­tic­i­ty of the mate­r­i­al after cur­ing, and the met­al-con­tain­ing com­po­nent increas­es the strength and hard­ness of the binder. Cold weld­ing is pro­duced in liq­uid and plas­tic form. Spec­i­fi­ca­tions, includ­ing oper­at­ing tem­per­a­ture and method of appli­ca­tion, are indi­cat­ed on the pack­ag­ing. It remains only to choose the right type of sealant that cor­re­sponds to the oper­at­ing con­di­tions and the mate­r­i­al of man­u­fac­ture of the ther­mal cir­cuit.

If the heat­ing pipe does not leak sig­nif­i­cant­ly, then the ques­tion of how to cov­er up the cir­cuit in a straight sec­tion or a joint of a thread­ed con­nec­tion can also be solved with impro­vised means, for exam­ple, using Min­ut­ka glue or iden­ti­cal in action. To do this, the repaired sur­face or crack must be cleaned of paint, degreased and dried. Then the pre­pared area is wrapped with a lay­er of sick­le end-to-end and ordi­nary bak­ing soda is rubbed into the cells of the grid (pre­lim­i­nar­i­ly, the first turn is point­wise attached to the pipe with glue). Then anoth­er lay­er of mesh coils, already over­lapped, is applied to the pipe, and the cells are again filled with soda. After lay­ing the third lay­er of sick­le with soda, the last turn of the tape is fixed with a nylon clamp, and glue from a tube is applied to the result­ing clutch, start­ing from the site of dam­age. The glue is instant­ly absorbed into the soda and, react­ing with it, also instant­ly hard­ens, form­ing a strong shell. It is nec­es­sary to apply glue to the entire sur­face of the wind­ing, the tubes are squeezed out one by one as they are emp­tied, the num­ber of tubes depends on the area of ​​the repaired area.

If the dam­age to the pipe is a crack, then it is also stuffed with soda and glue is dripped on top, instant­ly seal­ing the dam­age. A sick­le ban­dage is applied over the crack in the man­ner described above.

The method is applic­a­ble for the repair of both steel and poly­mer pipes.

There is anoth­er way to seal coolant leaks on a straight or oval sec­tion of a steel heat­ing pipeline, as well as on top of a thread­ed con­nec­tion — using a rein­forced cement mor­tar ban­dage. To do this, the sys­tem is depres­sur­ized so that water does not ooze from the dam­age site, and the repaired area is cleaned of paint and rust. Then, an aque­ous solu­tion of the con­sis­ten­cy of sour cream is pre­pared from cement grade 400 or 500, and the prob­lem­at­ic sec­tion of the pipeline is ban­daged in lay­ers with a strip of can­vas fab­ric that pass­es liq­uid well through itself (you can use a sick­le or an ordi­nary med­ical ban­dage). Ban­dag­ing is car­ried out with coat­ing of each lay­er with cement mor­tar. As a result, a sleeve with a wall thick­ness of at least 2 cm should form on the pipe, which is cov­ered with the last lay­er of the same solu­tion.

The effec­tive­ness of the method can be increased if, for mix­ing cement, not water is used, but PVA glue, but not its pasty vari­ety, but emul­sion. In addi­tion, cement-based coat­ing water­proof­ing can be used instead of cement.

Cere­sit CR 65, designed specif­i­cal­ly for the instal­la­tion of water­proof coat­ings.

Impor­tant! The use of a cement ban­dage for seal­ing the heat­ing pipeline is a tem­po­rary mea­sure, since the cement is not plas­tic and poor­ly resists the ten­sile forces that will affect it dur­ing the ther­mal expan­sion of the pipes, so even rein­force­ment with sick­le will not save from the occur­rence of micro­c­racks in the repair shell over time.


Elimination of leakage in places of threaded connections

If the coolant flows at the junc­tion of pipe sec­tions made by a thread­ed method, or at the points of con­nec­tion to a heat­ing radi­a­tor, shut­off valves, then the best action would be to dis­man­tle the thread­ed con­nec­tion to diag­nose the cause of depres­sur­iza­tion. This refers to the sit­u­a­tion when, dur­ing the instal­la­tion of the heat­ing sys­tem, fit­tings designed for adjust­ment — adjust­ment with a seal were not used. The dis­man­tling of the thread­ed con­nec­tion, which is car­ried out after the coolant is drained from the sys­tem, will show the cause of the leak — thread wear or loss of sealant qual­i­ties.

In the first case, the thread pro­file is refreshed by pass­ing a ler­ki (die) along it with cut­ting an addi­tion­al 2–3 turns. If the thread is sig­nif­i­cant­ly destroyed, then you will have to insert a new pipeline frag­ment by weld­ing or, again, a thread­ed con­nec­tion (dri­ve).

If the thread is in sat­is­fac­to­ry con­di­tion, the seal­ing mate­r­i­al is replaced. To do this, the threads are cleaned of the rem­nants of the old sealant and a new one is applied to it. For reli­able seal­ing, it is rec­om­mend­ed to use a com­bi­na­tion of a fiber sealant (linen strand) and one of the types of sealant for thread­ed joints, includ­ing anaer­o­bic ones, designed for inde­pen­dent use.

You can sim­pli­fy this pro­ce­dure by using a spe­cial uni­ver­sal impreg­nat­ed seal­ing thread. The mate­r­i­al of the thread can be nat­ur­al or syn­thet­ic, impreg­na­tion is most often sil­i­cone. Such a thread is attrac­tive by its ease of use, ver­sa­til­i­ty and afford­abil­i­ty, which allows you to car­ry out repairs your­self and with­out sig­nif­i­cant costs.

FUM-tape is wide­ly used as a sealant for a thread­ed joint — a syn­thet­ic mate­r­i­al that, due to its flu­o­rine con­tent, is resis­tant to high tem­per­a­tures and chem­i­cals.

FUM tape is pro­duced in three types:

  • FUM‑1 — with vase­line-based lubri­cant, for use in indus­tri­al pipelines, includ­ing those with aggres­sive media;
  • FUM‑2 — does not con­tain lubri­cant, suit­able for envi­ron­ments with oxi­diz­ing agents;
  • FUM‑3 — for pipelines with non-aggres­sive media.

All three types of FUM tape are suit­able for use in domes­tic heat­ing sys­tems and are quite effec­tive when prop­er­ly applied to the thread.

In cas­es where the leak­age inten­si­ty is not sig­nif­i­cant, the dis­man­tling of the thread­ed con­nec­tion can be post­poned until the end of the heat­ing sea­son, and the tight­ness of the con­nec­tion can be restored by apply­ing a rein­forced ban­dage over the joint using one of the seal­ing com­pounds described above — sil­i­cone, rub­ber, cold weld­ing.


When fix­ing a leak in a heat­ing sys­tem, the effec­tive­ness and longevi­ty poten­tial of the repair should be objec­tive­ly assessed. Most of the reme­dies offered by man­u­fac­tur­ers to elim­i­nate leak­age are designed to tem­porar­i­ly elim­i­nate an emer­gency before rad­i­cal mea­sures are tak­en, includ­ing a major over­haul of the heat­ing sys­tem. There­fore, after diag­nos­ing the caus­es of the leak and choos­ing how to cov­er up the dam­age, it is nec­es­sary to con­sult with pro­fes­sion­als, not rely­ing only on mar­ket­ing advice in the store, some­times pro­vid­ed by work­ers with­out expe­ri­ence in repair and con­struc­tion activ­i­ties. This will allow you to get an objec­tive assess­ment of the sit­u­a­tion and cor­rect­ly plan repair activ­i­ties at the end of the heat­ing sea­son in order to avoid aggra­vat­ing the sit­u­a­tion in the cold sea­son.


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