Overview of asbestos pipes, dimensions, connection methods

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In many indus­tri­al com­mu­ni­ca­tions, as well as in the con­struc­tion of res­i­den­tial premis­es, asbestos or asbestos-cement pipes are used. The wide pop­u­lar­i­ty of the use of prod­ucts con­tributes to their high wear resis­tance to var­i­ous adverse fac­tors. In addi­tion, asbestos pipes have a large assort­ment of sizes that dif­fer in diam­e­ter and length.

Materials used in the manufacture

The main mate­ri­als used in the man­u­fac­ture are cement and asbestos fiber. To obtain asbestos fiber, asbestos is pre-crushed. The result­ing pow­dery mass is divid­ed into fibers and added to the cement mor­tar.

The amount of fibers in the solu­tion does not exceed 15% of the total weight, but this results in a mate­r­i­al with low weight and low ther­mal con­duc­tiv­i­ty. Rein­forc­ing the con­crete solu­tion with asbestos makes it pos­si­ble to obtain a mate­r­i­al with a strength of 40% more than that of con­ven­tion­al con­crete prod­ucts.

asbestos pipes

Types and application of asbestos-cement pipelines

Asbestos-cement prod­ucts are divid­ed into two types depend­ing on the pres­sure of the con­duct­ed medi­um: pres­sure and non-pres­sure. In turn, the indus­try pro­duces 4 types of pres­sure pipelines with the fol­low­ing des­ig­na­tion:

  • VT6 — designed for a pres­sure of 0.6 MPa;
  • VT9 — with­stands a pres­sure of 0.9 MPa;
  • VT12 — design pres­sure of the con­duct­ed medi­um 1.2 MPa;
  • VT15 — max­i­mum pres­sure 1.5 MPa.

The scope of non-pres­sure pipes is as fol­lows:

  • in the man­u­fac­ture of pipeline net­works for water sup­ply of res­i­den­tial build­ings;
  • for use as chim­ney pipes;
  • in drainage col­lec­tors and when lay­ing sew­er sys­tems;
  • as foun­da­tion piles when installing pre­fab­ri­cat­ed hous­es in flood­ed unsta­ble soils with a diam­e­ter of the used asbestos pipe of more than 200 mm;
  • elec­tric and tele­phone cables are placed when lay­ing inside the small diam­e­ters of the prod­uct, for pro­tec­tion against dam­age and insu­la­tion.
Asbestos pipe on the roof

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The use of asbestos pipes in the chim­ney should be done with cau­tion, espe­cial­ly if the flue out­let has a high tem­per­a­ture. Such chim­neys can crack from high tem­per­a­tures, and the rub­ber seals that ensure the tight­ness of the con­nec­tion will burn out.

In addi­tion, a large accu­mu­la­tion of soot and con­den­sate occurs on the walls, which also weak­en its strength and reduce the draft of fur­naces. If the source of fire is at a suf­fi­cient­ly large dis­tance, then the use of asbestos prod­ucts can be com­plete­ly allowed.

The scope of appli­ca­tion of pres­sure pipelines is no less exten­sive:

  • trans­porta­tion of gas, water and oil refin­ery prod­ucts;
  • instal­la­tion of ven­ti­la­tion sys­tems;
  • use for sys­tems with a hot con­duc­tive medi­um with a per­mis­si­ble tem­per­a­ture up to 115ºС;
  • when lay­ing sew­er sys­tems under pres­sure and for arrang­ing water wells.

Pres­sure pipes dif­fer from non-pres­sure pipes in wall thick­ness and the size of the inner diam­e­ter. For non-pres­sure pipelines, the wall thick­ness is car­ried out with dimen­sions of 7 … 18 mm, and for pres­sure pipelines 9 … 43.5 mm. The inner diam­e­ter in the first case is 50 … 500 mm, and in the sec­ond case up to 600 mm.

Impor­tant! Low ther­mal con­duc­tiv­i­ty and the abil­i­ty to main­tain the tem­per­a­ture of the medi­um for a long time con­tributes to their wide­spread use in heat­ing sys­tems. And in accor­dance with SNiP, these prod­ucts are allowed to be used even for drink­ing water sup­ply sys­tems.

Dimensions of asbestos-cement pipelines

Non-pres­sure pipelines are avail­able in lengths of 4 or 5 meters. Oth­er dimen­sions are shown in the table.

Tab. 1 Dimen­sions of non-pres­sure asbestos-cement pipelines

The pres­sure pipes are 5 meters long, the dimen­sions are shown in the table below.

Tab. 2 Pres­sure pipe dimen­sions

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Main advantages and disadvantages

Com­pared with met­al pipelines, asbestos-cement prod­ucts have a num­ber of advan­tages, espe­cial­ly in terms of cor­ro­sion resis­tance and a ser­vice life of more than 40 years with­out repair and replace­ment. Oth­er ben­e­fits include:

  • Easy instal­la­tion of pipelines when lay­ing the route. They do not need to be weld­ed or con­nect­ed with thread­ed fit­tings.
  • No need for addi­tion­al insu­la­tion due to low coef­fi­cient of ther­mal expan­sion.
  • Pos­si­bil­i­ty of lay­ing pipelines in any type of soil.
  • High resis­tance to exter­nal load deter­mines their use where the tracks pass under the roads with reg­u­lar traf­fic.
  • No main­te­nance is required dur­ing oper­a­tion.
  • There are no build-ups on the inner walls that nar­row the inner diam­e­ter.
Sew­er lay­ing

Sewer laying

If water is sup­plied through the pipes, then over time the wall becomes stronger due to the com­paction of the cement com­po­nent. Accord­ing to stud­ies by sci­en­tists from a num­ber of coun­tries, the use of such prod­ucts for drink­ing water is safe for humans. If asbestos par­ti­cles enter the body, it is quick­ly elim­i­nat­ed from the body with­out any harm.

Well, the main dis­ad­van­tage of asbestos-cement mate­ri­als is their fragili­ty. They can eas­i­ly be dam­aged dur­ing trans­porta­tion, care­less unload­ing, or being hit by a heavy object. To pre­vent this from hap­pen­ing, care must be tak­en to main­tain their integri­ty dur­ing trans­porta­tion and instal­la­tion.

Cutting of asbestos pipelines

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When lay­ing asbestos sys­tems, there is often a need for a cut to size of the prod­uct. This oper­a­tion is per­formed using a grinder with a dia­mond disc installed.

cut­ting grinder

cutting grinder

First, the required cut length is marked, and the risk is applied around the entire perime­ter. To pre­vent the prod­uct from mov­ing when cut­ting, it must be fixed, but not in a vice, as you can inad­ver­tent­ly squeeze the sur­face. If there is an assis­tant, then you can hold it with your hands, or install it for fix­a­tion between two bars.

When cut­ting, the small­est asbestos dust is formed, the inhala­tion of which is harm­ful to health. To pro­tect your­self from dust, you must wear a res­pi­ra­tor or pro­tec­tive mask, and gog­gles over your eyes. Cut­ting can be done with a dia­mond disc of any diam­e­ter, turn­ing the prod­uct over in order to make the disc acces­si­ble.

Connection and installation methods

The lay­ing of the pipeline can be done man­u­al­ly with small diam­e­ters up to 100 mm, and with large sizes it is nec­es­sary to use con­struc­tion equip­ment. If a grav­i­ty sew­er sys­tem is being installed, then the pipelines must be installed with a slope in accor­dance with the norms of SNiP, and com­plete­ly lie on the base.

Cou­plings

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Couplings

All the nec­es­sary tech­nol­o­gy require­ments: how to con­nect asbestos pipes to each oth­er, and how to adhere to cer­tain rules, are set out below:

  1. The inter­con­nec­tion of pipelines is car­ried out using cou­plings. Grooves are made in the cou­plings for insert­ing seal­ing rub­ber rings. This type of con­nec­tion pro­vides a tight con­nec­tion between the cou­pling and the pipe, which ensures tight­ness at design pres­sure.
  2. When installing pipes with a diam­e­ter of more than 150 mm, it is nec­es­sary to pro­vide a gap between the con­nect­ed ele­ments. This is nec­es­sary to exclude the pos­si­bil­i­ty of installing addi­tion­al expan­sion joints along the length.
  3. Asbestos pipelines must have sup­ports along the entire length, voids are not allowed, which can lead to defor­ma­tion of the pipeline.
  4. When using prod­ucts for hot heat sup­ply, when the max­i­mum tem­per­a­ture is more than 100ºС, an increase in the size of the walls occurs due to heat­ing. In order not to dam­age the rub­ber seals, they are deformed by the end of the pipe by 0.2 mm.

To con­nect pipes with a diam­e­ter of up to 150 mm, plas­tic cou­plings are used. To install the cou­pling, it is heat­ed with a build­ing hair dry­er, and then put on the junc­tion. The cou­pling cools and tight­ly tight­ens both ends, pro­vid­ing the nec­es­sary tight­ness. Instead of a hair dry­er, you can use hot water, where a PVC sleeve is low­ered for 10 min­utes.

Some­times, when installing sew­er drains for a house, it becomes nec­es­sary to con­nect an asbestos-cement pipe with a plas­tic one. Many do not know how to prop­er­ly con­nect an asbestos pipe with a plas­tic one so that there are no leaks. For such a con­nec­tion, a spe­cial MAGNAPLAST fit­ting is used, with its help non-pres­sure dis­sim­i­lar pipes of 100 … 300 mm in diam­e­ter are joined. In indus­try, this con­nec­tion is also used when lay­ing com­mu­ni­ca­tion cables inside prod­ucts.

MAGNAPLAST fitting

When arrang­ing chim­neys, in order to pro­tect the asbestos prod­uct from con­tact with high tem­per­a­tures, it is nec­es­sary to con­nect asbestos pipes with met­al ones. If the prod­ucts are of dif­fer­ent diam­e­ters, then use a branch pipe with dif­fer­ent diam­e­ters of the ends. One end should be equal to the diam­e­ter of the met­al, and the oth­er to the asbestos-cement pipe. It is weld­ed onto the met­al pipe, and the asbestos pipe is con­nect­ed to the pipe with a con­ven­tion­al cou­pling. Anoth­er option is to cut the end of the met­al to the size of the asbestos-cement diam­e­ter.

Estimated cost of products

The approx­i­mate cost of prod­ucts depends on the type, diam­e­ter and pur­pose of the pipe. Some items are priced below:

  • The cost of a non-pres­sure one with a nom­i­nal bore of 100 … 600 mm, a length of 3.95 m. Is 450 … 22$, when equipped with a cou­pling of the appro­pri­ate diam­e­ter, the price increas­es by 40–210 rubles.
  • For a pres­sure prod­uct with a pres­sure of 0.9 MPa, a nom­i­nal bore of 250, a length of 5 m, the price will be 43$, and for the Du-400 already 71$.
  • The price of a cou­pling equipped with rub­ber rings will be 260–9,5 dol­lars.

These prices are indica­tive, they may dif­fer from the region of loca­tion and from the sea­son, but for an approx­i­mate esti­mate of the esti­mate, you can use it.

Asbestos-cement prod­ucts are used in many indus­tries and among pri­vate house­holds. They are espe­cial­ly in demand in the arrange­ment of sew­er sys­tems, which allows to increase the ser­vice life of such com­mu­ni­ca­tions sev­er­al times.

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