Heating furnace lining: what is it and how to do it yourself. Lining of various furnaces

Ecology of consumption. Homestead: Only refractory materials are used for the construction of furnaces. But even they are not able to withstand high temperatures for a long time. To protect the outer walls near the firebox from radiation, thermal or chemical influences, a lining is arranged inside.

In order for the lining made with fireclay products to be strong, durable and efficient, a special solution is required. The best option- ready-made dry mixes adapted for chamotte and laboratory-tested for the mode of operation. Heat-resistant and refractory compounds for masonry are presented on the market in an assortment, and the prices are quite affordable, and experiments with lining are more expensive, since the repair and restoration work of heating structures is a laborious and long process.

Lining with fireclay bricks

Ready-made dry mixes for lining have manufacturer's instructions on the packaging and information on the exact purpose of the composition. The lining of the furnace sections of furnaces requires refractory mixtures, and heat-resistant solutions can also be used for the remaining sections. Refractory compositions are much more expensive, but only they should be used for lining furnaces, especially since a little mortar is required - you can take it at the rate of 70 kg of dry matter per 100 pieces. bricks.

When lining with fireclay bricks, it should not always be soaked before laying, but in certain cases:

Dry brick quickly absorbs water from the mortar, as a result, the mortar joint sets faster and loses its plasticity. Correcting something is very difficult, so a good masonry skill is required. If the brick is soaked before work, then it is possible to obtain an additional resource for correcting errors in the masonry by extending the mobility of the mortar mixture.
When reusing bricks from the disassembly of old stoves, soaking opens the capillaries and pore structures of the brick, into which dust and solutions have entered during the service. Moisture and solutions as a result of moisture penetrate the brick more easily, the adhesion and strength of the masonry increases.
During summer masonry work, when air temperatures are high, it is recommended to soak the brick for a short time before laying. In autumn and winter, this procedure becomes superfluous and harmful, since the overmoistened brick in the masonry must be dried, and it is unacceptable to heat the stove before the mortar dries naturally and sets in the masonry joints - this can cause deformations in the masonry joints and reduce its strength. Sometimes drying is carried out using heat from a powerful electric incandescent lamp with all oven doors fully open.

Dry fireclay bricks for masonry are preferable, so instead of soaking the bricks, you can make the mortar mixture a little less thick in order to have a little time to correct possible flaws in masonry work.

Linings with refractory adhesives and pastes

Alternatively, the use of refractory aluminosilicate adhesive for linings, rather than fireclay solutions, has invaluable advantages. These compositions are used not only for the lining of household furnaces as masonry and coating mortars, but also in metallurgy. high-temperature adhesives are used for mounting products made of basalt and kaolin fiber, ceramic fiber, fireclay products, with excellent adhesion as a result.

Sold aluminosilicate adhesive ready to use, in a sealed plastic container different packing, at least 2 kg.

Refractory adhesive lining includes the following steps:

Before work, the glue is thoroughly mixed until completely homogeneous.
Apply glue to pre-moistened surfaces with steel spatulas. On the walls of the furnace section and / or other elements of the lining, the adhesive is applied in a thin layer - no more than 3 mm. In the case when the lining is carried out only with an adhesive layer, without sticking cardboard or other materials, the adhesive is applied 3-4 times, with each layer holding for about 15 minutes.
When fixing basalt cardboard on horizontal surfaces, the adhesive mass can be diluted with water up to 15%. The consumption of the adhesive composition is affected by the quality of the treated surfaces and the thickness of the applied layers, the adhesive can go per square meter. Meter within 2-4 kg.
The adhesive layer dries completely in a day, if the temperature is not lower than 25⁰С and the application thickness is not more than 3 mm. At high temperatures (more than 85⁰С), complete drying occurs in 5-7 hours.

Furnace linings for brick ovens and fireplaces

When lining the walls of the furnace departments, it is imperative to take into account the inevitable thermal expansion of materials under temperature effects when stoves, fireplaces or boilers are in operation. The internal protection of the fireclay layer and the outer masonry layer of ordinary red brick must have a compensation gap of 0.7-1.0 cm and / or a gasket layer of asbestos cardboard, basalt or kaolin sheet, or rolled material. Direct contact of the outer wall of the furnace section with the lining of the furnace is unacceptable; there must be either free clearance or filling with heat-resistant material, otherwise the difference in the thermal expansion of materials will cause deformations and the structure will gradually collapse.

Before starting masonry, the need for materials is calculated. Fireclay bricks are more common standard sizes 250*150*65 mm. Fireclay products are produced in a large assortment, which makes it possible to select fireclay for a configuration of any complexity - for combustion chambers, a fireplace vault, arches, etc. It is possible to lay out inclined surfaces along the frames of grates and form the rear walls of fireplaces, the so-called streams. In fireplaces, the inner walls are made with a slope so that the heat goes into the room, and the combustion products are directed into a precisely calculated hole. In the same way as in furnaces, in fireplaces, compensation gaps are required between the fireclay lining and the outer walls of brick.

The thickness and materials for lining are selected based on the operating mode of the furnace or boiler unit. In order to strengthen the fireclay masonry, reinforcement is also used. Reinforce the seams with steel wire with a diameter of 3 - 5 mm in every second row. When furnaces are built according to ordering schemes, the linings are made in parallel, and all dimensions are already calculated and painted in order, as well as the shapes and sizes of fireclay products.

But if you need to carry out the lining of the furnace of an already built furnace, the process steps are as follows:

The first row of fireclay bricks is laid around the grates, and a brick with a sloped edge is preferred to provide a slope towards the grates.
In ready-made fireboxes, it is extremely difficult to lay out the back wall with an inclination, so you have to make them even. The rear and side walls of the lining are lifted simultaneously.
With small sizes of furnaces and the need for their lining, not fireclay bricks are used, but thin-walled fireclay panels or coatings with a paste-like refractory composition. When performing coatings, it is necessary that the entire surface has been treated. Before work, they arrange an upper illumination by removing cast-iron rings from the burners.

When lining furnaces of any size, as well as when laying, it is unacceptable to combine ceramic heat-resistant bricks and refractory fireclay bricks. These materials differ greatly in density and linear expansion, and in addition, they have different thermal conductivity. The combination of fireclay and red brick will give masonry that is subject to deformation when heated, unstable and unreliable, with the main red brick cracking and breaking first. To compensate for thermal expansion, gaps are always required between fireclay and ceramics with a lining of refractory sheet made of asbestos board, basalt or kaolin. In small furnaces, when lining, it is also difficult to arrange gaps, but this is necessary, at least minimum size half a centimetre.

Metal furnace furnace lining

The linear expansion of metal and fireclay is incomparable with similar parameters of bricks of various types, therefore, when lining steel furnaces, the issue of gaps does not even arise. Thermal gaps between the steel sheet of the furnace and fireclay are filled with asbestos, but kaolin or basalt wool or mats are preferred.

The lining of metal heating furnaces inevitably reduces the efficiency of heating, since part of the heat from the combustion of fuel will go not to heat the walls, but to the chimney. Therefore, in the presence of an internal lining of furnaces outer cladding steel stove ceramic brick it is completely unnecessary to do this - the high heat capacity and low thermal conductivity of ceramics will greatly reduce heat transfer from the furnace.

They begin to line a metal firebox from the bottom to the top, just like a brick one - they lay out the bottom, along the flooring of, for example, basalt cardboard not thinner than 1 cm. Cardboard or sheets of other heat-resistant material are fixed with refractory glue.

Differences in the lining of heating solid fuel boilers

Features of the lining of boilers consist in taking into account the specifics of work - the boiler unit must generate thermal energy and continuously transfer it to the heat exchange circuit to the circulating coolant, and heat dissipation through the outer casing by boiler structures is reduced to a minimum, since in the context of boilers, heat transfer to the outside is heat loss. All this determines the differences in the lining of various boilers, depending on their shielding.

The main three methods of boiler lining

Rarely used for domestic boilers - heavy linings. If the boiler has weak shielding and heats up during operation above 1200⁰С, then there are risks that the walls of sheet steel will quickly burn out. In addition, servicing such a unit is no longer safe, and fires are possible. When making heavy linings, fireclay bricks are laid with a spoon in two or even three layers. As a result, the temperature of the outer surfaces of the boiler drops to 80⁰С.
A single-layer fireclay lining is considered lightweight. At the same time, from the outside, the surface of the boilers is additionally lined with non-combustible material based on the specific temperatures to which the unit is heated, and from above, sheathing with sheet steel is also possible.
External lining of refractory compounds - glue, viscous coatings or pastes in order to thermally insulate the pipes from above. This simple lining method is used in areas where it is difficult or impossible to use other heaters due to strong heating. Coating lining is applied with brushes for two, less often three or four times, laying a reinforcing fiberglass mesh. Steel meshes are not used, because when heated, they give too much linear expansion. The mesh provides protection against possible through mechanical damage to the lining layer. Such a thickened multi-layer lining prevents heat loss through the pipes.

Features of the lining of fireboxes of stucco clay stoves

The stucco adobe stove is now in great fashion, and the variety of such stoves in terms of design, construction and dimensions is growing, despite the huge range of cast-iron and steel stoves and all the necessary building materials for the construction of brick stoves. Stucco stoves are special - they are very ancient, time-tested and highly functional, and heat, and "treat", and create an exclusive chic. A bizarre stucco stove with stove benches is now an unconditional powerful trend. The firebox of a stucco adobe furnace also needs protection - a lining.

For stucco furnaces, experts recommend using fireclay as linings. A small exception - if the stove is made of a mortar mixture with stone reinforcement (a rather complex technology on the verge of art), then it is possible to limit the coating lining with refractory glue or pastes. The same compositions are used as for furnace furnaces and boiler pipes - mullite or corundum mixture, special expanding alumina cements, fireclay mortar mixtures or marls, as well as adhesive aluminosilicate compositions.

Lining with pastes and viscous adhesives is simple and does not require high qualifications, but only accuracy and attention. When the refractory coating hardens, it forms a monolithic protective shell and will not allow cracking of the main clay walls of the furnace during strong heating.

Lining, repair and restoration of furnace chambers

All furnaces before starting a new season of operation after summer months are subject to audits. During the summer downtime, impacts are possible, the results of which are not immediately noticeable, but will lead to cracks and chips at the start of the furnace. These phenomena not only reduce the efficiency of heat transfer from the stove, but can also become very dangerous - these are the risks of carbon monoxide in the residential area. Carbon monoxide, or carbon monoxide, is a tasteless, colorless and odorless gas that is extremely dangerous to health and life - this information is trivial and familiar to everyone. Revisions of the furnace after downtime are carried out on external brick (lined, plastered, tiled, etc.) layers, as well as without fail on the internal surfaces of the existing lining. All cracks and damage are carefully sealed.

The lining is repaired with refractory coatings - mastic, glue, mortar. It is enough to restore the outer surfaces with a heat-resistant material. Fire up the stove after repair work should not be earlier than the refractory and heat-resistant material is completely dry and seized, and only by natural drying. Deformations in the areas of embedding occur if the furnace is started to be fired immediately after repair.

Independent lining of the furnace and boiler is possible, but it requires knowledge and some experience, therefore, professionals are often turned to these issues. After all, it is not enough just to carry out the work, you also need to calculate the required thickness of the lining and choose the right material from a considerable range of materials. published

If you have any questions on this topic, ask them to specialists and readers of our project.

Furnaces are built from refractory materials. But due to the fact that during the combustion of fuel a very high temperature is formed, reaching several hundred degrees, this material is not able to withstand it. To protect the outer walls inside the furnace, a lining is equipped.

What is lining

The lining is a brick shell that is built inside the furnace. It is very resistant to even the highest temperatures. it allows the oven to serve for many years because it is protected from overheating.

The lining cannot be considered as independent element, because it closely interacts with the materials from which the furnace is lined, and with the internal environment of the furnace in which the combustion process takes place.

The lining can be not only a laying out of bricks, but also from other materials. Three types of refractory substances are distinguished as such materials, differing in their chemical properties:

Sour.
Basic.
Neutral.

They have a different reaction to substances that arise during the combustion of fuel.

The lining is produced only when all engineering calculations have been carried out and the material for it has been selected. With this calculation, one obtains maximum effect, taking into account the characteristics of the material and the furnace itself. In addition, lining protects various elements of the furnace from chemical and mechanical influences.

Furnace thermal protection methods

Surface inside the furnace can be protected in two ways:

Using a material with low heat conductivity, which is used to treat the inner surface of the firebox.
Using protective screens that reflect thermal radiation. In this case, the heat from the radiation is removed from the furnace along with the smoke.

It is worth paying attention that the first method does not provide for thermal insulation, but thermal protection. With thermal insulation, the heat that the furnace emits remains inside it. And thermal protection protects a certain area of \u200b\u200bthe furnace structure from radiation, removing heat from it. Therefore, when lining, heat-insulating materials are used.

In the recent past, furnaces were made mainly of ordinary bricks, which, under the influence of high temperatures, very quickly became unusable. Then, for quite a long time, bricks with more dense structure. Currently, fireclay bricks are gaining popularity. It is made from clay, which is mixed with fired clay powder and then fired at high temperatures.

Fireclay brick is an ideal option for lining furnace structures. It differs from ordinary bricks in its excellent heat-shielding properties. Lining means wrapping inner surface stoves with just such a brick.

brick kiln lining

Lining brick oven has some features. It must not be laid too close to bricks, which are elements of the outer walls. The fact is that the stove is very hot and cracking occurs under the influence of high temperatures. The hot inner layers push the cold outer layers out of their places. The outer walls, which retain the shape of the furnace, begin to diverge to the sides due to the effect of the expanded inner layers. Bricks are covered with cracks, and some may even collapse. This can allow carbon monoxide to enter the room.

The situation can be aggravated by the fact that the clay used to connect the outer layer of bricks has little adhesion and expands more when heated than the brick itself. As a result of overheating, the seam is destroyed.

That is why, when building a furnace structure, a plastic solution is used with its subsequent testing. To do this, two bricks are connected to each other using this solution and fired at a high temperature. This checks mortar adhesion, expansion and cracking. If everything is fine, the solution can be used for the entire structure.

When lining metal furnaces attention should be paid to the fact that the metal under the influence of high temperatures expands more than a brick. Therefore, a gap must be made for thermal expansion between the lining layer and the furnace metal walls, otherwise the lining is often destroyed when the metal is heated. To seal the gap, use basalt wool in the form of a canvas or bundles. When the stove is located not in a residential building, instead of basalt wool asbestos can be used.

Metal stoves are often lined with brick both outside and inside to improve the heating of the stove and its safety. However this method is considered wrong., because:

The brick is characterized by low thermal conductivity and high heat capacity, as a result of which the heat arising from the combustion of fuel remains inside the furnace and leaves with the smoke.
In this case, the furnace surface is deprived of air access to remove heat, which leads to burnout of the walls. As a result, carbon monoxide which is life-threatening.

Thus, the lining of the furnace is made so that it does not collapse due to exposure to high temperatures. The most important thing is to use quality material so that the stove can last for a long time.

Ph.D. V.P. Frolov, chief technologist, A.S. Sebyakin, shop manager, Vermolit LLC, Podolsk

During the operation of boiler equipment, both domestic and European production, the lining of the boiler cover can be destroyed in the place where the burner is located, as well as the lining of the manhole covers, which is typical for domestic boilers.

Due to the fact that it is not always possible to promptly deliver a new boiler cover (especially made in Europe) to the equipment operation site in Russia, many organizations themselves, using "improvised" means, are trying to repair the lining. As practice shows, this operation brings a short-term effect, which ultimately comes down to frequent shutdowns of the boiler and subsequent inefficient alterations of the lining using all kinds of refractory materials (often of dubious quality), which can be found in great abundance on the Internet.

These experiments can ultimately lead to sad consequences: the metal wall of the boiler lid can be deformed or burn out, moreover, the high temperature of the lid surface is a violation of the requirements safe operation equipment. Taking into account the fact that many European models of boilers operated in Russia are no longer produced, then, accordingly, the most optimal solution is to contact specialists who will help solve the problem associated with the repair of worn insulation.

Experience in performing work related to the replacement of thermal insulation of boiler covers has shown that it is better to perform these works in industrial (production) conditions, because. using household tools at hand (such as a bucket, a drill with a nozzle, etc., instead of specialized and technically sophisticated equipment), it is impossible to achieve uniformity in pouring the prepared solution (charge), which, in turn, is fraught with a heterogeneous distribution of material densities, and its further rapid destruction.

The raw material base and production capacities of Vermolit allow:

Select a refractory high-temperature mixture;

In special installations, prepare a mixture of the desired fractional composition;

Fill the material in one step, which will allow you to evenly distribute the charge density over the entire occupied volume of the lid;

With the help of furnaces, smoothly distill water from the poured heat-insulating material, which will give the material the necessary heat-insulating and strength properties, and also avoid possible errors when drying the lid in place (as part of the boiler), because it is not the correct drying mode that can lead to the destruction of the lining of the cover.

Below are two examples: 1 - non-industrial lining of the cover of a European boiler, 2 - an example of manufacturing the cover of the inspection hole of the KVGM-30/150 boiler, poured in an industrial way.

1. In 2011, we were approached by a company from Tula - food production. In view of the non-standard - sectoral design of the boiler cover, the customer asked to carry out work to replace the insulation at the place of operation of the equipment. It should be noted that the implementation of such work is not often possible due to a number of design and other features.

There are three Italian-made boilers of the same type in the workshop, two of which run on gas and one on fuel oil. Steel fire-tube steam boilers, horizontal, manufactured in 1995, with a capacity of 3.5 MW, with a maximum operating pressure of up to 16 bar, a maximum steam temperature of up to +210 ° C. The boiler lining is partially worn out and has local destruction (Fig. 1) .

Rice. 1. Old boiler lining.

The boiler has three prefabricated parts, which at the same time are the formwork, into which, just, the filling of the refractory heat-insulating mixture (charge) was made (Fig. 2).

The mixture ready for pouring was prepared using a drill with a nozzle, with the possibility of switching the rotation speed when using warm water(more than 25 °C) in a warm workshop. This ensures relatively good foamability of the material, but at the same time, the volume of the mixture obtained must be carefully controlled so as not to overfoam the material. The prepared mixture was thoroughly mixed and distributed according to the shape with a trowel (Fig. 2). After initial curing, the molds were covered plastic wrap and left in this state for more than 30 days.

After repair, the covers continue to be used for more than 3 years.

Rice. 2. Preparation and application of the mixture.

I would like to note that in the vast majority of cases, such a design of the boiler cover, which is given above, is rare. Today, thermal insulation is mounted directly into the cover, the inner diameter of which can reach 3 m or more, and the volume of thermal insulation mixture required for lining can exceed 200 liters. Such a volume of the mixture cannot be prepared, poured and dried with the help of an improvised tool.

Mixers are used to prepare the mixture in our production. different types, allowing to obtain a homogeneous mixture in the quantity and quality required for pouring. Empirically, the time was selected (from 7 to 10 days), during which the lid with the charge poured into it is dried, with intrashop temperature conditions(20-25 °C). After natural in-shop drying, the lid is placed in an oven, where stepwise heating to a temperature of 120-140 ° C takes place - this allows you to remove most of the free water from the poured lining material. Since a certain amount of water still remains in the filled material, the first start-up of the boiler with new thermal insulation should be as soft and not long as possible. After the first start-up, a small surface cracking may appear, which is not deep and critical for the operation of the cover.

2. Repair of covers of inspection hatches of boilers installed on boilers KVGM-30/150, operated by JSC "Podilsk Heat and Power Company".

A fairly common problem in KVGM type boilers is the destruction of the lining of the side inspection hatch cover. Since the destruction of the lining causes deformation of the cast-iron mold in which the lining material was placed, further operation of this mold is not possible. This, in turn, entails contacting the manufacturer (who does not sell individual molds, but only the entire hatch assembly) and a series of experiments with improvised, inefficient refractory materials.

Rice. 3. Iron mold manhole cover. View from above. Rice. 4. The same mold filled with lining.

Together with the company's employees, an effective and optimal solution was developed to replace the cast-iron factory mold: a round billet was made from the pipe with three guides, which was reinforced with steel bars (Fig. 3). Next, the mold was filled with an allowance to completely isolate the edges metal surface, as well as on the side surfaces was glued, using high-temperature adhesive, a special mineral wool(Fig. 4). After pouring, the mold was subjected to stepwise temporary heating to remove moisture from the lining refractory charge. The finished form was mounted on the manhole cover.

Furnace lining is a special surface finish of a product to protect against possible damage during operation resulting from thermal, mechanical, chemical and other effects. The lining of furnace equipment is designed to extend the life of the walls and other parts of the furnace.

Features of the protective finish of furnaces

With regular use of the oven, all materials from which it is made are exposed to very high temperatures. They depend on the combustion temperatures of specific substances that are used as fuel. Of course, the walls of the stove are made of refractory materials, but extreme thermal effects change their structure and properties, which leads to gradual destruction. It is to protect against such influences that the lining is used.

The lining will be the best internal protection for your hearth from burning through and other damage.

In what cases does it apply

If a we are talking about a small hearth, which is used periodically - for heating country house on a day off or cooking on fresh air(barbecues), then additional protection is not needed. In such cases, if damage does occur, it is minimal and will not damage the device in the near future.

Mandatory lining will be required for the following types of furnace products:

Large household and industrial.
Designed for very long-term use - for example, constant heating of a home.
Flame chambers, which are arranged for regular cooking in "Russian" and other similar stoves.
Fuel units, the smoke channels of which are arranged directly along the walls of the furnace.
In cases where high-calorie fuel with exceptionally high combustion temperature is used.

Lining types

Lining work is carried out directly inside the firebox of metal, stone and brick devices. It can be done different ways depending on what effect is expected and what goals should be achieved:

It is possible to use special protective screens thermal insulation action. They will influence the percentage of heating of flue gases, absorbing a significant part of the heat radiation flows and removing most of the heat through the chimneys.
The use of materials that will take most of the thermal impact on themselves - fire-resistant with low thermal conductivity, slowing down the process of heating the materials of the furnace and excluding their direct contact with the fire.

Lining work in a brick furnace is carried out by laying out brickwork

ATTENTION! Heat-insulating screens significantly reduce heat transfer, so they are not used for furnaces intended for space heating.

Ways to do it

The lining of the hearth is usually carried out using the so-called "fireclay" materials - specially treated substances and their mixtures with the inclusion of firing elements that destroy the plastic properties and bring their particles to sintering, as well as other refractory products. It can be:

Hewn stone made from natural rock such as sandstone or quartz or conglomerate, resistant to particularly high temperatures.
Finished fireclay bricks, from which the inner wall is laid out. Their refractory properties are achieved through a special manufacturing technology with the addition of pre-fired clay powder and other substances that improve the properties of the final product. Protection from such bricks is very popular, as it can withstand almost any temperature of the heating furnace and is relatively cheap.
Roll materials, plates and mats:
- basalt fiber;
- vermiculite plates;
- kaolin in the form of paper or cardboard, consisting of mineral white clay.
Solutions and substances that cover the walls of the furnace:
- fireclay, which are refractory concrete with the addition of a thinning component,
- mullite - silicate liquid glass mixtures with various composition variations.

Vermiculite finish can be a great alternative to brick and stone

Comparative table of lining materials

IMPORTANT! In production conditions - at metallurgical and other enterprises where processing of raw materials and finished products in a hot way, stove protection is most often made of stone or fireclay bricks. In "cramped" home conditions, alternative options are more acceptable.

Your own master

Of course, for the installation of a lining layer in hearth you can resort to the services of specialists, but with some work skills and relevant knowledge, this operation can be carried out independently.

Brick lining

Do-it-yourself furnace lining from fireclay bricks is carried out taking into account the following features:

The brick is carefully laid out "edge by edge", without shifting the masonry elements relative to each other, along all the walls of the internal firebox.
The seams between the individual bricks are filled with a mortar based on fireclay and clay.
If the main masonry is also made of brick, then the lining and the main layer are joined by means of one vertical seam, but without dressing.
If the material of the firebox itself is metal (cast iron or steel), then a small gap must be left between its walls and masonry, designed for thermal expansion of the metal, otherwise regular heating and cooling can soon destroy it.

Finishing with fireclay bricks occurs according to the scheme - along all walls with a gap, taking into account the expansion of materials

ATTENTION! In-furnace masonry of refractory red brick is also possible, but it is impossible to mix types of bricks (fireclay plus refractory), since they have different linear expansion and thermal conductivity, which will make the building short-lived.

The old masonry of fireclay bricks is subject to regular inspection and repair of worn areas, which is carried out by grouting with fireclay mortar and aluminous cement.

from roll material

The benefit of using rolled materials (as well as plates and mats) is that they take up very little space and do not "steal" the total volume required for fuel loading and smoke passage. The standard thickness of most of them does not exceed 1 cm (for example, thick kaolin cardboard can be up to 7 mm thick). To spend necessary work, you need to remember that:

The amount of materials required for lining is calculated taking into account their linear expansion during heating.
In some cases, it is possible to lay the canvas in 2 layers, but for domestic needs this is not at all necessary.
Separate plates are fastened with reinforcement elements - metal pins that are inserted into pre-made grooves.
When finishing with refractory mats or plates, the sequence of their fastening should be observed: first, the bottom is covered, then side surface, and then the "ceiling" of the furnace department.

INTERESTING! Many modern factory-made furnaces already have a lining layer on the walls of the furnace sections and do not require additional processing. In particular, steel aggregates are often treated with vermiculite.

Interior decoration can be carried out with basalt cardboard

Coating with solutions

Coating with refractory solutions gives even more thin layer linings. This method is characterized by the following nuances:

For the preparation of solutions, dry compositions of fireclay, mullite or corundum mixtures are usually used, which are then diluted with water to the desired consistency.
After application, the solution must be fired in vivo(when the oven is operating) or with a blowtorch. In the second case, work is carried out until a hard crust appears.

IMPORTANT! The advantage of the solution method is also the creation of absolutely monolithic surfaces, giving the best protection of materials from the effects of fire. However, such a monolith will require repair faster than stone and brick masonry.

Pre-thought-out protection of the stove will guarantee warmth and comfort on long years

How long will a new lining last?

Any coating can wear out over time. Even the strongest lining inside your firebox can gradually lose its initial tightness. To save it, consider the following:

The internal protection of the furnace needs to be periodically checked for integrity. Damage must be repaired in time with solutions prepared from a mixture of fireclay and clay.
Surfaces that were originally made with better quality will last much longer (an even sealed layer of uniform thickness without cracks or other damage).

ATTENTION! The installation of the lining is a complex engineering task that is best left to the knowledgeable people, i.e. to carry out the work under the guidance of a specialist or to leave it completely in the hands of professionals. High-quality performance of this responsible work will allow you to forget about the repair of the hearth for a long time.

Video: furnace furnace lining

What is a lining, and is it always necessary? Let's try to understand this issue.

Lining - this is a way to protect the walls of the furnace or fireplace from overheating at very high temperatures. The walls of the firebox can crack, and the metal can get too hot and break down over time if the temperatures in the firebox exceed 700-800 degrees Celsius. This occurs, as a rule, when burning coal, although pellets can be very hot.

Overheating is not the only effect that negatively affects the walls of a metal or brick firebox. The lining can also have the following functions:

Protection against temperature extremes (thermal insulation properties).
Protection against aggressive reagents (acid-resistant lining).
Lining as a facing material.

In general, the lining can create a tight environment inside the firebox and can extend the life of the furnace firebox and the stove / fireplace as a whole.

Negative moments of lining:

The inner lining of the firebox absorbs or reflects part of the radiant heat fluxes (heat goes into the chimney), and, accordingly, the fireplace heats up less.
Actually, the labor costs and the cost of lining.

In what cases is it necessary to do without a furnace lining?

The lining is necessary if you have a metal firebox (cast iron, steel), and the firebox is powerful enough to generate a temperature of 700-800 degrees Celsius. Large fireplaces with a large amount of firewood on one tab, almost all, even without coal, are able to reach this temperature, and the lining will significantly extend the life of the fireplace.

For a medium-sized potbelly stove made of cast iron, whose task is to smolder firewood, lining is not necessary.

A fireclay firebox also does not need a lining: fireclay is a lining in its essence.

Lining of the inner surface of the chimney , in addition to protection against high temperatures, it helps to smooth the inner surface of the chimney (as a result, combustion products accumulate less in it, and the chimney does not need to be cleaned so often) and its sealing.

What materials are used for lining the stove/fireplace?

Furnace lining materials, depending on the degree of protection, are divided into 3 classes:

Class A materials - based on silica. These are artificial materials (bricks made of pressed rocks) and natural (rocks) materials. Such materials are suitable for lining the fireplace portal (these are well-known granite, sandstone, quartz), but for lining the furnace from the inside, thermal protection is weak, since the materials have low thermal conductivity and are prone to cracking.
Class B materials - based on clay and alumina. This is the usual, familiar to us fireclay refractory bricks and bauxite bricks (fired bricks made of alumina with an admixture of iron oxide and bauxite). Suitable for lining inside the furnace, withstand high temperatures.
Class C materials are mixed materials that cannot be attributed to the first two classes. These are refractory mortars, coal bricks and basic heels based on hammer scale, ore and slag.

Lining errors

Many craftsmen, making a brick lining, join it to the firebox end-to-end, leaving no gap. The fact is that under the influence of high temperatures, brick and metal expand in different ways, and such laying can lead to cracking of the lining.

In addition, conventional brick used for lining has low thermal conductivity. A metal furnace lined with it back to back will be screened with a brick from the environment (the room that needs to be heated), and all the heat will go into the chimney instead of the room.

How are the lining bricks attached inside the firebox?

There are two popular ways of fixing bricks inside the firebox:

With the help of clay.
Bricks are stacked on top of each other with an intersection, and fastened with metal bolts to each other, for which holes are made in the bricks.