WO2002063204A1

WO2002063204A1 - Arrangement, methods as well as apparatus for producing technical insulation materials

Info

Publication number: WO2002063204A1
Application number: PCT/DK2002/000079
Authority: WO
Inventors: Niels-Verner Lund; Knud Lund Eriksen
Original assignee: Niels-Verner Lund; Knud Lund Eriksen
Priority date: 2001-02-07
Filing date: 2002-02-05
Publication date: 2002-08-15
Also published as: EP1358427A1

Abstract

Cement based technical insulating system which inter alia can be used for insulating chimneys, degassing and exhaust pipes, valves, boilers, pumps and furnaces, insulation of noise nuisances, acoustical improvements, moisture regulation, traditional heat insulation in e.g. residential buildings, where the items are characterised by being fibre reinforced with e.g. fibres of glass, steel, graphite or the like. The items are prefabricated in a factory, which makes the manufacturing process very controlled and cheap. The density is considerably below what other comparable elements with the same mechanical properties have, namely a density below 350 kg/m3.

Description

Arrangement, Methods as well as Apparatus for Producing Technical Insulation Materials

Background of the invention The present invention concerns a system of pre-fabricated elements made of a very light fibre reinforced cement based on a foamed material, particularly applied to technical insulation.

The invention comprises a cement based, technical insulation arrangement, preferably for thermal insulation of objects such as chimneys, degassing and exhaust pipes, valves, boilers, pumps and furnaces, fire insulation, traditional thermal insulation in e.g. residential buildings, and for noise insulation, acoustical improvements, moisture regulation. Moreover, two different methods for making insulating elements in a cement based, technical insulating arrangement, preferably for thermal insulation of ob- jects such as chimneys, degassing and exhaust pipes, valves, boilers, pumps and furnaces, fire insulation, traditional thermal insulation in e.g. residential buildings, and for noise insulation, acoustical improvements, moisture regulation, together with an apparatus for making insulating elements used in the arrangement.

By technical insulation is to be understood inter alia insulation of chimneys, degassing and exhaust pipes, valves, steam pipes in power plants, pumps, boilers and other industrial plants, where technical insulation is traditionally used. Here, the case is in particular insulation at very high temperatures, i.e. from 150°C to above 1000°C. The system is also very applicable for insulation against noise nuisances, acoustical im- provements, moisture regulation (moisture buffer), traditional thermal insulation in e.g. residential buildings etc.

Within technical insulation, it is prior art to use traditional insulating materials, such as glass and mineral wool, different foamed polymer based foam products etc. All these have a relatively good insulating ability and low density. On the other hand, they have very inferior tensile, compressive and bending properties, why these materials are not suited for many applications. Where tensile, compressive and bending proper- ties are important, e.g. if pre-fabricated elements are desired, or certain constructional conditions are to be met, there are various cellular concrete products. Besides that, and also important with regard to technical insulation, mineral wool (both glass and rock wool) are made by mineral fibres being bonded with phenol. Phenol cannot endure temperatures above about 130°C. Above this temperature, the phenol is decomposed under formation of inter alia hydrochloric acid which, besides being very corrosive, is also very detrimental to health.

Due to vibrations always occurring in process plants, another drawback is that mineral wool disintegrates, particularly when the phenol is decomposed, and the mineral wool with consequently collapse. In chimneys it is of particular significance that the flue temperature can be controlled accurately, for controlling the speed of the flue in the pipe, for preventing soot due to too cold flue gas in the pipe, and for optimising the combustion processes and thereby the energy consumption. When the mineral wool insulation disintegrates and collapses over time, the insulation characteristic of the flue pipe will also be changed. It may seldom be expected to happen linearly over time and uniformly over the entire chimney, consequently making difficult the control of the chimney.

A further drawback by traditional mineral wool insulation is that concurrently with the material being broken down as a function of temperature and vibrations, se the discussion above, mineral fibres are released to the surroundings, influencing the air quality and thereby the working climate in the surrounding environment. The materials are also indicated on the WHO list over potential carcinogenic substances.

A cement-based material is known from DE A 4215468 which is made up of different layers which together provide many properties, e.g. low density, great fire resistance, stability of shape, and the fact that the structure can be designed to display certain tensile, compressive and bending properties. By composing the products of different lay- ers with different properties, a complicated making process with associated costs appear. This becomes pronounced particularly when speaking of complicated geometrical shapes, as when speaking of insulating valves, pumps, etc. Besides, a complicated manufacturing process also requires a very efficient quality control in order to ensure that the products achieve the desired properties homogenously in relation to the object, which it is designed to insulate.

In DE-C-39 23 284 there is disclosed another cement based insulating material displaying some of the same properties as those known from DE-A-42 15 468. In the production of special product objects, these are sawn off a raw matrix. At the making of the elements, the base materials are mixed, foamed and then baked for consolidating the pore structure, i.e. giving the material the desired stability of shape. Then the elements are formed, e.g. by sawing or the like. In order to give mechanical properties

(tensile, compressive and bending strength) to the material, the surface of the elements are finally reinforced by a final treatment. Hence it appears that it is a relatively work and energy intensive process (baking) to produce insulation elements according to the prior art method; here, sawing of elements to fit non-linear insulation surfaces, such a spherical surfaces (valves, pumps, furnaces and the like) are again to be considered.

Furthermore, it is known from DE C 42 07 235 to make elements for technical insulation of a fibre reinforced cement based material. Here, the case is particularly plate elements (plaster board like), granulate, plaster, or as extruded elements. The charac- terising feature in this invention is that the density of material varies depending on the final product. The void percentage may vary from 20 to 80%, something which according to estimate gives a density in the range 1800 kg/m³ to about 500 kg/m³ (it is assumed that the density for the cement based material part is about 2400 kg m³). Different end products are described, but conclusively is indicated that with increasing void percentage (decreasing density) the material, and thereby the elements produced thereof, loses their mechanical stability (tensile, compressive and bending strength). By large densities, there may thus be produced plate-like elements, whereas products with lower densities are most suited for granulate making, or in other words, at lower densities, the elements cannot be pre-fabricated.

The prior art insulating materials all have different drawbacks which does not make them optimal in use. The complicated production runs contain possibility of mistakes as well as the elements are provided their different properties by building together different materials, that each adds its properties to the finished element(s). This also means that the composition of elements is to be designed particularly for the intended application. Furthermore, it is not economically attractive to make elements requiring intensive manual treatment under or after the production process. On the other hand prior art indicates that the mechanical properties are reduced by low densities, even if the elements are fibre reinforced.

The purpose of the present invention is therefore to provide a technical insulating arrangement where the elements of the arrangement possess the following properties:

- high stability of shape, i.e. good tensile, compressive and bending properties, great plasticity, i.e. elements can be made geometrically freely in three dimensions;

- high heat insulation ability and thereby indirectly low density; - low density with respect to manual handling of the finished elements on the site of installation, fireproof, i.e. the elements are to resist high temperatures for a long time; friendly to the environment, both with respect to the manufacturing process, dust, fibre and gas nuisances during use as well as to dumping/recycling the material.

The technical insulation arrangement according to main patent claim 1 and the methods for making elements for the arrangement according to the independent claims 9 and 10 fulfil the object of the invention as described above. The apparatus according to the independent claim 17 is particularly developed for making extruded insulating elements according to the present invention.

The pre-fabricated elements may be produced by moulding in mould, extrusion or other known forms of production used within pouring of traditional cement based ma- terials (plaster, concrete). Common to all methods is that the elements very quickly attain their stability of shape, can be moved to stock or delivered for further/final mounting. The dry matter part of the material is provided by Cemsystems of Odense NV, Denmark.

The elements appear by making moulds corresponding to the object to be insulated, calculate the amount of material, place the material in the mould, after which it foams and thereby fills the mould. After very short time, typically less than an hour, the elements may be removed from the moulds, and the mould can be used again. Since the element is made by a process where the amount of material is precisely adapted to the volume of the mould, no or very limited finishing treatment is necessary.

The elements attain their stability of shape and bending strength due to the fibre content in the rapidly setting cement based material. Since the material has to resist very high temperatures, there may advantageously be used mineral fibres such as e.g. glass, graphite, but also steel fibres may be used with advantage. The type of fibre is selected with regard to the application, i.e. a fibre is to be selected which can resist the influence, including temperatures in particular, to which the element can be exposed. The cement based material itself does not set any limitation to which types of fibres can be used.

The combination of surprisingly low density and, in this connection, relatively high mechanical stability, provides that the elements can be produced as relatively large elements while simultaneously being easy to mount due to the low weight. The good heat insulation is achieved due to the content of air pores (foam structure) of the mate- rial. Due to the large pore volume, the elements have sound dampening effect, which together with the low weight opens possibility for many applications. Surprisingly, it has also appeared that plates suspended/put up in rooms tend to regulate the humidity. When the room humidity increases, e.g. in connection the presence of may people, the plate absorbs some of the moisture released. Later, when the room returns to the nor- mal condition, i.e. after the room has been emptied for people, and the humidity begins to fall, the plate are giving off the surplus moisture again. In this way, the plates act as a kind of moisture buffer or moisture regulating medium. Furthermore, extruded plates can be used as traditional insulation. Here it is utilised that the plates can be produced by extrusion into very long elements, which, besides the good insulating ability, is profitable when the insulation is to be fitted in. Since the plates do neither absorb water nor are influenced by chemical compounds other than those also being detrimental to traditional concrete, the good insulating ability is maintained for a very long time, whereas traditional glass or rock wool insulation may have an ability of absorbing liquid and thereby become compressed and loose its insulation ability. By using plate elements as described in the present invention, the good insulation ability is retained without regard to possible moisture influence. Besides, the material is completely harmless to the environment, with respect to use but also with respect to discarding the material. As opposed to mineral wool which cannot be recycled/reused, and which furthermore by discarding is to be deposited on supervised dumpsites, the elements of the fibre reinforced, cement based foam material can, on the same conditions as common concrete materials, be either crushed and reused as aggregate in new concrete or be deposited on common dumpsites. However, the material cannot be burned off as it is classified as non-combustible.

A particularly suitable application of the elements is achieved by technical insulation of pipes. By traditional insulation with mineral wool, a number of problems arise, be- sides the general problems described above. By pipe insulation one winds the mineral wool around the pipe, and often there is bonded an outer layer on the mineral wool, e.g. aluminium film, which becomes the finished surface of the pipe, alternatively the insulated pipe can be wound with gauze or hessian, which is finally painted. The suspension means are fastened directly on the pipe where the pipe is fastened/suspended in/on the surrounding construction. Hereby arises a cold bridge through the insulation where there is a risk that the dew point will lie in the moisture absorbing insulation with consequent deterioration of the insulation. By using elements of the fibre reinforced, cement based foam, suspension means may be fastened externally of the technical insulation, as the compressive strength of the material allows this. Hereby is pre- vented formation of cold bridges, and a far better degree of insulation is achieved.

The material possesses the following properties: Mean compressive strength 2 MPa

- Mean bending tensile strength⁴ 0.4 - 0.8 MPa

- Density 275 - 345 kg/m³

Specific heat transmission 0.06 - 0.08 W/mK - Heat capacity about 275 kJ/°C

- Fibre content⁴ ± 3%

Fire resistance contribution¹: at 60 mm thickness, surface temp. <100°C in 80 min.; at 120 mm thickness, surface temp.< 100°C for more than 137 min.

- Moisture resistance number Z_p = 0.54 GPa s m³/kg - Capillarity number 0.64

- Sound absorption coefficient in frequency range 50-1600 Hz 0.07-0.30

- Sound insulation at 250mm thickness, density 325kg/m³, RF=55% about 51dB Environmental data³:

- energy consumption at density 230 kg/m³ 1150 MJ/m³ - emission to air per 1000 m³:

SO₂ 52.3 kg

NO_x 588.0 kg particles 287.9 kg

- greenhouse gases per 1000 m³ CO₂ equivalent 153.2 kg

¹ tested according to DS 1051.1 at Aalborg University according to "Standard Fire Curve". The test shows that the material can be classified as BS, class 1 covering and non-combustible material according to DS 1057.1 ² tested by BKM according to prEN ISO 15148 : 1998

³ high energy consumption mainly caused by the manufacturing process of Portland Cement mean bending tensile strength depends on the fibre content. The material parameters indicated are therefore only valid in this combination; rising fibre content will provide greater mean bending tensile strength

Description of the drawings More advantages, characteristics, and details appear from the subsequent detailed description and the enclosed drawings. Since elements can be made in infinite geometrical variation, the subsequent description of a few examples of elements are not meant as any kind of limitation regarding the application of the invention.

Fig. 1 a illustrates elements with semi-circular cross-section and moulds for making elements, Fig. lb illustrates how an element can be divided into sections used for insulating bends on pipes, Fig. 2 illustrates an oil drilling platform with exhaust pipes insulated according to the invention, Fig. 3 a illustrates an apparatus for extruding elements, Fig. 3b illustrates a cross-section in the conveyor belt with side moulds fitted, Fig. 4 illustrates a sandwich element, Fig. 5 illustrates a pump with insulation mounted according to the invention, and

Fig. 6 illustrates a pipe with insulation and suspension.

In Fig. la is shown an element 1 made of the cement based foam material. The element is made specially for fire insulation of exhaust pipes 3 on drilling platforms 5 as illustrated in Fig. 2. The element appear by moulding foam concrete material in moulds 2. For this application, the moulds are built up in suitable height, e.g. 1000 mm, so that the finished elements 1 can be mounted under the particular conditions existing on a drilling platform 5, e.g. in the North Sea.

In Fig. lb is shown how elements are moulded, or after moulding are sawn into semi- bowl shaped elements particularly suited for insulating pipe bends. On oil drilling platforms, strict requirements for the fire insulation are made, as it may have catastrophic consequences if fire should arise simultaneously with oil drilling platforms being constructed so compact as possible, something which in return make demands on the materials used. The elements shown in Figs, la and lb are particularly well suited for this purpose as they can be mounted without use of crane equipment. They are moulded in moulds where their geometry has been accurately determined, which means that the mounting is simple and very rapid. The elements are shipped/flown to the platforms. Here, the fitters place two semi bowl shaped elements 1 around the pipe 3 to be insulated. The semi bowl shaped elements are made with an inner diameter a corresponding to the outer diameter of the exhaust pipe, and an outer diameter b de- termined as the relation between the insulation ability of the material and the desired insulating effect. The exhaust gases are typically 6-700°C, and there is a requirement that the surface temperature of the exhaust pipes is to be 55°C at the most. The fibre reinforced cement based foam elements fulfils this insulation requirement at a thickness of about 100 mm. In connection with the mounting, the surfaces 6 are applied a heat resisting adhesive, after which the elements 1 are pressed together. Hereby, the pipe 3 is fire insulated 4. As the elements are very light, supplementing reinforcement of the exhaust pipe 3 may be avoided to a large degree. The elements are frost resistant, resist the action of salty water and salty air in the marine environment. Due to the very complicated pipe systems on oil drilling platforms, power plants, refineries etc., it is often desirable to provide a certain colour to the certain kinds of pipes. The elements 1 can be painted directly. Since the elements are not decomposed as discussed in connection with mineral wool insulation, the technical insulation with elements according to the present invention do not have to be exchanged with regular intervals - 1-2 years for traditional mineral wool insulation, but may in principle be in place for an infinite period of time. This implies great savings for the operator of the oil platform.

In the case of more complicated shapes as e.g. valves or pumps, the moulds are shapes as impressions of the object in question. The element is divided into suitable sections with regard to removal from mould and to mounting of the elements. Particularly by insulating objects requiring maintenance, the insulating elements are mounted so that they may be dismounted again, or at least the part of the insulation covering parts that have to/may be exchanged is mounted detachably.

In situations where frequent maintenance is not expected, pieces corresponding to the access hole desired may be sawn out. The material has such character that sawing may be effected with a common hand saw. After finished inspection or repair, the hole is closed again by gluing on a piece of material corresponding to the hole geometry. By insulating very large objects, like pumps, valves or furnaces, the insulating element can be mounted on wheels and bolted around the object. This facilitates access to the object in connection with maintenance.

Plate elements may typically be used for heat insulation, both horizontally or vertically. These may be made by extrusion, where the extruder determines the dimensions of the elements; this is illustrated in Fig. 3.

Since the apparatus for making insulating elements according to the invention is also comprised by the invention, it shall be described briefly. The apparatus is made with containers 13, e.g. silos for storing the dry materials: cement, additives and fibres, together with a water container. All containers 13 are connected to separate dosing units 15 which are connected to a control unit. From the containers 13 the sub materi- als are led to a mixing facility 14 via the dosing units 15. After the component materials have been mixed to a homogenous mixture, the mixed material 18 is transferred to an extruder 10 having exchangeable extrusion nozzles adapted for the insulating element to be extruded. The material 8 is extruded directly upon a conveyor belt 9, the conveying speed of which is adapted so that the extruded material 8 can foam up and attain stability of shape in time during the conveying time from one end of the belt 9 to the other. Subsequently, the elements are cut or sawn off in suitable lengths by a tool 11 , which is provided close to the end of the conveyor belt 9 which is farthest from the extruder 10. In order to prevent the material 8 from sticking to the conveyor belt 9, a spray nozzle 16 may be arranged before the extruder, and which sprays the conveyor belt surface with mould oil. Where sandwich elements are to be produced, i.e. insulating elements either a metal sheet 12 on one or on both sides of the cement based insulating material, a metal plate feeder unit 17 may be arranged under and over the extruder 10, respectively, which continuously can lay out metal sheet 12 on the belt 9 and upon the foamed material 8.

Due to the homogenous character of the material, the thickness t of the sheets will be directly proportional to the insulating ability (the thicker plate, the better insulation). The extrusion process then very simply runs while controlling very few parameters. In order to attain uniform modular width M, a side mould 7 is arranged after the extruder 10 so that the element 8 may only expand upwards. By knowing how much material expands at the actual temperature and by controlling the speed of the belt 9, the thick- ness t of the elements may be determined and controlled accurately.

At typical modular dimensions with plates 600 mm wide and 200 mm thick and a max. weight of 40 kg/plate due to the mounting, the plates typically become 1100 mm long (density 300 kg/m³). If the mounting is not performed manually, the plates are made with longer dimension as the element have god tensile, compressive and bending properties due to the fibre reinforcement. Vertically or horizontally disposed plates may be used as noise screening, where the mechanical properties are utilised again as the plates are self-supporting up to a height of about 30 m. This is also an important area of application for the elements. In shipbuilding and particularly by rebuilding of ships, there is often made requirements to noise attenuation and fire protection. Both of the requirements can be met with elements according to the present invention. The pre-fabricated elements may be bonded directly on metal plates on the ship as sound insulation and fire protection. E.g. in engine compartments there is thus achieved a double effect: 1) in the engine compartment, noise from machines is attenuated by noise absorption in the bonded plates and noise to other parts of the ship are also attenuated, and 2) in case of fire, the bonded elements prevent high temperatures outside the engine compartment for a very long time (which prolongs time for evacuation).

For new ship buildings, sandwich elements, i.e. pre-fabricated elements where the cement based foam material is co-extruded between two metal plates, see Fig. 4, can be used as fireproof bulkheads or as usual construction elements. During the extrusion process, the foam material 8 is pressed out upon a metal sheet 12 after which an additional metal sheet 12 is laid on. During the foaming and setting process, the material is very strongly bonded to the two metal sheets 12. Hereby, a very strong, fireproof structure, which can be cut into shape, welded etc. comes into being, without loosing the combined properties of the metal sheets and the foamed cement based insulating material. In Fig. 5 is illustrated a pump 20 insulated with elements 22,23, which are made according to the invention. In the example there is used a pump but in principle it could be any kind of object desired to be technically insulated. During the process of manu- facturing of the insulating elements 22,23, the pump 20 is used as a part of the mould.

The number of insulating elements 22,23 are determined from the size and geometry of the object 20 with regard to transport of the elements 22,23 and the mounting conditions on the site where the technical insulation of the object is to take place. By using the object to be technically insulated as mould, insulating elements fitting pre- cisely around the object to be insulated are achieved, something which again ensures optimal insulation ability, with respect to thermal as well as noise insulation. Furthermore, the manufacturing process is substantially cheaper compared with manual adaptation of the modular elements to a specific task. Due to the size of the pump 20, the insulating elements 22,23 can be put on wheels 21 which facilitate separation of the insulation 22,23 in case the pump 20 is to be inspected/repaired. For holding together the individual insulating elements 22,23 there are used suitable holding means (not shown), e.g. bolts, clamps or the like. As top insulating element 25 there may either be made a special element like the insulating elements 22,23, or an element made by extrusion may be adapted. In the illustrated example, there is used a pump, but the method of manufacture may be used straight away on all items with a complicated geometrical shape.

In Fig. 6 is illustrated how a pipe 3, e.g. an exhaust pipe insulated according to the invention, may be mounted. The pipe 3 is insulated with semi bowl shaped insulating items 1 that are either bonded together or assembled with detachable fastening means

(not shown). Pipes with insulation are then suspended at e.g. the underside of a concrete construction by means of a band 32 surrounding pipes with insulation, and a mounting item 31 connecting the band and thereby the insulated pipe with the concrete construction. With this suspension principle it is prevented that a cold/heat bridge is formed between the pipe and the surrounding environment.

Claims

1. A cement based, technical insulating arrangement, preferably for thermal insulation of objects such as chimneys, degassing and exhaust pipes, valves, boilers, pumps and i furnaces, fire insulation, traditional thermal insulation in e.g. residential buildings, and for noise insulation, acoustical improvements, moisture regulation, characterised in that it includes pre-fabricated homogenous elements (1) of a foamed cement based material containing fibre reinforcement, and that the elements (1) have a density less than 350 kg/m³.

2. An arrangement according to claim 1, characterised in that the fibre reinforcement includes fibres made of e.g. glass, graphite, polymers, steel, ceramics, cellulose, and mineral fibres.

3. An arrangement according to any preceding claim, characterised in that the element

(1) has the shape of a shell element, i.e. the element is defined by an inner diameter (a), an outer diameter (b) and a length (1).

4. An arrangement according to claim 3, characterised in that the elements (1) are adapted so that two or more elements (1) may be assembled for enclosing a cylindrical object (3) with an outer diameter no greater than the inner diameter (a) of the element

5. An arrangement according to claim 3 and/or 4, characterised in that the element is cut off obliquely at the ends in such a way that several elements (1) by mutual turning during mounting will form a bend in relation to a centre axis (c,) for the cylindrical object (3).

6. An arrangement according to any of claims 3 - 5, characterised in that the insulat- ing element (1) may be fastened to a structure (30) nearby by means of an externally fitted fastening (31,32).

7. An arrangement according to any preceding claim, characterised in that the element (1) for insulating an object is built up of several detachable elements (1), so that the individual insulating elements (1) may be removed after releasing from fastening devices.

8. An arrangement according to claim 7, characterised in that each insulating element (1) is provided with wheels (21) for facilitating mounting and dismounting of the insulating element (1) in use.

9. An arrangement according to claim 1 - 5, characterised in that an adhesive particularly suited for resisting temperatures of at least 500°C is used.

10. A method for making elements forming part of a cement based technical insulating arrangement, preferably for thermal insulation of objects such as chimneys, degassing and exhaust pipes, valves, boilers, pumps and furnaces, fire insulation, traditional thermal insulation in e.g. residential buildings, and for noise insulation, acoustical improvements, and moisture regulation, including the following steps: a material (8) is mixed of a cement material, additives, fibre, water and foaming initiator; - the mixed material is extruded upon a conveyor (9); the material (8) expands due to the foam initiator and is thereby imparted its foam structure; the material (8) is cut off in desired lengths whereby the desired insulating elements (1) are formed; - the finished insulating elements (1) are removed from the conveyor (9).

11. A method according to claim 10, characterised in that the finished insulating elements have a density less than 350 kg/m³.

12. A method according to claim 10 or 11, characterised in that the material (8) only expands in one dimension immediately after the extruding.

13. A method according to claim 12, characterised in that the material (8) is limited to the sides of forming elements (7) arranged at both sides of the conveyor (9), whereby the material (8) only can expand in height.

14. A method according to any of claims 10 - 13, characterised in that the material (8) is extruded upon a metal plate (12) placed on the conveyor (9); that the material (8) is completely foamed; that a second metal plate (12) is placed upon the foamed material (8) imme- diately after finishing the foaming; and that the material sets.

15. A method for making insulating elements forming part of a cement based technical insulating arrangement, preferably for thermal insulation of objects such as chim- neys, degassing and exhaust pipes, valves, boilers, pumps and furnaces, fire insulation, traditional thermal insulation in e.g. residential buildings, and for noise insulation, acoustical improvements, and moisture regulation, including the following steps: a material (8) is mixed of a cement material, additives, fibre, water and foaming initiator; - the mixed material (8) is poured into a mould (2); the elements (1,22,23,25) are imparted their shape by foaming of the material (8) in the mould (2); the mould is removed from the elements (1), when their shape is stable.

16. A method for making insulating elements according to claim 15, characterised in that the object (20), or a suited section thereof, is used as a section of the mould (2) for making insulating elements (1).

17. A method for making insulating elements according to claim 16, characterised in that the method is executed in situ, whereby the mould is removed.

18. A method for making insulating elements according to claim 16, characterised in that the elements are pre-fabricated, after which the elements are removed from the object.

19. An apparatus for extruding material by making insulating elements, preferably for thermal insulation of objects such as chimneys, degassing and exhaust pipes, valves, boilers, pumps and furnaces, fire insulation, traditional thermal insulation in e.g. residential buildings, and for noise insulation, acoustical improvements, moisture regulation, characterised in that - it includes separate containers (13) for cement, additives, fibres, foaming initiator, and water; a dosing apparatus (15) communicating with a mixing facility (14); the mixing facility (14) is arranged with a device for transferring the mixed material to an extruder (10) having exchangeable extruding nozzles; - a conveyor (9) arranged after the extruder (10), the transport speed of which being adapted so that the extruded material (8) can foam in time and achieve stability of shape during the time of transport from one end of the conveyor (9) to the other.

20. An apparatus according to claim 19, characterised in that a tool (11) is provided close to the end of the conveyor (9) remotest from the extruder (10), and that this tool

(11) is adapted to cut off the foamed material (8), which is stable in shape, for forming separate insulating elements (1).