GB2246772A

GB2246772A - Lining chimneys

Info

Publication number: GB2246772A
Application number: GB9118366A
Authority: GB
Inventors: Allan Barnes
Original assignee: NORTHERN CHIMNEY LININGS SYSTE
Current assignee: NORTHERN CHIMNEY LININGS SYSTE
Priority date: 1990-11-06
Filing date: 1991-08-27
Publication date: 1992-02-12
Anticipated expiration: 2011-08-27
Also published as: GB9024114D0; GB2246772B; GB9118366D0

Abstract

A method of lining a chimney 10 comprises lining the chimney with a specially developed composition. The composition comprises, by weight, 50 - 80% of base cement, 8-28% by weight of high alumina cement and 12 - 24% by weight of expanded perlite. The alumina content of the high alumina cement not only brings about additional heat insulation properties, because of its refractory nature, but it also brings about a preliminary setting of the cement after about one hour. This has important advantages, particularly when the composition is applied to the chimney by pumping the composition between the walls of the chimney and an inflatable former.

Description

LINING CHIMNEYS The invention relates to the lining of chimneys.

The Applicants have very considerable experience of the lining of chimneys, to reline the chimneys. The Applicants presently employ a method in which an inflatable rubber former is positioned centrally in a chimney, and liquid cement is then pumped into the chimney filling the space between the former and the walls of the chimney. After the cement has hardened, the former can be deflated and removed, leaving a smooth cylindrical flue within the chimney.

The Applicants have made small improvements to their concrete mix over the years, but they have recently developed a new composition which gives significantly improved results.

Accordingly, the invention provides a method of lining a chimney comprising lining the chimney with a composition comprising, by weight, 50 - 80% of base cement, 8 - 28% of high alumina cement and 12 - 24% of expanded perlite.

Preferred ranges are 60 - 76% of base cement, 10 - 20% of high alumina cement and 15 - 19% of expanded perlite.

The base cement may comprise ordinary portland cement or sulphur resistant cement.

Preferably the compositions applied by mixing the ingredients with water in a volume ratio of from 2 to 3 parts of composition to 1 part water. A preferred ratio is 2l/2 parts composition to 1 part water.

The composition may be applied to the chimney by pumping the composition between the walls of the chimney and an inflatable former.

Preferably the three components of the composition are thoroughly mixed in bulk under controlled conditions, and quantities of the mixture are then transported to the chimney site for mixture with water.

Preferably the components are pre-mixed to provide a basic supply of up to one ton by weight of composition, or multiples thereof.

The expanded perlite provides good heat resistance because of its insulation properties. However, the high alumina cement brings about two important additional advantages. Firstly, the alumina content of the cement brings about additional heat insulation properties, because of its refractory nature.

More importantly however, we have discovered that the addition of the small quantity of high alumina cement means that a preliminary setting takes place after about one hour which is sufficiently effective to enable the inflatable former to be removed. With present mixtures, it may not be possible to remove the former for up to 12 hours.

The invention includes a chimney lining composition comprising, by weight, 50 - 80% of base cement, 8 - 28% of high alumina cement, and 12 - 24% of expanded perlite.

The invention also includes chimneys when lined using the method or composition of the invention.

By way of example, a specific embodiment of the invention will now be described, with reference to the accompanying drawings, in which : Figure 1 is a diagrammatic elevational view of the chimney being lined according to the invention; and Figure 2 is a plan view of the chimney after it has been lined.

Figure 1 shows a chimney 10 which requires a lining. This may be because the brickwork or mortar has deteriorated, with the result that flue gases are escaping through the walls of the chimney.

The chimney is first cleaned and then an inflated rubber former 11 is positioned centrally in the chimney. A bottom seal is provided at 12.

A particulate chimney sealing composition is then mixed with water to provide a slurry 13 which is fed into the hopper 14 of a pump 15.

The slurry is provided by mixing the composition with rate in a ratio by volume of 21/2 parts of mixture to 1 part of water.

The mixture is provided in a ready mixed manner, from bulk supply which is prepared away from the chimney site, for example under factory controlled conditions.

The mixture comprises 60- - 76% by weight of ordinary portland cement or other sulphur resistant cement, 10 - 20% by weight of high alumina cement and 15 19% by weight of expanded perlite.

The expanded perlite has the following particle size distribution.

PARTICLE SIZE DISTRIBUTION. COARSER THAN % 100 mesh 67 0.15 mm 50 mesh 38 0.3 mm I 30 mesh 8 0.6 mm 20 mesh 1 0.84 0.84 mm 16 mesh 1.2 mm

The slurry is pumped by the pump 15 along a feed pipe 16 and into the space between the chimney 10 and the former 11. The slurry gradually fills up this annular space, and once the chimney has been filled to the top, pumping is ceased, the composition is allowed to harden, and the former 11 is then removed.

If desired, the pumping can be carried out in various stages, for example three stages, each stage being allowed to harden before the next stage continues.

However, it has been found that the addition of the small quantity of high alumina cement brings about an initial set within about 1 hour, as compared to 12 hours with normal materials. It may therefore be possible to carry out the pumping in a single operation. As soon as the composition reaches the bottom of the chimney, it begins to set, and this provides support for the composition which is added above, so reducing outward pressure on the base of the chimney.

The invention obviously makes it possible to line chimneys more quickly than with normal methods.

As already mentioned, the quicker setting material places less stress on the structure of the chimney.

The composition according to the invention requires less water, so here again less weight is placed on the chimney structure during lining, and there is also a reduction in the possibility of pockets or gaps occurring within the flue lining.

Not only does the blend of high alumina cement with ordinary cement bring about a quick initial set, but it also brings about higher heat resistance because of the refractory nature of alumina.

During the setting of cement, a certain amount of the water becomes chemically bonded with the cement composition. Eventually all the water is removed, any remaining free water being evaporated when the flue reaches a temperature of 100 C, and the chemically bonded water eventually being driven off at higher temperatures often for example 650"C.

With a composition according to the invention, more of the water is initially held within the composition by chemical bonding. Thus the amount of free water is reduced, and this reduces the possibility of damp patches occurring on the walls of the chimney.

The pre-mixing of the composition in bulk, under controlled conditions, has two major advantages.

Firstly, very thorough mixing is ensured, which reduces the risk that there will be local anomalies when water is added. Local anomalies can for example bring about quick local setting in the slurry, which may make it impossible to pump the slurry.

Secondly, the very thorough mixing brings about an extremely smooth slurry which has enhanced flowability. This means that small holes in the chimney are sealed almost immediately by material which sets quickly, and this reduces the chance of the composition seeping out of the chimney.

The composition can be pre-mixed to suit the conditions under which it will be used. Although the chimney eventually reaches a high temperature, once the flue is put into use, basic setting occurs under ambient temperature conditions. During cold weather, the setting time for a given composition will increase. Therefore, the high alumina cement content is increased in inverse proportion to the ambient temperature.

It is not essential to use a single former and provide a single flue. Where a chimney is to be used to provide more than one flue, for example coming from different appliances, two or more formers can be used to provide two or more flues within a single chimney. Figure 2 shows an arrangement in which three flues 17, 18 and 19 have been provided within the chimney 10. This is simply achieved by appropriately spacing three different formers. It will be seen that the flues can have different diameters.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s).

The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A method of lining a chimney comprising lining the chimney with a composition comprising, by weight, 50 - 80% of base cement, 8 - 28% of high alumina cement and 12 - 24% of expanded perlite.

2. A method as claimed in Claim 1, in which the composition comprises, by weight, 60 - 76% of base cement, 10 - 20% of high alumina cement and 15 19% of expanded perlite.

3. A method as claimed in Claim 1 or Claim 2, in which the base cement comprises portland cement.

4. A method as claimed in Claim 1 or Claim 2, in which the cement comprises sulphur resistant cement.

5. A method as claimed in any one of the preceding claims, in which the composition is applied by mixing the ingredients with water in a volume ratio of from 2 to 3 parts of composition to 1 part water.

6. A method as claimed in Claim 5, in which the volume ratio is 2l/2 parts composition to 1 part water.

7. A method claimed in any one of the preceding claims, in which the composition is applied to the chimney by pumping the composition between the walls of the chimney and an inflatable former.

8. A method as claimed in any one of the preceding claims, in which the components of the composition are thoroughly mixed in bulk under controlled conditions, and quantities of the mixture are then transported to the chimney site for mixture with water.

9. A method as claimed in Claim 8, in which the components are premixed to provide a basic supply of up to one ton by weight of composition, or multiples thereof.

10. A method of lining chimneys substantially as hereinbefore described, with reference to the accompanying drawings.

11. A chimney lining composition comprising, by weight, 50 - 80% of base cement, 8 - 28% of high alumina cement, and 12 - 24% of expanded perlite.

12. A chimney lining composition as claimed in Claim 11, comprising, by weight, 60 - 76% of base cement, 10 - 20% of high alumina cement and 15 - 19% of expanded perlite.

13. A chimney lining composition as claim in Claim 11 or Claim 12, in which the base cement comprises portland cement.

14. A chimney lining composition as claimed in Claim 11 or Claim 12, in which the base cement comprises sulphur resistant cement.

15. A chimney lining composition substantially as hereinbefore described.

16. A chimney when lined by the method of any one of Claims 1 to 10, and/or using the composition claimed in any one of Claims 11 to 15.