US3391506A - Flue construction with separate epoxy liner - Google Patents

Description

July 9, 1968 us ETAL 3,391,506

FLUE CONSTRUCTION WITH SEPARATE EPOXY LINER Filed March 5, 1966 FIG.

FIG. 3

INVENTORS.

RUDOLF GUSNER HARTMUT SCHNEIDER wan- 561%,

ATTORNEYS United States atent O FLUE CONSTRUCTION WITH SEPARATE EPOXY LINER Rudolf Gusner, Erbach, Germany, and Hartmu Schneider, Ulm (Danube), Germany Filed Mar. 3, 1966, Ser. No. 531,492

Claims priority, applicationzGgrmany, Apr. 2, 1965,

4 Claims. cl. 52-309 ABSTRACT OF THE DISCLGSURE Summary of the invention This invention generally relates to flues and is particularly directed to a novel flue construction having a heat and corrosion resistant liner or inset.

The term flue is used herein an a broad sense and is deemed to include any conduit means such as, for example, chimneys, stacks and waste gas-and exhaust pipes for leading away wasteand off gases.

In conventional flue constructions, a variety of different materials are used for lining the interior flue passage through which the gases are conducted. These linings are sometimes in the form of separate liners or tubular insets which are secured or attached to the inner face of the exterior flue wall and which define the actual flue passage through which the gases pass.

During more recent times and in view of the widespread heating by oil as contrasted to coal and wood, high brick chimneys or flues have been replaced by shorter constructions which essentially consist of a pipe surrounded by brick or concrete. A variety of materials have been proposed for these pipes or insets such as fireproof clays or metal, predominantly in the form of thin steel sheets. Such prior art pipe insets (hereinafter referred to as liners), when made of fire brick or clay and the like refractory materials are quite suited for carrying oif waste gases since the material is corrosion and heat resistant. However, such liners have the disadvantage that, due to the brittleness of the refractory material, they are extremely susceptible to shocks and impact. Such flue constructions therefore have the tendency to crack and develop fissures after sometime which, in turn, requires frequent repair. Moreover, these prior art refractory materials are very heavy and from a ractical point of view, it is not possible to work such material into thin-walled liners of appreciable lengths. For this reason, the refractory liners have to be produced in very short lengths. This, in turn, results in the drawback that a flue construction of ordinary height requires a large.

number of liner sections which have to be connected to each other by mortar. This is not only disadvantageous from a technical and assembly view of view, but the con- 3,3915% Patented July 9, 1968 meeting areas of mortar present weak zones which are easily corroded and subject to attack, particularly by chemically aggressive combustion gases. Moreover, the many mortar areas have a tendency of being negatively affected 'by atmospheric influences to which the flue construction is exposed. Liners made of refractory bricks and clay have the additional disadvantage that, due to their brittleness and weight, it is difficult to ship and handle them at the building site. Still a further disadvantage of liners of the conventional construction is that they present a rough interior surface which offers considera'ble frictional resistance to the waste gas flow. This, in turn, results in deposits and pockets of pre-ciptiated solid material along the flue wall which affect the effectiveness of the flue.

In respect to pipe insets or liners made of metal, such as sheet steel, experience has demonstrated that this material is not particularly suitable for conveying hot and chemically aggressive waste gases. Self-supporting steel fines without surrounding brick have the drawback that their exterior surface is constantly exposed to the atmosphere which has a strong corrosive effect, particularly with fluctuating temperature conditions, to wit, when the fiue is alternately heated and cooled. The interior surface of such flues is particularly strongly attacked when the waste gases are below a predetermined temperature in which event acid-containing deposits are formed on the wall surface. Moreover, such metal flues are not suitable for fixed assembly since they have a tendency strongly to expand upon heating and due to their heat conductivity, conduct the heat of the off-gases to their surroundings. This increases the fire danger and in many localities the use of metal flues is therefore prohibited by local ordinances.

Accordingly, it is a primary object of the present invention to overcome the disadvantages of the prior art flue constructions having liners of metal or refractory materials such as clay or brick.

It is also an object of this invention to provide a flue construction having a heat and corrosion resistant inset or liner of a plastic material, which is superior to prior art constructions and may be produced in a simple and inexpensive manner.

Generally, it is an object of this invention to improve on the art of flue constructions as presently practiced.

Briefly, and in accordance with this invention, the flue construction has an exterior confining wall and an interior liner of a heat and corrosion resistant synthetic resin admixed with fillers. It has been ascertained that liners of viscous synthetic resins of the glycidyl ether of phenol formaldehyde type, admixed with fillers such as quartz, asbestos, glass fibers or dolomite powder yield superior results.

It will be appreciated that, prior to this invention, a serious prejudice existed against the use of plastic materials in flue constructions, since it was generally assumed that plastics are not able to withstand the temperatures and chemical conditions to which flues are generally subjected by the combustion or waste gas flow. Surprisingly, it has now been found that this prejudice is unfounded if a liner of the indicated kind is employed. Experiments have demonstrated that the inventive flue construction fitted with an inventive liner of a glycidyl ether of phenol formaldehyde-filler material is superiorly 3 suitable for conducting any kind of waste gas, including strongly aggressive combustion gases at very high temperatures. The inventive construction is thus suitable for use .in chimneys and flues in apartment buildings and in industrial plants.

The inventive liners of synthetic resin and fillers are preferably produced in the form of jointless pipes by ieans of centrifugal casting procedures. The individual pipes may be of considerable length, dependent on the size of the casting equipment. If several lengths of pipe are necessary for a single flue construction, the individual sections may be easily connected together by chemical or mechanical means.

The fillers should be used in comminuted form and homogeneously and uniformly distributed through the synthetic material. The fillers consolidate and reinforce the liner structure and increase the flash point of the resin. Moreover, the presence of the fillers advantageously alters the heat conductivity of the material. It is also within the scope of this invention to add chemicals to the liner mixture which reduce the inflammability of the pipes or which have a tendency to extinguish fire. Further, antistatica may be added in order to minimize the undesired effect of strong electrostatic charges of the plastic material.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

In the drawings:

FIG. 1 is a sectional view through one embodiment of an inventive flue constructions;

FIG. 2 is a detail view corresponding to FIG. 1; and

FIG. 3 is a plan view of FIG. 1.

Referring now to the figures, it will be noted that FIG. 1 illustrates a flue construction generally indicated by reference numeral 100. The flue is located above a fire, diagrammatically indicated by reference numeral 2 and extends in an upright position above its supporting wall or roof member 4. The flue proper consists of an outer confining wall, generally indicated by reference numeral and an interior liner indicated by reference numeral 15. The exterior confining wall 19 consists of individual bricks 11 of conventional refractory material which are joined together as indicated by reference numeral 12. Since the exterior brick wall construction of the flue 100 is of conventional design no further description in this respect would appear to be necessary.

In accordance with the invention, the liner 15 consists of a synthetic resin admixed with filler material. The composition of the liner mixture is indicated in detail in the following example. It will be noted that the interior liner 15 consists of individual sections 16 which are joined together in any suitable manner as, for example, by cementing. For this purpose, the individual pipe sections 16 have upwardly projecting flange portions 17 which fit into complementarily shaped recess portions 18 of the adjoining pipe sections. It should also be appreciated that the liner 15 composed of the pipe section 16 does not actually contact the brick wall It) but that there is a space 19 between the pipe 15 and the brick wall 10 to permit for expansion. In order to mount the pipe 15 within the brick wall 10, spacer means 21 of suitable construction may be provided.

The invention will now be described in connection with the following example, it being understood, however, that this example is given by way of illustration and not by way of limitation, and that many changes in choice of starting compounds and process conditions in general may be effected without departing in any way from the scope and spirit of this invention as recited in the appended claims.

by centrifugally casting a mixture consisting of 50 parts by weight of an epoxy novolac resin of the formula our -c in U ll wherein the average value of n is about 1.5, the resin being admixed with about 1% of antimonytrioxidc to decrease the inflammability of the material;

50 Parts by weight of quartz powder of an average particle diameter of 1 to 5 micron;

Parts by weight of a curing agent, such as for eX- anrple p, p'-methylenedianiline and 2 Parts by weight of a hardening catalyst of conven tional composition.

It will be appreciated that other resins of the glycidyl ether of phenol formaldehyde type may be used for the manufacture of the inventive liners.

The filler content of the pipes may be varied between 35 to 70% by weight depending on the size of the particles of the filler. It has been established that the heat conductivity of the material is increased, the smaller the size of the filler particles. For this reason, extremely small particles are preferred. Particulate filler material of a particle size of 0.5 to microns is particularly suitable.

The mixture of this example was cast in a centrifugal casting machine to form a jointless pipe section having an inner diameter of millimeters and a wall thickness of 6 millimeters.

Tests were performed with the inventive liners. The pipe sections were thus used as liners in a brick chimney of the nature shown in the figures. It was found that the inventive pipe liners are completely heat resistant in respect to waste gases having a temperature of 620 C. and above. The heat resistance remained for a long period of time. Tests were also performed in which combustion gases emanating from intentionally incompletely burnt heating oil were passed through the liner for eight hours. These combustion gases thus contained a large amount of soot. It was ascertained that no significant soot deposition or precipitation occurred which is contrary to the experience had in connection with the conventional brick or clay lined lines.

The inventive pipe liners, besides their surprisingly high heat resistance have thus the additional advantage that no deposits are formed within the flue passage which could lead to chimney fires. Therefore, flue or chimney constructions with the inventive liners have a considerable ad vantage over conventional constructions. The invention construction has a long life and requires insignificant main tenance only. Due to the smooth inner face of the liners, friction of laminar waste gas flow is reduced to a minimum and undesired turbulences of the waste gas flow caused by friction is thus prevented.

An additional advantage of the plastic liners is that they are easily transported and assembled in view of their light weight and have considerable tensile strength. The danger of breakage is non-existent. The connection of the individual sections to each other may be effected by screwing, cementing or welding. In this manner, the assembly of chimney constructions is considerably facilitated and accelerated.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. In a flue construction having an outer confining wall and an interior liner, the improvement comprising that the interior liner consist of a liner pipe separate from said outer confining wall formed of a synthetic resin of the glycidal ether of phenol formaldehyde type admixed with a filler material for increasing the heat conductivity of the liner pipe.

2. In a flue construction as set forth in claim 1 wherein said filler material consist of quartz, glass, asbestos or dolomite powder having a particle size of between about 0.05 to 100 microns.

3. In a flue construction as set forth in claim 1 wherein said liner pipe is formed by centrifugal casting.

4. In a flue construction having an exterior confining wall and an interior liner for the passage therethrough of flue gases, the improvement which comprises that the liner is a separate jointless pipe essentially consisting of 35 to 70% of filler particles of a size of 0.05 to 100 microns and about 30 to 65% of an epoxy novolac resin of the formula References Cited UNITED STATES PATENTS 3,094,498 6/ 1963 Landolt.

3,177,902 4/ 1965 Rubenstein.

3,288,171 11/1966 Hucks 138145 3,297,056 1/ 1967 McLauglin.

OTHER REFERENCES D.E.N. Epoxy Novolac Resins Form No. l-143A by Plastics Dept., Dow Chemical Co., Midland, Mich. pp. 1, 4 and 15. Copy received Nov. 17, 1965, copy group 145.

JOHN E. MURTAGH, Primary Examiner.

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