US3839993A

US3839993A - Seals for boilers

Info

Publication number: US3839993A
Application number: US00339809A
Authority: US
Inventors: E Peterson
Original assignee: American Standard Inc
Current assignee: Trane US Inc
Priority date: 1973-03-09
Filing date: 1973-03-09
Publication date: 1974-10-08
Anticipated expiration: 1991-10-08
Also published as: CA978039A

Abstract

This application covers a boiler having adjacent outer wall sections which have grooves or channels at the interfaces or lands of the adjacent sections, into which are inserted a fibrous rope material, such as asbestos rope, impregnated with and surrounded by a pliable elastic sealant, such as silicone rubber, filling the grooves or channels, thereby rendering the wall sections leak-proof for the flue gases at all ambient temperatures encountered in the operation of the boiler and at all flue pressures, including super-atmospheric flue pressures encountered in forced draft boilers.

Description

States Patent 11 1 [111 3,839,993 Peterson Oct. 8, 1974 SEALS FOR BOILERS [75] Inventor: Edgar M. Peterson, Fanwood, NJ. Pmfwry Examlf'er' carron D or I Assistant Exammer-Larry I. Schwartz [73] Assigneez American Standard Inc., New York, A t A or Firm-R b rt G, C ok Jefferson Ehrlich; James J. Salerno, Jr. [22] Filed: Mar. 9, 1973 211 Appl. No.: 339,809 [57] ABSTRACT 4 This application covers a boiler having ad acent outer wall sections which have grooves or channels at the if g 122/ 122031 277/229 interfaces or lands of the adjacent sections, into which [581 Fltt. F1221) 23/04. are inserted a fibrous rope material, Such as asbestos 1 IBM or earch 122/225, 231, 126/190, rope impregnated i and Surrounded by a pliable 277/229 elastic sealant, such as silicone rubber, filling the grooves or channels, thereby rendering the wall sec- [56] References C'ted tions leak-proof for the flue gases at all ambient tem- UNITED STATES PATENTS peratures encountered in the operation of the boiler 1,516,130 11/1924 Wirfs 126/190 X and at all flue pressures, including super-atmospheric 3,261,328 7/1966 Mueller 122/225 R flue pressures encountered in forced draft boilers. 3,533,379 lO/l970 Martin et al.... l22/23l 3,729,205 4/1973 Kwok 277/229 6 Claims, 7 Drawing Flgures OUTSIDE OF BOILER INSIDE OF BOILER PATENTEDUCI 81974 3.839.993 SUE" 1 of 3 FI.G.|-

ISI AR GV |s2 AR GR PAIENIEU BT 81914 I SHEET 2 0F 3 F I G 2 OUTSIDE OF BOILER INSIDE O BOILER F l G 4 SEALS FOR BOILERS This invention relates to boilers and, more particularly, to boilers which are to be operated under forced draft and sealed against super-atmospheric pressures and temperatures encountered in operation.

Forced draft boilers of the sectional type are often preferred against conventional boilers operating at normal pressures for furnishing heat required by large commercial installations and even by small homes. It is an acknowledged fact that a forced draft boiler advantageously requires very little, if any, draft-creating chimney or venting passages, i.e., passages extending above the rooftop of the building in which the boiler may be installed. Forced draft sectional boilers may be useful with vents or chimneys no more than about 3 feet high and oft times without any protruding upwardly extending passages reaching out of a building.

However, the installation and use of forced draft boilers have heretofore been resisted by architects because there may be real hazard in the leakage of obnoxious or lethal gases which may be dissipated through crevices however small, especially through openings at the adjacent interfaces or lands at which the sections of the boiler are mated for confining the generated gases. Such reactions have, at times, affected potential sales of such boilers and cost-savings to users of them.

Asbestos rope has heretofore found acceptance for insertion into the adjacent grooves or channels at the mating ends of the sections, but such structures have not been approved, and should not be approved, for use in boilers operating under forced draft. Such boilers having asbestos rope construction are shown and described, for example, in the J. C. Mueller US. Pat. No. 2,935,052, filed May 3, 1960; US. Pat. No. 3,215,125, issued Nov. 2, 1965; and US. Pat. No. 3,261,328, issued July 19, 1966. It is acknowledged that asbestos rope is especially undesirable for sealing forced draft boiler construction unless suitably tall chimneys or other exvacuators of the gaseous fumes are employed. This is principally because asbestos rope is porous and embodies numerous void spaces and therefore is not, and cannot be, impervious to the flue gases developed in the firebox, especially at superatmospheric pressures. Furthermore, such asbestos rope is usually driven into the grooves or channels of the mating adjacent wall sections so as to extend beyond the edges of the grooves or channels and hence, when the sections are drawn together, the segments of the asbestos rope extending beyond the grooves or channels may well provide avenues for the escape of the pressurized gases. Even when the asbestos rope is confined within the spaces provided by the grooves or channels, similar escape routes will be provided through the spaces however small between the outer surface of the rope and the inner wall of the grooves or channels, again thereby providing free exit for the developed pressurized gases. Therefore, notwithstanding the desirably qualities of asbestos rope structures, they are unsuitable for sealing boilers developing pressurized gaseous fumes.

According to the present invention, a rope material, such as conventional asbestos rope, has been specially developed for pressurized gases of boilers. The rope material developed should be fully coated with a pliable and elastic material, which is leak-proof at all ambient temperatures and fluid pressures encountered in forced draft boiler systems. The material should remain pliable and elastic material even after it is applied and even when it is subjected to gaseous pressure. The composite material should effectively seal the void spaces within the rope material and also the spaces between the rope material and the inner walls of the grooves or channels in the mating faces of adjacent section walls of a boiler so to render the joined section walls leakproof and safe at all times even for use in homes. The elastic sealant material preferably should have the consistency of a toothpaste and yet be easily and rapidly applicable to the rope material. Such elastic sealant may be conveniently applied, for example, by a conventional hand-caulking gun. The elastic sealant may be applied to the rope and, furthermore, the ropetreating process may be applied even at the site where the boiler sections are to be assembled and the finished boiler mounted for use.

One of the principal objects of this invention, therefore, is to provide a grooved joint at the mating lands or interfaces of adjacent sections of a multi-section boiler, the joint comprising a combination of materials composed of a form of stranded rope together with a superimposed elastic sealant supplied to fill the groove to prevent leakage of gas through or around the joint.

Another of the objects of this invention is to provide a permanent sealant arrangement within the grooves or channels at the interfaces or lands of adjacent sections of a boiler, the grooves or channels being filled with a fibrous material impregnated with a pliable elastomer to render the boiler impervious to gases and leak-proof even at super-atmospheric pressures and invulnerable to radiant heat generated within the boiler.

These and other objects of this invention, as well as its features and advantages, will be better and more clearly understood from the following more detailed description and explanation hereinafter following when read in connection with the accompanying drawing in which:

FIG. 1 schematically illustrates a cross-sectional view taken along a centerline perpendicular to the front of a boiler incorporating the invention;

FIG. 2 illustrates a simplified sketch, in amplified form, of one form of structure insertable into the grooving or channeling for sealing adjacent mating sections of a boiler according to this invention;

FIGS. 3, 4, 5 and 6 schematically illustrate other modifications of the channeling or grooving of adjacent boiler sections for practicing this invention; and

FIG. 7 schematically illustrates a front elevational view of the inner side of a single section of a boiler arranged according to this invention, the figure showing generally the application of the invention to the internal wall surface.

The same or similar reference characters will be employed throughout the drawing to designate and illustrate the same or similar parts wherever they may occur throughout the drawing.

Referring to the drawing, FIG. 1 illustrates only the important apparatus or components of a boiler required to explain the invention. FIG. 1 shows, in schematic form, a four-section cast iron boiler suitable for operation not only at normal pressures, but also at super-atmospheric pressures. The construction of FIG. 1 includes the front section FS of the boiler, the rear section RS and two intermediate sections 181 and [S2, all of which are adjacent to each other as shown. The illustrative embodiment includes a burner unit (not shown) which would be adjacent to, or partly within, the lower left-hand corner of the boiler, as illustrated in FIG. 1, and which would be mounted and operated in the customary way to supply a flame for igniting, on a continuing basis, gas which is supplied to the burner, together with means to introduce pressurized air to aid and accompany the flame. The gas will be ignited in the firebox FB and, under the influence of the pressurized air, radiant heat will be generated and channeled between the several sections somewhat along the direction lines shown in FIG. 1 to the smoke chamber SC leading to the exhaust vent EX. The burner unit may be of any type such as, for example, described in a patent of A. E. Martin, US Pat. No. 3,406,002, issued Oct. 15, 1968, entitled Cup Cone Flame Retention Burner," assigned to the assignee of the present application. The burner unit is preferably designed to operate on fluid fuel and to generate heated gas at a pressure within the firebox FB which is above atmospheric pressure. The pressure of the flue gases within the firebox FB may be, for example, 0.2 or 0.5 inches of water, and it may be as high as, or substantially much higher than 3 inches of water. However, it is a sufficient pressure to readily overcome the normal resistances encountered by the flue gases in traveling through the several non-linear passages shown by the direction lines of FIG. 1. Notwithstanding the operation of the boiler at superatmospheric pressures, the customary chimney or venting passages, which are external to the boiler and usually extend to or above the rooftop of the building in which the boiler is installed, may be unnecessary and may be dispensed with and instead a much shorter passage, such as a 3 foot high vent or chimney EX, for example, may be sufflcient for most, if not all, contemplated installations, whether for a commercial building or for a one-family or multi-family home.

It will be observed from FIG. 1 that a groove or channel, or a plurality of grooves or channels, are provided at the mating or land segments of adjacent cast iron channels. FIG. 2 illustrates, in amplified form, a view of the two adjacent cast iron channels I81 and IS2 which are leaklessly coupled to each other, according to the invention.

The mating surfaces of FIG. 2 illustrate a substantially V-shaped groove GV formed in one of the channels IS2 in which is inserted an asbestos rope AR encased in a pliable elastic sealant SE so as to completely fill the lengthy longitudinal V-shaped groove GV. The flue gases, which may be at super-atmospheric pressure, impinge against the inner walls of sections 181 and [S2 but are incapable of leaking through the protective barrier provided by the combination of the rope AR and seal SE within groove GV. By viture of the full closure at the inner wall of the two adjacentsections I81 and [S2, the radiant heat generated within the boiler is incapable of attacking nd deteriorating or otherwise adversely affecting the sealant SE as well as the enveloped rope AR even at temperatures exceeding 500F. The composite joint is, therefore, fully protected against the high temperatures and the destructive effect of the radiation generated by the flue gases.

FIG. 3 shows two adjacent sections, marked [S3, of a multi-section boiler in which two triangular grooves, both designated GV3, are provided, one in each of the respective sections 153, as shown. A similar fibrous rope of, for example, asbestos and designated AR3 is inserted into the ajacent longitudinal V-shaped grooves, and the sealant SE3 is inserted into both grooves GV3 to fill the spaces within the rope AR3 and the spaces exterior to the surfaces of the rope AR3. The sealant SE3 so inserted into the interstices of the rope AR3 renders the rope substantially leak-proof against the generated flue gases. The sealant SE3 also applied to the spaces about the rope AR3 within the two grooves GV3 of both sections 153, as shown, renders these spaces leakproof against the flue gases. The inner lands of the mating sections are virtually closed against access by the gases for the further protection of the lengthy longitudinal joint. It will be apparent from the shape of the outer lands of the FIG. 3 arrangement that the sealant SE3 may be applied from a handcaulking gun. This makes possible and practical the assembly of the wall sections of the boiler on the location where the sections are to be installed and used.

FIG. 4 shows two wall sections, both designated I54 and each having a semi-cylindrical longitudinal groove GV4 within which is inserted a similar fire-proof rope AR4 surrounded by a sealant SE4 to render the combination joint impregnable and impervious against the flue gases even at super-atmospheric pressures.

FIG. 5 is another variation of the companion wall sections 185, each of which is channeled by semicylindrical grooves GV5 of elliptical cross-section. Asbestos rope ARS, or a like medium, is inserted into the elliptical cross-section and the exterior of the rope ARS encased in pliable elastic sealant SE5. The upper outer portions of the mating walls are provided with suffrciently wide spaces, as shown, to enable the sealant to be applied from the exterior of the wall structures and, if desired, at the place where the boiler installation is to be made. The rope ARS may have a diameter which is less than the minor axis of the cylindrical cavity of elliptical cross-section so that, when the conventional rods of the boiler are drawn up to tighten the wall sections, the rope ARS may be subjected to mechanical pressure to hold the rope ARS firmly in place. The sealant SE5 may be applied to the rope AR5 and to the grooves GVS either before the wall assembly or after the wall assembly, as may be desired. An excess of the sealant SE5 will not adversely affect the protective ability of the joint.

FIG. 6 shows the mating walls of two adjacen cast iron sections [86 arranged so that but one of the mating walls is grooved to have a semi-cylindrical contour of semi-circular crosssection and of sufficient dimensions so as to conveniently receive the rope AR6. The sealant SE6 not only surrounds the rope AR6 but also fills the internal spaces of the rope AR6 so that the groove GV6 is completely filled and may be filled to over-flowing, as already suggested supra. The sealant SE6 also may be applied from an exterior position after assembly of the sections because of the spacing on the upper-outer portions of the mating walls of the adjacent sections IS6.

FIG. 7 illustrates schematically one form of the inner wall of a section IS7 of a super-atmospheric boiler according to this invention. It will be observed that the groove GV7 extends, or may extend, around the entire periphery of the internal wall of the section 187. Within the groove GV7 will be inserted the rope AR7 and the sealant SE7 in order to completely fill the groove GV7, as already observed supra.

The fibrous rope above referred to is preferably formed of asbestos and selected for its well-known fireproof qualities which resist destruction even at much higher temperatures than are normally developed in super-atmospheric boilers. The rope may have, for example, a diameter of about /2 inch. Such a rope may, and ordinarily is, formed of a group of strands, perhaps four in number, which are braided and twisted in serpentine fashion along a longitudinal axis. As is well known, each of the strands is capable of being unravelled and is stretchable. The components of each strand, and of the strands that are joined together, easily fall apart. Such a flimsy structure is, per se, highly unsuitable as a sealant for gases under any applied gaseous pressure however small. The interstices of the fibers and of the overall rope in general are open avenues for the free release of any and all gases that reach the rope.

According to the present invention, the asbestos rope above referred to is made useful and practical as a sealant under pressurized flue gases merely by coating the rope and filling, partially of completely, the interstices of its fibers and filling the spaces ajdacent the outer periphery of the rope. A sealant which is pliable and elastic and has a silicone rubber base not alone serves to render the rope impervious to pressurized gases but, equally importantly, binds the fibers and their strands together so that they are unified and encased and remain unified and encased thereafter.

The draw rods for drawing the sections of the boiler together have not been shown to avoid needless complication in the drawing. However, they are customarily employed to hold the sections in place and, in the present case, they serve to maintain the treated internal wall formed by the sections continuously leak-proof.

A flexible rope impregnated with a silicone rubber of the type involved in this invention will resist destruction by high gas temperatures and, even should some part of the external sealant for the rope becomes weakened, the combination of the rope and the remainder of the active silicone material within the groove will be shielded and will maintain protection for a long time.

One form of sealant, entirely satisfactory for use in the present invention, is known as Silastic and it is made by Dow-Coming Corporation and sold as Silastic 732RTV Silicone Rubber. A similar product is made by other manufacturers. Such material is easily applied by hand or through a caulking gun. Smaller boilers may be built and sealed at the factory, but very large boilers can easily be installed and sealed at the site of use without difficulty.

While this invention has been shown and described in certain particular embodiments for illustration, it will be understood that the features and objectives of this invention are readily applicable in many and varied forms.

What is claimed is:

l. A boiler having two exteriorly arranged wall sections with closely adjoining mating sides facing the flue gas produced within the boiler and having a groove at the interface filled with a gas impervious sealing means to prevent the leakage of flue gas therethrough,

said sealing means comprising:

a fibrous flexible asbestos rope, and

a coating of a pliable silicone sealant of the type that is resistant to deterioration at temperatures exceeding 500F. and which partially penetrates the outer surfaces of the rope to at least fill and seal the voids and interstices at the periphery of the rope to provide a sealing means which is impervious to the gases generated within the boiler and resistant to destruction by said high flue gas temperatures even where partial destruction of the sealant occurs at the flue gas side of the boiler section.

2. A forced draft boiler having a plurality of mating wall sections arranged and constructed to form at least one of the exterior walls of the boiler,

each pair of wall sections having a groove at the interface thereof,

sealing means positioned in said groove between said sections to provide a leakproof seal against flue gases under super-atmospheric pressures,

said sealing means comprising:

a fibrous flexible asbestos rope formed to fill a large part of said groove, and

a coating of pliable silicone sealant of the type that is resistant to deterioration at temperatures exceeding 500F. and which partially penetrates the outer surfaces of the rope to at least fill and seal the voids and interstices at the periphery of the rope to provide a sealant means which is impervious to the gases generated within the boiler and resistant to destruction by said high flue gas temperatures even where partial destruction of the sealant occurs at the flue gas side of the boiler section.

3. A boiler for operation at atmospheric and superatmospheric flue gas pressures comprising:

at least two adjacent wall sections,

said adjacent wall sections having a groove formed at their interface and sealing means positioned in said groove to provide a leakproof seal against said flue gases,

said sealing means comprising:

a coating of a pliable silicone sealant of the type that is resistant to deterioration at temperatures exceeding 500F. and which partially penetrates the outer surfaces of the rope to at least fill and seal the voids and interstices at the periphery of the rope to provide a sealing means which is impervious to the gases generated within the boiler and resistant to destruction by said high flue gas temperatures even where partial destruction of the sealant occurs at the flue gas inside of the boiler section.

4. A forced draft boiler according to claim 3 in which the fibrous rope is formed into strands which are twisted in serpentine fashion about each to form a substantially cylindrical contour.

5. The combination of two adjoining longitudinal plates having similarly mated end walls,

and having retaining means adapted to receive sealing means between two adjoining longitudinal plates to provide a leakproof seal against flue gases,

said sealing means positioned in said retaining means and capable of maintinaing a seal at superatmospheric pressures extending above 3 inches of of the rope to provide a sealing means which is impervious to the gases generated within the boiler and resistant to destruction by said high flue gas temperatures even where partial destruction of the sealant occurs at the flue gas side of the boiler section. 6. The combination of claim 5 in which the plates are made of ferrous material and the fibrous rope is made of asbestos material.

Claims

1. A boiler having two exteriorly arranged wall sections with closely adjoining mating sides facing the flue gas produced within the boiler and having a groove at the interface filled with a gas impervious sealing means to prevent the leakage of flue gas therethrough, said sealing means comprising: a fibrous flexible asbestos rope, and a coating of a pliable silicone sealant of the type that is resistant to deterioration at temperatures exceeding 500*F. and which partially penetrates the outer surfaces of the rope to at least fill and seal the voids and interstices at the periphery of the rope to provide a sealing means which is impervious to the gases generated within the boiler and resistant to destruction by said high flue gas temperatures even where partial destruction of the sealant occurs at the flue gas side of the boiler section.

2. A forced draft boiler having a plurality of mating wall sections arranged and constructed to form at least one of the exterior walls of the boiler, each pair of wall sections having a groove at the interface thereof, sealing means positioned in said groove between said sections to provide a leakproof seal against flue gases under super-atmospheric pressures, said sealing means comprising: a fibrous flexible asbestos rope formed to fill a large part of said groove, and a coating of pliable silicone sealant of the type that is resistant to deterioration at temperatures exceeding 500*F. and which partially penetrates the outer surfaces of the rope to at least fill and seal the voids and interstices at the periphery of the rope to provide a sealant means whiCh is impervious to the gases generated within the boiler and resistant to destruction by said high flue gas temperatures even where partial destruction of the sealant occurs at the flue gas side of the boiler section.

3. A boiler for operation at atmospheric and super-atmospheric flue gas pressures comprising: at least two adjacent wall sections, said adjacent wall sections having a groove formed at their interface and sealing means positioned in said groove to provide a leakproof seal against said flue gases, said sealing means comprising: a fibrous flexible asbestos rope formed to fill a large part of said groove, and a coating of a pliable silicone sealant of the type that is resistant to deterioration at temperatures exceeding 500*F. and which partially penetrates the outer surfaces of the rope to at least fill and seal the voids and interstices at the periphery of the rope to provide a sealing means which is impervious to the gases generated within the boiler and resistant to destruction by said high flue gas temperatures even where partial destruction of the sealant occurs at the flue gas inside of the boiler section.

5. The combination of two adjoining longitudinal plates having similarly mated end walls, and having retaining means adapted to receive sealing means between two adjoining longitudinal plates to provide a leakproof seal against flue gases, said sealing means positioned in said retaining means and capable of maintinaing a seal at super-atmospheric pressures extending above 3 inches of water, and when exposed to flue gases radiating heat at temperatures up to and above 500*F. said sealing means comprising: a fibrous flexible asbestos rope formed to fill a large part of said groove, and a coating of a pliable silicone sealant of the type that is resistant to deterioration at temperatures exceeding 500*F, and which partially penetrates the outer surfaces of the rope to at least fill and seal the voids and interstices at the periphery of the rope to provide a sealing means which is impervious to the gases generated within the boiler and resistant to destruction by said high flue gas temperatures even where partial destruction of the sealant occurs at the flue gas side of the boiler section.

6. The combination of claim 5 in which the plates are made of ferrous material and the fibrous rope is made of asbestos material.